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Search Results (811)

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Keywords = nitride phases

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22 pages, 6737 KB  
Article
Molecular Dynamics Study on the Effect of Surface Films on the Nanometric Grinding Mechanism of Single-Crystal Silicon
by Meng Li, Di Chang, Pengyue Zhao and Jiubin Tan
Micromachines 2025, 16(10), 1141; https://doi.org/10.3390/mi16101141 - 2 Oct 2025
Viewed by 393
Abstract
To investigate the influence of surface films on the material removal mechanism of single-crystal silicon during nanogrinding, molecular dynamics (MD) simulations were performed under different surface-film conditions. The simulations examined atomic displacements, grinding forces, radial distribution functions (RDF), phase transformations, temperature distributions, and [...] Read more.
To investigate the influence of surface films on the material removal mechanism of single-crystal silicon during nanogrinding, molecular dynamics (MD) simulations were performed under different surface-film conditions. The simulations examined atomic displacements, grinding forces, radial distribution functions (RDF), phase transformations, temperature distributions, and residual stress distributions to elucidate the damage mechanisms at the surface and subsurface on the nanoscale. In this study, boron nitride (BN) and graphene films were applied to the surface of single-crystal silicon workpieces for nanogrinding simulations. The results reveal that both BN and graphene films effectively suppress chip formation, thereby improving the surface quality of the workpiece, with graphene showing a stronger inhibitory effect on atomic displacements. Both films reduce tangential forces and mitigate grinding force fluctuations, while increasing normal forces; the increase in normal force is smaller with BN. Although both films enlarge the subsurface damage layer (SDL) thickness and exhibit limited suppression of crystalline phase transformations, they help to alleviate surface stress release. In addition, the films reduce the surface and subsurface temperatures, with graphene yielding a lower temperature. Residual stresses beneath the abrasive grain are also reduced when either film is applied. Overall, BN and graphene films can enhance the machined surface quality, but further optimization is required to minimize subsurface damage (SSD), providing useful insights for the optimization of single-crystal silicon nanogrinding processes. Full article
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15 pages, 3394 KB  
Review
Progress and Prospect of Sm-Fe-N Magnets
by Tetsuji Saito
Inorganics 2025, 13(10), 322; https://doi.org/10.3390/inorganics13100322 - 29 Sep 2025
Viewed by 305
Abstract
High-performance but expensive neodymium-iron-boron (Nd-Fe-B) magnets are widely used in automotive and electrical applications. Prospective candidates for rare-earth-free magnets include Fe-based magnets such as L10-FeNi and α″-Fe16N2 phase. However, these rare-earth-free magnets cannot replace Nd-Fe-B magnets due to [...] Read more.
High-performance but expensive neodymium-iron-boron (Nd-Fe-B) magnets are widely used in automotive and electrical applications. Prospective candidates for rare-earth-free magnets include Fe-based magnets such as L10-FeNi and α″-Fe16N2 phase. However, these rare-earth-free magnets cannot replace Nd-Fe-B magnets due to their lower coercivity. Thus, the development of Sm-based magnets, using the relatively abundant rare-earth element Sm, has become a focus of attention. A promising, cheaper alternative with excellent magnetic properties is the Samarium-iron-nitride (Sm-Fe-N) magnet. This paper describes the production and magnetic properties of Sm-Fe-N powders with Th2Zn17 and TbCu7 phases. The production process and magnetic properties of Sm-Fe-N bonded magnets prepared from the powders are also described. Current approaches for producing Sm-Fe-N sintered magnets are included. Full article
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22 pages, 5662 KB  
Article
Physical Vapor Deposited TiN and TiAlN on Biomedical β-Type Ti-29Nb-13Ta-4.6Zr: Microstructural Characteristics, Surface Hardness Enhancement, and Antibacterial Activity
by Hakan Yilmazer
Coatings 2025, 15(10), 1126; https://doi.org/10.3390/coatings15101126 - 29 Sep 2025
Viewed by 461
Abstract
Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was [...] Read more.
