Materials

15 pages, 2580 KiB

Open AccessEditor’s ChoiceArticle

Dual-Particle Synergy in Bio-Based Linseed Oil Pickering Emulsions: Optimising ZnO–Silica Networks for Greener Mineral Sunscreens

by Marina Barquero, Luis A. Trujillo-Cayado and Jenifer Santos

Materials 2025, 18(13), 3030; https://doi.org/10.3390/ma18133030 - 26 Jun 2025

Viewed by 428

Abstract

The development of mineral, biodegradable sunscreens that can offer both high photoprotection and long-term colloidal stability, while limiting synthetic additives, presents a significant challenge. A linseed oil nanoemulsion co-stabilised by ZnO nanoparticles and the eco-friendly surfactant Appyclean 6552 was formulated, and the effect [...] Read more.

The development of mineral, biodegradable sunscreens that can offer both high photoprotection and long-term colloidal stability, while limiting synthetic additives, presents a significant challenge. A linseed oil nanoemulsion co-stabilised by ZnO nanoparticles and the eco-friendly surfactant Appyclean 6552 was formulated, and the effect of incorporating fumed silica/alumina (Aerosil COK 84) was evaluated. A central composite response surface design was used to ascertain the oil/ZnO ratio that maximised the in vitro sun protection factor at sub-300 nm droplet size. The incorporation of Aerosil at concentrations ranging from 0 to 2 wt.% resulted in a transformation of the dispersion from a nearly Newtonian state to a weak-gel behaviour. This alteration was accompanied by a reduction in the Turbiscan Stability Index. Microscopic analysis has revealed a hierarchical particle architecture, in which ZnO forms Pickering shells around each droplet, while Aerosil aggregates bridge neighboring interfaces, creating a percolated silica scaffold that immobilises droplets and amplifies multiple UV scattering. The findings demonstrate that coupling interfacial Pickering armour with a continuous silica network yields a greener, physically robust mineral sunscreen and offers a transferable strategy for stabilising plant-oil emulsions containing inorganic actives. Full article

(This article belongs to the Section Materials Chemistry)

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17 pages, 10861 KiB

Open AccessEditor’s ChoiceArticle

Corrosion Behaviors of Ni80A Alloy Valve in Marine Engine Within Ammonia-Rich Environment

by Ying-ying Liu, Guo-zheng Quan, Yan-ze Yu, Wen-jing Ran and Wei Xiong

Materials 2025, 18(13), 3006; https://doi.org/10.3390/ma18133006 - 25 Jun 2025

Viewed by 445

Abstract

Ammonia fuel is regarded as a promising zero-carbon alternative to diesel in next-generation marine engines. However, the high-temperature ammonia-rich environment poses significant corrosion challenges to hot-end components such as valves. This study investigates the corrosion behavior of Ni80A alloy marine valves under the [...] Read more.

Ammonia fuel is regarded as a promising zero-carbon alternative to diesel in next-generation marine engines. However, the high-temperature ammonia-rich environment poses significant corrosion challenges to hot-end components such as valves. This study investigates the corrosion behavior of Ni80A alloy marine valves under the coupled effects of a high temperature and ammonia atmosphere. Using computational fluid dynamics (CFD), the service temperature of the valve and the ammonia concentration distribution inside the engine cylinder were identified. High-temperature corrosion experiments were conducted with a custom-designed setup. Results show that corrosion kinetics accelerated markedly with temperature: the initial corrosion rate at 800 °C was four times that at 500 °C, and the maximum corrosion layer thickness reached 37 μm—double that at lower temperatures. Microstructural analysis revealed a transition from a dense, defect-free corrosion layer at 500 °C to a non-uniform layer with coarse CrN particles and aggregated nitrides at 800 °C. Notably, surface hardness increased at both temperatures, peaking at 590 HV at 500 °C, while matrix hardness at 800 °C declined due to γ′ phase coarsening and grain growth. This work provides detailed insight into the temperature-dependent ammonia corrosion mechanisms of marine Ni-based alloy valves, offering essential data for material design and durability assessment in ammonia-fueled marine engines. Full article

(This article belongs to the Special Issue Advances in Corrosion and Protection of Metallic Materials)

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17 pages, 4709 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Particle-Reinforced Resin Using Highly Functional ZnO Particle Filler Driven by Supramolecular Interactions

by Haruka Nakagawa and Kohei Iritani

Materials 2025, 18(13), 2986; https://doi.org/10.3390/ma18132986 - 24 Jun 2025

Viewed by 392

Abstract

The surface modification of zinc oxide nanoparticles (ZnONPs) with organic compounds has been shown to improve their dispersibility. In this study, to develop a highly functional material, ZnONP modified with 6-amino-1-hexanol bearing both amino and hydroxyl functional groups was synthesized. Scanning electron microscopy–energy [...] Read more.

The surface modification of zinc oxide nanoparticles (ZnONPs) with organic compounds has been shown to improve their dispersibility. In this study, to develop a highly functional material, ZnONP modified with 6-amino-1-hexanol bearing both amino and hydroxyl functional groups was synthesized. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirmed that functionalized ZnONP was successfully obtained by a hydrothermal synthetic method. The mechanical properties of composite films of polylactic acid (PLA) reinforced with the functionalized ZnONP were then evaluated. The composite containing functionalized ZnONP exhibited a higher maximum stress than that containing unmodified ZnONP. These ZnONP/polymer composites therefore show promise as novel high-performance materials. Full article

(This article belongs to the Special Issue Fabrication, Characteristics and Applications of Multifunctional Polymer Nanocomposites)

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22 pages, 3675 KiB

Open AccessEditor’s ChoiceArticle

Study and Evaluation of Equivalent Conductivities of [SiO(OH)₃]⁻ and [SiO₂(OH)₂]²⁻ in NaOH-Na₂SiO₃-H₂O Solutions at 277.85 K to 308.45 K

by Kai Yang, Guang Ye and Geert De Schutter

Materials 2025, 18(13), 2996; https://doi.org/10.3390/ma18132996 - 24 Jun 2025

Viewed by 354

Abstract

The equivalent conductivities of two aqueous silicate species,

{[SiO {(OH)}_{3}]}^{-}

and

{[Si O_{2} {(OH)}_{2}]}^{2 -}

, are fundamental to understanding many physico-chemical phenomena of silicate materials in electrolyte solutions. These phenomena include diffusion, adsorption, and phase transformations. But [...] Read more.

The equivalent conductivities of two aqueous silicate species,

{[SiO {(OH)}_{3}]}^{-}

and

{[Si O_{2} {(OH)}_{2}]}^{2 -}

, are fundamental to understanding many physico-chemical phenomena of silicate materials in electrolyte solutions. These phenomena include diffusion, adsorption, and phase transformations. But significant inconsistencies have been presented in published equivalent conductivities of the two silicate aqueous ions. Also, little work has so far been undertaken to discuss how aspects, such as temperature and solution composition, may influence electrolytic conductivity of silicate aqueous solutions. This work presents the equivalent conductivities of the two silicate species, measured with electrochemical impedance spectroscopy (EIS) from 277.85 K to 308.45 K. A conductivity model for mixed electrolytes of high alkaline was first established. This model was then verified with the electrolyte conductivities of

NaOH - H_{2} O

solutions and

NaOH - N a_{2} C O_{3} - H_{2} O

solutions. Next, the equivalent conductivities of

{[SiO {(OH)}_{3}]}^{-}

and

{[Si O_{2} {(OH)}_{2}]}^{2 -}

, were calculated by solving the overdetermined equation groups for different temperatures, based on electrolyte conductivities of

NaOH - N a_{2} Si O_{3} - H_{2} O

solutions. The accuracy of both calculations and measurements are examined in depth from various viewpoints. This work presents essential inputs for quantitatively understanding multiple physico-chemical properties of silicate materials in electrolyte solutions. Full article

(This article belongs to the Section Materials Chemistry)

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14 pages, 2266 KiB

Open AccessEditor’s ChoiceArticle

Solid-State Transformation (S_total = 0, 1, and 2) in a Ni²⁺ Chelate with Two tert-Butyl 5-(p-Biphenylyl)-2-pyridyl Nitroxides

by Masataka Mitsui and Takayuki Ishida

Materials 2025, 18(12), 2793; https://doi.org/10.3390/ma18122793 - 13 Jun 2025

Viewed by 506

Abstract

A novel S = 1/2 paramagnetic chelating ligand tert-butyl 5-(p-biphenylyl)-2-pyridyl nitroxide (bppyNO) and its S = 1 nickel(II) ion complex [Ni(bppyNO)₂Br₂] were synthesized. X-ray crystallography revealed a 2p–3d–2p heterospin triad, with half of the molecule being [...] Read more.

A novel S = 1/2 paramagnetic chelating ligand tert-butyl 5-(p-biphenylyl)-2-pyridyl nitroxide (bppyNO) and its S = 1 nickel(II) ion complex [Ni(bppyNO)₂Br₂] were synthesized. X-ray crystallography revealed a 2p–3d–2p heterospin triad, with half of the molecule being crystallographically independent. A relatively planar chelate geometry with the torsion angle ϕ(Ni-O-N-C_2py) = −10.6(5)° at 300 K becomes significantly out-of-plane distorted with ϕ = −46.9(8) and 26.1(11)° at 90 K accompanied by disorder at the oxygen site. The torsion angle changes, Δϕ = 36° and 37°, are among the largest reported for related compounds. Magnetic measurements indicate gradual and incomplete spin transition-like behavior around 143(2) K. A three-state model involving an intermediate-spin (S_total = 1) state is proposed to explain non-zero χ_mT plateau in a low-temperature region. Density functional theory calculations using the determined structures support the proposed mechanism. Furthermore, geometry optimizations assuming S_total = 0, 1, and 2 are in good agreement with the present model. Full article

(This article belongs to the Special Issue From Molecular to Supramolecular Materials)

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38 pages, 6561 KiB

Open AccessEditor’s ChoiceReview

Emerging Trends in Thermo-Optic and Electro-Optic Materials for Tunable Photonic Devices

by Muhammad A. Butt

Materials 2025, 18(12), 2782; https://doi.org/10.3390/ma18122782 - 13 Jun 2025

Cited by 1 | Viewed by 1608

Abstract

Tunable photonic devices are increasingly pivotal in modern optical systems, enabling the dynamic control over light propagation, modulation, and filtering. This review systematically explores two prominent classes of materials, thermo-optic and electro-optic, for their roles in such tunable devices. Thermo-optic materials utilize refractive [...] Read more.

Tunable photonic devices are increasingly pivotal in modern optical systems, enabling the dynamic control over light propagation, modulation, and filtering. This review systematically explores two prominent classes of materials, thermo-optic and electro-optic, for their roles in such tunable devices. Thermo-optic materials utilize refractive index changes induced by temperature variations, offering simple implementation and broad material compatibility, although often at the cost of slower response times. In contrast, electro-optic materials, particularly those exhibiting the Pockels and Kerr effects, enable rapid and precise refractive index modulation under electric fields, making them suitable for high-speed applications. The paper discusses the underlying physical mechanisms, material properties, and typical figures of merit for each category, alongside recent advancements in organic, polymeric, and inorganic systems. Furthermore, integrated photonic platforms and emerging hybrid material systems are highlighted for their potential to enhance performance and scalability. By evaluating the tradeoffs in speed, power consumption, and integration complexity, this review identifies key trends and future directions for deploying thermo-optic and electro-optic materials in the next generation tunable photonic devices. Full article

(This article belongs to the Section Optical and Photonic Materials)

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16 pages, 3519 KiB

Open AccessEditor’s ChoiceArticle

Flexible Moisture–Electric Generator Based on Vertically Graded GO–rGO/Ag Films

by Shujun Wang, Geng Li, Jiayue Wen, Jiayun Feng, He Zhang and Yanhong Tian

Materials 2025, 18(12), 2766; https://doi.org/10.3390/ma18122766 - 12 Jun 2025

Viewed by 772

Abstract

Moisture–electricity generators (MEGs) hold great promise for green energy conversion. However, existing devices focus on the need for complex gradient distribution treatments and the improvement in output voltage, overlooking the important role of the graphene oxide (GO) oxidation degree and the response time [...] Read more.

