Next Issue
Volume 13, May
Previous Issue
Volume 13, March
 
 

Crystals, Volume 13, Issue 4 (April 2023) – 163 articles

Cover Story (view full-size image): Ni-based single-crystal (SX) superalloys with low specific weight are vital for developing aero engines with a high strength-to-weight ratio. A team in Zhejiang University have designed compositions of a series of new Ni-based superalloys with 3 wt.% Re but without W, whose specific weights are all lower than 8.4 g/cm3. SXs are successfully grown, and a typical γ/γ′ two-phase microstructure has been obtained after solid solution and aging treatments. The new SX alloys have comparable strength to commercial 2nd generation superalloys. Moreover, the topological close-packed phase does not appear at 1050 °C for up to 500 h, indicating excellent phase stability. The current work might provide scientific insights for developing Ni-based SX superalloys with low specific weight. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
15 pages, 2992 KiB  
Article
Optimizing Struvite Crystallization at High Stirring Rates
by Atef Korchef, Salwa Abouda and Imen Souid
Crystals 2023, 13(4), 711; https://doi.org/10.3390/cryst13040711 - 21 Apr 2023
Cited by 4 | Viewed by 1838
Abstract
Phosphorus and ammonium can both be recovered in the presence of magnesium through struvite (MgNH4PO4·6H2O) crystallization. The present work aimed to optimize struvite crystallization at turbulent solution flow. Struvite was crystallized by magnetic stirring at different initial [...] Read more.
Phosphorus and ammonium can both be recovered in the presence of magnesium through struvite (MgNH4PO4·6H2O) crystallization. The present work aimed to optimize struvite crystallization at turbulent solution flow. Struvite was crystallized by magnetic stirring at different initial phosphorus concentrations between 200 and 800 mg·L−1 and high stirring rates between 100 and 700 rpm. The crystals obtained were analyzed by powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. For all experiments, the only phase detected was struvite. It was shown that for an initial phosphorus concentration of 200 mg·L−1, increasing the stirring rate to 500 rpm accelerated the precipitation of struvite, improved the phosphorus removal efficiency, and obtained larger struvite crystals. A decrease in the phosphorus removal efficiency and smaller struvite crystals were obtained at higher stirring rates. This was attributed to the solution turbulence. The limiting effect of turbulence could be overcome by enhancing the initial phosphorus concentration or by lowering the stirring rate. The highest phosphorus removal efficiency (~99%) through large struvite crystals (~400 μm in size) was obtained for an initial phosphorus concentration of 800 mg·L−1 and a stirring rate of 100 rpm. Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation)
Show Figures

Figure 1

14 pages, 2605 KiB  
Article
Crystal Structure of a Chimeric Antigen Receptor (CAR) scFv Domain Rearrangement Forming a VL-VL Dimer
by Jonah Cheung, Shagun Wazir, David R. Bell, James N. Kochenderfer, Wayne A. Hendrickson and Philippe Youkharibache
Crystals 2023, 13(4), 710; https://doi.org/10.3390/cryst13040710 - 21 Apr 2023
Viewed by 3132
Abstract
Chimeric Antigen Receptor T-cell (CAR-T) immunotherapies are dependent upon designed transmembrane proteins to bind target antigens and stimulate an immune response. The success or failure of these CARs is only partially predictable, yet recent work has highlighted the importance of antigen binding scFvs [...] Read more.
Chimeric Antigen Receptor T-cell (CAR-T) immunotherapies are dependent upon designed transmembrane proteins to bind target antigens and stimulate an immune response. The success or failure of these CARs is only partially predictable, yet recent work has highlighted the importance of antigen binding scFvs driving distinct oligomerization states with varied CAR-T efficacy. Here, we sought to determine the extracellular structure of the anti-CD19 CAR 47G4-CD828Z. Unexpectedly, the resolved crystal structure revealed an IgVL homodimer bound along an inverted VL|VL interface. We found that the VL-VH linker, designed to be cleavage resistant, was cleaved, and the VH and CAR hinge domains were absent from the crystal structure lattice. Molecular Dynamics simulations revealed that the inverted VL|VL interface was more stable than the canonical VL|VL configuration. Our work substantiates the need to interrogate the scFv structure and CAR oligomerization state for optimal CAR-T design. Full article
(This article belongs to the Topic Advanced Structural Crystals)
Show Figures

Figure 1

10 pages, 3112 KiB  
Article
High Current Density Trench CAVET on Bulk GaN Substrates with Low-Temperature GaN Suppressing Mg Diffusion
by Xinyi Wen, Kwang Jae Lee, Yusuke Nakazato, Jaeyi Chun and Srabanti Chowdhury
Crystals 2023, 13(4), 709; https://doi.org/10.3390/cryst13040709 - 21 Apr 2023
Cited by 2 | Viewed by 2254
Abstract
We report that, for the first time, a low-temperature GaN (LT-GaN) layer prepared by metal–organic chemical vapor deposition (MOCVD) regrowth was used as a Mg stopping layer (MSL) for a GaN trench current–aperture vertical electron transistor (CAVET) with p-GaN as a carrier blocking [...] Read more.
We report that, for the first time, a low-temperature GaN (LT-GaN) layer prepared by metal–organic chemical vapor deposition (MOCVD) regrowth was used as a Mg stopping layer (MSL) for a GaN trench current–aperture vertical electron transistor (CAVET) with p-GaN as a carrier blocking layer (CBL). Inserting LT-GaN on top of the p-GaN effectively suppresses Mg out-diffusion into the regrown AlGaN/GaN channel, contributing to the high current capability of GaN vertical devices with a p-GaN CBL. With different MOCVD growth conditions, MSLs inserted in trench CAVETs were comprehensively investigated for the influence of MSL regrowth temperature and thickness on device performance. With the best on-state current performance obtained in this study, the trench CAVET with a 100 nm thick MSL regrown at 750 °C shows a high drain current of 3.2 kA/cm2 and a low on-state resistance of 1.2 mΩ∙cm2. The secondary ion mass spectrometry (SIMS) depth profiles show that the trench CAVET with the 100 nm thick MSL regrown at 750 °C has a dramatically decreased Mg diffusion decay rate (~39 nm/decade) in AlGaN/GaN channel, compared to that of the CAVET without a MSL (~104 nm/decade). In developing GaN vertical devices embedded with a Mg-doped p-type layer, the LT-GaN as the MSL demonstrates a promising approach to effectively isolate Mg from the subsequently grown layers. Full article
(This article belongs to the Special Issue Research in GaN-based Materials and Devices)
Show Figures

