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
Thermal Field Simulation and Optimization of PbF2 Single Crystal Growth by the Bridgman Method
Crystals 2024, 14(5), 473; https://doi.org/10.3390/cryst14050473 - 17 May 2024
Abstract
PbF2 single crystals are usually grown in the temperature gradient region by the Bridgman–Stockbarger method. Temperature distribution during the growth process is particularly important for the preparation of high-quality crystals. In this study, the temperature field during the growth of the PbF
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PbF2 single crystals are usually grown in the temperature gradient region by the Bridgman–Stockbarger method. Temperature distribution during the growth process is particularly important for the preparation of high-quality crystals. In this study, the temperature field during the growth of the PbF2 single crystals was simulated based on the finite element method. The temperature distribution and temperature gradient changes in the crucible were investigated at different growth stages, including the seeding, shouldering, and iso-diameters stages. The calculated results show that as the crucible position continues downward during the growth process, the axial temperature gradient increases and then decreases from the bottom to the top of the crucible, with almost flat isotherms near the solid–liquid interface where the axial temperature gradient is larger. At the shoulder below the crucible, the solid–liquid interface was improved by adjusting the tilt angle. Furthermore, based on a novel design of the heat-insulating baffle, the concave solid–liquid interface in the iso-diameter stage can be effectively adjusted to realize a lower radial temperature gradient. This study provides theoretical guidance for the optimization of the growth of high-quality PbF2 crystals by the Bridgman method.
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(This article belongs to the Special Issue Photoelectric Functional Crystals)
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Al-Rich Titanites from Mont Blanc Alpine Fissures: Evidence of Ti-Nb-Y-REE Mobility during Water–Rock Interactions
by
Michel Cathelineau and Chantal Peiffert
Crystals 2024, 14(5), 472; https://doi.org/10.3390/cryst14050472 - 17 May 2024
Abstract
Titanites can be excellent markers of element transfer in medium-temperature retrograde metamorphism. Euhedral titanites from several alpine fissures from Mont Blanc, particularly those of Périades and Courtes, crystallised at the end of the main quartz stage and are synchronous with the formation of
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Titanites can be excellent markers of element transfer in medium-temperature retrograde metamorphism. Euhedral titanites from several alpine fissures from Mont Blanc, particularly those of Périades and Courtes, crystallised at the end of the main quartz stage and are synchronous with the formation of green biotites and albite before chlorite formation. Micro-XRF, SEM, electron probe, and LA-ICP-MS analyses show that these titanites have a wide range of Al2O3 content from 1 to 8%, are dominated by -OH versus F, and have a wide range of Nb (up to 4500 ppm), Y (up to 3000 ppm), Zr (up to 1800 ppm), and Sn (up to 1400 ppm) concentrations. The allanite from the granite, partly destabilised into epidote, is the most likely source of Nb, Y, Zr, Sn, and REE. Titanites are enriched in HREE and show variations in LREE depending on the studied sites. Like quartz, they formed at around 400 ± 20 °C, which is compatible with the formation of green biotites after the destabilisation of granite Fe-Mg silicates. This early stage of fluid circulation, synchronous with the Mont Blanc massif uplift, is therefore marked by the titanite formation at the transition between the biotite and chlorite stability fields.
Full article
(This article belongs to the Section Mineralogical Crystallography and Biomineralization)
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Open AccessCommunication
Role of Longitudinal Temperature Gradients in Eliminating Interleaving Inclusions in Casting of Monocrystalline Silicon Ingots
by
Lindong Li and Changbo Fu
Crystals 2024, 14(5), 471; https://doi.org/10.3390/cryst14050471 - 17 May 2024
Abstract
Infrared analysis reveals the presence of interwoven inclusions, primarily comprised of silicon nitride and silicon carbide, in the casting process of monocrystalline silicon ingots. This study investigates how the longitudinal temperature gradient affects the removal of inclusions during the casting of monocrystalline silicon
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Infrared analysis reveals the presence of interwoven inclusions, primarily comprised of silicon nitride and silicon carbide, in the casting process of monocrystalline silicon ingots. This study investigates how the longitudinal temperature gradient affects the removal of inclusions during the casting of monocrystalline silicon ingots through simulations and comparative experiments. Two monocrystalline silicon ingots were cast, each using different longitudinal temperature gradients: one employing smaller gradients and the other conventional gradients. CGSim (Version Basic CGSim 23.1) simulation software was utilized to analyze the melt flow and temperature distribution during the growth process of quasi–monocrystalline silicon ingots. The findings indicate that smaller longitudinal temperature gradients lead to a more robust upward flow of molten silicon at the solid–liquid interface, effectively carrying impurities away from this interface and preventing their inclusion formation. Analysis of experimental photoluminescence and IR results reveals that although inclusions may not be observed, impurities persist but are gradually displaced to the top of the silicon melt through a stable growth process.
Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation, Second Edition)
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Open AccessArticle
Surface Enhancement of Titanium-Based Coatings on Commercial Hard Steel Cutting Tools
by
Minh Nhat Dang, Surinder Singh, Hannah J. King, John H. Navarro-Devia, Hoang Le, Thomas G. Pattison, Rosalie K. Hocking, Scott A. Wade, Guy Stephens, Angelo Papageorgiou, Armando Manzano and James Wang
Crystals 2024, 14(5), 470; https://doi.org/10.3390/cryst14050470 - 17 May 2024
Abstract
This study investigates the mechanical properties, surface integrity, and chemical configuration of PVD-coated high-speed steel (HSS) cutting tools, with a particular focus on titanium nitride (TiN) and titanium aluminium nitride (TiAlN) coatings. A range of characterisation methodologies were employed to examine the impact
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This study investigates the mechanical properties, surface integrity, and chemical configuration of PVD-coated high-speed steel (HSS) cutting tools, with a particular focus on titanium nitride (TiN) and titanium aluminium nitride (TiAlN) coatings. A range of characterisation methodologies were employed to examine the impact of pre-coating surface conditions on the resulting coatings. This impact includes the effects of gas bubble production and unequal distribution of elements, which are two unwanted occurrences. Notwithstanding these difficulties, coatings applied on surfaces that were highly polished exhibited more consistency in their mechanical and elemental characteristics, with a thickness ranging from 2 to 4 µm. The study of mechanical characteristics confirms a significant increase in hardness, from an initial value of roughly 1000 HV0.5 for untreated tools to 1300 HV0.5 for tools with physical vapour deposition (PVD) coatings. Although PVD coatings produced on an industrial scale might not exceed the quality of coatings manufactured in a laboratory, they do offer substantial enhancements in terms of hardness. This study highlights the significant importance of thorough surface preparation in achieving enhanced coating performance, hence contributing to the efforts to prolong the lifespan of tools and enhance their performance even under demanding operational circumstances.
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(This article belongs to the Section Crystalline Metals and Alloys)
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Open AccessArticle
Cobalt and Iron Cyano Benzene Bis(Dithiolene) Complexes
by
António G. Costa, Gonçalo Lopes, João F. G. Rodrigues, Isabel C. Santos, Dulce Simão, Elsa B. Lopes, Laura C. J. Pereira, Nolwenn Le Breton, Sylvie Choua, Stéphane A. Baudron, Manuel Almeida and Sandra Rabaça
Crystals 2024, 14(5), 469; https://doi.org/10.3390/cryst14050469 - 17 May 2024
Abstract
New iron and cobalt bis(dithiolene) complexes [M(3cbdt)2] (3cbdt = 3-cyanobenzene-1,2-dithiolate) were prepared as tetraphenylphosphonium (Ph4P+) salts for Fe in the monoanionic state and for Co in both the dianionic and monoanionic states: (Ph4P)2[Fe(III)(3cbdt)
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New iron and cobalt bis(dithiolene) complexes [M(3cbdt)2] (3cbdt = 3-cyanobenzene-1,2-dithiolate) were prepared as tetraphenylphosphonium (Ph4P+) salts for Fe in the monoanionic state and for Co in both the dianionic and monoanionic states: (Ph4P)2[Fe(III)(3cbdt)2]2 (1); (Ph4P)2[Co(III)(3cbdt)2]2 (2); (Ph4P)2[Co(II)(3cbdt)2] (3). These compounds were characterized by single-crystal X-ray diffraction, cyclic voltammetry, EPR, and static magnetic susceptibility. Their properties are discussed in comparison with the corresponding complexes based on the isomer ligand 4-cyanobenzene-1,2-dithiolate (4cbdt) and 4,5-cyanobenzene-1,2-dithiolate (dcbdt), previously described by us. The Fe(III) and the Co(III) compounds (1 and 2) are isostructural, crystallizing in the triclinic space group, with cis [M(III)(3cbdt)2] complexes dimerized in a trans fashion, and the transition metal (M = Fe, Co) has a distorted 4+1 square pyramidal coordination geometry. The Co(II) compound (3) crystallizes in the triclinic space group, with the unit cell containing one cis and three trans inequivalent [Co(II)(3cbdt)2] complexes with the transition metal (Co) and having a square planar coordination geometry. The Fe(III) complex (1) is EPR-silent, and the static magnetic susceptibility shows a temperature dependence typical of dimers of antiferromagnetically coupled S = 3/2 spins with −J/kB = 233.6 K and g = 1.8. Static magnetic susceptibility measurements of compound (3) show that this Co(II) complex is paramagnetic, corresponding to an S = ½ state with g = 2, in agreement with EPR spectra showing in solid state a hyperfine structure typical of the I(59Co) = 7/2. Static susceptibility measurements of Co(III) complex (2) showed an increase in the paramagnetic susceptibility upon warming above 100 K, which is consistent with strong AFM coupling between dimerized S = 1 units with a constant −J/kB ~1286 K.
