Journal Description
Crystals
Crystals
is an international, peer-reviewed, open access journal on Crystallography published monthly online by MDPI. The Professional Committee of Key Materials and Technology for Electronic Components (PC-KMTEC) is affiliated with Crystals and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Crystallography) / CiteScore - Q2 (Condensed Matter Physics)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 10.6 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.7 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Electronic Structure Calculations of Rare-Earth-Doped Magnesium Oxide Based on Density Functional Theory
Crystals 2024, 14(5), 435; https://doi.org/10.3390/cryst14050435 - 02 May 2024
Abstract
In this paper, the electronic structures of rare earth (Nd, Er)-doped MgO were investigated using density functional theory (DFT), with Hubbard on-site corrections (Ueff) applied to rare earth elements. Li was considered a co-dopant. Defect complexes were involved, instead of a
[...] Read more.
In this paper, the electronic structures of rare earth (Nd, Er)-doped MgO were investigated using density functional theory (DFT), with Hubbard on-site corrections (Ueff) applied to rare earth elements. Li was considered a co-dopant. Defect complexes were involved, instead of a single dopant atom, in the supercell. The splitting and distribution of the 4f ground states of Nd and Er dopants in the band gap changed by co-doping Li. The calculation results provide insights into the influences of Li on the optical properties of rare-earth-doped MgO.
Full article
(This article belongs to the Special Issue Rare Earths-Doped Materials (3rd Edition))
►
Show Figures
Open AccessReview
Processing Techniques and Metallurgical Perspectives and Their Potential Correlation in Aluminum Bottle Manufacturing for Sustainable Packaging Solutions
by
Mousa Javidani, Siamak Nikzad Khangholi and Alain Chapdelaine
Crystals 2024, 14(5), 434; https://doi.org/10.3390/cryst14050434 - 01 May 2024
Abstract
This study explores the potential of aluminum wine bottles as a sustainable alternative to traditional glass bottles, emphasizing their recyclability and environmental advantages. It reviews the potential use of Al-Mn-Mg 3xxx alloys in beverage can bodies and examines various applications of aluminum containers
[...] Read more.
This study explores the potential of aluminum wine bottles as a sustainable alternative to traditional glass bottles, emphasizing their recyclability and environmental advantages. It reviews the potential use of Al-Mn-Mg 3xxx alloys in beverage can bodies and examines various applications of aluminum containers in packaging, including recyclable beverage containers. The manufacturing processes for aluminum bottles, including casting, rolling, punching, and deformation techniques, are discussed in detail, with a particular focus on their impact on mechanical properties and microstructure. The preference for 1xxx aluminum alloys in impact extrusion is explained, highlighting their lower flow stress and higher formability compared to 3xxx alloys, and the microstructural changes induced by various processing steps are analyzed. Challenges related to using recycled aluminum and their effects on mechanical properties and microstructure during aluminum bottle production are also addressed. One objective is to increase the proportion of recycled alloyed material used in aluminum bottle manufacturing. Depending on the technique employed, the fraction of alloyed recycled material can vary. The percentage of recycled alloyed material (3xxx series Al alloys) in cold backward impact extrusion could be raised by 60%. High-speed blow forming could facilitate the production of aluminum bottles with a recycled alloyed material ranging from 50 to 100% of the 3xxx series aluminum can body alloys. The high-speed drawing and ironing (DWI) process can produce large-format aluminum bottles (up to 750 mL), utilizing at least 90% of the recycled 3xxx series can body stock. Furthermore, the paper discusses the importance of optimized heat treatment designs in enhancing mechanical properties and controlling microstructural evolution in alloyed aluminum materials, such as 3xxx series alloys. The study concludes with a need for further research to deepen our understanding of the metallurgical aspects of aluminum bottle manufacturing and to optimize the use of recycled aluminum in packaging solutions, with a specific focus on improving mechanical properties and microstructural integrity. This comprehensive review aims to contribute to the development of more sustainable packaging practices in the beverage industry by providing insights into the interplay between manufacturing processes, mechanical properties, and microstructure of aluminum bottles.
Full article
(This article belongs to the Special Issue Progress in Light Alloys)
Open AccessReview
Neutron Macromolecular Crystallography for Biological Samples—Current State and Future Perspectives
by
Samuel John Hjorth-Jensen and Monika Budayova-Spano
Crystals 2024, 14(5), 433; https://doi.org/10.3390/cryst14050433 (registering DOI) - 30 Apr 2024
Abstract
Knowledge of hydrogen locations and protonation states is critical for a fundamental understanding of biological macromolecular function/interactions, and neutron macromolecular crystallography (NMX) is uniquely suited among the experimental structural-determination methods to provide this information. However, despite its potential, NMX remains a relatively niche
[...] Read more.
Knowledge of hydrogen locations and protonation states is critical for a fundamental understanding of biological macromolecular function/interactions, and neutron macromolecular crystallography (NMX) is uniquely suited among the experimental structural-determination methods to provide this information. However, despite its potential, NMX remains a relatively niche technique, due to substantial limitations. This review explores NMX’s role amongst the evolving landscape of structural biology, comparing and contrasting it to the historical gold standard of X-ray macromolecular crystallography (X-ray MX) and the increasingly prevalent electron-based methods—i.e., electron microscopy (EM) and electron diffraction (ED). Forthcoming developments (e.g., the European Spallation Source in Lund, Sweden, coming online) are expected to substantially address current limitations and ensure NMX will remain relevant in the coming decades.