Figure 1

11 pages, 2875 KiB  
Article
Unveiling the Transporting Mechanism of (Ti0.2Zr0.2Nb0.2Hf0.2Ta0.2)C at Room Temperature
by Tao Liu, Liwen Lei, Jinyong Zhang and Neng Li
Crystals 2023, 13(4), 708; https://doi.org/10.3390/cryst13040708 - 21 Apr 2023
Viewed by 1469
Abstract
High-entropy materials have been widely researched in recent years, and more work on their thermal and electrical properties is still needed. Herein, we fabricate a high-entropy carbide (Ti0.2Zr0.2Nb0.2Hf0.2Ta0.2)C ceramic and report the thermal [...] Read more.
High-entropy materials have been widely researched in recent years, and more work on their thermal and electrical properties is still needed. Herein, we fabricate a high-entropy carbide (Ti0.2Zr0.2Nb0.2Hf0.2Ta0.2)C ceramic and report the thermal and electrical conductivity at room temperature using first-principles calculations and experiments. The movement of phonons is suppressed in high-entropy carbides when analyzing the thermal and electrical conductivity at room temperature, but the movement of electrons is not. After the first-principles calculations on the electronic structure and lattice vibration and experiments, we give the reasons why the rule of mixture can predict electrical conductivity but not thermal conductivity at room temperature. Finally, we outline the cause of the similar lattice patterns between TaC and (Ti0.2Zr0.2Nb0.2Hf0.2Ta0.2)C. Full article
(This article belongs to the Special Issue Ceramics: Processes, Microstructures, and Properties)
Show Figures

Figure 1

13 pages, 7833 KiB  
Article
Enhancement of Intrinsic Temperature Reduction for Plasma Surface-Modified Nanoparticle-Doped Low-Density Polyethylene Films
by Chenlei Qiu, Yiping Qiu, Yinjia Zhang and Lina Cui
Crystals 2023, 13(4), 707; https://doi.org/10.3390/cryst13040707 - 21 Apr 2023
Viewed by 1369
Abstract
The cooling performance of nanoparticle (NP)-doped radiative cooling materials depends on the dispersion of the NPs in the polymer matrix. However, it is a technical challenge to suppress agglomeration of NPs due to their high surface energy, resulting in poor dispersion of the [...] Read more.
The cooling performance of nanoparticle (NP)-doped radiative cooling materials depends on the dispersion of the NPs in the polymer matrix. However, it is a technical challenge to suppress agglomeration of NPs due to their high surface energy, resulting in poor dispersion of the NPs in the polymer matrix. In order to optimize the dispersion of zinc oxide (ZnO) NPs in low-density polyethylene (LDPE), NPs were treated with atmospheric pressure plasmas for 30, 60 and 90 s. The ZnO NPs were dispersed in LDPE using a xylene solution method. The dispersion of the NPs was progressively improved as the plasma-treatment time increased, likely due to the roughened and perhaps also activated NP surfaces by the plasma treatment. This made the transmittances of the films decrease in the solar-radiation band and absorptivity increased monotonically in the high-energy band as the plasma-treatment time increased, while in the mid-infrared band, the films maintained a similar high transmittance to the untreated sample. The differential scanning colorimetry analysis revealed that the crystallinities of the plasma-treated NP-doped samples were similar to those of the untreated sample. The cooling-performance tests showed that the maximum temperature reductions of the films with NP plasma-treated for 0 s, 30 s, 60 s and 90 s were 6.82, 7.90, 9.34 and 10.34 °C, respectively, corresponded to the intrinsic temperature reductions of 7.27, 8.23, 10.54, and 11.40 °C, respectively, when calculated using Cui’s Model. The results of the current study show that a simple one-step atmospheric pressure plasma treatment to the ZnO NPs can indeed improve dispersion of the NPs in LDPE and lead to the greatly improved passive-cooling performance of the film. Full article
(This article belongs to the Special Issue Janus Particles)
Show Figures

Figure 1

13 pages, 31963 KiB  
Article
Microstructures and Mechanical Properties of Annealed Ti50Ni47Fe3 Shape Memory Alloy
by Shuwei Liu, Yanfeng Li, Xiaoyun Song, Yang Yu, Wenjun Ye and Songxiao Hui
Crystals 2023, 13(4), 706; https://doi.org/10.3390/cryst13040706 - 21 Apr 2023
Cited by 3 | Viewed by 1248
Abstract
The effect of annealing temperature on the microstructures and mechanical properties of Ti50Ni47Fe3 (at. %) shape memory alloy was investigated by using a cold-rolled alloy sheet. For this purpose, a scanning electron microscope, electron backscatter diffraction, a transmission [...] Read more.
The effect of annealing temperature on the microstructures and mechanical properties of Ti50Ni47Fe3 (at. %) shape memory alloy was investigated by using a cold-rolled alloy sheet. For this purpose, a scanning electron microscope, electron backscatter diffraction, a transmission electron microscope, X-ray diffraction, tensile tests and Vickers hardness tests were used. The evolution of the microstructures, mechanical properties and fracture morphology of Ti50Ni47Fe3 alloy was studied. The results show that the recovery occurs at an annealing temperature of 500 °C, and the recrystallization occurs at 600 °C. Because of the recrystallization at 600 °C, the <110>//RD texture disappears, and the intensity of the <111>//RD texture decreases; the alloy reaches its maximum elongation while maintaining a high strength, and at this annealing temperature, the alloy has excellent comprehensive mechanical properties. After the temperature exceeds 600 °C, the mechanical properties of the alloy decrease sharply. With the increase of the annealing temperature, the quantity and distribution of elliptical Ti2Ni-phase particles show almost no specific changes. Additionally, with the increase of annealing temperatures to 600 °C, the fracture surface of Ti50Ni47Fe3 alloys becomes flatter. Full article
(This article belongs to the Special Issue Emerging Topics on High Performance Alloys)
Show Figures

Figure 1

12 pages, 6486 KiB  
Article
Microwave-Assisted Synthesis of Room Temperature Long Persistent Luminescent Materials and Their Imaging Applications
by Yong Shen, Yunfei Xia, Ping Li, Shuo Zhang, Linlin Li, Die Hu, Dongfang Shi and Kai Song
Crystals 2023, 13(4), 705; https://doi.org/10.3390/cryst13040705 - 20 Apr 2023
Viewed by 1215
Abstract
In this study, we utilized a simple and efficient microwave heating method with polyethyleneimine (PEI) and phosphate as raw materials to synthesize room temperature persistent luminescence (RTPL) materials that emit phosphorescent light for up to 10 s. Our investigation revealed that the optimal [...] Read more.
In this study, we utilized a simple and efficient microwave heating method with polyethyleneimine (PEI) and phosphate as raw materials to synthesize room temperature persistent luminescence (RTPL) materials that emit phosphorescent light for up to 10 s. Our investigation revealed that the optimal synthesis conditions were a microwave radiation power of 560 W and a heating time of 5 min. The synthesized RTPL materials had an average particle size of 2 nm and exhibited excellent RTPL performance, with optimal excitation and emission wavelengths of 360 nm and 544 nm, respectively. Additionally, these materials displayed good water solubility. We conducted mapping experiments and in situ phosphorescent imaging of plants to showcase the potential applications of RTPL materials in the fields of biological imaging and anti-counterfeiting. Overall, our findings demonstrate the promising potential of these RTPL materials as versatile tools for various practical applications. Full article
(This article belongs to the Special Issue Synthesis, Characterization and Application of Novel Nanoparticles)
Show Figures