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(This article belongs to the Section Inorganic Crystalline Materials)
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Open AccessArticle
Low Temperature Raman Spectroscopy of Tetrahydrofuran: Phonon Spectra Compared to Matrix Isolation Spectra in Air
by
Vlasta Mohaček-Grošev
Crystals 2024, 14(5), 468; https://doi.org/10.3390/cryst14050468 - 16 May 2024
Abstract
The conformation of tetrahydrofuran (THF) molecules in vapor has been the subject of considerable computational and experimental studies, the most recent by Park and Kwon stated that the difference between the most stable, twisted C2 conformer and the bent Cs conformer
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The conformation of tetrahydrofuran (THF) molecules in vapor has been the subject of considerable computational and experimental studies, the most recent by Park and Kwon stated that the difference between the most stable, twisted C2 conformer and the bent Cs conformer is 17 ± 15 cm−1. Because of low symmetry, all modes from both conformers are allowed in the Raman and infrared spectra. In 1982, Aleksanyan and Antipov observed the emergence of two Raman bands at 249 and 303 cm−1 at 20 K, while only one band at 293 cm−1 was present in solid THF at 142. They assigned the 249 cm−1 band to the restricted pseudorotational motion of THF in the solid state, because on heating, the band diminishes and is too weak to be observed near melting point (at 142 K). Cadioli et al. reported a study of the vibrational spectrum of tetrahydrofuran, giving a complete assignment of all bands including those present in the low-temperature Raman spectrum at 85 K and infrared bands observed at 90 K. They assigned the band at 242 cm−1 in the Raman spectrum at 85 K as an overtone of the lowest normal mode (pseudorotational mode), while the 299 cm−1 band in the same spectrum was assigned as a radial mode. In the following, low-temperature Raman spectra of solid THF together with the Raman matrix isolated spectrum of THF in air will be presented and compared to published data. Our results indicate that the band observed at 245 cm−1 at 10 K is too strong to be assigned as an overtone, since its intensity is of the same magnitude as the 299 cm−1 band.
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(This article belongs to the Section Organic Crystalline Materials)
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First-Principles Calculations of P-B Co-Doped Cluster N-Type Diamond
by
Huaqing Lan, Sheng Yang, Wen Yang, Maoyun Di, Hongxing Wang, Yuming Tian and Kaiyue Wang
Crystals 2024, 14(5), 467; https://doi.org/10.3390/cryst14050467 - 16 May 2024
Abstract
To achieve n-type doping in diamond, extensive investigations employing first principles have been conducted on various models of phosphorus doping and boron–phosphorus co-doping. The primary focus of this study is to comprehensively analyze the formation energy, band structure, density of states, and ionization
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To achieve n-type doping in diamond, extensive investigations employing first principles have been conducted on various models of phosphorus doping and boron–phosphorus co-doping. The primary focus of this study is to comprehensively analyze the formation energy, band structure, density of states, and ionization energy of these structures. It is observed that within a diamond structure solely composed of phosphorus atoms, the formation energy of an individual carbon atom is excessively high. However, the P-V complex substitutes 2 of the 216 carbon atoms, leading to the transformation of diamond from an insulator to a p-type semiconductor. Upon examining the P-B co-doped structure, it is revealed that the doped impurities exhibit a tendency to form more stable cluster configurations. As the separation between the individually doped atoms and the cluster impurity structure increases, the overall stability of the structure diminishes, consequently resulting in an elevation of the ionization energy. Examination of the electronic density of states indicates that the contribution of B atoms to the impurity level is negligible in the case of P-B doping.