Beta (β)-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloys combine low modulus with biocompatibility but require improved surface properties for long-term implantation. This study aimed to enhance the surface mechanical strength and antibacterial performance of TNTZ by applying TiN and TiAlN coatings via PVD. Notably, TiAlN was deposited on TNTZ for the first time, enabling a direct side-by-side comparison with TiN under identical deposition conditions. Dense TiN (~1.06 μm) and TiAlN (~1.73 μm) coatings were deposited onto solution-treated TNTZ and characterized by X-ray diffraction, scanning probe microscopy, Vickers microhardness, Rockwell indentation test (VDI 3198), static water contact angle measurements, and a Kirby–Bauer disk-diffusion antibacterial assay against Escherichia coli (E. coli). Both coatings formed face-centered cubic (FCC) structures with smooth interfaces (Ra ≤ 5.3 nm) while preserving the single-phase β matrix of the substrate. The hardness increased from 192 HV (uncoated) to 1059 HV (TiN) and 1468 HV (TiAlN), and the adhesion quality was rated as HF2 and HF1, respectively. The surface wettability changed from hydrophilic (48°) to moderately hydrophobic (82°) with TiN and highly hydrophobic (103°) with TiAlN. Similarly, the diameter of the no-growth zones increased to 18.02 mm (TiN) and 19.09 mm (TiAlN) compared to 17.65 mm for uncoated TNTZ. The findings indicate that TiAlN, in particular, provided improved hardness, adhesion, and hydrophobicity. Preliminary bacteriostatic screening under diffusion conditions suggested a modest relative antibacterial response, though the effect was not statistically significant between coated and uncoated TNTZ. Statistical analysis confirmed no significant difference between the groups (p > 0.05), indicating that only a preliminary bacteriostatic trend— rather than a definitive antibacterial effect—was observed. Both nitride coatings strengthened TNTZ without compromising its structural integrity, making TiAlN-coated TNTZ a promising candidate for next-generation orthopedic implants. Full article
(This article belongs to the Special Issue Films and Coatings with Biomedical Applications)
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27 pages, 4068 KB  
Article
Microscopic Phase-Field Modeling with Accurate Interface Thickness Representation: Applied to Ceramic Matrix Composites
by Tong Wang, Xiaofei Hu, Zhi Sun and Weian Yao
Materials 2025, 18(19), 4496; https://doi.org/10.3390/ma18194496 - 27 Sep 2025
Viewed by 277
Abstract
Ceramic matrix composites (CMCs) are promising candidates for high-temperature structural applications. However, their fracture toughness remains low due to strong chemical bonding between fibers and the matrix. To improve toughness, engineered interfaces such as pyrolytic carbon (PyC) and hexagonal boron nitride (h-BN) are [...] Read more.
Ceramic matrix composites (CMCs) are promising candidates for high-temperature structural applications. However, their fracture toughness remains low due to strong chemical bonding between fibers and the matrix. To improve toughness, engineered interfaces such as pyrolytic carbon (PyC) and hexagonal boron nitride (h-BN) are commonly introduced. These interfaces promote crack deflection and fiber bridging, leading to improved damage tolerance and pseudo-ductile behavior. To investigate the influence of interface thickness on mechanical performance and to identify optimal thickness ranges, we propose a microscopic phase-field model that accurately resolves interface thickness and material contrast. This model overcomes the limitations of conventional smeared interface approaches, particularly in systems with variable interface thickness and closely packed fibers. We apply the model to simulate the fracture behavior of unidirectional SiC fiber reinforced SiC matrix (SiCf/SiCm) composites with PyC and h-BN interfaces of varying thickness. The numerical results show strong agreement with experimental findings from the literature and reveal optimal interface thicknesses that maximize toughening effects. These results demonstrate the model’s predictive capabilities and its potential as a tool for interface design in brittle composite systems. Full article
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13 pages, 25357 KB  
Article
Low-Temperature Formation of Aluminum Nitride Powder from Amorphous Aluminum Oxalate via Carbothermal Reduction
by Wenjing Tang, Yaling Yu, Zixuan Huang, Weijie Wang, Shaomin Lin, Ji Luo, Chenyang Zhang and Zhijie Zhang
Inorganics 2025, 13(10), 317; https://doi.org/10.3390/inorganics13100317 - 25 Sep 2025
Viewed by 304
Abstract
Aluminum nitride (AlN) powder, a cornerstone material for advanced ceramics. This study examines the low-temperature formation of AlN crystals as well as their phase transformation by employing amorphous aluminum oxalate (AAO) as a novel precursor for carbothermal reduction, contrasting it with conventional aluminum [...] Read more.