Full article
(This article belongs to the Section Macromolecular Crystals)
Open AccessReview
High-Entropy Engineering in Thermoelectric Materials: A Review
by
Subrata Ghosh, Lavanya Raman, Soumya Sridar and Wenjie Li
Crystals 2024, 14(5), 432; https://doi.org/10.3390/cryst14050432 (registering DOI) - 30 Apr 2024
Abstract
Thermoelectric (TE) materials play a crucial role in converting energy between heat and electricity, essentially for environmentally friendly renewable energy conversion technologies aimed at addressing the global energy crisis. Significant advances in TE performance have been achieved over the past decades in various
[...] Read more.
Thermoelectric (TE) materials play a crucial role in converting energy between heat and electricity, essentially for environmentally friendly renewable energy conversion technologies aimed at addressing the global energy crisis. Significant advances in TE performance have been achieved over the past decades in various TE materials through key approaches, such as nanostructuring, band engineering, and high-entropy engineering. Among them, the design of high-entropy materials has recently emerged as a forefront strategy to achieve significantly low thermal conductivity, attributed to severe lattice distortion and microstructure effects, thereby enhancing the materials’ figure of merit (zT). This review reveals the progress of high-entropy TE materials developed in the past decade. It discusses high-entropy-driven structural stabilization to maintain favorable electrical transport properties, achieving low lattice thermal conductivity, and the impact of high entropy on mechanical properties. Furthermore, the review explores the theoretical development of high-entropy TE material and discusses potential strategies for future advancements in this field through interactions among experimental and theoretical studies.
Full article
(This article belongs to the Section Materials for Energy Applications)
Open AccessArticle
Crystal Growth, Photoluminescence and Radioluminescence Properties of Ce3+-Doped Ba3Y(PO4)3 Crystal
by
Zhenggang Zou, Jiaolin Weng, Chun Liu, Yiyang Lin, Jiawei Zhu, Yijian Sun, Jianhui Huang, Guoliang Gong and Herui Wen
Crystals 2024, 14(5), 431; https://doi.org/10.3390/cryst14050431 (registering DOI) - 30 Apr 2024
Abstract
Inorganic scintillation crystals have been widely used in applications of high-energy physics, nuclear medical imaging, industrial nondestructive inspection, etc. In this work, a single crystal Ba3Y(PO4)3 (BYP) with 1.0 at% Ce3+-doping concentration was first grown by
[...] Read more.
Inorganic scintillation crystals have been widely used in applications of high-energy physics, nuclear medical imaging, industrial nondestructive inspection, etc. In this work, a single crystal Ba3Y(PO4)3 (BYP) with 1.0 at% Ce3+-doping concentration was first grown by the Czochralski method, and the electronic structure was calculated using first principles based on density functional theory. In addition, a series of Ce3+-doped BYP phosphors were synthesized, and the fluorescence emission under UV excitation was measured through low-temperature spectroscopy, containing double-peaked emission from 5d–4f transition and self-trapped exciton recombination. A comparison of the UV and X-ray-excited fluorescence spectra reveals the existence of oxygen vacancies as well as F+ centers in the crystal. The air annealing of the crystal effectively reduces the thermoluminescence defects but reduces the emission intensity under UV or X-ray excitation. The BYP:Ce crystal shows a fast decay lifetime of 15.5 ns, and the fast component is as short as 8 ns. The results show that the Ce3+-doped BYP crystal has potential as a kind of scintillator with fast decay properties.
Full article
(This article belongs to the Section Crystal Engineering)
Open AccessArticle
Synthesis and π-Hole vs. π Effects of Pt(II) Complexes with Pentafluorophenyl and Phenyl-Substituted Bipyridines
by
Akiko Hori, Yuta Takeuchi, Tadashi Kawasaki, Naoki Toyama, Hidetaka Yuge and Takashi Hiroi
Crystals 2024, 14(5), 430; https://doi.org/10.3390/cryst14050430 (registering DOI) - 30 Apr 2024
Abstract
Four types of perfluoroarene-substituted and the corresponding non-fluorinated Pt(II) complexes, [PtCl2L] (L = 1 and 2), were prepared with 4,4′-bis(pentafluorophenyl)-2,2′-bipyridine (1a), 4,4′-diphenyl-2,2′-bipyridine (1b), 4,4′-bis(2-pentafluorophenylethynyl)-2,2′-bipyridine (2a), and 4,4′-bis(2-phenylethynyl)-2,2′-bipyridine (2b), respectively, to
[...] Read more.