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(This article belongs to the Section Crystal Engineering)
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Open AccessFeature PaperReview
Reversible Crosslinking of LC-Materials by Gel-Formation
by
Rudolf Zentel
Crystals 2024, 14(5), 466; https://doi.org/10.3390/cryst14050466 - 16 May 2024
Abstract
The topic of this review is the physical gelling of liquid crystalline (LC) phases. It allows the combination of order and mobility of the LC-phase with macroscopic stability, which makes it a soft material. Thus, the gelled LCs acquire properties of LC-elastomers without
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The topic of this review is the physical gelling of liquid crystalline (LC) phases. It allows the combination of order and mobility of the LC-phase with macroscopic stability, which makes it a soft material. Thus, the gelled LCs acquire properties of LC-elastomers without the need for complicated chemistry to allow polymerization and crosslinking. But, instead, an LC-material (either a pure compound or a mixture) can be mixed with a few percent of a gel-forming agent, which self-assembles into long fibers that span the volume of the gel and make it a soft-solid. The use of azo-containing gel-forming agents thereby allows us to make gelation not only thermo-responsive, but also photo-responsive (trans-cis isomerization). This review discusses the micro-morphology of the gelled LCs and their influence on the mechanical properties and the switching in external electric fields. In addition, the potential of reversibility is discussed, which is not only interesting for recycling purposes, but also offers a route to inscribe a complex director pattern into the gelled liquid crystal.
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(This article belongs to the Special Issue Liquid Crystal Materials and Devices)
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Microstructural Optimization of Sn-58Bi Low-Temperature Solder Fabricated by Intense Pulsed Light (IPL) Irradiation
by
Hyeri Go, Taejoon Noh, Seung-Boo Jung and Yoonchul Sohn
Crystals 2024, 14(5), 465; https://doi.org/10.3390/cryst14050465 - 16 May 2024
Abstract
In this study, intense pulsed light (IPL) soldering was employed on Sn-58Bi solder pastes with two distinct particle sizes (T3: 25–45 μm and T9: 1–8 μm) to investigate the correlation between the solder microstructure and mechanical properties as a function of IPL irradiation
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In this study, intense pulsed light (IPL) soldering was employed on Sn-58Bi solder pastes with two distinct particle sizes (T3: 25–45 μm and T9: 1–8 μm) to investigate the correlation between the solder microstructure and mechanical properties as a function of IPL irradiation times. During IPL soldering, a gradual transition from an immature to a refined to a coarsened microstructure was observed in the solder, impacting its mechanical strength (hardness), which initially exhibited a slight increase followed by a subsequent decrease. It is noted that hardness measurements taken during the immature stage may exhibit slight deviations from the Hall–Petch relationship. Experimental findings revealed that as the number of IPL irradiation sessions increased, solder particles progressively coalesced, forming a unified mass after 30 sessions. Subsequently, after 30–40 IPL sessions, notable voids were observed within the T3 solder, while fewer voids were detected at the T9-ENIG interface. Following IPL soldering, a thin layered structure of Ni3Sn4 intermetallic compound (IMC) was observed at the Sn-58Bi/ENIG interface. In contrast, reflow soldering resulted in the abundant formation of rod-shaped Ni3Sn4 IMCs not only at the reaction interface but also within the solder bulk, accompanied by the notable presence of a P-rich layer beneath the IMC.
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(This article belongs to the Special Issue Welding and Joining of Metallic Materials: Microstructure and Mechanical Properties)
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Removal of Organic Materials from Mytilus Shells and Their Morphological and Chemical-Physical Characterisation
by
Alberto Ubaldini, Flavio Cicconi, Sara Calistri, Stefano Salvi, Chiara Telloli, Giuseppe Marghella, Alessandro Gessi, Stefania Bruni, Naomi Falsini and Antonietta Rizzo
Crystals 2024, 14(5), 464; https://doi.org/10.3390/cryst14050464 - 16 May 2024
Abstract
A simple and effective method to eliminate the organic component from mussel shells is presented. It is based on the use of hot hydrogen peroxide. Mollusc shells are composite materials made of a calcium carbonate matrix with different polymorphs and numerous biomacromolecules. The
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A simple and effective method to eliminate the organic component from mussel shells is presented. It is based on the use of hot hydrogen peroxide. Mollusc shells are composite materials made of a calcium carbonate matrix with different polymorphs and numerous biomacromolecules. The described method was used on mussel shells, but it is generalisable and allows the complete removal of these organic components, without altering the inorganic part. Specimens were kept in a H2O2 40% bath for few hours at 70 °C. The organic layers found on the faces of the shells were peeled away in this way, and biomacromolecules were degraded and removed. Their fragments are soluble in aqueous solution. This easily permits the chemical-physical characterisation and the study of the microstructure. The quality of calcite and aragonite microcrystals of biogenic origin is very high, superior to that of materials of geological or synthetic origin. This may suggest various industrial applications for them. Calcium carbonate is a useful precursor for cements and other building materials, and the one obtained in this way is of excellent quality and high purity.