Moisture–electricity generators (MEGs) hold great promise for green energy conversion. However, existing devices focus on the need for complex gradient distribution treatments and the improvement in output voltage, overlooking the important role of the graphene oxide (GO) oxidation degree and the response time and recovery time in practical application. In this work, we develop printed MEGs by synthesizing reduced graphene oxide/silver nanoparticle (rGO/Ag) composites and controlling the GO oxidation degree. The rGO/Ag layer serves as a functional component that enhances cycling stability and shortens the recovery time. Additionally, compared to conventional rigid-structure devices, these flexible MEGs can be produced by inkjet printing and drop-casting techniques. A 1 cm² MEG can generate a voltage of up to 60 mV within 2.4 s. Notably, higher output voltages can be easily achieved by connecting multiple MEG units in series, with 10 units producing 200 mV even under low relative humidity (RH). This work presents a low-cost, highly flexible, lightweight, and scalable power generator, paving the way for broader applications of GO and further advancement of MEG technology in wearable electronics, respiratory monitoring, and Internet of Things applications. Full article

(This article belongs to the Section Materials Chemistry)

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16 pages, 18981 KiB

Open AccessEditor’s ChoiceArticle

Dual-Broadband Topological Photonic Crystal Edge State Based on Liquid Crystal Tunability

by Jinying Zhang, Bingnan Wang, Jiacheng Wang, Xinye Wang and Yexiaotong Zhang

Materials 2025, 18(12), 2778; https://doi.org/10.3390/ma18122778 - 12 Jun 2025

Viewed by 415

Abstract

The rapid advancements in optical communication and sensing technologies have significantly increased the demand for advanced tunable spectral systems. This study presents a dual-band terahertz transmission and manipulation approach by leveraging the topologically protected properties of valley-topological photonic crystal edge states. The designed [...] Read more.

The rapid advancements in optical communication and sensing technologies have significantly increased the demand for advanced tunable spectral systems. This study presents a dual-band terahertz transmission and manipulation approach by leveraging the topologically protected properties of valley-topological photonic crystal edge states. The designed structure facilitates the excitation of the K valley within the range of 0.851–0.934 THz and the K′ valley from 1.604 to 1.686 THz, while also demonstrating anomalous refraction and birefringence. The calculated emission angles, derived through momentum matching, enable transitions between single-wave and dual-wave emissions and allow for precise angle control. The introduction of the liquid crystal material NJU-LDn-4 enables continuous tuning of the dual-band spectral range under a varying electric field, broadening the operating frequency bands to the ranges of 0.757–0.996 THz and 1.426–1.798 THz, respectively. These findings suggest promising applications in tunable filter design, optical communication, photonic computing, optical sensing, and high-resolution imaging, particularly in novel optical devices requiring precise control over spectral characteristics and light propagation. Full article

(This article belongs to the Special Issue Terahertz Materials and Technologies in Materials Science)

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18 pages, 7993 KiB

Open AccessEditor’s ChoiceArticle

The Influence of Cr₂N Addition and Ni/Mn Ratio Variation on Mechanical and Corrosion Properties of HIP-Sintered 316L Stainless Steel

by Minsu Lee, Hohyeong Kim, Seok-Won Son and Jinho Ahn

Materials 2025, 18(12), 2722; https://doi.org/10.3390/ma18122722 - 10 Jun 2025

Viewed by 503

Abstract

316L stainless steel is widely employed in various industrial sectors, including shipbuilding, offshore plants, high-temperature/high-pressure (HTHP) piping systems, and hydrogen infrastructure, due to its excellent mechanical stability, superior corrosion resistance, and robust resistance to hydrogen embrittlement. This study presents 316L stainless steel alloys [...] Read more.

316L stainless steel is widely employed in various industrial sectors, including shipbuilding, offshore plants, high-temperature/high-pressure (HTHP) piping systems, and hydrogen infrastructure, due to its excellent mechanical stability, superior corrosion resistance, and robust resistance to hydrogen embrittlement. This study presents 316L stainless steel alloys fabricated via hot isostatic pressing (HIP), conducted at 1300 °C and 100 MPa for 2 h, incorporating Cr₂N powder and an optimized Ni/Mn ratio based on the nickel equivalent (Ni_eq). During HIP, Cr₂N decomposition yielded a uniformly refined, dense austenitic microstructure, with enhanced corrosion resistance and mechanical performance. Corrosion resistance was evaluated by potentiodynamic polarization in 3.5 wt.% NaCl after 1 h of OCP stabilization, using a scan range of −0.25 V to +1.5 V (Ag/AgCl) at 1 mV/s. Optimization of the Ni/Mn ratio effectively improved the pitting corrosion resistance and mechanical strength. It is cost-effective to partially substitute Ni with Mn. Of the various alloys, C13Ni-N exhibited significantly enhanced hardness (~30% increase from 158.3 to 206.2 HV) attributable to nitrogen-induced solid solution strengthening. E11Ni-HM exhibited the highest pitting corrosion resistance given the superior PREN value (31.36). In summary, the incorporation of Cr₂N and adjustment of the Ni/Mn ratio effectively improved the performance of 316L stainless steel alloys. Notably, alloy E11Ni-HM demonstrated a low corrosion current density of 0.131 μA/cm², indicating superior corrosion resistance. These findings offer valuable insights for developing cost-efficient, mechanically robust corrosion-resistant materials for hydrogen-related applications. Further research will evaluate alloy resistance to hydrogen embrittlement and investigate long-term material stability. Full article

(This article belongs to the Special Issue Innovative Approaches to Enhancing Corrosion Resistance in Stainless Steel and Other Corrosion-Resistant Alloys)

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40 pages, 4806 KiB

Open AccessEditor’s ChoiceReview

On the Origin of Thermally Enhanced Upconversion Luminescence in Lanthanide-Doped Nanosized Fluoride Phosphors

by Shirun Yan

Materials 2025, 18(12), 2700; https://doi.org/10.3390/ma18122700 - 8 Jun 2025

Viewed by 718

Abstract

Thermally enhanced upconversion luminescence (UCL), also known as negative thermal quenching of UCL, denotes a continuous increase in the UCL emission intensity of a particular phosphor with a rising temperature. In recent years, the thermal enhancement of UCL has attracted extensive research attention, [...] Read more.

Thermally enhanced upconversion luminescence (UCL), also known as negative thermal quenching of UCL, denotes a continuous increase in the UCL emission intensity of a particular phosphor with a rising temperature. In recent years, the thermal enhancement of UCL has attracted extensive research attention, with numerous reports detailing this effect in phosphors characterized by varying particle sizes, architectures, and compositions. Several hypotheses have been formulated to explain the underlying mechanisms driving this thermal enhancement. This paper rigorously examines thermally enhanced UCL in fluoride nanoparticles by addressing two key questions: (1) Is the thermal enhancement of UCL an intrinsic feature of these nanoparticles? (2) Can the proposed mechanisms explaining this enhancement be unequivocally supported by the existing literature? Upon analyzing a compilation of experimental observations alongside the concurrent phenomena occurred during spectral measurements, it is postulated that thermally enhanced UCL intensity is likely a consequence of multiple extrinsic factors operating simultaneously at elevated temperatures, rather than being an intrinsic property of nanoparticles. These factors include moisture desorption, laser-induced local heating, and lattice thermal expansion. The size-dependent properties of nanoparticles, such as surface-to-volume ratio, thermal expansion coefficient, and quantum yield, are the fundamental reasons for the size-dependent thermal enhancement factor of UCL. Temperature-dependent emission spectral intensity is not a dependable indicator for assessing the thermal quenching properties of phosphors. This is because it is influenced not only by the phosphor’s quantum yield, but also by various extrinsic factors at high temperatures. The nonlinear nature of UCL further magnifies the impact of these extrinsic factors. Full article

(This article belongs to the Special Issue Advances in Optical and Photonic Materials)

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24 pages, 7912 KiB

Open AccessEditor’s ChoiceArticle

Corrosion Performance and Post-Corrosion Evolution of Tensile Behaviors in Rebar Reinforced Ultra-High Performance Concrete

by Yuchen Zhang, Sumei Zhang, Xianzhi Luo and Chaofan Wang

Materials 2025, 18(11), 2661; https://doi.org/10.3390/ma18112661 - 5 Jun 2025

Viewed by 463

Abstract

The application of rebar reinforced ultra-high-performance concrete (R-UHPC) has been increasingly adopted in engineering structures due to its exceptional mechanical performance and durability characteristics. Nevertheless, when subjected to combined saline and stray current conditions, R-UHPC remains vulnerable to severe corrosion degradation. This investigation [...] Read more.

The application of rebar reinforced ultra-high-performance concrete (R-UHPC) has been increasingly adopted in engineering structures due to its exceptional mechanical performance and durability characteristics. Nevertheless, when subjected to combined saline and stray current conditions, R-UHPC remains vulnerable to severe corrosion degradation. This investigation examined the corrosion performance and tensile behavior evolution of R-UHPC containing 2.0 vol% copper-coated steel fiber content and HRB400 steel rebar with a reinforcement ratio of 3.1%. The accelerated corrosion process was induced through an impressed current method, followed by direct tensile tests at varying exposure periods. The findings revealed that the embedding of rebar in UHPC led to the formation of fiber-to-rebar (F-R) conductive pathways, generating radial cracks besides laminar cracks. The bonding between rebar and UHPC degraded as corrosion progressed, leading to the loss of characteristic multiple-cracking behavior of R-UHPC in tension. Meanwhile, R-UHPC load-bearing capacity, transitioning from gradual to accelerated deterioration phases with prolonged corrosion, aligns with steel fibers temporally. During the initial 4 days of corrosion, the specimens displayed surface-level corrosion features with negligible steel fiber loss, showing less than 4.0% reduction in ultimate bearing capacity. At 8 days of corrosion, the steel fiber decreased by 22.6%, accompanied by an 18.3% reduction in bearing capacity. By 16 days of corrosion, the steel fiber loss reached 41.5%, with a corresponding bearing capacity reduction of 29.1%. During the corrosion process, corrosion cracks and load-bearing degradation in R-UHPC could be indicated by the ultrasonic damage factor. Full article

(This article belongs to the Special Issue Corrosion of Materials: Evaluation, Testing, Protection, and Failure Analysis, Second Edition)

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24 pages, 5160 KiB

Open AccessEditor’s ChoiceReview

Chiral Perovskite Single Crystals: Toward Promising Design and Application

by Lin Wang, Jie Ren and Hanying Li

Materials 2025, 18(11), 2635; https://doi.org/10.3390/ma18112635 - 4 Jun 2025

Viewed by 859

Abstract

Organic–inorganic hybrid halide perovskites have emerged as promising optoelectronic materials owing to their exceptional optoelectronic properties and versatile crystal structures. The introduction of chiral organic ligands into perovskite frameworks, breaking the inversion symmetry of the structure, has attracted significant attention toward chiral perovskites. [...] Read more.

Organic–inorganic hybrid halide perovskites have emerged as promising optoelectronic materials owing to their exceptional optoelectronic properties and versatile crystal structures. The introduction of chiral organic ligands into perovskite frameworks, breaking the inversion symmetry of the structure, has attracted significant attention toward chiral perovskites. Herein, the recent advances in various synthesis strategies for chiral perovskite single crystals (SCs) are systematically demonstrated. Then, we elucidate an in-depth understanding of the chirality transfer mechanisms from chiral organic ligands to perovskite inorganic frameworks. Furthermore, representative examples of chiral perovskite SC-based applications are comprehensively discussed, including circularly polarized light (CPL) photodetection, nonlinear optical (NLO) responses, and other emerging chirality-dependent applications. In the end, an outlook for future challenges and research opportunities is provided, highlighting the transformative potential of chiral perovskites in next-generation optoelectronic devices. Full article

(This article belongs to the Special Issue Halide Perovskite Crystal Materials and Optoelectronic Devices)

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28 pages, 3203 KiB

Open AccessEditor’s ChoiceArticle

From Pollutant Removal to Renewable Energy: MoS₂-Enhanced P25-Graphene Photocatalysts for Malathion Degradation and H₂ Evolution

by Cristian Martínez-Perales, Abniel Machín, Pedro J. Berríos-Rolón, Paola Sampayo, Enrique Nieves, Loraine Soto-Vázquez, Edgard Resto, Carmen Morant, José Ducongé, María C. Cotto and Francisco Márquez

Materials 2025, 18(11), 2602; https://doi.org/10.3390/ma18112602 - 3 Jun 2025

Viewed by 1264

Abstract

The widespread presence of pesticides—especially malathion—in aquatic environments presents a major obstacle to conventional remediation strategies, while the ongoing global energy crisis underscores the urgency of developing renewable energy sources such as hydrogen. In this context, photocatalytic water splitting emerges as a promising [...] Read more.