Four types of perfluoroarene-substituted and the corresponding non-fluorinated Pt(II) complexes, [PtCl2L] (L = 1 and 2), were prepared with 4,4′-bis(pentafluorophenyl)-2,2′-bipyridine (1a), 4,4′-diphenyl-2,2′-bipyridine (1b), 4,4′-bis(2-pentafluorophenylethynyl)-2,2′-bipyridine (2a), and 4,4′-bis(2-phenylethynyl)-2,2′-bipyridine (2b), respectively, to understand the role of perfluoroaromatic substitution and acetylene linkers on molecular structures and their induced supramolecular associations. The pentafluorophenyl groups lead to significant changes in electron distribution within the Pt(II) complexes, notably causing absorption bands to red-shift due to a metal-to-ligand charge transfer from nucleophilic platinum ions and demonstrating stabilization effects on the bands by fluorination in experimental and theoretical studies. The results of altering electron density and reducing the metal’s nucleophilic tendencies through fluorination and the use of an acetylene linker are discussed, accompanied by crystal structures, the corresponding Hirshfeld surface analysis, and DFT calculations.
Full article
(This article belongs to the Section Crystal Engineering)
Open AccessArticle
Machine Learning-Based Prediction of Stability in High-Entropy Nitride Ceramics
by
Tianyu Lin, Ruolan Wang and Dazhi Liu
Crystals 2024, 14(5), 429; https://doi.org/10.3390/cryst14050429 (registering DOI) - 30 Apr 2024
Abstract
The field of materials science has experienced a transformative shift with the emergence of high-entropy materials (HEMs), which possess a unique combination of properties that traditional single-phase materials lack. Among these, high-entropy nitrides (HENs) stand out for their exceptional mechanical strength, thermal stability,
[...] Read more.
The field of materials science has experienced a transformative shift with the emergence of high-entropy materials (HEMs), which possess a unique combination of properties that traditional single-phase materials lack. Among these, high-entropy nitrides (HENs) stand out for their exceptional mechanical strength, thermal stability, and resistance to extreme environments, making them highly sought after for applications in aerospace, defense, and energy sectors. Central to the design of these materials is their entropy forming ability (EFA), a measure of a material’s propensity to form a single-phase, disordered structure. This study introduces the application of the sure independence screening and sparsifying operator (SISSO), a machine learning technique, to predict the EFA of HEN ceramics. By utilizing a rich dataset curated from theoretical computational data, SISSO has been trained to identify the most critical features contributing to EFA. The model’s strong interpretability allows for the extraction of complex mathematical expressions, providing deep insights into the material’s composition and its impact on EFA. The predictive performance of the SISSO model is meticulously validated against theoretical benchmarks and compared with other machine learning methodologies, demonstrating its superior accuracy and reliability. This research not only contributes to the growing body of knowledge on HEMs but also paves the way for the efficient discovery and development of new HEN materials with tailored properties for advanced technological applications.
Full article
(This article belongs to the Special Issue Advances in High Entropy Ceramics)
Open AccessArticle
Electronic and Structural Properties of Antibacterial Ag–Ti-Based Surfaces: An Ab Initio Theoretical Study
by
Stefanos Papantoniou-Chatzigiosis, Athina C. Galani, Dimitra Fylaktopoylou, Christina Kourti, Androniki Mosxou, Maria E. Nousia, Thomas Anthopoulos, Elefterios Lidorikis and Christina E. Lekka
Crystals 2024, 14(5), 428; https://doi.org/10.3390/cryst14050428 - 30 Apr 2024
Abstract
Coatings with tunable multifunctional features are important for several technological applications. Ti-based materials have been used in diverse applications ranging from metallic diodes in electronic devices up to medical implants. This work uses ab initio calculations to achieve a more fundamental understanding of
[...] Read more.
Coatings with tunable multifunctional features are important for several technological applications. Ti-based materials have been used in diverse applications ranging from metallic diodes in electronic devices up to medical implants. This work uses ab initio calculations to achieve a more fundamental understanding of the structural and electronic properties of β-TiNb and its passive TiO2 film surfaces upon Ag addition, investigating the alterations in the electronic band gap and the stability of the antibacterial coating. We find that Ag’s 4d electrons introduce localized electron states, characterized by bonding features with the favoured Ti first neighbour atoms, approximately −5 eV below the fermi level in both β-TiNb bulk and surface. Ag’s binding energy on β-TiNb(110) depends on the local environment (the lattice site and the type of bonded surface atoms) ranging from −2.70 eV up to −4.21 eV for the adatom on a four-fold Ti site, offering a variety of options for the design of a stable coating or for Ag ion release. In Ti–O terminated anatase and rutile (001) surfaces, surface states are introduced altering the TiO2 band gap. Silver is bonded more strongly, and therefore creates a more stable antibacterial coat on rutile than on anatase. In addition, the Ag coating exhibits enhanced 4d electron states at the highest occupied state on anatase (001),which are extended from −5 eV up to the Fermi level on rutile (001), which might be altered depending on the coat structural features, thus creating systems with tunable electronic band gap that can be used for the design of thin film semiconductors.
Full article
(This article belongs to the Special Issue Advanced Surface Modifications on Materials)
►▼
Show Figures
Figure 1
Open AccessArticle
Influence of Chloride Ion Concentration on Corrosion Behavior of WC–MgO Composite
by
Bowen Fan, Tao Qin, Ying Zhang and Jinyi Wang
Crystals 2024, 14(5), 427; https://doi.org/10.3390/cryst14050427 - 30 Apr 2024
Abstract
The influence of chloride ion (Cl−) concentration on the corrosion mechanism of WC–MgO composites has been studied in this work. The results suggest that the corrosion resistance of WC–MgO composite decreases first and then increases with the increase in Cl−
[...] Read more.
