In the process of diamond wire cutting silicon wafers in the photovoltaic industry, tens of thousands of tons of high-purity silicon swarf are generated. There is an urgent need for the recycling and utilization of silicon swarf. Current research lacks systematic studies on the phase and morphology of silicon swarf under different nitriding atmospheres. In this paper, based on the analysis of the basic physical and chemical properties of silicon swarf, direct nitridation of silicon swarf was carried out to prepare Si3N4, and the influence of different gases (N2, N2/H2 (95:5), NH3) on the phase and morphology of nitriding products was investigated. The reaction heat and the gas-phase reaction between SiO and nitriding gas are the two main influencing factors. The reaction heat accumulation will increase the content of β-Si3N4, which mainly occurs in N2. The gas-phase reaction between SiO and nitriding gas is prone to form α-Si3N4 whiskers, and NH3 gas is beneficial for this gas-phase reaction. The above two conclusions have been proven through thermodynamic and kinetic calculations. This study has certain guiding significance for the direct nitridation of silicon swarf to prepare Si3N4 powders with different phases and morphologies.
Transparent and light-yellow TiNb2O7 (TNO) single crystals with a maximum thickness of approximately 3 mm were grown from a melt. This study used the grown crystals to experimentally demonstrate that lithium diffusion parallel to the b-axis was favorable for lithium diffusion in TNO. Lithium was successfully doped (Li+ insertion) into the TNO single crystals using a liquid-type cell with metallic Li as the negative electrode. Arrhenius plots of the Li-doped TNO crystals revealed that the activation energies for [010] (//b-axis) and [10 (1) over bar] (perpendicular to b-axis) were approximately 0.28 and 0.73 eV, respectively.
In oxide-based all-solid-state sodium-ion batteries, glass anodes containing a high concentration of tin oxide doped with iron ions strongly absorb near-infrared laser light (lambda approximate to 1 & micro;m), enabling localized melting and solidification through position-selective laser heating. To enhance ionic transport within the anode layer and to clarify the relationship between laser irradiation conditions, resulting microstructure, and electrochemical performance, 30 wt% of the sodium-ion conductor Na3Zr2Si2PO12 (NZSP) was incorporated into the glass anode as an active component. The laser-processed anode layer exhibited a dense, void-free microstructure and strong interfacial bonding with the solid electrolyte substrate. Owing to the high optical absorption of the glass matrix, the temperature at the laser focal point rapidly increased to approximately 1700 degrees C, which was sufficient to soften the glass within a short irradiation time. In contrast, NZSP, which is optically transparent at the laser wavelength, retained its crystalline structure during the rapid melting and quenching process, indicating minimal thermal degradation. NZSP incorporation significantly improved ionic conductivity in the anode layer, increasing the initial charge and discharge capacities by 5.3 and 7.2 times, respectively, and enhancing capacity after 100th cycles.
Aerosol deposition (AD) is a promising spray-coating process for producing dense ceramic coatings at room temperature on a wide variety of substrates. However, extensive lattice defects and high compressive residual stresses arising from the intense particle impact limit its applicability. Co-deposition of polymers and ceramics has emerged as a strategy to mitigate these issues by dissipating part of the ceramic particle impact energy through deformation of the polymer phase. A similar effect occurs when pure ceramic powders are deposited on soft polymer substrates. These internal and external shock-absorption effects modify the deposition mechanism and can increase crystallite size, reduce microstrain, and lower residual stresses. In this work, pure titanium dioxide (TiO2) powders and TiO2/Polystyrene composite powders were deposited on soft polymer substrates and hard borosilicate glass. High-resolution synchrotron X-ray diffraction and FIB-SEM cross-sections reveal how both shock-absorption effects influence microstructure and deposition behavior, demonstrating the beneficial role of polymer incorporation in reducing defects and residual stresses.
Silicon nitride powder is a crucial raw material for fabricating silicon nitride ceramics, with its properties exerting a decisive influence on the final product’s performance. This study investigates the influence of polyvinyl alcohol (PVA) and polyacrylic acid (PAA) as binder additives on the characteristics of the resulting ceramics. Silicon nitride powder was treated with varying concentration ratios of PVA and PAA, followed by spray granulation to produce granulated powder. Subsequent hot-pressing sintering was conducted, and the performance of the sintered silicon nitride ceramics was evaluated. The results indicate that the optimal ratio of PVA to PAA is 2 wt.% : 2 wt.%, which yielded superior comprehensive properties, including thermal conductivity, mechanical strength, hardness, and volume resistivity.