The widespread presence of pesticides—especially malathion—in aquatic environments presents a major obstacle to conventional remediation strategies, while the ongoing global energy crisis underscores the urgency of developing renewable energy sources such as hydrogen. In this context, photocatalytic water splitting emerges as a promising approach, though its practical application remains limited by poor charge carrier dynamics and insufficient visible-light utilization. Herein, we report the design and evaluation of a series of TiO₂-based ternary nanocomposites comprising commercial P25 TiO₂, reduced graphene oxide (rGO), and molybdenum disulfide (MoS₂), with MoS₂ loadings ranging from 1% to 10% by weight. The photocatalysts were fabricated via a two-step method: hydrothermal integration of rGO into P25 followed by solution-phase self-assembly of exfoliated MoS₂ nanosheets. The composites were systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) spectroscopy. Photocatalytic activity was assessed through two key applications: the degradation of malathion (20 mg/L) under simulated solar irradiation and hydrogen evolution from water in the presence of sacrificial agents. Quantification was performed using UV-Vis spectroscopy, gas chromatography–mass spectrometry (GC-MS), and thermal conductivity detection (GC-TCD). Results showed that the integration of rGO significantly enhanced surface area and charge mobility, while MoS₂ served as an effective co-catalyst, promoting interfacial charge separation and acting as an active site for hydrogen evolution. Nearly complete malathion degradation (~100%) was achieved within two hours, and hydrogen production reached up to 6000 µmol g⁻¹ h⁻¹ under optimal MoS₂ loading. Notably, photocatalytic performance declined with higher MoS₂ content due to recombination effects. Overall, this work demonstrates the synergistic enhancement provided by rGO and MoS₂ in a stable P25-based system and underscores the viability of such ternary nanocomposites for addressing both environmental remediation and sustainable energy conversion challenges. Full article

(This article belongs to the Special Issue Catalysis: Where We Are and Where We Go)

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15 pages, 4214 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of Porous Polymers by Nucleophilic Substitution Reaction of Polyamines and Monochlorotriazinyl-β-Cyclodextrin and Application to Dye Adsorption

by Naofumi Naga, Risa Hiura and Tamaki Nakano

Materials 2025, 18(11), 2588; https://doi.org/10.3390/ma18112588 - 1 Jun 2025

Viewed by 561

Abstract

Network polymers with β-cyclodextrin moieties were prepared by nucleophilic substitution reactions between polyamines, linear polyethyleneimine (LPEI), polyallylamine (PAA), (ε-poly-L-lysine) (EPL), and monochlorotriazinyl-β-cyclodextrin (MCTCD) in methanol/water mixed solvent or water. The reactions under conditions of high material concentration (30 wt%) and a feed ratio [...] Read more.

Network polymers with β-cyclodextrin moieties were prepared by nucleophilic substitution reactions between polyamines, linear polyethyleneimine (LPEI), polyallylamine (PAA), (ε-poly-L-lysine) (EPL), and monochlorotriazinyl-β-cyclodextrin (MCTCD) in methanol/water mixed solvent or water. The reactions under conditions of high material concentration (30 wt%) and a feed ratio of [MCT]/[NH] = 0.5 (mol/mol) successfully yield porous polymers via reaction-induced phase separation. The molecular structure of the polyamines and reaction conditions strongly affected the morphology of the resulting porous polymers. The porous polymers were composed of connected particles, gathered (slightly connected) particles, and/or disordered bulky structures, with sizes of 10⁻⁹ m–10⁻⁸ m. An increase in the molecular weight of LPEI and PAA and the feed molar ratio of [MCT]/[NH] tended to decrease the particle size. Young’s moduli of the LPEI-MCTCD and PAA-MCTCD porous polymers increased with an increase in bulk density, which was derived from small particle sizes. The wide particle size distribution and disordered structure caused collapse by the compression under 50 N of pressure. An LPEI-MCTCD adsorbed methyl orange, methylene blue, and phenolphthalein through ionic interactions, π–π interaction, and/or β-cyclodextrin inclusion. Full article

(This article belongs to the Special Issue An Overview of Highly Porous Adsorbent Materials: Synthesis, Properties and Applications)

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32 pages, 7994 KiB

Open AccessEditor’s ChoiceReview

Recent Advancements in Smart Hydrogel-Based Materials in Cartilage Tissue Engineering

by Jakob Naranđa, Matej Bračič, Uroš Maver and Teodor Trojner

Materials 2025, 18(11), 2576; https://doi.org/10.3390/ma18112576 - 31 May 2025

Viewed by 2393

Abstract

Cartilage tissue engineering (CTE) is an advancing field focused on developing biomimetic scaffolds to overcome cartilage’s inherently limited self-repair capacity. Smart hydrogels (SHs) have gained prominence among the various scaffold materials due to their ability to modulate cellular behavior through tunable mechanical and [...] Read more.

Cartilage tissue engineering (CTE) is an advancing field focused on developing biomimetic scaffolds to overcome cartilage’s inherently limited self-repair capacity. Smart hydrogels (SHs) have gained prominence among the various scaffold materials due to their ability to modulate cellular behavior through tunable mechanical and biochemical properties. These hydrogels respond dynamically to external stimuli, offering precise control over biological processes and facilitating targeted tissue regeneration. Recent advances in fabrication technologies have enabled the design of SHs with sophisticated architecture, improved mechanical strength, and enhanced biointegration. Key features such as injectability, controlled biodegradability, and stimulus-dependent release of biomolecules make them particularly suitable for regenerative applications. The incorporation of nanoparticles further improves mechanical performance and delivery capability. In addition, shape memory and self-healing properties contribute to the scaffolds’ resilience and adaptability in dynamic physiological environments. An emerging innovation in this area is integrating artificial intelligence (AI) and omics-based approaches that enable high-resolution profiling of cellular responses to engineered hydrogels. These data-driven tools support the rational design and optimization of hydrogel systems and allow the development of more effective and personalized scaffolds. The convergence of smart hydrogel technologies with omics insights represents a transformative step in regenerative medicine and offers promising strategies for restoring cartilage function. Full article

(This article belongs to the Section Biomaterials)

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10 pages, 5002 KiB

Open AccessEditor’s ChoiceCommunication

Computational Investigation of an All-sp³ Hybridized Superstable Carbon Allotrope with Large Band Gap

by Xiaoshi Ju, Kun Bu, Chunxiao Zhang and Yuping Sun

Materials 2025, 18(11), 2533; https://doi.org/10.3390/ma18112533 - 28 May 2025

Viewed by 471

Abstract

Carbon is one of nature’s basic elements, hosting a tremendous number of allotropes benefiting from its capacity to generate

s p

,

s p^{2}

, and

s p^{3}

hybridized carbon–carbon bonds. The exploration of novel carbon architectures has remained a pivotal [...] Read more.

Carbon is one of nature’s basic elements, hosting a tremendous number of allotropes benefiting from its capacity to generate

s p

,

s p^{2}

, and

s p^{3}

hybridized carbon–carbon bonds. The exploration of novel carbon architectures has remained a pivotal focus in the fields of condensed matter physics and materials science for an extended period. In this paper, we, by using first-principles calculation, carry on a detailed investigation an an all-

s p^{3}

hybridized carbon structure in a 20-atom tetragonal unit cell with

P 4_{3} 2_{1} 2

symmetry (

D_{4}^{8}

, space group No. 96), and call it T20 carbon. The equilibrium energy of T20 carbon is −8.881 eV/atom, only 0.137 eV/atom higher than that of diamond, indicating that T20 is a superstable carbon structure. T20 is also a superhard carbon structure with a large Vicker’s hardness about 83.5 GPa. The dynamical stability of T20 was verified by means of phonon band spectrum calculations. Meanwhile, its thermal stability up to 1000 K was verified via ab initio molecular dynamics simulations. T20 is an indirect band-gap insulator with approximately 5.80 eV of a band gap. This value is obviously greater than the value in the diamond (5.36 eV). Moreover, the simulated X-ray diffraction pattern of T20 displays a remarkable match with the experimental data found in the milled fullerene soot, evidencing that T20 may be a potential modification discovered in this experimental work. Our work has given a systematical understanding on an all-

s p^{3}

hybridized superstable and superhard carbon allotrope with large band gap and provided a very competitive explanation for previous experimental data, which will also provide guidance for upcoming studies in theory and experiment. Full article

(This article belongs to the Section Materials Chemistry)

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16 pages, 9841 KiB

Open AccessEditor’s ChoiceArticle

Photochromic Sensors for Paper Marking

by Elżbieta Sąsiadek-Andrzejczak, Malwina Jaszczak-Kuligowska, Mariusz Dudek, Adam K. Puszkarz and Marek Kozicki

Materials 2025, 18(11), 2501; https://doi.org/10.3390/ma18112501 - 26 May 2025

Viewed by 435

Abstract

This study presents UV radiation sensors for use as paper marking. The sensors turn pink under exposure to UVA radiation and the color change is reversible. Additionally, a UV radiation retarder was applied to the sensor to delay the reaction and weaken the [...] Read more.

This study presents UV radiation sensors for use as paper marking. The sensors turn pink under exposure to UVA radiation and the color change is reversible. Additionally, a UV radiation retarder was applied to the sensor to delay the reaction and weaken the change in sensor color. The color changes of the sensors were analyzed depending on the absorbed dose of UVA radiation using reflectance spectrophotometry. Furthermore, the chemical analysis and surface morphology of the samples were performed using Raman Spectroscopy and Scanning Electron Microscopy, respectively. In addition, the structure of the sensors on the paper surface was assessed using X-ray Micro-Computed Tomography. Finally, possible potential applications for these types of sensors were presented, including marking, securing, and protecting against the counterfeiting of documents, paper packaging, and other paper products, and creating decorative elements, as well as measuring the 2D/3D dose distribution of UV radiation on paper products. Full article

(This article belongs to the Special Issue Synthesis and Characterization of Materials for Sensors)

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16 pages, 11068 KiB

Open AccessEditor’s ChoiceArticle

Effect of Interlayers on Microstructure and Corrosion Resistance of 304/45 Stainless Steel Cladding Plate

by Yongtong Chen and Yi Ding

Materials 2025, 18(11), 2473; https://doi.org/10.3390/ma18112473 - 24 May 2025

Viewed by 580

Abstract

During the high-temperature preparation of stainless steel cladding plate, carbon atoms from carbon steel diffused into stainless steel. When temperatures were within 450–850 °C, carbides precipitated at grain boundaries, which initiated intergranular sensitization and thereby reduced the corrosion resistance of stainless steel. This [...] Read more.

During the high-temperature preparation of stainless steel cladding plate, carbon atoms from carbon steel diffused into stainless steel. When temperatures were within 450–850 °C, carbides precipitated at grain boundaries, which initiated intergranular sensitization and thereby reduced the corrosion resistance of stainless steel. This study designed NiP and NiCuP interlayer alloys to effectively block carbon diffusion in stainless steel cladding plates. The effect of adding interlayers on the microstructure of stainless steel cladding plate was studied by using optical microscopy and scanning electron microscopy. Electrochemical tests were subsequently conducted to evaluate the impact of interlayer incorporation on the corrosion resistance of stainless steel cladding. The results demonstrated that 304/45 specimens exhibited severe carbon diffusion, resulting in the poorest corrosion resistance. The addition of interlayers improved the corrosion resistance of stainless steel cladding to varying degrees. Among these, the 304/NiCuP/45 specimen showed the best performance. It had an intergranular corrosion susceptibility of only 0.25% and pitting potential as high as 0.336 V, which indicated its superior corrosion resistance. The passive film of stainless steel cladding exhibited n-type semiconductor characteristics. And 304/NiCuP/45 specimen demonstrated the lowest carrier density of 3.02 × 10¹⁸ cm⁻³, which indicated the formation of the densest passive film. Full article

(This article belongs to the Special Issue Recent Advances in Stainless Steel: Characterization, Properties and Applications)

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15 pages, 3774 KiB

Open AccessEditor’s ChoiceArticle

A View on the Synthesis and Characterization of Porous Microspheres Containing Pyrrolidone Units

by Małgorzata Maciejewska

Materials 2025, 18(11), 2432; https://doi.org/10.3390/ma18112432 - 22 May 2025

Viewed by 427

Abstract

Porous materials are used in many important applications, such as separation technologies, catalysis, and chromatography. They may be obtained from various monomers via diverse polymerization techniques and a wide range of synthesis parameters. The study is devoted to the synthesis and characterization of [...] Read more.