Figure 1

10 pages, 2545 KiB  
Communication
Crystal Structures of 3,3′,5,5′-Tetrabromo-4,4′-bipyridine and Co(II) Coordination Polymer Based Thereon
by Ilyas F. Sakhapov, Almaz A. Zagidullin, Alexey B. Dobrynin, Igor A. Litvinov, Dmitry G. Yakhvarov, Mikhail A. Bondarenko, Alexander S. Novikov, Vladimir P. Fedin and Sergey A. Adonin
Crystals 2023, 13(4), 704; https://doi.org/10.3390/cryst13040704 - 20 Apr 2023
Cited by 1 | Viewed by 1643
Abstract
The crystal structure of 3,3′,5,5′-tetrabromo-4,4′-bipyridine (BrBipy, 1) was determined, and the features of non-covalent interactions in solid state were investigated by theoretical methods. Using BrBipy as a linker ligand, 1D coordination polymer {[Co(BrBipy)(NO3)2(CH3OH)2]} (2) was obtained and characterized. Full article
(This article belongs to the Special Issue Mixed-Metal Coordination Polymers)
Show Figures

Figure 1

16 pages, 5905 KiB  
Article
Effect of Phosphorous Content on the Microstructure and Stress Rupture Properties of 15Cr–15Ni Titanium-Modified Austenitic Stainless Steel
by Yufei Qiao, Tian Liang, Sihan Chen, Yuanyuan Ren, Chunming Liu, Yue Qi, Yingche Ma and Kui Liu
Crystals 2023, 13(4), 703; https://doi.org/10.3390/cryst13040703 - 20 Apr 2023
Viewed by 1404
Abstract
The microstructure of solution-annealed and aged tensile properties and the stress rupture properties of 15Cr–15Ni titanium-modified austenitic stainless steel with different phosphorus contents were investigated using OM, SEM and TEM. The results showed that two phosphide morphologies were observed after long-term isothermal aging [...] Read more.
The microstructure of solution-annealed and aged tensile properties and the stress rupture properties of 15Cr–15Ni titanium-modified austenitic stainless steel with different phosphorus contents were investigated using OM, SEM and TEM. The results showed that two phosphide morphologies were observed after long-term isothermal aging at 850 °C for 1000 h. One was the needle-like M2P distributed within the grain. The other was the blocky M3P distributed at the grain boundaries and twins. The tensile properties of the alloy were unaffected by the phosphorus content, but the stress rupture properties were significantly impacted. With the increase in the phosphorus content from 70 ppm to 250 ppm, the stress rupture life increased from 148 to 269.7 h. Since the strengthening effect of phosphides within the grain or at the grain boundary has been shown to improve the stress rupture properties of alloys, many nanosized granular precipitates, such as the sigma phase, carbides and phosphides, have been observed at the grain boundary, capable of alleviating the stress concentration and limit the crack propagation between two phases, improving the strength of the grain boundary. Intragranular needle-like phosphides can hinder dislocation movements effectively, which improves the intragranular strength of alloys. Full article
Show Figures

Figure 1

14 pages, 5200 KiB  
Article
Features of the Spectroscopic Characteristics of Yttrium–Aluminum Garnets Doped with Europium at Different Concentrations
by Nurgul Zhanturina, Daulet Sergeyev, Zukhra Aimaganbetova, Abzal Zhubaev and Karlygash Bizhanova
Crystals 2023, 13(4), 702; https://doi.org/10.3390/cryst13040702 - 20 Apr 2023
Cited by 2 | Viewed by 1340
Abstract
The article presents the results of measuring the luminescence spectra and luminescence excitation spectra for YAG:Eu with europium concentrations of 2, 6, 8, and 10%. The materials were synthesized by solid-phase synthesis. For samples with europium concentrations of 2, 8, and 10%, the [...] Read more.
The article presents the results of measuring the luminescence spectra and luminescence excitation spectra for YAG:Eu with europium concentrations of 2, 6, 8, and 10%. The materials were synthesized by solid-phase synthesis. For samples with europium concentrations of 2, 8, and 10%, the diffraction patterns showed full agreement with the phases. However, the yttrium–aluminum–perovskite phase was present in the sample with a concentration of 6%, even though the samples were obtained under the same conditions. The spectra of the photoluminescence excitation and photoluminescence were recorded for all samples. The concentration dependences of the luminescence bands and luminescence excitation bands were also plotted. The bandgap and absorption spectra were simulated for the sample of YAG:Eu, doped with 2–4 ions of europium for comparison. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
Show Figures

Figure 1

13 pages, 5833 KiB  
Article
An Attempt to Design Thermosalient Crystals by Co-Crystallization: The Twisted Angle between Aromatic Rings
by Xingchen Hu, Yuntian Xiao, Luguang Qi, Yunhe Bai, Ying Sun, Yang Ye and Chuang Xie
Crystals 2023, 13(4), 701; https://doi.org/10.3390/cryst13040701 - 19 Apr 2023
Cited by 2 | Viewed by 1455
Abstract
Thermosalient (TS) crystals have gained considerable attention due to their potential applications in various fields, including in actuators, sensors, energy harvesting, and artificial muscles. Herein, co-crystallization was employed to construct TS crystals by forming a twisted angle between aromatic rings. Two multicomponent trimethoprim [...] Read more.
Thermosalient (TS) crystals have gained considerable attention due to their potential applications in various fields, including in actuators, sensors, energy harvesting, and artificial muscles. Herein, co-crystallization was employed to construct TS crystals by forming a twisted angle between aromatic rings. Two multicomponent trimethoprim (TMP) TS cocrystals, TMP-25HBA and TMP-OA, were obtained. Differential scanning calorimetry (DSC) and variable-temperature powder X-ray diffraction (VT-PXRD) revealed that TMP-OA undergoes a solid-to-solid phase transition, while TMP-25HBA does not exhibit any phase transition. To the best of our knowledge, TMP-25HBA is the first multicomponent TS crystal without phase transition. The TS effect of both crystals is a result of the unit cell’s anisotropic expansion. Full article
Show Figures

