- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Rapid synthesis of AlON powders by low temperature solid-state reaction
摘要： High synthesis temperatures and long soaking times are generally required to fabricate AlON powders, which can cause coarsening and aggregation of the powder. Solid-state reaction methods form AlON powders by a direct reaction of Al2O3 and AlN, enabling rapid synthesis of AlON powder at low temperatures. In this work, single phase AlON powders were fabricated by a solid-state reaction method using Al2O3 and AlN powders as raw materials. To lower the synthesis temperature and shorten the soaking time, the raw materials particle sizes and the homogeneity of the Al2O3/AlN mixture were investigated. The effects of AlN content, synthesis temperature, and soaking time on the synthesis of AlON powders were examined. When the AlN content was 27 mol %, single phase AlON powders were synthesized by calcining Al2O3/AlN mixture at 1680 °C for 20 min. After ball-milling at 250 rpm for 24 h, the synthesized AlON powder was ground into a single phase fine AlON powder with an average particle diameter of 320 nm, a narrow size distribution, and good dispersibility. Transparent AlON ceramics with dimensions of Φ100 mm × 1 mm were fabricated by pressureless sintering the produced fine AlON powder.
关键词： B.Grain size,Aluminum oxynitride,A. Powders: solid-state reaction
更新于2025-11-19 16:56:35
-
Preparation of α‐Si <sub/>3</sub> N <sub/>4</sub> by direct nitridation using the polysilicon waste by diamond wire cutting
摘要： With the rapid development of the semiconductor industry and solar photovoltaic industry, a large number of polysilicon wastes from diamond wire cutting are accumulated, which not only pollute the environment, but also cause safety problems due to the ultrafine particle size and high reactivity. The diamond wire cutting polysilicon waste was used to prepare α-Si3N4 by direct nitridation method. This method could not only fully recycle the waste and reduce environmental pollution, but also reduce the production cost of α-Si3N4. Furthermore, the effects of FeCl3, NaCl and metal Cu on the nitridation of polysilicon waste are investigated in detail, respectively. It is found that FeCl3 and NaCl are not ideal additives for the preparation of α-Si3N4. However, α-Si3N4 dominated Si3N4 can be obtained via adding 5 wt. % Cu after nitridation at 1250 oC for 8 h, and the relative content of α-Si3N4 reaches 92.37 %.
关键词： silicon nitride,crystal growth,nitridation,catalysts/catalysis,powders
更新于2025-11-14 14:48:53
-
Developing New Materials for Electron Beam Melting: Experiences and Challenges
摘要： Lack of industrially available materials for additive manufacturing (AM) of metallic materials along with the promises of materials with improved or unique properties provides a strong drive for developing new process/material combinations. As powder bed technologies for metallic materials are relatively new to the market, and to some extent are only maturing, developers of new process/material combinations have certain challenges to overcome. Firstly, basic knowledge on the behavior of materials (even those well established for other applications) under extreme conditions of melting/solidification with beam-based AM methods is far from being adequate. Secondly, manufacturing of the equipment is up to date driven by industrial application, thus optimization of the AM machines for small test batches of powders is still belongs to research and development projects. Also, majority of the powder manufacturers are primarily driven by the market development, and even they are well aware of the demands imposed by the powder bed AM machines, availability of small test batches of adequate powders may be problematic or at least quite costly for the R&D oriented users. Present paper describes the experiences in developing new materials for EBM A2 machine by Arcam EBM, modified for operating with powder batches of 100-200 ml and less. In particular it discusses achievements and challenges of working with powders from different materials with specifications far beyond the range suggested by machine manufacturer. Also it discusses the possibility of using blended rather than pre-alloyed powders for achieving both composite-like and alloyed materials in the same part by steering electron beam energy deposition strategy.
关键词： Electron Beam Melting,material development,composite materials,Additive Manufacturing,blended powders,in situ alloying
更新于2025-09-23 15:23:52
-
Hydrothermal synthesis of tellurium nanorods by using recovered tellurium from waste electronic devices
摘要： Tellurium (Te) nanostructures with controlled morphology have received considerable attention in various applications owing to tunable optic, thermoelectric, photoelectronic, piezoelectric, and electrochemical properties. Herein, we introduce the cost-effective and eco-friendly synthesis of Te nanorods (Te NRs) from end of life electronic devices via hydrothermal methods. The Te NRs show the average diameter of 44.6 nm and a length of 358 nm in presence of polyvinylpyrrolidone, as a stabilizing agent. Moreover, the bismuth and intact p-type semiconductor (i.e., Bi0.5Sb1.5Te3) are selectively recovered as intermediated products. The Te NRs exhibit the NO2 gas sensing properties with concentration as low as 1 ppm at room temperature and fast response/recovery times of 1.59 and 2.10 s at 1 ppm, respectively. We believe that this powerful approach can be expanded to not only selective recovery of valuable materials but synthesis of various nanomaterials from waste electronic devices.