Porous materials are used in many important applications, such as separation technologies, catalysis, and chromatography. They may be obtained from various monomers via diverse polymerization techniques and a wide range of synthesis parameters. The study is devoted to the synthesis and characterization of crosslinked porous polymeric spheres containing pyrrolidone subunits. To achieve this goal, two methods were applied: direct synthesis from N-vinyl-2-pyrrolidone (NVP) with ethylene glycol dimethacrylate (EGDMA) and via a modification reaction of porous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) with pyrrolidone (P). The polymerization was carried out with the use of different molar ratios of the monomers. In order to obtain highly porous materials, pore-forming diluents (toluene, dodecane, and dodecan-1-ol) were used. The synthesized copolymers were characterized using size distribution analysis, ATR-FTIR spectroscopy, scanning electron microscopy, thermogravimetry, and inverse gas chromatography. Determined by the nitrogen adsorption/desorption method, the specific surface area was in the range of 55–468 m²/g. The good thermal properties of the poly(VP-co-EGDMA) copolymers allowed them to be applied as the stationary phase in gas chromatography. Full article

(This article belongs to the Special Issue Porous Materials and Advanced Manufacturing Technologies (2nd Edition))

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22 pages, 2217 KiB

Open AccessEditor’s ChoiceReview

Biodegradability of Bioplastics in Managed and Unmanaged Environments: A Comprehensive Review

by Giovanni Gadaleta, Johana Carolina Andrade-Chapal, Sara López-Ibáñez, María Mozo-Toledo and Ángela Navarro-Calderón

Materials 2025, 18(10), 2382; https://doi.org/10.3390/ma18102382 - 20 May 2025

Cited by 1 | Viewed by 989

Abstract

The production and utilization of conventional plastics have raised concerns regarding plastic waste management and environmental safety. In response, the emergence of biodegradable bioplastics presents a possible solution for sustainability. On the other hand, the efficacy of biodegradation is strictly dependent on both [...] Read more.

The production and utilization of conventional plastics have raised concerns regarding plastic waste management and environmental safety. In response, the emergence of biodegradable bioplastics presents a possible solution for sustainability. On the other hand, the efficacy of biodegradation is strictly dependent on both the bioplastic type and the conditions in which the biodegradation occurs. This review offers a comprehensive overview of the biodegradation behavior of several bioplastics under a managed (industrialized or controlled) environment, such as industrial composting and anaerobic digestion (at either mesophilic or thermophilic temperature), as well as under less studied unmanaged (natural or open) environments, including soil, seawater, and freshwater. Although the biodegradation trend of some bioplastics is well known, further investigation should be pursued for others in order to clearly have the knowledge and the ability to choose the most viable bioplastic for a specific application and future end-of-life. Full article

(This article belongs to the Special Issue Recycling and Degradation of Polymeric Materials: Exploring Different Perspectives in Plastic Waste Management)

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12 pages, 2805 KiB

Open AccessEditor’s ChoiceArticle

Laser-Directed Energy-Deposited Ti-6Al-4V: The Anisotropy of Its Microstructure, Mechanical Properties, and Fracture Behavior

by Huan Wang, Chen-Wei Liu, Tianyu Wu and Hua-Xin Peng

Materials 2025, 18(10), 2360; https://doi.org/10.3390/ma18102360 - 19 May 2025

Cited by 2 | Viewed by 647

Abstract

Ti-6Al-4V (Ti64) is widely used in the additive manufacturing (AM) industry for its superior mechanical properties; however, severe anisotropy is inevitable. In this work, a Ti64 sample fabricated using laser-directed energy deposition is used for fundamental investigations into the anisotropy of its microstructure, [...] Read more.

Ti-6Al-4V (Ti64) is widely used in the additive manufacturing (AM) industry for its superior mechanical properties; however, severe anisotropy is inevitable. In this work, a Ti64 sample fabricated using laser-directed energy deposition is used for fundamental investigations into the anisotropy of its microstructure, mechanical properties, and fracture behaviors. The microstructure of martensite α and prior β-Ti grains are characterized in both the XOY and XOZ planes. The tensile/compressive properties and microhardness along the building direction (BD) and scanning direction (SD) are tested, and it is found that the sample along the SD has better comprehensive mechanical properties. Due to grain boundary α (GB-α), different fracture behaviors and crack propagation paths are found along the BD and SD. When tensile force is parallel to the growth orientation of GB-α, a much higher density of microcracks caused by fractured GB-α is found to contribute to a prolonged elongation and the weakening of strength. While stretching along the SD, the cracks would propagate along the GB-α easily and straightly, which might lead to lower elongation. Full article

(This article belongs to the Section Metals and Alloys)

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16 pages, 8824 KiB

Open AccessEditor’s ChoiceArticle

Role of Surface Morphology Evolution in the Tribological Behavior of Superalloy Under High-Temperature Fretting

by Xuan He, Zidan Wang, Ying Yan, Kailun Zheng and Qian Bai

Materials 2025, 18(10), 2350; https://doi.org/10.3390/ma18102350 - 18 May 2025

Viewed by 550

Abstract

High-temperature fretting wear typically occurs on mechanical contact surfaces in high-temperature environments, with displacement amplitudes generally in the micrometer range (≤300 μm), such as the turbine disks and blades in aerospace engines, and the piston rings in automotive engines. The study performed tangential [...] Read more.

High-temperature fretting wear typically occurs on mechanical contact surfaces in high-temperature environments, with displacement amplitudes generally in the micrometer range (≤300 μm), such as the turbine disks and blades in aerospace engines, and the piston rings in automotive engines. The study performed tangential fretting wear tests between superalloy specimens and Si₃N₄ balls under 700 °C to investigate the influence of ground and milled surface morphologies on the high-temperature fretting wear behavior. The experimental results show distinct wear mechanisms for the two surface types: ground specimens exhibit adhesive and oxidative wear, while milled specimens experience fatigue and abrasive wear. Both wear modes intensify with increasing load and fretting frequency. A comprehensive surface morphology characterization method, combining fractal dimension (FD) and surface roughness, is proposed. The study reveals that the roughness parameters Sa and Ra are strongly correlated with the Coefficient of Friction, while FD is strongly correlated with the wear volume. This study provides a novel approach to characterizing the evolution of surface morphology during high-temperature fretting wear. Full article

(This article belongs to the Section Metals and Alloys)

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26 pages, 12237 KiB

Open AccessEditor’s ChoiceArticle

Optimizing the Manufacturing Process Control of Si-Based Soft Magnetic Composites

by Seongsu Kang and Seonbong Lee

Materials 2025, 18(10), 2321; https://doi.org/10.3390/ma18102321 - 16 May 2025

Viewed by 569

Abstract

This study attempts to enhance the formability and electromagnetic properties of Fe-Si-based soft magnetic composites via process parameter optimization. Two silicon compositions (5.0 and 6.5 wt.%) were examined to determine their influence on density, internal stress, microstructure stability, and magnetic properties using a [...] Read more.

This study attempts to enhance the formability and electromagnetic properties of Fe-Si-based soft magnetic composites via process parameter optimization. Two silicon compositions (5.0 and 6.5 wt.%) were examined to determine their influence on density, internal stress, microstructure stability, and magnetic properties using a factorial design comprising 96 different condition combinations. A Pearson correlation analysis revealed a negative relationship between Si content and formability, while magnetic permeability increased with higher Si content. The 5.0 wt.% Si samples exhibited superior density (7.42 g/cm³ vs. 7.28 g/cm³), uniform microstructure, and coating stability. Conversely, the 6.5 wt.% Si samples achieved better permeability (126 at 10 kHz) than 5.0 wt.% Si samples but exhibited higher internal stress, uneven compaction, and thicker insulation layers (~400 nm vs. <10 nm). Scanning electron microscopy and transmission electron microscopy analyses identified necking and damage to the insulation layer. X-ray diffraction verified the stability of the Fe_1.6Si_0.4 phase after the forming and annealing processes. Secondary molding temperature exhibited the most significant impact on densification, and annealing generally degraded the quality factor (Q-factor). The highest Q-factor value (7.18 at 10 kHz), indicating lower core loss, was observed in the 5.0 wt.% Si samples without annealing. Full article

(This article belongs to the Section Materials Simulation and Design)

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25 pages, 33768 KiB

Open AccessEditor’s ChoiceArticle

Influence of Rust Layer on Corrosion-Critical Humidity in Outdoor Environments Based on Corrosion Sensors

by Qing Li, Xinyu Wang, Zibo Pei, Kui Xiao, Xiaojia Yang and Xuequn Cheng

Materials 2025, 18(10), 2299; https://doi.org/10.3390/ma18102299 - 15 May 2025

Viewed by 619

Abstract

In this study, the Fe/Cu-based two-electrode corrosion monitoring technique was employed to monitor the long-term atmospheric corrosion of carbon steel at five different outdoor sites within the China National Environmental Corrosion Platform. Based on the fitted monitoring data, the variation trend of corrosion-critical [...] Read more.

In this study, the Fe/Cu-based two-electrode corrosion monitoring technique was employed to monitor the long-term atmospheric corrosion of carbon steel at five different outdoor sites within the China National Environmental Corrosion Platform. Based on the fitted monitoring data, the variation trend of corrosion-critical humidity as a function of exposure time at different monitoring locations was obtained. The cross-sectional rust layer of corrosion coupons from different experimental periods at each location was characterized using scanning electron microscopy and Raman spectroscopy to identify variations in the thickness and phase composition of the carbon steel rust layer. The influence of rust layer thickness and phase structure on the critical humidity of carbon steel in atmospheric environments was investigated. Finally, the corrosion resistance of weathering steel in Tianjin, China, was validated using corrosion monitoring techniques, and the corrosion mechanism of weathering steel was elucidated by analyzing the influence of the acquired rust layer phase structure on the critical humidity of carbon steel in atmospheric environments. Full article

(This article belongs to the Section Corrosion)

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22 pages, 15244 KiB

Open AccessEditor’s ChoiceArticle

Corrosion Behavior of Shot Peened Ti6Al4V Alloy Fabricated by Conventional and Additive Manufacturing

by Mariusz Walczak, Wojciech Okuniewski, Wojciech J. Nowak, Dariusz Chocyk and Kamil Pasierbiewicz

Materials 2025, 18(10), 2274; https://doi.org/10.3390/ma18102274 - 14 May 2025

Viewed by 649

Abstract

Ti6Al4V titanium alloy is one of the most studied for its properties after additive manufacturing. Due to its widely use in medical applications, its properties are investigated in various aspects of surface layer property improvement and later compared to conventionally manufactured Ti-6Al-4V. In [...] Read more.

Ti6Al4V titanium alloy is one of the most studied for its properties after additive manufacturing. Due to its widely use in medical applications, its properties are investigated in various aspects of surface layer property improvement and later compared to conventionally manufactured Ti-6Al-4V. In this study, the corrosion behavior in a 0.9% NaCl solution of shot peened Ti-6Al-4V prepared using direct metal laser sintering (DMLS) was examined using corrosion electrochemical testing and compared with conventionally forged titanium alloy. Shot peening was performed on previously polished samples and subsequently treated with the CrNi steel shots. Two sets of peening pressure were selected: 0.3 and 0.4 MPa. X-ray diffraction analysis (XRD), X-ray micro-computed tomography (Micro-CT), scanning electron microscope (SEM) tests with roughness and hardness measurements were used to characterize the samples. The conventional samples were characterized by an α + β structure, while the additive samples had an α’ + β martensitic structure. The obtained results indicate that the corrosion resistance of the conventionally forged Ti-6Al-4V alloy was higher than DMLSed Ti-6Al-4V alloy. The lowest corrosion rates were noted for untreated surfaces of CM/ref and DMLS/ref samples and reached 0.041 and 0.070 µA/cm², respectively. Moreover, the development of the surface has an influence on corrosion behavior. Therefore, increasing pressure results in inferior corrosion resistance. However, better performance for shot peened samples was reported in the low frequency range. This is due to the refinement of the grain acquired after the peening process. All the results obtained, related to the corrosion behavior, were satisfactory enough that the all samples can be characterized as materials suitable for implant applications. Full article

(This article belongs to the Special Issue Study on Electrochemical Behavior and Corrosion of Materials)

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16 pages, 2251 KiB

Open AccessEditor’s ChoiceArticle

Thermo-Oxidative Aging Effects on Hyperelastic Behavior of EPDM Rubber: A Constitutive Modeling Approach

by Zhaonan Xie, Xicheng Huang, Kai Zhang, Shunping Yan, Junhong Chen, Ren He, Jiaxing Li and Weizhou Zhong

Materials 2025, 18(10), 2236; https://doi.org/10.3390/ma18102236 - 12 May 2025

Cited by 1 | Viewed by 621

Abstract

The effect of thermo-oxidative aging on the hyperelastic behavior of ethylene propylene diene monomer (EPDM) rubber was investigated by a combined experimental and theoretical modeling approach. Firstly, the uniaxial tensile test of aged and unaged EPDM rubber was carried out. The test results [...] Read more.