Graphical abstract

11 pages, 2992 KiB  
Article
Strain-Induced Band Gap Variation in InGaN/GaN Short Period Superlattices
by Polyxeni Chatzopoulou, Isaak G. Vasileiadis, Philomela Komninou, Vassilis Pontikis, Theodoros Karakostas and George P. Dimitrakopulos
Crystals 2023, 13(4), 700; https://doi.org/10.3390/cryst13040700 - 19 Apr 2023
Cited by 2 | Viewed by 1891
Abstract
The use of strained substrates may overcome indium incorporation limits without inducing plastic relaxation in InGaN quantum wells, and this is particularly important for short-period InGaN/GaN superlattices. By incorporating elastic strain into these heterostructures, their optoelectronic behavior is modified. Our study employed density [...] Read more.
The use of strained substrates may overcome indium incorporation limits without inducing plastic relaxation in InGaN quantum wells, and this is particularly important for short-period InGaN/GaN superlattices. By incorporating elastic strain into these heterostructures, their optoelectronic behavior is modified. Our study employed density functional theory calculations to investigate the variation in the band-gap energy of short-period InGaN/GaN superlattices that comprise pseudomorphic quantum wells with a thickness of just one monolayer. Heterostructures with equibiaxially strained GaN barriers were compared with respective ones with relaxed barriers. The findings reveal a reduction of the band gap for lower indium contents, which is attributed to the influence of the highly strained nitrogen sublattice. However, above mid-range indium compositions, the situation is reversed, and the band gap increases with the indium content. This phenomenon is attributed to the reduction of the compressive strain in the quantum wells caused by the tensile strain of the barriers. Our study also considered local indium clustering induced by phase separation as another possible modifier of the band gap. However, unlike the substrate-controlled strain, this was not found to exert a significant influence on the band gap. Overall, this study provides important insights into the behavior of the band-gap energy of strained superlattices toward optimizing the performance of optoelectronic devices based on InGaN/GaN heterostructures. Full article
(This article belongs to the Special Issue Group-III Nitride Quantum Wells)
Show Figures

Figure 1

10 pages, 4597 KiB  
Article
N-Polar Indium Nitride Quantum Dashes and Quantum Wire-like Structures: MOCVD Growth and Characterization
by Vineeta R. Muthuraj, Wenjian Liu, Henry Collins, Weiyi Li, Robert Hamwey, Steven P. DenBaars, Umesh K. Mishra and Stacia Keller
Crystals 2023, 13(4), 699; https://doi.org/10.3390/cryst13040699 - 19 Apr 2023
Viewed by 1234
Abstract
The electrical properties of InN give it potential for applications in III-nitride electronic devices, and the use of lower-dimensional epitaxial structures could mitigate issues with the high lattice mismatch of InN to GaN (10%). N-polar MOCVD growth of InN was performed to explore [...] Read more.
The electrical properties of InN give it potential for applications in III-nitride electronic devices, and the use of lower-dimensional epitaxial structures could mitigate issues with the high lattice mismatch of InN to GaN (10%). N-polar MOCVD growth of InN was performed to explore the growth parameter space of the horizontal one-dimensional InN quantum wire-like structures on miscut substrates. The InN growth temperature, InN thickness, and NH3 flow during growth were varied to determine optimal quantum wire segment growth conditions. Quantum wire segment formation was observed through AFM images for N-polar InN samples with a low growth temperature of 540 °C and 1–2 nm of InN. Below 1 nm of InN, quantum dashes formed, and 2-D layers were formed above 2 nm of InN. One-dimensional anisotropy of the electrical conduction of N-polar InN wire-like samples was observed through TLM measurements. The sheet resistances of wire-like samples varied from 10–26 kΩ/□ in the longitudinal direction of the wire segments. The high sheet resistances were attributed to the close proximity of the treading dislocations at the InN/GaN interface and might be lowered by reducing the lattice mismatch of InN wire-like structures with the substrate using high lattice constant base layers such as relaxed InGaN. Full article
Show Figures

Figure 1

12 pages, 11736 KiB  
Article
Dry Sliding Wear Behavior and Mild–Severe Wear Transition of the AA2195-T6 Alloy under Different Loads
by Qingqiang Chen, Yalei Yu, Guanjie Ma, Xingzi Sun and Laixiao Lu
Crystals 2023, 13(4), 698; https://doi.org/10.3390/cryst13040698 - 19 Apr 2023
Viewed by 1444
Abstract
The mild–severe wear transition of aluminum alloys is considered evidence that the wear changes from a stable state to an unstable state, which is of great importance in engineering applications. The purpose of this study is to evaluate the mild–severe wear transition of [...] Read more.
The mild–severe wear transition of aluminum alloys is considered evidence that the wear changes from a stable state to an unstable state, which is of great importance in engineering applications. The purpose of this study is to evaluate the mild–severe wear transition of the 2195 Al–Li alloy for different loads and to elucidate the causes behind it. To this end, dry sliding tribometric tests were carried out by varying the normal load from 2 to 40 N at room temperature. The results show that the change in wear rate can be divided into three distinct stages, including weak growth at low load (2–4 N), rapidly increased growth at medium load (8–16 N), and gradually increased growth at high load (32–40 N). The transition from mild to severe wear is observed at loads ranging from 4 to 8 N. Characterization of the worn surface of the Al–Li alloy via scanning electron microscopy shows that abrasion and oxidation are the dominant wear phenomena in the mild wear regime. On the other hand, delamination, adhesion, and severe plastic deformation become dominant in the severe wear regime. The reason for the occurrence of the transition is the tribo-induced plastic deformation of the substrate. Full article
Show Figures

Figure 1

11 pages, 3221 KiB  
Article
Developing the Fast Ionic Transport in the Semiconductor Ionic Heterostructure Composed of La0.8Sr0.2Co0.8Fe0.2-Gd0.1Ce0.9O2 for the Electrolyte Application in Ceramic Fuel Cells
by Dan Zhao, Rong Yan, Naveed Mushtaq, Jiaen Wu, M. A. K. Yousaf Shah, Henghui Li, Yuzheng Lu and Peng Wang
Crystals 2023, 13(4), 697; https://doi.org/10.3390/cryst13040697 - 19 Apr 2023
Cited by 1 | Viewed by 1311
Abstract
The challenging research topic for developing low-temperature ceramic fuel cells (LT-CFCs) is to design electrolytes with sufficient ionic conductivity either via doping or composite semiconductors with ionic conductors. Following this challenging topic, we have developed and synthesized a novel semiconductor ionic heterostructure La [...] Read more.
The challenging research topic for developing low-temperature ceramic fuel cells (LT-CFCs) is to design electrolytes with sufficient ionic conductivity either via doping or composite semiconductors with ionic conductors. Following this challenging topic, we have developed and synthesized a novel semiconductor ionic heterostructure La0.8Sr0.2Co0.8Fe0.2O3-Gd0.1Ce0.9O2 (LSCF-GDC) with different compositions and deployed it as an electrolyte to realize the functionality of the fuel cell. The developed LSCF-GDC electrolyte with mixed conduction of ions and protons possesses high ionic conductivity with only 0.06 Ohm·cm2 of ohmic area-specific resistance for the electrolyte component. The fuel cell using 3LSCF-7GDC as the electrolyte exhibits the best fuel cell performance of 1060 mW·cm−2 and an open circuit voltage (OCV) of 1.11 V at a low operating temperature of 550 °C among individual GDC, LSCF, and different heterostructures of LSCF and GDC. The attained performance and ionic conductivity are specially accredited to constructing heterostructures and massively deficient structures at the interface of the LSCF and GDC. The advanced semiconductor ionic heterostructure of LSCF-GDC provides new insight into designing new electrolytes with high ionic conductivity for LT-CFC applications. Full article
Show Figures