The influence of chloride ion (Cl−) concentration on the corrosion mechanism of WC–MgO composites has been studied in this work. The results suggest that the corrosion resistance of WC–MgO composite decreases first and then increases with the increase in Cl− concentration. Solution conductivity and dissolved oxygen content are the main influence factors. The solution conductivity determines the charge transfer process, and the dissolved oxygen determines the cathodic oxygen absorption reaction. The corrosion characteristic is typical pitting corrosion. Meanwhile, the corrosion mechanism contains an oxidation process of the WC matrix and the dissolution destruction of the MgO toughening phase. The formation of the WO3 corrosion layer hinders the general corrosion to protect the inner material. However, the dissolution of MgO induces the initiation of pitting. The local alkaline caused by MgO dissolution promotes the dissolution of the WC matrix, which leads to the expansion of pitting.
Full article
(This article belongs to the Special Issue Surface Modification Treatments of Metallic Materials)
►▼
Show Figures
Figure 1
Open AccessArticle
Modification and Stabilization of Collapsible Loess Using Diammonium Phosphate Solution
by
Chengjuan Ying, Lingxia Huang, Haiming Chen, Yadong Zhang and Duoxi Yao
Crystals 2024, 14(5), 426; https://doi.org/10.3390/cryst14050426 - 29 Apr 2024
Abstract
The collapsible loess will rapidly soften and lose its bearing capacity when soaked in water. Under a mild condition (20 °C), the biomimetic inorganic agent, diammonium phosphate (DAP), reacts with calcite in the collapsible loess, producing a stronger bonding material, hydroxyapatite (HAP), to
[...] Read more.
The collapsible loess will rapidly soften and lose its bearing capacity when soaked in water. Under a mild condition (20 °C), the biomimetic inorganic agent, diammonium phosphate (DAP), reacts with calcite in the collapsible loess, producing a stronger bonding material, hydroxyapatite (HAP), to modify and stabilize the soil. Uniaxial compression, permeability tests, and morphological analysis using X-ray diffraction and scanning electron microscopy equipped with an energy X-ray dispersive system were used to assess the effectiveness of DAP stabilization on the collapsible loess. The results indicated that HAP improved the inter-particle bonding within the loess, filled the pores within particles, reduced the permeability, and consequently mitigated the collapsibility of the loess. The compressive strength of the DAP-treated loess increased as DAP concentration increased. Following 28 days of curing, the compressive strength of the loess treated with a 3.0 mol/L DAP solution was six times greater than that of the untreated group. DAP’s reinforcement effect on the loess was superior to that of cement. The compressive strength of the DAP-treated loess was about double that of the cement-treated loess and the permeability coefficient was reduced by more than 50% at equivalent solid content. Furthermore, DAP generated 82% fewer carbon emissions compared to Portland cement. Considering eco-friendly and sustainable development, DAP offers a more competitive alternative for modification and stabilization of loess.
Full article
(This article belongs to the Section Inorganic Crystalline Materials)
Open AccessArticle
Polarization Coupling between Ferroelectric Liquids and Ferroelectric Solids: Effects of the Fringing Field Profile
by
Stefano Marni, Raouf Barboza, Ayomide S. Oluwajoba, Riccardo Zamboni and Liana Lucchetti
Crystals 2024, 14(5), 425; https://doi.org/10.3390/cryst14050425 - 29 Apr 2024
Abstract
Recent experiments devoted to characterizing the behavior of sessile ferroelectric liquid droplets on ferroelectric solid substrates have shown the existence of a droplet electromechanical Rayleigh-like instability. The instability is induced by the bulk polarization of the ferroelectric fluid, which couples to the polarization
[...] Read more.
Recent experiments devoted to characterizing the behavior of sessile ferroelectric liquid droplets on ferroelectric solid substrates have shown the existence of a droplet electromechanical Rayleigh-like instability. The instability is induced by the bulk polarization of the ferroelectric fluid, which couples to the polarization of the underlying substrate through its fringing field and solid–fluid interface coupling. With the aim of characterizing this phenomenon, namely the coupling between the polarizations of a fluid and a solid material, we studied the behavior of ferroelectric liquid droplets confined between two solid substrates, arranged in different configurations, realized to generate fringing fields with different profiles. The results show that the features of the droplets instability are indeed affected by the specific fringing field shape in a way dominated by the minimization of the electrostatic energy associated with the bulk polarization of the ferroelectric fluid.
Full article
(This article belongs to the Special Issue Liquid Crystal Research and Novel Applications in the 21st Century)
►▼
Show Figures
Graphical abstract
Open AccessArticle
Construction of a Predictive Model for Dynamic and Static Recrystallization Kinetics of Cast TC21 Titanium Alloy
by
Ziliang Li, Yunpeng Chai, Ling Qin, Yanchun Zhu, Yong Niu, Jiaxin Fan and Zhenwei Yue
Crystals 2024, 14(5), 424; https://doi.org/10.3390/cryst14050424 - 29 Apr 2024
Abstract
In this study, hot compression experiments were conducted on cast TC21 titanium alloy using a Gleeble-1500D thermal simulation compression tester, and the hot-compressed specimens were heat-treated. The data obtained after analyzing the thermal compression of cast TC21 titanium alloy were analyzed to construct
[...] Read more.