Aluminum nitride (AlN) powder, a cornerstone material for advanced ceramics. This study examines the low-temperature formation of AlN crystals as well as their phase transformation by employing amorphous aluminum oxalate (AAO) as a novel precursor for carbothermal reduction, contrasting it with conventional aluminum hydroxide (Al(OH)3). Through characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), High-Resolution Transmission Electron Microscope (HRTEM), 27Al Magic-Angle Spinning Nuclear Magnetic Resonance (27Al-MAS-NMR) energy-dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR), we unraveled the phase evolution pathways and the formation of AlN. Key findings reveal striking differences between the two precursors. When Al(OH)3 was used, no AlN phase was detected at 1350 °C, and even at 1500 °C, the AlN obtained with significant residual alumina impurities. In contrast, the AAO precursor demonstrated exceptional efficiency: nano-sized α-Al2O3 formed at 1050 °C, followed by the emergence of AlN phases at 1200 °C, ultimately gaining the pure AlN at 1500 °C. The phase transformation sequence—Al(OH)3 → γ-Al2O3 (950 °C) → (α-Al2O3 + δ-Al2O3) (1050 °C) → (AlN + α-Al2O3) (1200 °C~ 1350 °C) → AlN (≥1500 °C)—highlights the pivotal role of nano-sized α-Al2O3 in enabling low-temperature nano AlN synthesis. By leveraging the unique properties of AAO, we offer a transformative strategy for synthesizing nano-sized AlN powders, with profound implications for the ceramics industry. Full article
(This article belongs to the Special Issue New Advances into Nanostructured Oxides, 3rd Edition)
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13 pages, 2257 KB  
Article
Scalable High-Yield Exfoliation of Hydrophilic h-BN Nanosheets via Gallium Intercalation
by Sungsan Kang, Dahun Kim, Seonyou Park, Sung-Tae Lee, John Hong, Sanghyo Lee and Sangyeon Pak
Inorganics 2025, 13(10), 314; https://doi.org/10.3390/inorganics13100314 - 25 Sep 2025
Viewed by 400
Abstract
Hexagonal boron nitride (h-BN) possesses a unique combination of a wide bandgap, high thermal conductivity, and chemical inertness, making it a key insulating and thermal management material for advanced electronics and nanocomposites. However, its intrinsic hydrophobicity and strong interlayer van der Waals forces [...] Read more.
Hexagonal boron nitride (h-BN) possesses a unique combination of a wide bandgap, high thermal conductivity, and chemical inertness, making it a key insulating and thermal management material for advanced electronics and nanocomposites. However, its intrinsic hydrophobicity and strong interlayer van der Waals forces severely limit exfoliation efficiency and dispersion stability, particularly in scalable liquid-phase processes. Here, we report a synergistic exfoliation strategy that integrates acid-induced hydroxylation with gallium (Ga) intercalation to achieve high-yield (>80%) production of ultrathin (<4 nm) hydrophilic h-BN nanosheets. Hydroxylation introduces abundant -OH groups, expanding interlayer spacing and significantly increasing surface polarity, while Ga intercalation leverages its native Ga2O3 shell to form strong interfacial interactions with hydroxylated basal planes. This oxide-mediated adhesion facilitates efficient layer separation under mild sonication, yielding nanosheets with well-preserved lateral dimensions and exceptional dispersion stability in polar solvents. Comprehensive characterization confirms the sequential chemical and structural modifications, revealing the crucial roles of hydroxylation-induced activation and Ga2O3 assisted wettability enhancement. This combined chemical activation–soft metallic intercalation approach provides a scalable, solution-processable route to high-quality h-BN nanosheets, opening new opportunities for their integration into dielectric, thermal interface, and multifunctional composite systems. Full article
(This article belongs to the Special Issue Physicochemical Characterization of 2D Materials)
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19 pages, 4237 KB  
Article
Numerical Study of Incidence Angle-Tuned, Guided-Mode Resonant, Metasurfaces-Based Sensors for Glucose and Blood-Related Analytes Detection
by Zeev Fradkin, Maxim Piscklich, Moshe Zohar and Mark Auslender
Sensors 2025, 25(18), 5852; https://doi.org/10.3390/s25185852 - 19 Sep 2025
Viewed by 367
Abstract
In optical one-dimensional grating-on-layer planar structures, an optical resonance occurs when the incident light wave becomes phase-matched to a leaky waveguide mode excited in the layer underneath the grating by an appropriate tuning of the grating periodicity. Changing the refractive indices of the [...] Read more.