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(This article belongs to the Special Issue Polycrystalline Materials – from Design to (Micro)Structural Characterization and Applications)
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Open AccessArticle
Mineralization of Octacalcium Phosphate under Magnetic Field
by
Wenhao He, Bingyu Xue, Qi Qian, Shenye Chen, Zhengyi Fu and Kun Wang
Crystals 2024, 14(5), 463; https://doi.org/10.3390/cryst14050463 - 16 May 2024
Abstract
The mineralization of octacalcium phosphate (OCP) crystals in gel media was studied in the presence of a magnetic field. OCP crystal growth was found to be dependent on mineralization temperature, mineralization time, and the magnetic field. Higher temperatures significantly reduced the mineralization time,
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The mineralization of octacalcium phosphate (OCP) crystals in gel media was studied in the presence of a magnetic field. OCP crystal growth was found to be dependent on mineralization temperature, mineralization time, and the magnetic field. Higher temperatures significantly reduced the mineralization time, which is crucial for directional growth of OCP crystals. The growth of OCP crystals was accelerated by the applied magnetic field, while OCP crystals generated in the presence of a magnetic field exhibited increased length and width of oriented growth. This study provides valuable insights into the influence of mineralization factors in bioprocessing-inspired manufacturing processes.
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(This article belongs to the Section Mineralogical Crystallography and Biomineralization)
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Ozone-Assisted Hydrothermal Synthesis Method of Sb-Doped SnO2 Conductive Nanoparticles for Carbon-Free Oxygen-Reduction-Reaction Catalysts of Proton-Exchange-Membrane Hydrogen Fuel Cells
by
Takeshi Fukuda, Kenji Iimura, Takanori Yamamoto, Ryuki Tsuji, Maito Tanabe, Seiji Nakashima, Naoki Fukumuro and Seigo Ito
Crystals 2024, 14(5), 462; https://doi.org/10.3390/cryst14050462 - 15 May 2024
Abstract
Proton-exchange-membrane hydrogen fuel cells (PEMFCs) are an important energy device for achieving a sustainable hydrogen society. Carbon-based catalysts used in PEMFCs’ cathode can degrade significantly during operation-voltage shifts due to the carbon deterioration. The longer lifetime of the system is necessary for the
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Proton-exchange-membrane hydrogen fuel cells (PEMFCs) are an important energy device for achieving a sustainable hydrogen society. Carbon-based catalysts used in PEMFCs’ cathode can degrade significantly during operation-voltage shifts due to the carbon deterioration. The longer lifetime of the system is necessary for the further wide commercialization of PEMFCs. Therefore, carbon-free catalysts are required for PEMFCs. In this study, highly crystallized conducting Sb-doped SnO2 (Sb-SnO2) nanoparticles (smaller than 7 nm in size) were synthesized using an ozone-assisted hydrothermal synthesis. Pt nanoparticles were loaded on Sb-SnO2 supporting particles by polyol method to be “Pt/Sb-SnO2 catalyst”. The Pt/Sb-SnO2 catalyst showed a high oxygen reduction reaction (ORR) mass activity (178.3 A g−1-Pt @ 0.9 V), compared to Pt/C (149.3 A g−1-Pt @ 0.9 V). In addition, the retention ratio from the initial value of electrochemical surface area (ECSA) during 100,000-voltage cycles tests between 1.0 V and 1.5 V, Pt/SnO2 and Pt/Sb-SnO2 catalyst exhibited higher stability (90% and 80%), respectively, than that of Pt/C catalyst (47%). Therefore, the SnO2 and Sb-SnO2 nanoparticles synthesized using this new ozone-assisted hydrothermal method are promising as carbon-free catalyst supports for PEMFCs.