Figure 1

10 pages, 3584 KiB  
Communication
Angular Dependence of Guest–Host Liquid Crystal Devices with High Pretilt Angle Using Mixture of Vertical and Horizontal Alignment Materials
by Masahiro Ito, Eriko Fukuda, Mitsuhiro Akimoto, Hikaru Hoketsu, Yukitaka Nakazono, Haruki Tohriyama and Kohki Takatoh
Crystals 2023, 13(4), 696; https://doi.org/10.3390/cryst13040696 - 19 Apr 2023
Cited by 1 | Viewed by 1442
Abstract
To date, devices exhibiting incidence-angle-dependent transmittance have been fabricated by imparting an angle to a bulk liquid crystal (LC) by aligning the LC in the vicinity of one substrate horizontally (with respect to the substrate) while aligning the LC in the vicinity of [...] Read more.
To date, devices exhibiting incidence-angle-dependent transmittance have been fabricated by imparting an angle to a bulk liquid crystal (LC) by aligning the LC in the vicinity of one substrate horizontally (with respect to the substrate) while aligning the LC in the vicinity of another substrate vertically. Another approach has been to control LC angles near substrates by blending or layering horizontal and vertical alignment films. In this study, we control LC angles near substrates by controlling the pretilt angles of blended alignment films; for specific angles, we use dichroic dyes to characterize the incidence angle dependence of these LC devices. Using a guest/host LC device with a pretilt angle near 45°, we successfully construct an LC element with a transmittance peak near a polar angle of 45°. Full article
(This article belongs to the Special Issue State-of-the-Art Liquid Crystals Research in Japan)
Show Figures

Graphical abstract

10 pages, 3238 KiB  
Article
ZnSe Nanoparticles for Thermoelectrics: Impact of Cu-Doping
by Valeria Demontis, Muhammad Isram, Najaf Abbas Khan, Nasir Amin, Khalid Mahmood and Francesco Rossella
Crystals 2023, 13(4), 695; https://doi.org/10.3390/cryst13040695 - 19 Apr 2023
Viewed by 2052
Abstract
The present study investigates the impact of copper doping on the thermoelectric properties of zinc selenide (ZnSe) nanoparticles synthesized by the hydrothermal method. Nanoparticle samples with varying copper concentrations were prepared and their thermoelectric performances were evaluated by measuring the electrical transport properties, [...] Read more.
The present study investigates the impact of copper doping on the thermoelectric properties of zinc selenide (ZnSe) nanoparticles synthesized by the hydrothermal method. Nanoparticle samples with varying copper concentrations were prepared and their thermoelectric performances were evaluated by measuring the electrical transport properties, the Seebeck coefficient, and extracting the power factor. The results demonstrate that the thermoelectric properties of Cu-doped ZnSe nanoparticles are significantly enhanced by doping, mainly as an effect of an improved electrical conductivity, providing a promising avenue for energy applications of these nanomaterials. To gain further insights into the fundamental mechanisms underlying the observed improvements in thermoelectric performance of the samples, the morphological, structural, and vibrational properties were characterized using a combination of scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Full article
(This article belongs to the Special Issue Nanostructured Thermoelectric Materials)
Show Figures

Figure 1

19 pages, 5744 KiB  
Article
Crystal Structure, Hirshfeld Surface Analysis, and Computational Study of Quinolin-8-yl 4-Chlorobenzoate: Insights from Spectroscopic, Thermal, and Antitumor Properties
by Juan-Carlos Castillo, Diana Becerra and Mario A. Macías
Crystals 2023, 13(4), 694; https://doi.org/10.3390/cryst13040694 - 18 Apr 2023
Cited by 2 | Viewed by 1758
Abstract
We report the time-efficient synthesis of quinolin-8-yl 4-chlorobenzoate (3) via an O-acylation reaction between 8-hydroxyquinoline (1) and 4-chlorobenzoyl chloride (2) mediated by triethylamine in acetonitrile under heating at 80 °C for 20 min in the Monowave [...] Read more.
We report the time-efficient synthesis of quinolin-8-yl 4-chlorobenzoate (3) via an O-acylation reaction between 8-hydroxyquinoline (1) and 4-chlorobenzoyl chloride (2) mediated by triethylamine in acetonitrile under heating at 80 °C for 20 min in the Monowave 50 reactor. This protocol is distinguished by its short reaction time, operational simplicity, and clean reaction profile. The structure of 3 was fully characterized through a combination of analytical techniques, including NMR, IR, and UV–Vis spectroscopy, MS spectrometry, differential scanning calorimetry (DSC), thermogravimetry (TG), and crystallographic studies. Interestingly, X-ray diffraction analyses of 3 show that the crystal structure is characterized by C-H···N, C-H···O, Cl···π, and π···π interactions. The molecular conformation presents an orthogonal orientation between aromatic rings in the solid state. The calculated interaction energies using the CE-B3LYP model show that dispersion forces act in a higher proportion to build the crystal, which is consistent with the few short hydrogen interactions detected. Electrostatic potential maps suggest the formation of σ-holes over the Cl atoms. Although they can behave as both Lewis acid and base sites, Cl··Cl interactions are absent due to the shallow depth of these σ-holes. Quantum chemical descriptors and global reactivity descriptors were examined using the B3LYP method with the 6-31G(d,p) basis set implemented in CrystalExplorer. Finally, compound 3 exhibited low activity against HOP-92 and EKVX non-Small-cell lung and UO-31 Renal cancer cell lines, with a growth inhibition percentage (GI%) ranging from 6.2% to 18.1%. Full article
Show Figures

Figure 1

11 pages, 3519 KiB  
Article
Ellipsometry Characterisation for the Cd1-xZnxTe1-ySey Semiconductor Used in X-ray and Gamma Radiation Detectors
by Lidia Martínez Herraiz, Jose Luis Plaza Canga-argüelles and Alejandro Francisco Braña de Cal
Crystals 2023, 13(4), 693; https://doi.org/10.3390/cryst13040693 - 18 Apr 2023
Viewed by 1144
Abstract
The study of the optical properties of the Cd1-xZnxTe1-ySey (CZTS) crystal provides a clear idea about its response to incident X-ray or gamma radiation. This is important for selecting a proper composition of CZTS to achieve [...] Read more.
The study of the optical properties of the Cd1-xZnxTe1-ySey (CZTS) crystal provides a clear idea about its response to incident X-ray or gamma radiation. This is important for selecting a proper composition of CZTS to achieve superior quality and high-resolution X-ray and gamma radiation detectors at room temperature and reduce their production cost. This article’s novelty is in lowering the cost of the optical and compositional characterisation of CZTS using the ellipsometry technique. The most significant successes achieved are the composition ellipsometry model determination of CZTS based on the Effective Medium Approximation (EMA) substrate of the binary compound CdTe and ZnSe with an oxide layer of CdTe and the experimental verification that the bandgap moves to lower energies with the addition of Se. Full article
(This article belongs to the Topic Advanced Structural Crystals)
Show Figures