The effect of thermo-oxidative aging on the hyperelastic behavior of ethylene propylene diene monomer (EPDM) rubber was investigated by a combined experimental and theoretical modeling approach. Firstly, the uniaxial tensile test of aged and unaged EPDM rubber was carried out. The test results show that the unaged EPDM rubber had the nonlinear large deformation characteristic of a “S” shape. The stiffness of the EPDM rubber was found to increase with the aging time and aging temperature. Then, in order to quantitatively characterize the hyperelastic behavior of unaged EPDM rubber, the fitting performances of the Mooney–Rivlin, Arruda–Boyce, and Ogden models were compared based on a uniaxial tensile stress–strain curve. The results show that the Ogden model provided a more accurate representation of the hyperelastic behavior of unaged EPDM rubber. Subsequently, the Dakin dynamic equation was adopted to associate the parameters of the Ogden model with the aging time, and the Arrhenius relationship was utilized to introduce the aging temperature into the rate term of the Dakin dynamic equation, thereby establishing an improved Ogden constitutive model. This improved model expanded the Ogden model’s ability to explain aging time and aging temperature. Finally, the improved model prediction results and the test results were compared, and they indicate that the proposed improved Ogden constitutive model can accurately describe the hyperelastic behavior of aged and unaged EPDM rubber. Full article

(This article belongs to the Section Polymeric Materials)

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14 pages, 2100 KiB

Open AccessEditor’s ChoiceArticle

Improved Bone Regeneration Using Biodegradable Polybutylene Succinate Artificial Scaffold with BMP-2 Protein in a Rabbit Model

by Giulio Edoardo Vigni, Mariano Licciardi, Lorenzo D’itri, Francesca Terracina, Sergio Scirè, Giuseppe Arrabito, Bruno Pignataro, Lawrence Camarda, Giovanni Cassata, Roberto Puleio, Lucio Di Silvestre and Luca Cicero

Materials 2025, 18(10), 2234; https://doi.org/10.3390/ma18102234 - 12 May 2025

Viewed by 535

Abstract

Extensive bone loss represents a great challenge for orthopedic and reconstructive surgery. On an in vivo rabbit model, the healing of two bone defects on a long bone, tibia, was studied. A polybutylene succinate (PBS) microfibrillar scaffold was implemented with BMP-2 protein and [...] Read more.

Extensive bone loss represents a great challenge for orthopedic and reconstructive surgery. On an in vivo rabbit model, the healing of two bone defects on a long bone, tibia, was studied. A polybutylene succinate (PBS) microfibrillar scaffold was implemented with BMP-2 protein and hydroxyapatite (HA) as potential osteogenic factors. The present study was carried out on 6 male New Zealand white (4–6 months old) rabbits in vivo model. One bone defect was created in each subject on the tibia. The controls were left to heal spontaneously while the study samples were treated with the polybutylene succinate (PBS) microfibrillar scaffolds doped with BMP-2 and HA. Histological and immunohistochemical analyses were performed after euthanasia at 3 and 6 months. The bone defect treated with the BMP-2 PBS scaffold shows, from 3 months, a significantly increased presence of activated osteoblasts with mineralized bone tissue deposition. This study confirms the great potential of PBS scaffolds in the clinical treatment of bone defects. Full article

(This article belongs to the Special Issue Advanced Materials for Bone Regeneration and Treatment)

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15 pages, 3410 KiB

Open AccessEditor’s ChoiceArticle

CeO₂-Modified Ni₂P/Fe₂P as Efficient Bifunctional Electrocatalyst for Water Splitting

by Xinyang Wu, Dandan Wang, Yongpeng Ren, Haiwen Zhang, Shengyu Yin, Ming Yan, Yaru Li and Shizhong Wei

Materials 2025, 18(10), 2221; https://doi.org/10.3390/ma18102221 - 11 May 2025

Viewed by 879

Abstract

Developing efficient bifunctional electrocatalysts with excellent stability at high current densities for overall water splitting is a challenging yet essential objective. However, transition metal phosphides encounter issues such as poor dispersibility, low specific surface area, and limited electronic conductivity, which hinder the achievement [...] Read more.

Developing efficient bifunctional electrocatalysts with excellent stability at high current densities for overall water splitting is a challenging yet essential objective. However, transition metal phosphides encounter issues such as poor dispersibility, low specific surface area, and limited electronic conductivity, which hinder the achievement of satisfactory performance. Therefore, this study presents the highly efficient bifunctional electrocatalyst of CeO₂-modified NiFe phosphide on nickel foam (CeO₂/Ni₂P/Fe₂P/NF). Ni₂P/Fe₂P coupled with CeO₂ was deposited on nickel foam through hydrothermal synthesis and sequential calcination processes. The electrocatalytic performance of the catalyst was evaluated in an alkaline solution, and it exhibited an HER overpotential of 87 mV at the current density of 10 mA cm⁻² and an OER overpotential of 228 mV at the current density of 150 mA cm⁻². Furthermore, the catalyst demonstrated good stability, with a retention rate of 91.2% for the HER and 97.3% for the OER after 160 h of stability tests. The excellent electrochemical performance can be attributed to the following factors: (1) The interface between Ni₂P/Fe₂P and CeO₂ facilitates electron transfer and reactant adsorption, thereby improving catalytic activity. (2) The three-dimensional porous structure of nickel foam provides an ideal substrate for the uniform distribution of Ni₂P, Fe₂P, and CeO₂ nanoparticles, while its high conductivity facilitates electron transport. (3) The incorporation of larger Ce³⁺ ions in place of smaller Fe³⁺ ions leads to lattice distortion and an increase in defects within the NiFe-layered double hydroxide structure, significantly enhancing its catalytic performance. This research finding offers an effective strategy for the design and synthesis of low-cost, high-potential catalysts for water electrolysis. Full article

(This article belongs to the Section Catalytic Materials)

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16 pages, 3292 KiB

Open AccessEditor’s ChoiceArticle

Topology Optimization of Additively Manufactured Adherends for Increased Adhesive Bond Strength

by Michael Ascher and Ralf Späth

Materials 2025, 18(10), 2170; https://doi.org/10.3390/ma18102170 - 8 May 2025

Viewed by 511

Abstract

The limited build space of additive manufacturing (AM) machines constrains the maximum size of AM components, while manufacturing costs rise with geometric complexity. To enhance value and overcome size limitations, it can be more efficient to join non-AM and AM components to meet [...] Read more.

The limited build space of additive manufacturing (AM) machines constrains the maximum size of AM components, while manufacturing costs rise with geometric complexity. To enhance value and overcome size limitations, it can be more efficient to join non-AM and AM components to meet the requirements by means of a hybrid structure. Adhesive bonding is particularly suitable for such joints, as it imposes no constraints on the joining surface’s geometry or the adherend’s material. To ensure structural integrity, it is conceivable to exploit the design freedom underlying AM processes by optimizing the topology of the AM component to stress the adhesive layer homogeneously. This study explores the feasibility of this concept using the example of an axially loaded single-lap tubular joint between a carbon fiber-reinforced composite tube and an additively manufactured laser-based powder-bed-fusion aluminum alloy sleeve. The sleeve topology was optimized using the finite element method, achieving a

75 % P

reduction in adhesive stress increase compared to a non-optimized sleeve. Due to the pronounced ductility of the two-component epoxy-based adhesive, the static bond strength remained unaffected, whereas fatigue life significantly improved. The findings demonstrate the feasibility of leveraging AM design freedom to enhance adhesive joint performance, providing a promising approach for hybrid structures in lightweight applications. Full article

(This article belongs to the Special Issue Advances in the Experimentation and Numerical Modeling of Material Joining Processes (Second Edition))

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24 pages, 2746 KiB

Open AccessEditor’s ChoiceReview

Molecularly Imprinted Titanium Dioxide: Synthesis Strategies and Applications in Photocatalytic Degradation of Antibiotics from Marine Wastewater: A Review

by Xue Han, Yu Jin, Luyang Zhao, Yuying Zhang, Binqiao Ren, Xiaoxiao Song and Rui Liu

Materials 2025, 18(9), 2161; https://doi.org/10.3390/ma18092161 - 7 May 2025

Viewed by 642

Abstract

Antibiotic residues in the marine environment pose a serious threat to ecosystems and human health, and there is an urgent need to develop efficient and selective pollution control technologies. Molecular imprinting technology (MIT) provides a new idea for antibiotic pollution control with its [...] Read more.

Antibiotic residues in the marine environment pose a serious threat to ecosystems and human health, and there is an urgent need to develop efficient and selective pollution control technologies. Molecular imprinting technology (MIT) provides a new idea for antibiotic pollution control with its specific recognition and targeted removal ability. However, traditional titanium dioxide (TiO₂) photocatalysts have limited degradation efficiency and lack of selectivity for low concentrations of antibiotics. This paper reviews the preparation strategy and modification means of molecularly imprinted TiO₂ (MI-TiO₂) and its composites and systematically explores its application mechanism and performance advantages in marine antibiotic wastewater treatment. It was shown that MI-TiO₂ significantly enhanced the selective degradation efficiency of antibiotics such as tetracyclines and sulfonamides through the enrichment of target pollutants by specifically imprinted cavities, combined with the efficient generation of photocatalytic reactive oxygen species (ROS). In addition, emerging technologies such as magnetic/electric field-assisted catalysis and photothermal synergistic effect further optimized the recoverability and stability of the catalysts. This paper provides theoretical support for the practical application of MI-TiO₂ in complex marine pollution systems and looks forward to its future development in the field of environmental remediation. Full article

(This article belongs to the Section Catalytic Materials)

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23 pages, 4075 KiB

Open AccessEditor’s ChoiceArticle

CD44 Receptor-Mediated Ferroptosis Induction by Hyaluronic Acid Carbon Quantum Dots in Triple-Negative Breast Cancer Cells Through Downregulation of SLC7A11 Pathway

by Karthikeyan Chandrasekaran, Chae Eun Lee, Seojeong Yun, Ashok Kumar Jangid, Sungjun Kim and Kyobum Kim

Materials 2025, 18(9), 2139; https://doi.org/10.3390/ma18092139 - 6 May 2025

Cited by 2 | Viewed by 1121

Abstract

The field of cancer therapy is actively pursuing highly effective self-targeted drug delivery materials endowed with exceptional properties. Recently, hyaluronic acid (HA), a naturally occurring polysaccharide, has been recognized as a potential target ligand for CD44 receptors, which are frequently expressed on various [...] Read more.

The field of cancer therapy is actively pursuing highly effective self-targeted drug delivery materials endowed with exceptional properties. Recently, hyaluronic acid (HA), a naturally occurring polysaccharide, has been recognized as a potential target ligand for CD44 receptors, which are frequently expressed on various solid tumor cells targeted in cancer therapy. HA carbon quantum dots (CQDs) exhibit several advantageous properties, including a high surface area-to-volume ratio, small particle size, biocompatibility, and low cytotoxicity, making them ideal for biomedical applications, such as CD44-targeted drug delivery in ferroptosis-based cancer therapy. In this study, we synthesized HA-CQDs to enhance CD44-mediated ligand–receptor interactions targeting triple-negative breast cancer (TNBC). CQDs facilitate the intracellular generation of reactive oxygen species (ROS), leading to glutathione depletion. These processes result in crucial actions such as the downregulation of glutathione peroxidase 4, downregulation of solute carrier family 7 member 11, and inhibition of cystine intake. The subsequent intracellular ROS, originating from lipid peroxidation, induces ferroptosis. Our HA-CQDs engage CD44 receptors, selectively targeting TNBCs and enhancing cancer recognition. This interaction potentially enhances the nanoplatform-based CD44 targeted therapeutic effects in inducing ferroptosis. Full article

(This article belongs to the Special Issue Functional Polymers for Energy, Biomedical and Electrical Applications)

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12 pages, 2540 KiB

Open AccessEditor’s ChoiceArticle

Monolithic GaN-Based Dual-Quantum-Well LEDs with Size-Controlled Color-Tunable White-Light Emission

by Seung Hun Lee, Dabin Jeon, Gun-Woo Lee and Sung-Nam Lee

Materials 2025, 18(9), 2140; https://doi.org/10.3390/ma18092140 - 6 May 2025

Viewed by 531

Abstract

We report a monolithic GaN-based light-emitting diode (LED) platform capable of color-tunable white-light emission via LED size scaling. By varying the LED size from 800 µm to 50 µm, the injection current density was effectively controlled under constant driving current, enabling precise modulation [...] Read more.