In this study, hot compression experiments were conducted on cast TC21 titanium alloy using a Gleeble-1500D thermal simulation compression tester, and the hot-compressed specimens were heat-treated. The data obtained after analyzing the thermal compression of cast TC21 titanium alloy were analyzed to construct a thermal machining diagram with a strain of 0.8 and to optimize the machining window. This study investigated the microstructure of the alloy after hot pressing experiments and heat treatment, applying the study of the microstructure evolution law of cast TC21 titanium alloy. The analysis of the tissue evolution law established the dynamic and static recrystallization volume fraction as a function of heat deformation parameters. The results show that the optimal processing window for cast TC21 titanium alloy is a deformation temperature in the range of 1373 K–1423 K and a strain rate of 0.1 s−1. The increase in deformation volume and deformation temperature both favor recrystallization and make the recrystallization volume fraction increase, but the increase in strain rate will inhibit the increase in the recrystallization degree to some extent. The dynamic and static recrystallization equations for the cast TC21 titanium alloy at different temperatures were constructed. The experimental measurements of recrystallization volume fraction are in good agreement with the predicted values.
Full article
(This article belongs to the Special Issue Solidification Processing of Metal Alloys under External Fields)
Open AccessArticle
Enhancing Salt Stress Tolerance in Rye with ZnO Nanoparticles: Detecting H2O2 as a Stress Biomarker by Nanostructured NiO Electrochemical Sensor
by
Vjaceslavs Gerbreders, Marina Krasovska, Eriks Sledevskis, Irena Mihailova, Valdis Mizers, Jans Keviss and Andrejs Bulanovs
Crystals 2024, 14(5), 423; https://doi.org/10.3390/cryst14050423 - 29 Apr 2024
Abstract
This article is devoted to the study of the effect of ZnO nanoparticles on the development of tolerance to salt stress in rye samples. As a quantitative criterion for assessing the degree of oxidative stress, the amount of H2O2 released
[...] Read more.
This article is devoted to the study of the effect of ZnO nanoparticles on the development of tolerance to salt stress in rye samples. As a quantitative criterion for assessing the degree of oxidative stress, the amount of H2O2 released in the samples during growth was determined. For these purposes, an electrochemical sensor based on hydrothermally synthesized wall-shaped NiO nanostructures was developed. This sensor has been proven to demonstrate high sensitivity (2474 µA·mM−1), a low limit of detection (1.59 µM), good selectivity against common interferents, and excellent long-term stability. The investigation reveals that the incorporation of ZnO nanoparticles in irrigation water notably enhances rye’s ability to combat salt stress, resulting in a decrease in detected H2O2 levels (up to 70%), coupled with beneficial effects on morphological traits and photosynthetic rates.
Full article
(This article belongs to the Special Issue Novel Nanomaterials for Catalytic and Biological Applications (Volume II))
Open AccessArticle
Further Insight into the Manganese(II) 2,2′-Bipyridine-1,1′-dioxide Homoleptic Complex: Single-Crystal X-ray Structure Determination of the Perchlorate Salt and DFT Calculations
by
Jesús Castro, Valentina Ferraro and Marco Bortoluzzi
Crystals 2024, 14(5), 422; https://doi.org/10.3390/cryst14050422 - 29 Apr 2024
Abstract
The homoleptic cationic complex formed by reacting suitable manganese(II) salts with 2,2′-bipyridine-1,1′-dioxide (bipyO2) has been subjected to several studies in the past because of its peculiar absorption and electrochemical features. Here, the first single-crystal X-ray structure determination of a [Mn(bipyO2
[...] Read more.
The homoleptic cationic complex formed by reacting suitable manganese(II) salts with 2,2′-bipyridine-1,1′-dioxide (bipyO2) has been subjected to several studies in the past because of its peculiar absorption and electrochemical features. Here, the first single-crystal X-ray structure determination of a [Mn(bipyO2)3]2+ salt is reported, where the charge of the cation is balanced by perchlorate anions. The hydrated salt [Mn(bipyO2)3](ClO4)2 crystallizes in the monoclinic system (P21/n space group) and the asymmetric unit contains three cationic complexes and six perchlorate anions. The environment of the manganese(II) ions is best described as octahedral, with scarce variations among the three cations in the asymmetric unit. The bipyO2 ligands exhibit κ2 coordination mode, forming seven-membered metallacycles. The X-ray outcomes have been used as the starting point for DFT and TDDFT calculations, aimed to elucidate the charge transfer origin of the noticeable absorption in the visible range. The MLCT nature is confirmed by the hole and electron distributions associated with the spin-allowed transitions. DFT calculations on the related manganese(III) complex indicate that the geometry of [Mn(bipyO2)3]2+ changes only slightly upon oxidation, in agreement with the reversible electrochemical behaviour experimentally observed.