Figure 1

12 pages, 4495 KiB  
Article
Intrafibrillar Growth of Hydroxyapatite Nanocrystals in Multiscale Collagen
by Bingyu Xue, Yidi Li, Zhengyi Fu, Hang Ping and Kun Wang
Crystals 2023, 13(4), 692; https://doi.org/10.3390/cryst13040692 - 18 Apr 2023
Cited by 2 | Viewed by 1536
Abstract
Collagen fibrils hierarchically assemble from microscale to macroscale, which endows the natural composite bone with good mechanical properties and remodeling functions. Revealing the intrafibrillar growth process of hydroxyapatite nanocrystals of collagen will guide the research of bone repair or collagen-based composites. Herein, we [...] Read more.
Collagen fibrils hierarchically assemble from microscale to macroscale, which endows the natural composite bone with good mechanical properties and remodeling functions. Revealing the intrafibrillar growth process of hydroxyapatite nanocrystals of collagen will guide the research of bone repair or collagen-based composites. Herein, we investigated the mineralization of multiscale collagen matrices and strongly proved the intrafibrillar hydroxyapatite nanocrystals in the collagen fibrils. The hydroxyapatite nanocrystals were deposited within collagen fibrils with co-orientation along the (002) crystal plane, which is the longitude of the fibril. The whole growth process was captured by TEM to demonstrated the five stages of the intrafibrillar growth process of hydroxyapatite nanocrystals. The infiltration and transformation of amorphous calcium phosphate in isolated collagen fibrils are both demonstrated. The intrafibrillar growth process of hydroxyapatite nanocrystals in collagen film was also investigated, showing that the growth area of collagen films increased linearly with time and the growth process. By studying the in situ mineralization under different reaction conditions, the kinetic equation of the mineralized area of collagen film under each condition was obtained, and the optimal hydroxyapatite mineralized solution was proved to be a solution with polyacrylic acid of 50 μG/mL and a pH of 7.5. Our work provides more detailed information of the growth process of HAP nanocrystals during the mineralization of collagen at different scales and would contribute to future research on the formation process of more minerals in collagen. Full article
(This article belongs to the Special Issue Biomaterials for Medical and Dental Applications)
Show Figures

Figure 1

15 pages, 18665 KiB  
Article
Crystallographic and TEM Features of a TBC/Ti2AlC MAX Phase Interface after 1300 °C Burner Rig Oxidation
by James L. Smialek, Anita Garg, Bryan J. Harder and Michael D. Cuy
Crystals 2023, 13(4), 691; https://doi.org/10.3390/cryst13040691 - 17 Apr 2023
Viewed by 1348
Abstract
A FIB/STEM interfacial study was performed on a TBC/Ti2AlC MAX phase system, oxidized in an aggressive burner rig test (Mach 0.3 at 1300 °C for 500 h). The 7YSZ TBC, α-Al2O3 TGO, and MAXthal 211TM Ti2 [...] Read more.
A FIB/STEM interfacial study was performed on a TBC/Ti2AlC MAX phase system, oxidized in an aggressive burner rig test (Mach 0.3 at 1300 °C for 500 h). The 7YSZ TBC, α-Al2O3 TGO, and MAXthal 211TM Ti2AlC base were variously characterized by TEM/STEM, EDS, SADP, and HRTEM. The YSZ was a mix of “clean” featureless and “faulted” high contrast grains. The latter exhibited ferro-elastic domains of high Y content tetragonal t″ variants. No martensite was observed. The TGO was essentially a duplex α-Al2O3 structure of inner columnar plus outer equiaxed grains. It maintained a perfectly intact, clean interface with the Ti2AlC substrate. The Ti2AlC substrate exhibited no interfacial Al-depletion zone but, rather, numerous faults along the basal plane of the hexagonal structure. These are believed to offer a means of depleting Al by forming crystallographic, low-Al planar defects, proposed as Ti2.5AlC1.5. These characterizations support and augment prior optical, SEM, and XRD findings that demonstrated remarkable durability for the YSZ/Ti2AlC MAX phase system in aggressive burner tests. Full article
(This article belongs to the Section Crystalline Metals and Alloys)
Show Figures

Figure 1

13 pages, 4715 KiB  
Article
Two-Step Solvothermal Process for Nanoarchitectonics of Metastable Hexagonal WO3 Nanoplates
by Zanlin Qiu, Joerg R. Jinschek and Pelagia-Irene Gouma
Crystals 2023, 13(4), 690; https://doi.org/10.3390/cryst13040690 - 17 Apr 2023
Cited by 4 | Viewed by 1963
Abstract
Hexagonal tungsten trioxide (h-WO3) has shown great potential for application in electrochromic devices, gas sensors, battery electrodes, and as photo-catalysts. The h-WO3 structure features a unique large network of open hexagonal channels that allow for intercalation. The hydrothermal synthesis of [...] Read more.
Hexagonal tungsten trioxide (h-WO3) has shown great potential for application in electrochromic devices, gas sensors, battery electrodes, and as photo-catalysts. The h-WO3 structure features a unique large network of open hexagonal channels that allow for intercalation. The hydrothermal synthesis of h-WO3 using sodium tungstate dihydrate as a precursor is widely explored, however, the residual alkaline ions are difficult to eliminate during the synthesis. The solvothermal synthesis using tungsten hexachloride as starting materials largely avoids the use of alkaline ions, but the effect of various synthesis parameters is not well-understood yet. To resolve these ambiguities, this study provides a reliable route to obtain h-WO3 via solvothermal synthesis and dehydration annealing. The effects of precursor concentration, water content, synthesis temperature, and synthesis time, as well as dehydration temperature, on the as-synthesized crystal structure and crystal morphology are studied. Full article
Show Figures