In optical one-dimensional grating-on-layer planar structures, an optical resonance occurs when the incident light wave becomes phase-matched to a leaky waveguide mode excited in the layer underneath the grating by an appropriate tuning of the grating periodicity. Changing the refractive indices of the grating’s constituents, and/or thickness, changes the resonance frequency. In the case of a two-dimensional grating atop such a smooth layer, a similar and also cavity-mode resonance can occur. This idea has straightforward usage in diverse optical sensor applications. In this study, a novel guided-mode resonance sensor design for detecting glucose and hemoglobin in minute concentrations at a wide range of incidence angles is presented. In this design, materials of the grating, such as a polymer and cesium-lead halide with a perovskite crystal structure, are examined, which will allow flexible, low-cost fabrication by soft-lithography/imprint-lithography methods. The sensitivity, figure of merit, and quality factor are reported for one- and two-dimensional grating structures. The simulations performed are based on rigorous coupled-wave analysis. Optical resonance quality factor of ∼5·105 is achieved at oblique incidence for a structure comprising a one-dimensional grating etched in a poly-vinylidene chloride layer atop a silicon nitride waveguide layer on a substrate. Record values of the above-noted characteristics are achieved with a synergetic interplay of the materials, structural dimensions, incidence angle, polarization, and grating geometry. Full article
(This article belongs to the Special Issue Optoelectronic Devices and Sensors)
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11 pages, 3388 KB  
Communication
On-Chip Etchless and Tunable Silicon Nitride Waveguide Mode Converter Based on Low-Loss Phase Change Material
by Tianman Shu, Yuexiang Guo, Shengxiong Lai, Lun Zhang, Yin Xu and Hualong Bao
Photonics 2025, 12(9), 934; https://doi.org/10.3390/photonics12090934 - 19 Sep 2025
Viewed by 530
Abstract
The development of reconfigurable photonic integrated circuits (PICs) demands photonic devices with high-efficiency tuning capabilities, yet conventional thermo-optic and electro-optic methods suffer from limited index modulation and excessive power consumption. To overcome these limitations, we propose an etchless and tunable silicon nitride waveguide [...] Read more.
The development of reconfigurable photonic integrated circuits (PICs) demands photonic devices with high-efficiency tuning capabilities, yet conventional thermo-optic and electro-optic methods suffer from limited index modulation and excessive power consumption. To overcome these limitations, we propose an etchless and tunable silicon nitride waveguide mode converter based on low-loss phase change material, antimony triselenide (Sb2Se3). By depositing an Sb2Se3 layer on the silicon nitride wafer and using a laser-induced phase transition technique, we can write and erase the waveguide structure in the phase change wafer without waveguide etching, where the input/output waveguide is a strip waveguide and the conversion region is built using a tilted subwavelength grating structure. From the results, the obtained TE0-TE1 mode conversion efficiency, crosstalk, and insertion loss are higher than 96%, lower than −16 dB, and lower than 0.4 dB at a wavelength of 1.55 µm, respectively. The proposed device enables post-fabrication tuning of the grating duty cycle, allowing working wavelength adjustment for the same device. Furthermore, the device exhibits scalability to other higher-order mode conversions (e.g., TE0-TE2). Consequently, we expect that such devices could have important uses in programmable and multifunctional PICs. Full article
(This article belongs to the Special Issue Emerging Technologies for Silicon Photonics and Integrated Circuits)
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14 pages, 4771 KB  
Article
Brazed–Resin Composite Grinding Wheel with CBN Segments: Fabrication, Brazing Mechanism, and Rail Grinding Performance
by Haozhong Xiao, Shuyi Wang, Bing Xiao, Zhenwei Huang and Jingyan Zhu
Coatings 2025, 15(9), 1083; https://doi.org/10.3390/coatings15091083 - 15 Sep 2025
Viewed by 505
Abstract
To enhance the grinding performance and service life of rail grinding wheels, a novel brazed–resin composite wheel was developed by embedding brazed CBN (cubic boron nitride) segments into a resin working layer. The brazed CBN segments were fabricated using a Cu–Sn–Ti + WC [...] Read more.