We report a monolithic GaN-based light-emitting diode (LED) platform capable of color-tunable white-light emission via LED size scaling. By varying the LED size from 800 µm to 50 µm, the injection current density was effectively controlled under constant driving current, enabling precise modulation of carrier distribution within a dual-composition multi-quantum well (MQW) structure. The active layer consists of five lower In_0.15Ga_0.85N/GaN QWs for blue emission and strain induction, and an upper In_0.3Ga_0.7N/GaN single QW engineered for red-orange emission. The strain imposed by lower QWs promotes indium segregation in the last QW through spinodal decomposition, resulting in a broadened emission spanning from ~500 nm to 580 nm. High-resolution TEM and EDX analyses directly confirmed the indium segregation and phase-separated structure of the last QW. Spectral analysis revealed that larger devices exhibited dominant emission at 580 nm with a correlated color temperature (CCT) of 2536 K and a CIE coordinate of (0.501, 0.490). As LED size decreased, increased hole injection allowed recombination to occur in deeper QWs, resulting in a blueshift to 450 nm and a CCT of 9425 K with CIE (0.224, 0.218) in the 50 × 50 µm² LED. This approach enables phosphor-free white-light generation with tunable color temperatures and chromaticities using a single wafer, offering a promising strategy for compact, adaptive solid-state lighting applications. Full article

(This article belongs to the Special Issue Advances in Nanophotonic Materials, Devices, and Applications)

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19 pages, 9507 KiB

Open AccessEditor’s ChoiceArticle

Mechanical Strength of Waste Materials: A Cone Penetration Testing-Based Geotechnical Assessment for the Reclamation of Landfills

by Marek Bajda, Mariusz Lech, Katarzyna Markowska-Lech, Piotr Osiński and Eugeniusz Koda

Materials 2025, 18(9), 2130; https://doi.org/10.3390/ma18092130 - 6 May 2025

Viewed by 556

Abstract

The stability and mechanical properties of municipal solid waste (MSW) deposits in closed landfills are critical for safe land reclamation and infrastructure development. This study employs Cone Penetration Testing (CPT) to evaluate the geotechnical parameters of aged waste at three closed landfill sites [...] Read more.

The stability and mechanical properties of municipal solid waste (MSW) deposits in closed landfills are critical for safe land reclamation and infrastructure development. This study employs Cone Penetration Testing (CPT) to evaluate the geotechnical parameters of aged waste at three closed landfill sites in central Poland. Key parameters, including shear strength, internal friction angle, density, and liquidity index, were assessed to determine slope stability and bearing capacity for future redevelopment. Due to the heterogeneous nature of MSW, CPT results were analyzed in conjunction with empirical correlations and nomograms to improve accuracy, so the parameters can be used for future numerical modeling and proposing new computational approaches for landfill body elastic and mechanical behavior predictions. The findings indicate significant variability in landfill waste mechanical properties, influenced by waste composition, decomposition stage, and compaction history. The study highlights CPT’s reliable detremination of geotechnical parameters for landfill restoration projects, particularly for infrastructure, creating the potential for green energy and sustainable development. The results contribute to improving engineering practices in landfill restoration and ensuring the long-term stability of post-closure land use. This study also contributes to obtaining reliable results on anthropogenic waste material mechanical parameters at both the material point and at the overall structural scale, benefiting future computational methods and modeling approaches for analyzing structural and geotechnical safety of such complex and demanding structures as landfills. Full article

(This article belongs to the Special Issue Computational and Experimental Methodologies for Advanced and Sustainable Structural Materials)

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14 pages, 5435 KiB

Open AccessEditor’s ChoiceArticle

Electroanalysis of Apocynin Part 2: Investigations on a Boron-Doped Diamond Electrode in Aqueous Buffered Solutions

by Agata Skorupa, Magdalena Jakubczyk and Slawomir Michalkiewicz

Materials 2025, 18(9), 2044; https://doi.org/10.3390/ma18092044 - 29 Apr 2025

Viewed by 375

Abstract

In this study, the voltammetric behavior of apocynin on a boron-doped diamond electrode in a phosphate buffer (pH 7.3) has been reported for the first time. The oxidation process is quasi-reversible, diffusion-controlled, and involves one electron and one proton. The product of the [...] Read more.

In this study, the voltammetric behavior of apocynin on a boron-doped diamond electrode in a phosphate buffer (pH 7.3) has been reported for the first time. The oxidation process is quasi-reversible, diffusion-controlled, and involves one electron and one proton. The product of the electrode reaction is an unstable radical that undergoes successive chemical transformations near the working electrode. The proposed mechanism of this process can be described as E_qC_i and served as the basis for the development of a new voltammetric method for determining apocynin in natural samples. The analytical signal was the anodic peak on DPV curves at a potential of 0.605 V vs. Ag/AgCl. A linear response was observed in the concentration range of 0.213–27.08 mg L⁻¹. The estimated LOD and LOQ values were 0.071 and 0.213 mg L⁻¹, respectively. The effectiveness of the method was demonstrated both in control determinations and in the analysis of the dietary supplement. This procedure is simple, fast, sensitive, selective, and requires no complicated sample preparation, which is limited only to a simple extraction with ethanol. The low consumption of non-toxic reagents makes it environmentally friendly. To the best of our knowledge, this is the first presentation of a voltammetric procedure to determine this analyte studied in a phosphate buffer solution on a boron-doped diamond electrode. It can also be easily adapted to determine other phenolic compounds with antioxidant properties in various matrices. Full article

(This article belongs to the Special Issue Advanced Research of Organic Molecules and Materials for Modern Chemical and Biological Applications)

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14 pages, 10139 KiB

Open AccessEditor’s ChoiceArticle

Ultra-Low Core Loss and High-Frequency Permeability Stability in Hot-Press Sintered FeSi Soft Magnetic Composites by Fe₂O₃ Nanoparticles Air Gap Filling

by Muhammad Arif, Donghun Han, Wonchan Shin, Seunghun Cha, Changsun Pak, Youngkwang Kim, Sangwoo Kim, Bowha Lee and Jongsoo Rhyee

Materials 2025, 18(9), 2013; https://doi.org/10.3390/ma18092013 - 29 Apr 2025

Viewed by 1219

Abstract

Soft magnetic materials are crucial in motors, generators, transformers, and many electronic devices. We synthesized the FeSi soft magnetic composites (SMCs) with different doping contents of Fe₂O₃ nanopowders as fillers via the hot-press sintering technique. This work explores the incorporation [...] Read more.

Soft magnetic materials are crucial in motors, generators, transformers, and many electronic devices. We synthesized the FeSi soft magnetic composites (SMCs) with different doping contents of Fe₂O₃ nanopowders as fillers via the hot-press sintering technique. This work explores the incorporation of high-resistivity magnetic fillers through a novel compaction technique and investigates the influence of Fe₂O₃ nanopowder on the structure and magnetic properties of Fe₂O₃ nanopowder-filled composites. The finding reveals that Fe₂O₃ nanopowders effectively fill the air gaps between FeSi powders, increasing SMC density. Moreover, all samples exhibit excellent effective permeability frequency stability, ranging from 15 kHz to 100 kHz. Notably, the effective permeability µ_e improves from 22.32 to 30.45, a 36.42% increase, when the Fe₂O₃ doping concentration increases from 0 to 2 wt%. Adding Fe₂O₃ nanopowders also enhances electrical resistivity, leading to a 37.21% reduction in eddy current loss in samples for 5 wt% Fe₂O₃ addition, compared to undoped samples. Furthermore, as Fe₂O₃ content increases from 0 to 5 wt%, the power loss P_cv of the Fe₂O₃-doped Fe-6.5Si SMCs decreases from 25.63 kW/m³ to 16.13 kW/m³, a 37% reduction. These results suggest that Fe₂O₃-doped FeSi SMCs, with their superior soft magnetic properties, hold significant potential for use in high-power and high-frequency electronic applications. Full article

(This article belongs to the Section Materials Chemistry)

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26 pages, 4573 KiB

Open AccessEditor’s ChoiceReview

Flexible Glass: Myth and Photonic Technology

by Giancarlo C. Righini, Maurizio Ferrari, Anna Lukowiak and Guglielmo Macrelli

Materials 2025, 18(9), 2010; https://doi.org/10.3390/ma18092010 - 29 Apr 2025

Viewed by 2498

Abstract

The recent fast advances in consumer electronics, especially in cell phones and displays, have led to the development of ultra-thin, hence flexible, glasses. Once available, such flexible glasses have proven to be of great interest and usefulness in other fields, too. Flexible photonics, [...] Read more.

The recent fast advances in consumer electronics, especially in cell phones and displays, have led to the development of ultra-thin, hence flexible, glasses. Once available, such flexible glasses have proven to be of great interest and usefulness in other fields, too. Flexible photonics, for instance, has quickly taken advantage of this new material. At first sight, “flexible glass” appears to be an oxymoron. Glass is, by definition, fragile and highly breakable; its structure has puzzled scientists for decades, but it is evident that in most conditions it is a rigid material, so how can it bend? This possibility, however, has aroused the interest of artists and craftsmen since ancient times; thus, in Roman times the myth of flexible glass was born. Furthermore, the myth appeared again in the Middle Age, connected to a religious miracle. Today, however, flexible glass is no more a myth but a reality due to the fact that current technology permits us to produce micron-thick glass sheets, and any ultra-thin material can be bent. Flexibility is coming from the present capability to manufacture glass sheets at a tens of microns thickness coupled with the development of strengthening methods; it is also worth highlighting that, on the micrometric and nanometric scales, silicate glass presents plastic behavior. The most significant application area of flexible glass is consumer electronics, for the displays of smartphones and tablets, and for wearables, where flexibility and durability are crucial. Automotive and medical sectors are also gaining importance. A very relevant field, both for the market and the technological progress, is solar photovoltaics; mechanical flexibility and lightweight have allowed solar cells to evolve toward devices that possess the advantages of conformability, bendability, wearability, and moldability. The mature roll-to-roll manufacturing technology also allows for high-performance devices at a low cost. Here, a brief overview of the history of flexible glass and some examples of its application in solar photovoltaics are presented. Full article

(This article belongs to the Special Issue Advances in Electronic and Photonic Materials)

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35 pages, 5269 KiB

Open AccessEditor’s ChoiceArticle

The Quantum Transport of Dirac Fermions in Selected Graphene Nanosystems Away from the Charge Neutrality Point

by Adam Rycerz

Materials 2025, 18(9), 2036; https://doi.org/10.3390/ma18092036 - 29 Apr 2025

Viewed by 688

Abstract

The peculiar electronic properties of graphene, including the universal dc conductivity and the pseudodiffusive shot noise, are usually found in a small vicinity close to the charge neutrality point, away from which the electron’s effective mass raises, and nanostructures in graphene start to [...] Read more.

The peculiar electronic properties of graphene, including the universal dc conductivity and the pseudodiffusive shot noise, are usually found in a small vicinity close to the charge neutrality point, away from which the electron’s effective mass raises, and nanostructures in graphene start to behave similarly to familiar Sharvin contacts in semiconducting heterostructures. Recently, it was pointed out that as long as abrupt potential steps separate the sample area from the leads, some graphene-specific features can be identified relatively far from the charge neutrality point. These features include greater conductance reduction and shot noise enhancement compared to the standard Sharvin values. The purpose of this paper is twofold: First, we extend the previous analysis based on the effective Dirac equation, and derive the formulas that allow the calculation of the arbitrary charge transfer cumulant for doped graphene. Second, the results of the analytic considerations are compared with numerical simulations of quantum transport on the honeycomb lattice for selected nanosystems for which considerations starting from the Dirac equation cannot be directly adapted. For a wedge-shaped constriction with zigzag edges, the transport characteristics can be tuned from graphene-specific (sub-Sharvin) values to standard Sharvin values by varying the electrostatic potential profile in the narrowest section. A similar scenario is followed by the half-Corbino disk. In contrast, a circular quantum dot with two narrow openings showing a mixed behavior appears: the conductance is close to the Sharvin value, while the Fano factor approaches the value characterizing the symmetric chaotic cavity. Carving a hole in the quantum dot to eliminate direct trajectories between the openings reduces the conductance to sub-Sharvin value, but the Fano factor is unaffected. Our results suggest that experimental attempts to verify the predictions for the sub-Sharvin transport regime should focus on systems with relatively wide openings, where the scattering at the sample edges is insignificant next to the scattering at the sample–lead interfaces. Full article

(This article belongs to the Special Issue Quantum Transport in Novel 2D Materials and Structures)

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16 pages, 8149 KiB

Open AccessEditor’s ChoiceArticle

Multifunctional Sol–Gel Coatings for Both Anticorrosion and Electrical Conduction Properties

by Clément Genet, Hiba Azougaghe, Edouard Bréniaux, Robin Montpellaz, Marie Gressier, Florence Ansart, Olivier Gavard and Marie-Joëlle Menu

Materials 2025, 18(9), 2011; https://doi.org/10.3390/ma18092011 - 29 Apr 2025

Viewed by 476

Abstract

This work is part of a current and essential issue aiming to find a solution for the replacement of chromium(VI) and cadmium in the surface treatment process applied to electrical connectors. The application of a protective coating obtained by the sol–gel route proves [...] Read more.