Figure 1

10 pages, 2474 KiB  
Article
High-Performance Nanoplasmonic Enhanced Indium Oxide—UV Photodetectors
by Eric Y. Li, Andrew F. Zhou and Peter X. Feng
Crystals 2023, 13(4), 689; https://doi.org/10.3390/cryst13040689 - 17 Apr 2023
Cited by 2 | Viewed by 1434
Abstract
In this paper, high-performance UV photodetectors have been demonstrated based on indium oxide (In2O3) thin films of approximately 1.5–2 μm thick, synthesized by a simple and quick plasma sputtering deposition approach. After the deposition, the thin-film surface was treated [...] Read more.
In this paper, high-performance UV photodetectors have been demonstrated based on indium oxide (In2O3) thin films of approximately 1.5–2 μm thick, synthesized by a simple and quick plasma sputtering deposition approach. After the deposition, the thin-film surface was treated with 4–5 nm-sized platinum (Pt) nanoparticles. Then, titanium metal electrodes were deposited onto the sample surface to form a metal–semiconductor–metal (MSM) photodetector of 50 mm2 in size. Raman scattering spectroscopy and scanning electron microscope (SEM) were used to study the crystal structure of the synthesized In2O3 film. The nanoplasmonic enhanced In2O3-based UV photodetectors were characterized by various UV wavelengths at different radiation intensities and temperatures. A high responsivity of up to 18 A/W was obtained at 300 nm wavelength when operating at 180 °C. In addition, the fabricated prototypes show a thermally stable baseline and excellent repeatability to a wide range of UV lights with low illumination intensity when operating at such a high temperature. Full article
(This article belongs to the Special Issue 1D and 2D Nanomaterials for Sensor Applications)
Show Figures

Figure 1

14 pages, 1740 KiB  
Article
Determination of the Relationship between Proportional and Non-Proportional Fatigue Damage in Magnesium Alloy AZ31 BF
by Vitor Anes, Francisco Bumba, Luís Reis and Manuel Freitas
Crystals 2023, 13(4), 688; https://doi.org/10.3390/cryst13040688 - 17 Apr 2023
Cited by 1 | Viewed by 1397
Abstract
In this work, the magnesium alloy AZ31BF subjected to proportional and non-proportional loads has been studied. For this purpose, a series of experimental multiaxial fatigue tests were carried out according to the ASTM E466 protocol. The main objective was to determine the relationship [...] Read more.
In this work, the magnesium alloy AZ31BF subjected to proportional and non-proportional loads has been studied. For this purpose, a series of experimental multiaxial fatigue tests were carried out according to the ASTM E466 protocol. The main objective was to determine the relationship between the multiaxial fatigue strength of this alloy under these two different types of loading. The results showed that the AZ31BF magnesium alloy has different fatigue strengths depending on the loading type. Based on these results, it was found that the ratio between proportional and non-proportional damage in AZ31BF magnesium alloy varies depending on the number of loading cycles. To represent this variation, parameter Y was used to modulate the non-proportional damage of AZ31BF. In this way, two Y functions were considered, one for the normal stress component and the other for the shear stress component. The results obtained for the non-proportional parameter Y are of particular interest since the multiaxial fatigue models do not distinguish between these two types of loading when evaluating fatigue life. In this sense, the results of this study can be used in these models to overcome this limitation. Full article
Show Figures

Figure 1

12 pages, 4187 KiB  
Article
Deep-Blue Organic Light-Emitting Diodes Employed Traditional Hole Transporting Material as Emitter for 31-Inch 4K Flexible Display
by Yan Xue, Qiong Nie, Xin Hou, Baolei Wang, Yanbo Chen, Yu Zhang and Lijuan Xiang
Crystals 2023, 13(4), 687; https://doi.org/10.3390/cryst13040687 - 17 Apr 2023
Cited by 2 | Viewed by 1564
Abstract
High-efficiency deep-blue organic light-emitting diodes (OLEDs) play a crucial role in realizing ultra-high-definition (UHD) flat-panel displays and reducing power consumption. Generally, most reported OLEDs with a Commission Internationale de L’Eclairage (CIE) y coordinate < 0.06 are achieved by traditional fluorescent deep-blue emitters. However, [...] Read more.
High-efficiency deep-blue organic light-emitting diodes (OLEDs) play a crucial role in realizing ultra-high-definition (UHD) flat-panel displays and reducing power consumption. Generally, most reported OLEDs with a Commission Internationale de L’Eclairage (CIE) y coordinate < 0.06 are achieved by traditional fluorescent deep-blue emitters. However, it is challenging to obtain deep-blue fluorescent OLEDs with a high external quantum efficiency (EQE) (reaching the theoretical limit of 5%). In this work, we have successfully employed a hole-transporting material for an emitter, which can increase the efficiency in deep-blue OLEDs. The device employed with the proposed hole-transporting material exhibits deep-blue emission peaks at 427.0 nm with CIE coordinates of (0.155, 0.051), a turn-on voltage (Von) of 4.5 V, and an EQE of 4.5%. The performance of the OLED can be improved by 5.0% by optimizing the device structure. Finally, the flexible display when using the OLED devices exhibited a high image quality. Full article
(This article belongs to the Special Issue Feature Paper in "Materials for Energy Applications" 2022–2023)
Show Figures

Figure 1

12 pages, 32644 KiB  
Article
Influence of Strain Amplitude on Low-Cycle Fatigue Behaviors of a Fourth-Generation Ni-Based Single-Crystal Superalloy at 980 °C
by Pengfei Wang, Xinbao Zhao, Quanzhao Yue, Wanshun Xia, Qingqing Ding, Hongbin Bei, Yuefeng Gu, Yuefei Zhang and Ze Zhang
Crystals 2023, 13(4), 686; https://doi.org/10.3390/cryst13040686 - 17 Apr 2023
Viewed by 1766
Abstract
Total strain-control, low-cycle fatigue experiments of a fourth-generation Ni-based single-crystal superalloy were performed at 980 °C. Scanning electron microscopy and transmission electron microscopy are employed to determine fracture morphologies and dislocation characteristics of the samples. As the strain amplitude increased from 0.6 to [...] Read more.
Total strain-control, low-cycle fatigue experiments of a fourth-generation Ni-based single-crystal superalloy were performed at 980 °C. Scanning electron microscopy and transmission electron microscopy are employed to determine fracture morphologies and dislocation characteristics of the samples. As the strain amplitude increased from 0.6 to 1.0%, the cyclic stress and plastic strain per cycle increased, the cyclic lifetime decreased, more interfacial dislocation networks were formed, and the formation rate accelerated. Cyclic hardening is associated with the reaction of accumulated dislocations and dislocation networks, which hinder the movement of dislocations. The presence of interfacial dislocations reduces the lattice mismatch between the γ and γ′ phases, and the presence of dislocation networks that absorb mobile dislocations results in cyclic softening. At a strain amplitude of 1.0%, the reaction of a high density of dislocations results in initial cyclic hardening, and the dislocation cutting into the γ′ phase is one of the reasons for cyclic softening. The crack initiation site changed from a near-surface defect to a surface defect when the strain amplitude increased from 0.6 to 0.8 to 1.0%. The number of secondary cracks initiated from the micropores decreased during the growth stage as the strain amplitude increased. Full article
(This article belongs to the Special Issue Experiments and Simulations of Superalloys)
Show Figures