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(This article belongs to the Special Issue New Materials for Electrochemical Energy Storage Systems and Catalysis)
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Influence of Austenite Grain Size on the Variant Configurations of Martensite in a Fe-30.5Ni-0.155C Alloy
by
Loïc Malet and Stéphane Godet
Crystals 2024, 14(5), 461; https://doi.org/10.3390/cryst14050461 - 14 May 2024
Abstract
A Fe-30.5wt%Ni-0.155wt%C alloy was annealed at two different temperatures to produce two different austenite grain sizes. In the coarse-grained specimen, hierarchical configurations of variants are formed and carefully analyzed using EBSD. These typical patterns result from the alternate formation of two perpendicular plate
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A Fe-30.5wt%Ni-0.155wt%C alloy was annealed at two different temperatures to produce two different austenite grain sizes. In the coarse-grained specimen, hierarchical configurations of variants are formed and carefully analyzed using EBSD. These typical patterns result from the alternate formation of two perpendicular plate groups of variants over several length scales, and two distinct types of mechanical couplings are shown to occur sequentially in the process of the transformation of an austenitic grain. In the fine-grained specimen, the martensite start temperature is depressed below liquid nitrogen temperature, and the martensitic transformation can only occur under stress assistance. Grain size reduction brings about a dramatic change in the morphology of martensite and its configurations. Martensite is fully twinned, and martensite variants arrange themselves into self-accommodating configurations involving all four variants of the same plate group. Those specific configurations share striking similarities with those usually encountered in conventional shape memory alloys. The reversion of such microstructures upon heating is believed to be at the origin of the observed shape memory effect.
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(This article belongs to the Section Crystalline Metals and Alloys)
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Effect of Polyoxyethylene-Based Nonionic Surfactants on Chemical–Mechanical Polishing Performance of Monocrystalline Silicon Wafers
by
Bowen Jiang, Jie Guan, Peng Zhao, Yulin Chen and Zefang Zhang
Crystals 2024, 14(5), 460; https://doi.org/10.3390/cryst14050460 - 14 May 2024
Abstract
The use of surfactants is crucial in the chemical–mechanical polishing fluid system for silicon wafers. This paper examines the impact of the functional group structure of polyoxyethylene-based nonionic surfactants and the variation in the polyoxyethylene (EO) addition number on the polishing performance of
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The use of surfactants is crucial in the chemical–mechanical polishing fluid system for silicon wafers. This paper examines the impact of the functional group structure of polyoxyethylene-based nonionic surfactants and the variation in the polyoxyethylene (EO) addition number on the polishing performance of monocrystalline silicon wafers, to achieve the appropriate material removal rate and surface quality. The results demonstrated that the straight-chain structure of fatty alcohol polyoxyethylene ether (AEO-9) exhibited superior performance in wafer polishing compared to octylphenol polyoxyethylene ether (OP-9) and isoprenol polyoxyethylene ether (TPEG) and polyethylene glycol (PEG). By varying the number of EO additions of AEO-type surfactants, this study demonstrated that the polishing performance of monocrystalline silicon wafers was affected by the number of EO additions. The best polishing effect was achieved when the number of EO additions was nine. The mechanism of the role of polyoxyethylene-type nonionic surfactants in silicon wafer polishing was derived through polishing experiments, the contact angle, abrasive particle size analysis, zeta potential measurement, XPS, and other means of characterization.
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(This article belongs to the Special Issue Surface Modification Treatments of Metallic Materials)
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Structural and Optical Characterization of a New Tetra- and Hexa-Coordinated Cd-Based Hybrid Compound with White Light Emission
by
Imen Sayer, Rawia Msalmi, Edoardo Mosconi, Ahlem Guesmi, Ammar Houas, Naoufel Ben Hamadi and Houcine Naïli
Crystals 2024, 14(5), 459; https://doi.org/10.3390/cryst14050459 - 12 May 2024
Abstract
The present paper deals with a new two-in-one zero-dimensional (0D) organic–inorganic hybrid compound namely (C6H10N2)4[CdBr6][CdBr4]2. This molecular crystal structure contains isolated CdBr4 tetrahedra and CdBr6 octahedra. The
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The present paper deals with a new two-in-one zero-dimensional (0D) organic–inorganic hybrid compound namely (C6H10N2)4[CdBr6][CdBr4]2. This molecular crystal structure contains isolated CdBr4 tetrahedra and CdBr6 octahedra. The optical characterization by UV–Vis–NIR spectroscopy shows that the (C6H10N2)4[CdBr6][CdBr4]2 exhibits a large gap energy of 4.97 eV. Under UV excitation, this hybrid material shows a bright cold white light emission (WLE) at room temperature. The photoluminescence (PL) analysis suggests that the WLE originates from the organic molecules. Density of states (DOS) analysis using the density functional theory (DFT) demonstrates that the calculated HOMO(Br)→LUMO(organic) absorption transition (4.1 eV) does not have significant intensity, while, the transition involving the valence band (VB) and the second and third conduction bands (CB) around 5 eV are allowed, which is in good agreement with the experimental gap value. The interesting theoretical result is that the LUMO(organic)→HOMO(Br) emission is allowed, which confirms the important role of the organic molecule in the emission mechanism, in good agreement with the experimental PL analysis.