This work is part of a current and essential issue aiming to find a solution for the replacement of chromium(VI) and cadmium in the surface treatment process applied to electrical connectors. The application of a protective coating obtained by the sol–gel route proves to be an interesting alternative method and numerous studies describe efficient anticorrosion coatings to protect various metallic alloys. The issue of electrical connectors made of 6061 alloy is to combine anticorrosion protection and electrical conduction, which are antagonistic properties, so multifunctional sol–gel coatings and/or architectures have to be synthesized and shaped on connectors. In this work, several experimental parameters, such as the type of carbon filler, the hydrolysis ratio, the precursors’ introduction order are studied and evaluated to achieve industrial requirements. Thus, aqueous suspensions of carbon fillers have been introduced into sol–gel formulations to give rise to conductive coatings (200–500 mΩ_□) with high anticorrosion properties (500 h NSS resistance), in which thickness is less than 10 microns. The incorporation of organic additives poly(2-ethyl-2-oxazoline) or hydroxypropylmethylcellulose positively impacts the flash point of the sol (>60 °C) making the sol–gel process compatible with the HSE recommendation and the ATEX standard. Full article

(This article belongs to the Section Materials Chemistry)

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14 pages, 6228 KiB

Open AccessEditor’s ChoiceArticle

Microstructure and Mechanical Property of 6082 Aluminum Alloy via Sc and Zr Addition Combined with Squeeze Casting

by Yushi Qi, Fangming Wei, Yu Wang, Yu Jin, Xusheng Chang and Gang Chen

Materials 2025, 18(9), 1988; https://doi.org/10.3390/ma18091988 - 27 Apr 2025

Cited by 1 | Viewed by 784

Abstract

To enhance the mechanical properties of 6082 aluminum alloy, a novel Sc- and Zr-microalloyed 6082 alloy was fabricated through squeeze casting technology. Microalloying with Sc and Zr substantially refined the microstructure of alloy, achieving an average grain size of 136.36 μm—a 31.7% reduction [...] Read more.

To enhance the mechanical properties of 6082 aluminum alloy, a novel Sc- and Zr-microalloyed 6082 alloy was fabricated through squeeze casting technology. Microalloying with Sc and Zr substantially refined the microstructure of alloy, achieving an average grain size of 136.36 μm—a 31.7% reduction compared to the baseline 6082 alloy. Furthermore, the addition of Sc and Zr effectively refined the coarse AlFeMnSi intermetallic phases, mitigating their inherent brittleness. The Sc/Zr-modified alloy exhibited delayed age-hardening kinetics, requiring 100% longer aging time to reach peak hardness due to Sc/Zr-induced retardation of β’’-phase precipitation. The optimized alloy demonstrated better mechanical properties, showing 10.4%, 8.0%, and 71.8% enhancements in yield strength, ultimate tensile strength, and elongation, respectively, over the non-microalloyed counterpart. The squeeze-cast Sc/Zr-modified alloy valve body showed yield strength exceeding 300 MPa and elongation above 10% across various sections, which verifies the effectiveness of this integrated microalloying and forming approach. Full article

(This article belongs to the Special Issue Review and Feature Papers in "Metals and Alloys" Section (2nd Edition))

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25 pages, 16068 KiB

Open AccessEditor’s ChoiceArticle

Mechanical Properties and Fracture Analysis of Advanced Nickel-Based Nanomembranes

by Janik Marius Lück and Joachim Rösler

Materials 2025, 18(9), 1961; https://doi.org/10.3390/ma18091961 - 25 Apr 2025

Cited by 1 | Viewed by 345

Abstract

Nanoporous membranes based on the single crystalline nickel-based superalloy CMSX-4 are a promising class of materials for membranes, especially for use in premix membrane emulsification. In addition to the pore size, the strength and stability of the membrane structure are key factors for [...] Read more.

Nanoporous membranes based on the single crystalline nickel-based superalloy CMSX-4 are a promising class of materials for membranes, especially for use in premix membrane emulsification. In addition to the pore size, the strength and stability of the membrane structure are key factors for subsequent use. The production of the membranes is based on the directional coarsening of the γ/γ′-microstructure by creep deformation, in which the material is subjected to a tensile load at high temperatures so that a bicontinuous network of the γ- and γ′-phase is formed. The subsequent dissolution of the γ-phase leaves a network of γ′-phase, which can be used as a membrane structure; the former γ-matrix channels now serve as pores. Previous investigations focusing on the evolution of the microstructure during membrane fabrication found that a particularly small pore size can be achieved when the creep deformation temperature is lowered from 1000 °C to 950 °C while increasing the stress from 170 MPa to 250 MPa. This study will now investigate the strength and fracture behaviour of membranes produced by these improved parameters. For this purpose, four creep states with creep strains between 1.3% and 5.7% are investigated in tensile tests at room temperature, with the load being applied perpendicular and parallel to the raft structure. The results show that the strength of nanomembranes during perpendicular loading essentially depends on the cross-linking between γ′-rafts. Generally, an increase in creep strain leads to an increase of the cross-linking resulting in higher tensile strength. During parallel loading, γ′-inhomogeneities play an important role resulting in a loss of strength. The analysis of the fracture surfaces and evaluation of EBSD measurements reveal an insufficient cross-linking between dendrites and around γ′-inhomogeneities, leading to preferred crack paths. Therefore, the differences in orientation within the single crystal play a key role in the strength of the nanomembranes. Full article

(This article belongs to the Special Issue Advanced Nanoporous and Mesoporous Materials)

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26 pages, 5352 KiB

Open AccessEditor’s ChoiceArticle

Optimization of Rotary Friction Welding Parameters Through AI-Augmented Digital Twin Systems

by Piotr Lacki, Janina Adamus, Kuba Lachs and Wiktor Lacki

Materials 2025, 18(9), 1923; https://doi.org/10.3390/ma18091923 - 24 Apr 2025

Viewed by 702

Abstract

In this study, Artificial Neural Networks (ANN) were employed to develop a Digital Twin (DT) of the Rotary Friction Welding (RFW) process. The neural network models were trained to predict the peak temperature generated during the welding process of dissimilar Ti Grade 2/AA [...] Read more.

In this study, Artificial Neural Networks (ANN) were employed to develop a Digital Twin (DT) of the Rotary Friction Welding (RFW) process. The neural network models were trained to predict the peak temperature generated during the welding process of dissimilar Ti Grade 2/AA 5005 joints over a temperature range of 20–640 °C. This prediction was based on a parametric numerical model of the RFW process constructed using the Finite Element Method (FEM) within the ADINA System software. Numerical simulations enabled a detailed analysis of the temperature distribution within the weldment. Accurate temperature predictions are essential for assessing the mechanical properties and microstructural integrity of the welded materials. Artificial Intelligence (AI) models, trained on historical data and real-time inputs, dynamically adjust critical process parameters—such as rotational speed, axial force, and friction time—to maintain optimal weld quality. A key advantage of employing AI-augmented DT systems in the RFW process is the ability to conduct real-time (less than 0.1 s) optimization and adaptive control. By integrating a Genetic Algorithm (GA) with the DT algorithm of the RFW process, the authors developed an effective tool for analyzing parameters such as axial force and rotational speed, in order to determine the optimal welding conditions, which translates into improved joint quality, minimized defects, and maximized process efficiency. Full article

(This article belongs to the Special Issue Artificial Intelligence in Materials Science and Engineering)

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12 pages, 2913 KiB

Open AccessEditor’s ChoiceArticle

Structural and Magnetic Characterization of Mechanically Alloyed (Fe₂O₃)_1−x(Al₂O₃)_x Solid Solutions via Pulsed Neutron Powder Diffraction

by Dong Luo, Hayato Nakaishi, Takeshi Yabutsuka, Takashi Saito, Takashi Kamiyama, Masato Hagihala and Shigeomi Takai

Materials 2025, 18(9), 1911; https://doi.org/10.3390/ma18091911 - 23 Apr 2025

Cited by 1 | Viewed by 734

Abstract

Neutron powder diffraction experiments were carried out to characterize mechanochemically synthesized (Fe₂O₃)_1−x(Al₂O₃)_x solid solutions with corundum-type structure, focusing on their lattice and magnetic structures with varying temperature and composition. The neutron diffraction [...] Read more.

Neutron powder diffraction experiments were carried out to characterize mechanochemically synthesized (Fe₂O₃)_1−x(Al₂O₃)_x solid solutions with corundum-type structure, focusing on their lattice and magnetic structures with varying temperature and composition. The neutron diffraction experiments for (Fe₂O₃)_0.5(Al₂O₃)_0.5 in the temperature range between 4 K and 300 K reveal that no significant structural phase transition occurred. The behavior of temperature variation of lattice parameters is different from α-Fe₂O₃ and α-Al₂O₃ and reveals the thermal expansion coefficients of α_a = 5.76(2) × 10⁻⁶ K⁻¹ and α_c = 6.19(5) × 10⁻⁶ K⁻¹ between 200 K and 300 K. The room temperature neutron diffraction of (Fe₂O₃)_1−x(Al₂O₃)_x shows a linear decrease in lattice parameters with the aluminum substitution, following Vegard’s law, along with a decrease in the magnetic moment, indicating the dilution effect on spin interactions. With the increase in the aluminum substitution from x = 0 to 0.5, the deduced magnetic moment decreases from 2.224 μ_B to 0.862 μ_B. Full article

(This article belongs to the Section Materials Chemistry)

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30 pages, 3765 KiB

Open AccessEditor’s ChoiceArticle

Antibacterial Activity of GO-Based Composites Enhanced by Phosphonate-Functionalized Ionic Liquids and Silver

by Xinyu Liu, Xing Zhao, Hongda Qiu, Weida Liang, Linlin Liu, Yunyu Sun, Lingling Zhao, Xiao Wang and Hongze Liang

Materials 2025, 18(8), 1889; https://doi.org/10.3390/ma18081889 - 21 Apr 2025

Viewed by 802

Abstract

The development of antibiotic-independent antimicrobial materials is critical for addressing bacterial resistance to conventional antibiotics. Currently, there is a lack of comprehensive understanding of ionic liquid-modified composites in antimicrobial applications. Here, we innovatively prepared GO-based composites modified with phosphonate ionic liquids via a [...] Read more.

The development of antibiotic-independent antimicrobial materials is critical for addressing bacterial resistance to conventional antibiotics. Currently, there is a lack of comprehensive understanding of ionic liquid-modified composites in antimicrobial applications. Here, we innovatively prepared GO-based composites modified with phosphonate ionic liquids via a series of surface functionalizations. The resulting antibacterial composites exhibit significant broad-spectrum activity against both Gram-negative and Gram-positive bacteria, including drug-resistant strains, with stronger efficacy against Gram-negative species. Additionally, the material features excellent long-term reusability and the ability to inhibit/destroy biofilms, which is vital for combating persistent infections. Mechanistic studies reveal its antibacterial effects through multiple pathways: disrupting bacterial membranes, inducing ROS, and inactivating intracellular substances—mechanisms less likely to promote resistance. Overall, these phosphonate ionic liquid-modified polycationic materials demonstrate substantial potential in treating bacterial infections, offering a promising strategy to tackle antibiotic resistance challenges. Full article

(This article belongs to the Special Issue Ionic Liquids: New Trends in Advanced Applications)

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47 pages, 4349 KiB

Open AccessEditor’s ChoiceReview

Metal Nanocomposites as Biosensors for Biological Fluids Analysis

by Dan Chicea and Alexandra Nicolae-Maranciuc

Materials 2025, 18(8), 1809; https://doi.org/10.3390/ma18081809 - 15 Apr 2025

Cited by 1 | Viewed by 777

Abstract

Metal nanocomposites are rapidly emerging as a powerful platform for biosensing applications, particularly in the analysis of biological fluids. This review paper examines the recent advancements in the development and application of metal nanocomposites as biosensors for detecting various analytes in complex biological [...] Read more.