Figure 1

14 pages, 4842 KiB  
Article
Quantum Chemical Approaches to the Encapsulation of Parathion, Chlorpyrifos and Coumaphos by Armchair and Zigzag Boron Nitride Nanotubes Doped with Aluminum
by Rong-Lieh Wang and Chia Ming Chang
Crystals 2023, 13(4), 685; https://doi.org/10.3390/cryst13040685 - 17 Apr 2023
Viewed by 1730
Abstract
Boron nitride nanotubes have been widely used as drug delivery vehicles and for the controlled release of targeted therapeutic drugs. In this study, we calculated the encapsulation efficiencies of three organophosphorus pesticides, parathion, chlorpyrifos, and coumaphous, using quantum chemical methods. The results show [...] Read more.
Boron nitride nanotubes have been widely used as drug delivery vehicles and for the controlled release of targeted therapeutic drugs. In this study, we calculated the encapsulation efficiencies of three organophosphorus pesticides, parathion, chlorpyrifos, and coumaphous, using quantum chemical methods. The results show that the encapsulation energy of zigzag BNNT(20,0) is lower than that of armchair BNNT(12,12) to encapsulate parathion. Al doping helps to decrease the encapsulation energy and Al-doped zigzag BNNT(20,0) + parathion has the greatest binding affinity. In addition, the energy gap of armchair BNNT(12,12) encapsulating organophosphorus pesticides changed significantly. Al doping reduces the band gap of boron nitride nanotubes. Al-doped armchair BNNT(12,12) has the strongest electron-accepting ability and is a promising sensor material. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
Show Figures

Figure 1

11 pages, 3671 KiB  
Article
Growth Mechanism of Eutectic Si in Super-Gravity Solidified Al-Si Alloy during Annealing
by Yuehui Lu, Chuandong Wu, Hao Wu, Jiamin Wang, Yin Su, Zhanghua Gan and Jing Liu
Crystals 2023, 13(4), 684; https://doi.org/10.3390/cryst13040684 - 17 Apr 2023
Cited by 3 | Viewed by 1457
Abstract
Herein, we report that the influence of annealing time on the microstructure and mechanical properties of Al-14.5Si alloys solidified under a super-gravity field. The results indicate that the coarsening of metastable eutectic Si and formation of precipitated Si could be observed at the [...] Read more.
Herein, we report that the influence of annealing time on the microstructure and mechanical properties of Al-14.5Si alloys solidified under a super-gravity field. The results indicate that the coarsening of metastable eutectic Si and formation of precipitated Si could be observed at the early stage of annealing. A slight increase in yield strength and tensile strength could be observed in the sample annealed for 0.25 h, which can be ascribed to the formation of precipitated Si with limited size during the early stage of annealing. The intensified diffusion of Si atoms during annealing led to the coarsening and coalescence of the eutectic Si, as well as the coarsening of precipitated Si with further extension of the annealing time. Full article
(This article belongs to the Special Issue Advances of Aluminum Alloys: Innovation and Application Potential)
Show Figures

Figure 1

9 pages, 2578 KiB  
Article
Laser Processing of Liquid Crystal Droplets with Diverse Internal Structures
by Jin-Kun Guo, Jinzhong Ling, Ying Yuan, Fengjiao Chang, Xiaorui Wang and Jang-Kun Song
Crystals 2023, 13(4), 683; https://doi.org/10.3390/cryst13040683 - 16 Apr 2023
Cited by 5 | Viewed by 2135
Abstract
To control the spatial placement and organize micro/nanodroplets (NDs) has fundamental importance both in science and engineering. Cholesteric liquid crystal (CLC) droplets with topological diversity can offer many self-assembly modalities to arrange guest NDs in their spherical confinement; however, limited progress has been [...] Read more.
To control the spatial placement and organize micro/nanodroplets (NDs) has fundamental importance both in science and engineering. Cholesteric liquid crystal (CLC) droplets with topological diversity can offer many self-assembly modalities to arrange guest NDs in their spherical confinement; however, limited progress has been achieved due to difficulties of loading NDs into stabilized host droplets. Here, a laser injection technique is introduced, through which a controlled number of NDs were injected from a pre-selected location onto the surface of the host droplet. The sequentially injected NDs spontaneously drifted toward areas with topological defects and self-assembled along its geometry or local director field into a predefined shape. Within CLC droplets with different topological structures, guest NDs self-assembled near areas with defect points as twisting radial chains and quill-like assembly structures, and along defect lines as discrete beads and helical threads, respectively. The injection speed of the NDs, controlled by laser power, was found to play a key role in the assembly geometry of NDs as well as the internal structure of the CLC droplet processed. This study expands our abilities to precisely organize NDs in a spherical confinement and such droplet-based microsystems have potential applications for sensors, photonic devices, pharmaceuticals, and biotechnology. Full article
(This article belongs to the Special Issue Liquid Crystals and Their Advanced Applications)
Show Figures

Figure 1

9 pages, 4420 KiB  
Communication
Ab-Initio Calculation of the Electrical Conductivity, Optical Absorption, and Reflectivity of the 2D Materials SnC and NbC
by Nadxiieli Delgado, Osiris Salas, Erick Garcés and Luis Fernando Magaña
Crystals 2023, 13(4), 682; https://doi.org/10.3390/cryst13040682 - 16 Apr 2023
Cited by 1 | Viewed by 2099
Abstract
Using density functional theory (DFT), we performed first-principles calculations of the electrical conductivity, optical absorption, and reflectivity for the 2D carbides SnC and NbC. We calculated the electronic energy band structure of the materials. We performed the calculations without considering the spin–orbit coupling [...] Read more.
Using density functional theory (DFT), we performed first-principles calculations of the electrical conductivity, optical absorption, and reflectivity for the 2D carbides SnC and NbC. We calculated the electronic energy band structure of the materials. We performed the calculations without considering the spin–orbit coupling (SOC) term and including it. We determined that 2D SnC is a semiconductor material and 2D NbC is a conductor. We compared the optical absorption and reflectivity with those of graphene. We found that the 2D SnC and graphene optical absorptions in the infrared region are similar and small; the corresponding values for 2D NbC are approximately ten times larger. In the visible range, the absorption values for 2D SnC and 2D NbC are of the same magnitude and much more significant than graphene. We found that the 2D NbC optical absorption for the ultraviolet region was close to zero. Graphene and 2D SnC have similar maximum values for absorption but at different energies. We determined that graphene reflectivity is larger but similar to that of 2D NbC, and that the 2D SnC reflectivity is near zero. Finally, the 2D NbC electrical conductivity value was about ten times larger than the corresponding value for 2D SnC. As expected, when there was a change of dimensionality, the related 3D materials showed a vastly different value for the electrical conductivity. The 2D materials showed conductivities significantly smaller than those of 3D materials in both cases. The results we obtained for 2D SnC and 2D NbC when we included the SOC term showed that the electrical conductivity for 2D SnC increased by 13.18% and 2D NbC by 18.16%. The optical properties changed, particularly the location of the peaks in the optical absorption and reflectivity. Full article
(This article belongs to the Special Issue 2D Crystalline Nanomaterials)
Show Figures

Figure 1

Previous Issue
Next Issue
Back to TopTop