To enhance the grinding performance and service life of rail grinding wheels, a novel brazed–resin composite wheel was developed by embedding brazed CBN (cubic boron nitride) segments into a resin working layer. The brazed CBN segments were fabricated using a Cu–Sn–Ti + WC (tungsten carbide) composite filler via a cold-press forming–vacuum brazing process. Microstructural and phase analyses revealed the formation of Ti–B and Ti–N compounds at the CBN–filler interface, indicating metallurgical bonding, while the incorporation of WC reduced excessive wetting, enabling precise shape retention of the segments. Comparative laboratory and field grinding tests were conducted against conventional resin-bonded wheels. Under all tested pressures, the composite wheel exhibited lower grinding temperatures, generated predominantly strip-shaped chips with lower oxygen content, and produced fewer spherical oxide-rich chips than the resin-bonded wheel, confirming reduced thermal load. Field tests demonstrated that the composite wheel matched the resin-bonded wheel in grinding efficiency, extended service life by approximately 28.8%, and achieved smoother rail surfaces free from burn-induced blue marks. These results indicate that the brazed–resin composite grinding wheel effectively leverages the superior hardness and thermal conductivity of CBN abrasives, offering improved thermal control, wear resistance, and surface quality in rail grinding applications. Full article
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19 pages, 3413 KB  
Article
Activated Carbon-Modified Porous Carbon Nitride Decorated with Molybdenum Disulfide for Enhanced Photocatalytic Degradation of Rhodamine B
by Kunyang Li, Di Wang, Ning Tang, Zhou Zhou, Wen Zhang, Bohan Liu and Yiying Yue
Catalysts 2025, 15(9), 875; https://doi.org/10.3390/catal15090875 - 12 Sep 2025
Viewed by 443
Abstract
Photocatalytic technology offers significant potential for pollutant remediation through efficient, cost-effective mineralization but faces inherent limitations, including catalyst agglomeration and rapid charge recombination. To address these challenges, we developed activated carbon-modified porous graphitic carbon nitride (APCN) synthesized through the co-polycondensation of dicyandiamide with [...] Read more.
Photocatalytic technology offers significant potential for pollutant remediation through efficient, cost-effective mineralization but faces inherent limitations, including catalyst agglomeration and rapid charge recombination. To address these challenges, we developed activated carbon-modified porous graphitic carbon nitride (APCN) synthesized through the co-polycondensation of dicyandiamide with NH4Cl and fir-wood-derived activated carbon (AC). The incorporated AC effectively prevented the agglomeration of carbon nitride frameworks, thereby enhancing the specific surface area (SBET) of APCN. This matrix was subsequently composited with hydrothermally prepared (1T/2H) mixed-phase MoS2 through ultrasonication, forming a MoS2/APCN heterostructure. Characterizations including Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and N2 adsorption–desorption isotherms (BET) confirmed that MoS2 was successfully loaded onto APCN via an ultrasonic synthesis method. The composite exhibited outstanding photocatalytic activity, degrading 95.5% RhB in 40 min (pH = 7) and 97.4% in 25 min (pH = 3.5), with 87.3% efficiency retention after four cycles (pH = 7). Crucially, AC enhanced visible-light absorption and functioned as an electron-mediating component. Photoelectrochemical analyses and radical-trapping experiments confirmed a direct Z-scheme charge transfer mechanism, wherein conductive AC accelerates electron transport and suppresses carrier recombination. This study establishes both an efficient RhB degradation photocatalyst and a sustainable strategy for valorizing agricultural waste in advanced material design. Full article
(This article belongs to the Section Photocatalysis)
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19 pages, 10755 KB  
Article
Corrosion Performance of (TiAlZrTaNb)Nx High-Entropy Nitrides Thin Films Deposited on 304 Stainless Steel via HiPIMS
by Maria-Camila Castañeda, Oscar Piamba and Jhon Olaya
Metals 2025, 15(9), 988; https://doi.org/10.3390/met15090988 - 6 Sep 2025
Viewed by 458
Abstract
In this study, the electrochemical corrosion behavior of TiAlZrTaNb nitride thin films deposited on 304 stainless steel substrates was investigated. The thin films were synthesized using high-power impulse magnetron sputtering (HiPIMS) and are classified as high-entropy alloys (HEAs). The microstructure, morphology, and chemical [...] Read more.