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(This article belongs to the Special Issue Advances in Organic Semiconductors)
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Two Consecutive Negative Electrocaloric Peaks in <001>-Oriented PMN-30PT Single Crystals
by
Yu Zhang, Weiping Gong, Zhen Li, Jianting Li, Changyu Li, Jun Chen, Yaodong Yang, Yang Bai and Wei-Feng Rao
Crystals 2024, 14(5), 458; https://doi.org/10.3390/cryst14050458 - 12 May 2024
Abstract
The versatile electrocaloric (EC) behaviors of the (1-x)Pb(Mg1/3Nb2/3)O3-xPT (PMN-100xPT) single crystal are closely related to the multiple phase transitions under the multiple fields of electric field and temperature. In this work, the EC effect of
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The versatile electrocaloric (EC) behaviors of the (1-x)Pb(Mg1/3Nb2/3)O3-xPT (PMN-100xPT) single crystal are closely related to the multiple phase transitions under the multiple fields of electric field and temperature. In this work, the EC effect of <001>-oriented PMN-30PT single crystals with chemical composition at morphotropic phase boundary has been studied during the phase transformation process from the ferroelectric rhombohedral (R) phase to the tetragonal (T) phase. Two consecutive negative EC peaks have been achieved for the first time. Based on the projection of the EC effect in the electric field-temperature phase diagram, the relationship between the EC behaviors and the phase transitions is further established. It was found that the monoclinic (M) phase actually existed during the transformation from the R phase to the T phase, and the related R-M phase transition and M-T phase transition could both induce negative EC peaks. Under the electric field of E = 10 kV/cm, the first negative EC peaks induced by the R-M phase transition is at 57 °C with ΔTmax = −0.11 K. And the M-T phase transition can produce a higher negative EC peak, and its value can reach −0.22 K at 68 °C. Based on thermodynamic calculations, the relationship between the entropy change in different phase transitions and the EC behaviors has been further elucidated. The negative EC effect originates from the structural entropy increase in the electric field-induced phase transition process. This work not only advances the research on the electrical properties of relaxor ferroelectric single crystals but also provides a new insight into high-performance ferroelectric materials design.
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(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)
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Open AccessArticle
Hierarchically Porous Carbon Cloth–Polyaniline (CC–PANI) Composite Supercapacitor Electrodes with Enhanced Stability
by
Svetlana V. Stakhanova, Ilya S. Krechetov, Kristina E. Shafigullina, Tatiana L. Lepkova, Valentine V. Berestov, Eugene S. Statnik, Zlatotsveta E. Zyryanova, Elena A. Novikova and Alexander M. Korsunsky
Crystals 2024, 14(5), 457; https://doi.org/10.3390/cryst14050457 - 12 May 2024
Abstract
In this work, hierarchically porous composites were prepared in the form of activated carbon cloth (CC) Busofit T–1–055 filled with an electrically conductive polymer, polyaniline (PANI), for use as pseudocapacitive electrodes of electrochemical supercapacitors (SCs). CC fibers have high nanoporosity and specific surface
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In this work, hierarchically porous composites were prepared in the form of activated carbon cloth (CC) Busofit T–1–055 filled with an electrically conductive polymer, polyaniline (PANI), for use as pseudocapacitive electrodes of electrochemical supercapacitors (SCs). CC fibers have high nanoporosity and specific surface area, so it was possible to deposit (via the chemical oxidative polymerization of aniline) a significant amount of PANI on them in the form of a thin layer mainly located on the inner surface of the pores. Such morphology of the composite made allowed the combining of the high capacitive characteristics of PANI with the reversibility of electrochemical processes, high columbic efficiency and cyclic stability rather typical for carbon materials of double-layer SCs. The highest capacitance of composite electrodes of about 4.54 F/cm2 with high cyclic stability (no more than 8% of capacity loss after 2000 charge–discharge cycles with a current density of 10 A/cm2) and columbic efficiency (up to 98%) was achieved in 3 M H2SO4 electrolyte solution when PANI was synthesized from an aniline hydrochloride solution with a concentration of 0.25 M. Trasatti analysis revealed that 27% of specific capacitance corresponded to pseudocapacitance, and 73% to the double-layer capacitance.