Full article
(This article belongs to the Section Inorganic Crystalline Materials)
►▼
Show Figures
Figure 1
Open AccessArticle
Low-Temperature Migration-Enhanced Epitaxial Growth of High-Quality (InAs)4(GaAs)3/Be-Doped InAlAs Quantum Wells for THz Applications
by
Linsheng Liu, Zhen Deng, Guipeng Liu, Chongtao Kong, Hao Du, Ruolin Chen, Jianfeng Yan, Le Qin, Shuxiang Song, Xinhui Zhang and Wenxin Wang
Crystals 2024, 14(5), 421; https://doi.org/10.3390/cryst14050421 - 29 Apr 2024
Abstract
This investigation explores the structural and electronic properties of low-temperature-grown (InAs)4(GaAs)3/Be-doped InAlAs and InGaAs/Be-doped InAlAs multiple quantum wells (MQWs), utilizing migration-enhanced epitaxy (MEE) and conventional molecular beam epitaxy (MBE) growth mode. Through comprehensive characterization methods including transmission electron microscopy
[...] Read more.
This investigation explores the structural and electronic properties of low-temperature-grown (InAs)4(GaAs)3/Be-doped InAlAs and InGaAs/Be-doped InAlAs multiple quantum wells (MQWs), utilizing migration-enhanced epitaxy (MEE) and conventional molecular beam epitaxy (MBE) growth mode. Through comprehensive characterization methods including transmission electron microscopy (TEM), Raman spectroscopy, atomic force microscopy (AFM), pump–probe transient reflectivity, and Hall effect measurements, the study reveals significant distinctions between the two types of MQWs. The (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown via the MEE mode exhibit enhanced periodicity and interface quality over the InGaAs/Be-InAlAs MQWs grown through the conventional molecule beam epitaxy (MBE) mode, as evidenced by TEM. The AFM results indicate lower surface roughness for the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. Raman spectroscopy reveals weaker disorder-activated modes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs by using the MEE mode. This originates from utilizing the (InAs)4(GaAs)3 short period superlattices rather than InGaAs, which suppresses the arbitrary distribution of Ga and In atoms during the InGaAs growth. Furthermore, pump–probe transient reflectivity measurements show shorter carrier lifetimes in the (InAs)4(GaAs)3/Be-doped InAlAs MQWs, attributed to a higher density of antisite defects. It is noteworthy that room temperature Hall measurements imply that the mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs grown at a low temperature of 250 °C via the MEE mode is superior to that of InGaAs/Be-doped InAlAs MQWs grown in the conventional MBE growth mode, reaching 2230 cm2/V.s. The reason for the higher mobility of (InAs)4(GaAs)3/Be-doped InAlAs MQWs is that this short-period superlattice structure can effectively suppress alloy scattering caused by the arbitrary distribution of In and Ga atoms during the growth process of the InGaAs ternary alloy. These results exhibit the promise of the MEE growth approach for growing high-performance MQWs for advanced optoelectronic applications, notably for high-speed optoelectronic devices like THz photoconductive antennas.
Full article
(This article belongs to the Special Issue Materials and Devices Grown via Molecular Beam Epitaxy)
►▼
Show Figures
Figure 1
Open AccessFeature PaperArticle
Characterization, Concentration, and Speciation of Metal Elements in Copper Slag: Implications for Secondary Metal Recovery
by
Zirou Liu, Xinhang Xu, Li Guo, Qiusong Chen and Chongchong Qi
Crystals 2024, 14(5), 420; https://doi.org/10.3390/cryst14050420 - 29 Apr 2024
Abstract
The treatment of large amounts of copper slag is an unavoidable issue resulting from the high demand for copper during the global transition to a sustainable development path. Metal-rich copper slag might serve as a potential source of metals through secondary recovery. In
[...] Read more.
The treatment of large amounts of copper slag is an unavoidable issue resulting from the high demand for copper during the global transition to a sustainable development path. Metal-rich copper slag might serve as a potential source of metals through secondary recovery. In this study, two copper slags (CS1 and CS2) with different metallurgical properties were characterized, focusing on secondary metal recovery. The X-ray diffraction (XRD) results show that fayalite (Fe2SiO4) and magnetite (Fe3O4) were the main crystalline phases in both CS1 and CS2. In addition, CS2 exhibited a more stable amorphous silicate network than CS1, which was attributed to the differences in the content of Si-O-3NBO linkages. The sequential extraction of Zn, Cu, Fe, and Pb from the slags was also explored, with the Cu content in CS1 being substantially lower than that in CS2. All metals were distributed in the F5 residue fraction. Cu was the most mobile metal as a result of the large proportion of soluble fractions (F1–F3), followed by Zn and Fe. This study explored the chemical speciation of Zn, Cu, Fe, and Pb from copper slags, which has practical implications for secondary metal recovery from such materials.
Full article
(This article belongs to the Section Crystalline Metals and Alloys)
►▼
Show Figures
Graphical abstract
Open AccessArticle
Investigation of the Positive Temperature Coefficient Resistivity of Nb-Doped Ba0.55Sr0.45TiO3 Ceramics
by
Yifei Wang and Xiaoyang Chen
Crystals 2024, 14(5), 419; https://doi.org/10.3390/cryst14050419 - 29 Apr 2024
Abstract
The demands of low-Curie-temperature (~−10 °C) positive temperature coefficient (PTC) thermistors are increasing in advanced precision integrated circuits and other industries. In this paper, the Nb-doped Ba0.55Sr0.45TiO3(BST)-based PTC resistivity materials are reported. The effects of the sintering
[...] Read more.