In this study, the electrochemical corrosion behavior of TiAlZrTaNb nitride thin films deposited on 304 stainless steel substrates was investigated. The thin films were synthesized using high-power impulse magnetron sputtering (HiPIMS) and are classified as high-entropy alloys (HEAs). The microstructure, morphology, and chemical composition of the coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. Corrosion resistance was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests, employing tap water, acetic acid, and citric acid solutions at room temperature as electrolytes. The results demonstrated that the TiAlZrTaNbN coating exhibits a dense and homogeneous structure with a uniform elemental distribution. XRD analysis revealed the presence of face-centered cubic (FCC) crystalline phases, which significantly contribute to the coating’s corrosion resistance. Furthermore, the coating displayed exceptional corrosion performance in both acetic acid and citric acid electrolytes—simulating food environments with a pH ≤ 4.5—as revealed by a substantial reduction in corrosion current density and a positive shift in corrosion potential. These findings provide valuable insights into the properties of TiAlZrTaNbN coatings and underscore their potential for enhancing the durability of mechanical components employed in the food industry. Full article
(This article belongs to the Section Corrosion and Protection)
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18 pages, 8428 KB  
Article
Effect of Temperature, Heating Rate, and Cooling Rate on Bonding and Nitriding of AlSi10Mg Powder Occurring During Supersolidus Liquid-Phase Sintering
by Alena Kreitcberg, Mohamed Khaled Trigui, Abdelberi Chandoul, Roger Pelletier and Vincent Demers
J. Manuf. Mater. Process. 2025, 9(9), 296; https://doi.org/10.3390/jmmp9090296 - 1 Sep 2025
Viewed by 797
Abstract
This study investigated the effect of supersolidus liquid-phase sintering conditions on the powder particle bonding and the AlN-phase formation of an AlSi10Mg alloy. Sintering was conducted at temperatures between 550 and 579 °C, with a holding duration of 2 h under a nitrogen [...] Read more.
This study investigated the effect of supersolidus liquid-phase sintering conditions on the powder particle bonding and the AlN-phase formation of an AlSi10Mg alloy. Sintering was conducted at temperatures between 550 and 579 °C, with a holding duration of 2 h under a nitrogen atmosphere. The sintering cycles included four heating segments, performed at rates ranging from 0.2 to 5 °C/min for a total of between 5 and 15 h, and a cooling segment performed at two different cooling rates, 0.15 and 5 °C/min, resulting in durations of 12 and 70 h, respectively. Three powder batches exhibiting different particle size distributions were tested. An X-ray diffractometer, optical microscopy, and scanning electron microscopy were used to characterize phase formation and particle bonding. The results show that higher sintering temperatures and faster heating/cooling rates led to a lower fraction of AlN. In contrast, lower sintering temperatures or slow heating promoted the development of a thicker AlN shell around powder particles, inhibiting the bonding of the AlSi10Mg powder and preventing densification via the sintering process. These findings suggest that sintering at temperatures between 570 and 575 °C, with heating and cooling rates of at least 2 °C/min, constitutes a more favorable window for the densification of AlSi10Mg under a nitrogen atmosphere. Full article
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15 pages, 8373 KB  
Article
Development of Amorphous AlN Thin Films on ITO-Glass and ITO-PET at Low Temperatures by RF Sputtering
by Miriam Cadenas, Michael Sun, Susana Fernández, Sirona Valdueza-Felip, Ana M. Diez-Pascual and Fernando B. Naranjo
Micromachines 2025, 16(9), 993; https://doi.org/10.3390/mi16090993 - 29 Aug 2025
Viewed by 667
Abstract
Aluminum nitride (AlN) is a material of wide interest in the optoelectronics and high-power electronics industry. The deposition of AlN thin films at elevated temperatures is a well-established process, but its implementation on flexible substrates with conductive oxides, such as ITO-glass or ITO-PET, [...] Read more.