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(This article belongs to the Special Issue Synthesis, Characterization and Applications of Crystalline Electroconductive Polymers)
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Open AccessArticle
Impact of Zinc Oxide on the Structure and Surface Properties of Magnesium–Potassium Glass–Crystalline Glazes
by
Katarzyna Pasiut, Janusz Partyka, Dawid Kozień and Piotr Pańtak
Crystals 2024, 14(5), 456; https://doi.org/10.3390/cryst14050456 - 11 May 2024
Abstract
The present work describes test results for glass crystal materials based on the SiO2-Al2O3-MgO-K2O system after 5, 10, 15, and 20 wt.% zinc oxide was added. The glazing analysis involved determining the effect of the
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The present work describes test results for glass crystal materials based on the SiO2-Al2O3-MgO-K2O system after 5, 10, 15, and 20 wt.% zinc oxide was added. The glazing analysis involved determining the effect of the additive on the characteristic temperatures and properties of the surface obtained, such as color, gloss, and roughness, as expressed by a Ra parameter. The obtained glazes were also analyzed for changes in phase composition (quantitative and qualitative XRD tests), changes in microstructure (based on images obtained with a scanning electron microscope), and structure (based on analyses and decomposition of spectra obtained using mid-infrared spectroscopy). As a result, the maximum addition of zinc oxide provided the best results.
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(This article belongs to the Special Issue Porous Ceramics and Their Composite Materials)
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Aluminium-Silicon Lightweight Thermal Management Alloys with Controlled Thermal Expansion
by
Peter Lewis, Andrew Tarrant, Andreas Frehn, Fritz Grensing, James Nicholson, Nick Farrah and Martyn Acreman
Crystals 2024, 14(5), 455; https://doi.org/10.3390/cryst14050455 - 11 May 2024
Abstract
With the ever-growing emphasis on global decarbonization and rapid increases in the power densities of electronics equipment in recent years, new methods and lightweight materials have been developed to manage heat load as well as interfacial stresses associated with coefficient of thermal expansion
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With the ever-growing emphasis on global decarbonization and rapid increases in the power densities of electronics equipment in recent years, new methods and lightweight materials have been developed to manage heat load as well as interfacial stresses associated with coefficient of thermal expansion (CTE) mismatches between components. The Al–Si system provides an attractive combination of CTE performance and high thermal conductivity whilst being a very lightweight option. Such materials are of interest to industries where thermal management is a key design criterion, such as the aerospace, automotive, consumer electronics, defense, EV, and space sectors. This paper will describe the development and manufacture of a family of high-performance hypereutectic Al–Si alloys (AyontEX™) by a powder metallurgy method. These alloys are of particular interest for structural heat sink applications that require high reliability under thermal cycling (CTE of 17 μm/(m·°C)), as well as reflective optics and instrument assemblies that require good thermal and mechanical stability (CTE of 13 μm/(m·°C)). Critical performance relationships are presented, coupled with the microstructural, physical, and mechanical properties of these Al–Si alloys.
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(This article belongs to the Special Issue Advances in Metal Matrix Composites: Structure, Properties and Applications)
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Manufacturing of TiO2, Al2O3 and Y2O3 Ceramic Nanotubes for Application as Electrodes for Printable Electrochemical Sensors
by
Alexandru Florentin Trandabat, Romeo Cristian Ciobanu, Oliver Daniel Schreiner, Mihaela Aradoaei and Sebastian Teodor Aradoaei
Crystals 2024, 14(5), 454; https://doi.org/10.3390/cryst14050454 - 11 May 2024
Abstract
This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered
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This paper describes the process to obtain ceramic nanotubes from titanium dioxide, alumina and yttrium oxide by a feasible, replicable and reliable technology, including three stages, starting from an electrospinning process of poly(methyl methacrylate) solutions. A minimum diameter of 0.3 μm was considered optimal for PMMA nanofibers in order to maintain the structural stability of covered fibers, which, after ceramic film deposition, leads to a fiber diameter of 0.5–0.6 μm. After a chemical and physical analysis of the stages of obtaining ceramic nanotubes, in all cases, uniform deposition of a ceramic film on PMMA fibers and, finally, a uniform structure of ceramic nanotubes were noted. The technological purpose was to use such nanotubes as ingredients in screen-printing inks for electrochemical sensors, because no study directly targeted the subject of ceramic nanotube applications for printed electronics to date. The printing technology was analyzed in terms of the ink deposition process, printed electrode roughness vs. type of ceramic nanotubes, derived inks, thermal curing of the electrodes and the conductivity of electrodes on different support (rigid and flexible) at different curing temperatures. The experimental inks containing ceramic nanotubes can be considered feasible for printed electronics, because they offer fast curing at low temperatures, reasonable conductivity vs. electrode length, good printability on both ceramic or plastic (flexible) supports and good adhesion to surface after curing.
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(This article belongs to the Special Issue Metal Oxide Thin Films, Nanomaterials and Nanostructures)
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