Metal nanocomposites are rapidly emerging as a powerful platform for biosensing applications, particularly in the analysis of biological fluids. This review paper examines the recent advancements in the development and application of metal nanocomposites as biosensors for detecting various analytes in complex biological matrices such as blood, serum, urine, and saliva. We discuss the unique physicochemical properties of metal nanocomposites, including their high surface area, enhanced conductivity, and tunable optical and electrochemical characteristics, which contribute to their superior sensing capabilities. The review will cover various fabrication techniques, focusing on their impact on the sensitivity, selectivity, and stability of the resulting biosensors. Furthermore, we will analyze the diverse applications of these biosensors in the detection of disease biomarkers, environmental toxins, and therapeutic drugs within biological fluids. Finally, we will address the current challenges and future perspectives of this field, highlighting the potential for improved diagnostic tools and personalized medicine through the continued development of advanced metal nanocomposite-based biosensors. Full article

(This article belongs to the Special Issue Progress and Challenges of Advanced Metallic Materials and Composites)

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15 pages, 3554 KiB

Open AccessEditor’s ChoiceArticle

Study of ZrO₂ Gate Dielectric with Thin SiO₂ Interfacial Layer in 4H-SiC Trench MOS Capacitors

by Qimin Huang, Yunduo Guo, Anfeng Wang, Zhaopeng Bai, Lin Gu, Zhenyu Wang, Chengxi Ding, Yi Shen, Hongping Ma and Qingchun Zhang

Materials 2025, 18(8), 1741; https://doi.org/10.3390/ma18081741 - 10 Apr 2025

Viewed by 736

Abstract

The transition of SiC MOSFET structure from planar to trench-based architectures requires the optimization of gate dielectric layers to improve device performance. This study utilizes a range of characterization techniques to explore the interfacial properties of ZrO₂ and SiO₂/ZrO₂ [...] Read more.

The transition of SiC MOSFET structure from planar to trench-based architectures requires the optimization of gate dielectric layers to improve device performance. This study utilizes a range of characterization techniques to explore the interfacial properties of ZrO₂ and SiO₂/ZrO₂ gate dielectric films, grown via atomic layer deposition (ALD) in SiC epitaxial trench structures to assess their performance and suitability for device applications. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements showed the deposition of smooth film morphologies with roughness below 1 nm for both ZrO₂ and SiO₂/ZrO₂ gate dielectrics, while SE measurements revealed comparable physical thicknesses of 40.73 nm for ZrO₂ and 41.55 nm for SiO₂/ZrO₂. X-ray photoelectron spectroscopy (XPS) shows that in SiO₂/ZrO₂ thin films, the binding energies of Zr 3d_5/2 and Zr 3d_3/2 peaks shift upward compared to pure ZrO₂. Electrical characterization showed an enhancement of E_BR (3.76 to 5.78 MV·cm⁻¹) and a decrease of I_{ON_EBR} (1.94 to 2.09 × 10⁻³ A·cm⁻²) for the SiO₂/ZrO₂ stacks. Conduction mechanism analysis identified suppressed Schottky emission in the stacked film. This indicates that the incorporation of a thin SiO₂ layer effectively mitigates the small bandgap offset, enhances the breakdown electric field, reduces leakage current, and improves device performance. Full article

(This article belongs to the Special Issue Feature Papers in Materials Physics (2nd Edition))

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14 pages, 8353 KiB

Open AccessEditor’s ChoiceArticle

Design and Characterization of an Equibiaxial Multi-Electrode Dielectric Elastomer Actuator

by Simon Holzer, Bhawnath Tiwari, Stefania Konstantinidi, Yoan Civet and Yves Perriard

Materials 2025, 18(8), 1693; https://doi.org/10.3390/ma18081693 - 8 Apr 2025

Viewed by 482

Abstract

With the ongoing journey of automation advancements and a trend towards miniaturization, the choice of actuator plays a crucial role. Over recent years, soft actuators have demonstrated their usefulness in various applications, especially where light weight and high strain are required. Dielectric elastomer [...] Read more.

With the ongoing journey of automation advancements and a trend towards miniaturization, the choice of actuator plays a crucial role. Over recent years, soft actuators have demonstrated their usefulness in various applications, especially where light weight and high strain are required. Dielectric elastomer actuators (DEAs) are a class of soft actuators that provide high-strain actuation possibilities in applications like biomedicine, logistics, or consumer electronics. A variety of work featuring DEAs for actuation has been carried out in recent years, but a single work detailing the design conception, fabrication, modeling and experimental validation is lacking, especially in the context of achieving high strains with the integration of multiple electrodes and their interaction. This work discusses these issues with an equibiaxial DEA, enabling optimized equibiaxial strain patterns due to full use of the available actuation area. The developed DEA can achieve an equibiaxial strain of 12.75% for actuation at 60 V μm⁻¹ over an active area of 7 cm² which is an improvement of 1.3 times compared to traditional dot actuators. These properties position the device as a promising alternative for various applications like cell cultures or microassembly and provide an advantage of optimized use of passive regions within the actuator. Full article

(This article belongs to the Special Issue Electroactive Polymers: Fundamentals and Applications)

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31 pages, 5436 KiB

Open AccessEditor’s ChoiceArticle

Study of the Relationship Between the Structures and Biological Activity of Herbicides Derived from Phenoxyacetic Acid

by Grzegorz Świderski, Natalia Kowalczyk, Gabriela Tyniecka, Monika Kalinowska, Renata Łyszczek, Aleksandra Bocian, Ewa Ciszkowicz, Leszek Siergiejczyk, Małgorzata Pawłowska and Jacek Czerwiński

Materials 2025, 18(7), 1680; https://doi.org/10.3390/ma18071680 - 7 Apr 2025

Cited by 1 | Viewed by 1307

Abstract

Chloroderivatives of phenoxyacetic acid are a group of compounds commonly used as plant protection products. Differences in the molecular structure of these compounds are related to varying substitution and the number of chlorine atoms in the aromatic ring. Different molecular structures may affect [...] Read more.

Chloroderivatives of phenoxyacetic acid are a group of compounds commonly used as plant protection products. Differences in the molecular structure of these compounds are related to varying substitution and the number of chlorine atoms in the aromatic ring. Different molecular structures may affect the activity of these compounds, their physicochemical properties, as well as their toxicity and biological effects. A group of 6 chemical compounds derived from phenoxyacetic acid was tested. The molecular structure was analysed using spectroscopic methods (FTIR, FTRaman, UV-VIS, ¹HNMR, ¹³CNMR) and quantum chemical computational methods (DFT). The reactivity of the tested compounds was determined using DFT calculations and experimentally in reaction with a hydroxyl radical. The electronic charge distribution of NBO, CHelpG and ESP was analysed and aromaticity indices were calculated for theoretically modeled structures and structures examined by X-ray diffraction (data obtained from the CSD database). Phenoxyacetic acid derivatives were tested for antimicrobial activity on soil bacterial strains. Cytotoxicity tests were performed on normal human skin fibroblasts (BJ CRL-2522) and the human prostate cancer cell line (DU-145 HTB-81). The purpose of this study was to investigate the relationship between the molecular structure of phenoxyacetic acid derivatives and their reactivity and biological activity. Full article

(This article belongs to the Special Issue From Molecular to Supramolecular Materials)

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30 pages, 4998 KiB

Open AccessEditor’s ChoiceArticle

A Material Study of Persian-Period Silver Coins and Hacksilber from Samaria

by Dana Ashkenazi, Maayan Cohen, Haim Gitler, Mati Johananoff and Oren Tal

Materials 2025, 18(7), 1678; https://doi.org/10.3390/ma18071678 - 7 Apr 2025

Viewed by 790

Abstract

An assembly of fourth-century BCE Samarian silver coins and late-fifth-century BCE Samarian cut silver sheets, Sidonian and Philistian coins from a hacksilber hoard allegedly found in the region of Samaria belonging to the David and Jemima Jeselsohn collection, were characterized by metallurgical analyses. [...] Read more.

An assembly of fourth-century BCE Samarian silver coins and late-fifth-century BCE Samarian cut silver sheets, Sidonian and Philistian coins from a hacksilber hoard allegedly found in the region of Samaria belonging to the David and Jemima Jeselsohn collection, were characterized by metallurgical analyses. The aims of the research were to identify the items’ composition and manufacturing processes. We affirmed that the Samarian coins were made of silver–copper alloy produced by a controlled process. The microstructural and elemental analyses revealed that the sheets were produced from various materials, including pure silver, silver–copper, and silver–copper–gold alloys, whereas the Sidonian and Philistian coins were made of silver–copper alloy. Continuity in style and production techniques was observed. This information provides a better understanding of the material culture and technological skills in the Persian-period province of Samaria. Full article

(This article belongs to the Section Metals and Alloys)

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19 pages, 5369 KiB

Open AccessEditor’s ChoiceArticle

Interactions of Terahertz Photons with Phonons of Two-Dimensional van der Waals MoS₂/WSe₂/MoS₂ Heterostructures and Thermal Responses

by Jingwen Huang, Ningsheng Xu, Yumao Wu, Xue Ran, Yue Fang, Hongjia Zhu, Weiliang Wang, Huanjun Chen and Shaozhi Deng

Materials 2025, 18(7), 1665; https://doi.org/10.3390/ma18071665 - 4 Apr 2025

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Abstract

The interaction between terahertz (THz) photons and phonons of materials is crucial for the development of THz photonics. In this work, typical two-dimensional (2D) van der Waals (vdW) transition metal chalcogenide (TMD) layers and heterostructures are used in THz time-domain spectroscopy (TDS) measurements, [...] Read more.

The interaction between terahertz (THz) photons and phonons of materials is crucial for the development of THz photonics. In this work, typical two-dimensional (2D) van der Waals (vdW) transition metal chalcogenide (TMD) layers and heterostructures are used in THz time-domain spectroscopy (TDS) measurements, low-wavenumber Raman spectroscopy measurements, calculation of 2D materials’ phonon spectra, and theoretical analysis of thermal responses. The TDS results reveal strong absorption of THz photons in the frequency range of 2.5–10 THz. The low-wavenumber Raman spectra show the phonon vibration characteristics and are used to establish phonon energy bands. We also set up a computational simulation model for thermal responses. The temperature increases and distributions in the individual layers and their heterostructures are calculated, showing that THz photon absorption results in significant increases in temperature and differences in the heterostructures. These give rise to interesting photothermal effects, including the Seebeck effect, resulting in voltages across the heterostructures. These findings provide valuable guidance for the potential optoelectronic application of the 2D vdW heterostructures. Full article

(This article belongs to the Special Issue Terahertz Vibrational Spectroscopy in Advanced Materials)

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Open AccessEditor’s ChoiceArticle

Monitoring Antioxidant Consumption and Build-Up in Polypropylene During Open-Loop and Closed-Loop Mechanical Recycling

by Niek Knoben, Max Vanhouttem, Aike Wypkema and Nithya Subramanian

Materials 2025, 18(7), 1640; https://doi.org/10.3390/ma18071640 - 3 Apr 2025

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Abstract

Polypropylene (PP), a widely used recyclable plastic in packaging and engineering applications, is prone to thermo-oxidative degradation during reprocessing and molding at high temperatures. Antioxidants (AOs) are essential for stabilizing PP in both its virgin and recycled states. The quantity of AO added [...] Read more.

Polypropylene (PP), a widely used recyclable plastic in packaging and engineering applications, is prone to thermo-oxidative degradation during reprocessing and molding at high temperatures. Antioxidants (AOs) are essential for stabilizing PP in both its virgin and recycled states. The quantity of AO added is critical: insufficient amounts can lead to poor stabilization, while excessive amounts can cause safety concerns due to build-up. This study presents a modified approach to measure the Oxidation Induction Temperature (OIT) using Differential Scanning Calorimetry (DSC), particularly for recycled PP from waste that contains unpredictable contaminations. This modified approach ensures the safety of the calorimetry cell by limiting the oxidation reaction and preventing the release of volatile compounds during measurements. By performing DSC measurements in inert environments, we obtain the OIT, which can be correlated to residual intact AO levels. This approach to monitoring AO levels is demonstrated in both open- and closed-loop recycling of rigid PP. Although the presence of contamination is known to catalyze thermo-oxidative degradation in PP, our results indicate that recycled PP from open-loop collection still contains sufficient residual AO that allows it to withstand limited thermal reprocessing. However, this tendency of AO retention leads to significant build-up during closed-loop recycling when AOs are added to each cycle, where the PP grade remains fairly homogeneous and the dispersity (Đ) does not significantly increase over multiple recycling loops. Full article

(This article belongs to the Special Issue Recycling and Degradation of Polymeric Materials: Exploring Different Perspectives in Plastic Waste Management)

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