Aluminum nitride (AlN) is a material of wide interest in the optoelectronics and high-power electronics industry. The deposition of AlN thin films at elevated temperatures is a well-established process, but its implementation on flexible substrates with conductive oxides, such as ITO-glass or ITO-PET, poses challenges due to the thermal degradation of these materials. In this work, the deposition and characterization of AlN thin films by reactive sputtering at a low temperature (RT and 100 °C) on ITO-glass and ITO-PET substrates are presented. The structural, optical, and electrical properties of the samples have been analysed as a function of the sputtering power and the deposition temperature. XRD analysis revealed the absence of peaks of crystalline AlN, indicative of the formation of an amorphous phase. EDX measurements performed on the ITO-glass substrate with a radiofrequency power applied to the Al target of 175 W confirmed the presence of Al and N, corroborating the deposition of AlN. SEM analyses showed the formation of homogeneous and compact layers, and transmission optical measurements revealed a bandgap of around 5.82 eV, depending on the deposition conditions. Electrical resistivity measurements indicated an insulating character. Overall, these findings confirm the potential of amorphous AlN for applications in flexible optoelectronic devices. Full article
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15 pages, 4071 KB  
Article
Electrostatic MEMS Phase Shifter for SiN Photonic Integrated Circuits
by Seyedfakhreddin Nabavi, Michaël Ménard and Frederic Nabki
J. Sens. Actuator Netw. 2025, 14(5), 88; https://doi.org/10.3390/jsan14050088 - 29 Aug 2025
Viewed by 1894
Abstract
Optical phase modulation is essential for a wide range of silicon photonic integrated circuits used in communication applications. In this study, an optical phase shifter utilizing photo-elastic effects is proposed, where mechanical stress is induced by electrostatic micro-electro-mechanical systems (MEMS) with actuators arranged [...] Read more.
Optical phase modulation is essential for a wide range of silicon photonic integrated circuits used in communication applications. In this study, an optical phase shifter utilizing photo-elastic effects is proposed, where mechanical stress is induced by electrostatic micro-electro-mechanical systems (MEMS) with actuators arranged in a comb drive configuration. The design incorporates suspended serpentine silicon nitride (SiN) optical waveguides. Through extensive numerical simulations, it is shown that the change in the effective refractive index (neff) of the optical waveguide is a function of the voltage applied to the electrostatic actuators and that such neff tuning can be achieved for a broad range of wavelengths. Implemented within one arm of an unbalanced Mach–Zehnder interferometer (MZI), the phase shifter achieves a phase change of π when the stressed optical path measures 4.7 mm, and the actuators are supplied with 80 V DC and consume almost no power. This results in a half-wave voltage-length product (VπL) of 37.6 V·cm. Comparative analysis with contemporary optical phase shifters highlights the proposed design’s superior power efficiency, compact footprint, and simplified fabrication process, making it a highly efficient component for reconfigurable MEMS-based silicon nitride photonic integrated circuits. Full article
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20 pages, 6318 KB  
Article
Mechanical, Tribological, and Corrosion Behavior of Magnetron-Sputtered VN Coatings Deposited at Different Substrate Temperatures
by Stanislava Rabadzhiyska, Dimitar Dechev, Nikolay Ivanov, Maria Shipochka, Genoveva Atanasova, Velichka Strijkova, Vesela Katrova and Nina Dimcheva
Metals 2025, 15(9), 955; https://doi.org/10.3390/met15090955 - 28 Aug 2025
Viewed by 716
Abstract
Vanadium nitride (VN) ceramic layers were deposited on 304L stainless steel specimens by direct current (DC) magnetron sputtering in an Ar/N2 gas mixture at substrate temperatures of 250 °C, 300 °C, and 350 °C. The obtained films were evaluated by X-ray diffraction [...] Read more.
Vanadium nitride (VN) ceramic layers were deposited on 304L stainless steel specimens by direct current (DC) magnetron sputtering in an Ar/N2 gas mixture at substrate temperatures of 250 °C, 300 °C, and 350 °C. The obtained films were evaluated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The results showed the existence of VN and V2N phases in the as-deposited coatings. It was found that the surface roughness parameter (Ra = 10 nm) decreased with increasing substrate temperatures up to 350 °C. The highest hardness (10.6 GPa) was achieved in the layer produced at 300 °C. The low values of plastic and elastic deformation, as well as a low friction coefficient (0.38), led to an enhancement in the coatings’ tribological properties. The film’s thickness increased with increasing temperature due to the presence of nucleation centers in the films. The highest thickness (557 nm) was achieved in the layer deposited at 350 °C. The electrochemical tests exhibited reliable protection against corrosion in strongly aggressive electrolytes. It has been proven that the temperature significantly affects the ceramic coatings’ structural, morphological, tribological, and corrosion properties. Full article
(This article belongs to the Special Issue Surface Treatments and Coating of Metallic Materials)
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