The demands of low-Curie-temperature (~−10 °C) positive temperature coefficient (PTC) thermistors are increasing in advanced precision integrated circuits and other industries. In this paper, the Nb-doped Ba0.55Sr0.45TiO3(BST)-based PTC resistivity materials are reported. The effects of the sintering process, especially the cooling rate on the PTC properties of the material, are investigated. The results indicate that the Ba0.55Sr0.45Ti0.9985Nb0.0015O3 composition of the prepared PTC ceramics demonstrates promising PTC characteristics. These include a Curie temperature as low as −13 °C, a high temperature coefficient of 0.296 at −3.4 °C, a large enough resistivity change of 3.1 over a narrow phase transition temperature range of approximately 38 °C, and moderate resistivity below the Curie temperature. Such properties suggest that the Ba0.55Sr0.45Ti0.9985Nb0.0015O3 ceramics are likely suitable for use in thermal management systems designed for low-temperature control.
Full article
(This article belongs to the Special Issue Crystal Structure and Dielectric Properties of Ceramics)
►▼
Show Figures
Figure 1
Open AccessArticle
Effect of Changing and Combining Trivalent Metals in the Structural and Electronic Properties of Cu-Based Crystal Delafossite Materials
by
Joeluis Cerutti Torres, Pablo Sánchez-Palencia, José Carlos Jiménez-Sáez, Perla Wahnón and Pablo Palacios
Crystals 2024, 14(5), 418; https://doi.org/10.3390/cryst14050418 - 29 Apr 2024
Abstract
Cu-based ternary oxides with delafossite structure have received considerable attention in recent years for their versatility in a wide range of applications, among which is the possibility to use them in heterostructure solar cells as hole transport layers, due to their promising behavior
[...] Read more.
Cu-based ternary oxides with delafossite structure have received considerable attention in recent years for their versatility in a wide range of applications, among which is the possibility to use them in heterostructure solar cells as hole transport layers, due to their promising behavior as p-type conducting oxides. Ab initio calculations have been performed with density functional theory to investigate the role of the trivalent metal within the CuMO2 structure and the dependence of structural and electronic properties with the species (M = Al, Ga, In, Fe, Cr, Co, Sc, Y) occupying the site of the metal. Generalized Gradient Approximation also including a Hubbard term and nonlocal Heyd–Scuseria–Enzerhof screened hybrid functional schemes were tested and their results were compared. Excellent agreement with experimental lattice parameters and measured gaps have been found. The use of hybrid functionals in HSE approximation considerably improves the bandgaps when compared with the experimental results but takes considerable time to converge, hence the need to explore less demanding methodologies. Trends in the geometry as well as in the electronic properties are discussed, and the effect of mixing different metals (CuMxN1−xO2, M, N being the aforementioned elements) in the geometry and electronic properties of these delafossite materials is investigated. Due to the high cost of HSE calculations, especially when supercells are needed to model several x concentrations, statistical models and techniques based on machine learning have also been explored to predict HSE bandgap values from GGA and structural information.
Full article
(This article belongs to the Special Issue Metal Oxides: Synthesis, Characterization, Theoretical Investigations and Applications)
►▼
Show Figures
Figure 1
Open AccessArticle
Irradiation Effects on Tensile Properties of Reduced Activation Ferritic/Martensitic Steel: A Micromechanical-Damage-Model-Based Numerical Investigation
by
Yifei Liu, Yao Xie, Lei Peng, Jingyi Shi, Shangming Chen and Yongjie Sun
Crystals 2024, 14(5), 417; https://doi.org/10.3390/cryst14050417 - 29 Apr 2024
Abstract
The tensile properties of reduced activation ferritic/martensitic (RAFM) steels are significantly influenced by neutron irradiation. Here, a mechanism-based model taking account of the typical ductile damage process of void nucleation, growth, and coalescence was used to study the temperature and irradiation effects. The
[...] Read more.
The tensile properties of reduced activation ferritic/martensitic (RAFM) steels are significantly influenced by neutron irradiation. Here, a mechanism-based model taking account of the typical ductile damage process of void nucleation, growth, and coalescence was used to study the temperature and irradiation effects. The elastic–plastic response of RAFM steels irradiated up to 20 dpa was investigated by applying the GTN model coupled with different work hardening models. Through a numerical study of tensile curves, the GTN parameters were identified reasonably and satisfying simulation results were obtained. A combination of Swift law and Voce law was used to define the flow behavior of irradiated RAFM steels. The deformation localization could be adjusted effectively via setting the nucleation parameter εn close to the strain where necking occurs. Because εn changed with uniform elongation, εn decreased with the testing temperature and rose with an irradiation temperature above 300 °C. The nucleation parameter fn increased with the testing temperature for RAFM steels before irradiation. For irradiated RAFM steels, fn barely changed when the irradiation temperature was below 300 °C and then it rose at a higher irradiation temperature. Meanwhile, the ultimate strength of the simulated and experimental curves showed good agreement, indicating that this method can be applied to engineering design.
Full article
(This article belongs to the Section Crystalline Metals and Alloys)
►▼
Show Figures
Figure 1
Open AccessArticle
Novel Detector Configurations in Cone-Beam CT Systems: A Simulation Study
by
Evangelia Karali, Christos Michail, George Fountos, Nektarios Kalyvas and Ioannis Valais
Crystals 2024, 14(5), 416; https://doi.org/10.3390/cryst14050416 - 29 Apr 2024
Abstract
Cone-beam computed tomography (CBCT) has emerged in recent years as an adequate alternative to mammography and tomosynthesis due to the several advantages over traditional mammography, including its ability to provide 3D images, its reduced radiation dose, and its ability to image dense breasts
[...] Read more.
Cone-beam computed tomography (CBCT) has emerged in recent years as an adequate alternative to mammography and tomosynthesis due to the several advantages over traditional mammography, including its ability to provide 3D images, its reduced radiation dose, and its ability to image dense breasts more effectively and conduct more effective breast compressions, etc. Furthermore, CBCT is capable of providing images with high sensitivity and specificity, allowing a more accurate evaluation, even of dense breasts, where mammography and tomosynthesis may lead to a false diagnosis. Clinical and experimental CBCT systems rely on cesium iodine (CsI:Tl) scintillators for X-ray energy conversion. This study comprises an investigation among different novel CBCT detector technologies, consisting either of scintillators (BGO, LSO:Ce, LYSO:Ce, LuAG:Ce, CaF2:Eu, LaBr3:Ce) or semiconductors (Silicon, CZT) in order to define the optimum detector design for a future experimental setup, dedicated to breast imaging. For this purpose, a micro-CBCT system was adapted, using GATE v9.2.1, consisting of the aforementioned various detection schemes. Two phantom configurations were selected: (a) an aluminum capillary positioned at the center of the field of view in order to calculate the system’s spatial resolution and (b) a breast phantom consisting of spheres of different materials, such that their characteristics are close to the breast composition. Breast phantom contrast-to-noise ratios (CNRs) were extracted from the phantom’s tomographic images. The images were reconstructed with filtered back projection (FBP) and ordered subsets expectation-maximization (OSEM) algorithms. The semiconductors acted satisfactorily in low-density matter, while LYSO:Ce, LaBr3:Ce, and LuAG:Ce presented adequate CNRs for all the different spheres’ densities. The energy converters that are presented in this study were evaluated for their performance against the standard CsI:Tl crystal.
Full article
(This article belongs to the Special Issue Crystals, Films and Nanocomposite Scintillators Volume III)
►▼
Show Figures
Figure 1
Journal Menu
► ▼ Journal Menu-
- Crystals Home
- Aims & Scope
- Editorial Board
- Reviewer Board
- Topical Advisory Panel
- Instructions for Authors
- Special Issues
- Topics
- Sections & Collections
- Article Processing Charge
- Indexing & Archiving
- Editor’s Choice Articles
- Most Cited & Viewed
- Journal Statistics
- Journal History
- Journal Awards
- Society Collaborations
- Conferences
- Editorial Office
Journal Browser
► ▼ Journal BrowserHighly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Applied Sciences, Crystals, J. Compos. Sci., Materials, Metals
Modern Material Technologies Intended for Industrial Applications
Topic Editors: Tomasz Tański, Andrzej N. Wieczorek, Marcin StaszukDeadline: 30 June 2024
Topic in
Catalysts, Coatings, Crystals, Energies, Materials, Nanomaterials
Interfacial Bonding Design and Applications in Structural and Functional Materials
Topic Editors: Junlei Qi, Pengcheng Wang, Yaotian YanDeadline: 20 July 2024
Topic in
Crystals, Mathematics, Symmetry, Fractal Fract, Axioms
Mathematical Applications of Nonlinear Wave Properties in Crystalline and Dispersive Media
Topic Editors: Mahmoud A.E. Abdelrahman, Emad El-ShewyDeadline: 31 August 2024
Topic in
Acoustics, Crystals, Designs, Environments, Sustainability
Towards Sustainable and Liveable Cities: Recent Advances in Noise Control Measures
Topic Editors: Heow Pueh Lee, Linus Yinn Leng AngDeadline: 30 September 2024
Conferences
Special Issues
Special Issue in
Crystals
Effect of Solvents and Solution Chemistry on the Properties of Perovskite Solar Cells
Guest Editors: Zhanglin Guo, Gyumin KimDeadline: 10 May 2024
Special Issue in
Crystals
Hot Corrosion and Oxidation of Alloys
Guest Editors: Marzena Mitoraj-Królikowska, Marcela E. Trybula, James L. SmialekDeadline: 20 May 2024
Special Issue in
Crystals
Wide Bandgap Semiconductor: GaN and SiC Material and Device
Guest Editors: Hao-chung Kuo, Chun-Hsiung Lin, Kung-Yen LeeDeadline: 30 May 2024
Special Issue in
Crystals
Advances in Low-Dimensional Materials for Electronics and Sensing Applications
Guest Editors: Hu Li, Klaus LeiferDeadline: 20 June 2024
Topical Collections
Topical Collection in
Crystals
Reviews in Liquid Crystals
Collection Editors: Vladimir Chigrinov, Aleksey Kudreyko
Topical Collection in
Crystals
Research on REBCO Films and Conductors
Collection Editors: Pablo Cayado, Jens Hänisch, Hannes Rijckaert