关键词： Recycling,Grain growth,Chemical properties,Powders: chemical preparation,Sensors
更新于2025-09-23 15:23:52
-
Sol-Gel Preparation of Thick TiO<sub>2</sub> Films for Structural Coloration
摘要： We studied sol-gel processing of thick and crack-free TiO2 films to synthesize structural color materials. The viscosity of the alkoxide-based precursor sols was stabilized by the addition of acetyl acetone, which improved control of the spin coating thickness. We used a TiO2/SiO2/TiO2 triple-layer structure and second-order reflection conditions to produce structural coloration. This design yielded a sharp spectral peak and bright coloration; however, a TiO2 layer with a thickness greater than 200 nm was required, which is much thicker than that required for the first-order of reflection. Crack formation in the thick films was suppressed by the addition of ethyl cellulose to the precursor sols. As a consequence, color-tuned TiO2/SiO2/TiO2 films were successfully prepared and exhibited various bright colors in the visible light wavelength range, including two primary colors of light, namely blue and green. Green coloration from flake-shaped particles was also demonstrated.
关键词： TiO2,structural color,crack formation,flake-like powders,sol-gel method
更新于2025-09-23 15:22:29
-
Intense red emission and two-way energy transfer in Sm3+, Eu3+ co-doped NaLa(WO4)2 phosphors
摘要： NaLa(WO4)2 phosphors with various Eu3+ and Sm3+ concentrations were prepared via a molten salt method. The structure and luminescent properties of the prepared samples were analyzed by the X-ray diffraction (XRD) and fluorescence spectrophotometer. The results show that the crystal phase of all the prepared samples is single tetragonal crystal structure. The energy transfer type between Eu3+ ions is proved to be the exchange interaction and the electron-phonon coupling is weak. With the increase of the Sm3+ concentration, the energy transfer from Sm3+ to Eu3+ in NaLa(WO4)2:0.15Eu3+,xSm3+ is transformed from Eu3+ to Sm3+, and the mechanism for energy transfer is given.
关键词： Nanophosphor powders NaLa(WO4)2: xEu3+ ySm3+,Electron-phonon coupling,Photoluminescence,Energy transfer
更新于2025-09-23 15:21:21
-
Characteristics of Upconversion Luminescence of CaF2:Er Powders Excited by 1.5-?μm Laser Radiation
摘要： The characteristics of upconversion luminescence of CaF2:Er crystalline powders upon laser excitation of Er3+ ions to the 4I13/2 level at a wavelength of 1531.8 nm are studied. The upconversion luminescence energy yields for the spectral regions of 380–780 and 380–1100 nm are determined. It is found that upconversion luminescence of CaF2:Er powders with Er3+ concentrations of 0.5, 2, 4, 6, 8, 10, 11, 13, 15, and 17% is characterized by correlated color temperatures of 5100, 2142, 1726, 1738, 1773, 1757, 1762, 1765, 1735, and 1714 K, respectively.
关键词： luminescence,crystalline powders,upconversion
更新于2025-09-23 15:21:01
-
Boosting Efficiency and Stability of Planar Inverted (FAPbI <sub/>3</sub> ) <sub/><i>x</i> </sub> (MAPbBr <sub/>3</sub> ) <sub/> 1- <i>x</i> </sub> Solar Cells <i>via</i> FAPbI <sub/>3</sub> and MAPbBr <sub/>3</sub> Crystal Powders
摘要： Solution processed perovskite precursor especially for MAPbBr3 assisted FAPbI3 crystallization has been noted to achieve high power conversion efficiency (PCE) for perovskite solar cells (PSCs). However, this low-temperature processed (FAPbI3)x(MAPbBr3)1-x typical precursor derived from commercial products (FAI, PbI2, MABr and PbBr2) suffers from environmental sensitivity, poor film crystallinity and less than ideal device reproducibility. Herein, (FAPbI3)x(MAPbBr3)1-x (0.80≤x≤0.90) based planar inverted PSCs were fabricated by employing grinded monocrystalline MAPbBr3 and powdered polycrystalline FAPbI3 as precursors. The champion device with optimal molar ratio x=0.85 comprising highly crystalline larger-grained perovskite film with enhanced carrier transport kinetics and reduced trap-state density exhibits boosted efficiency reaching 20.50%, which shows 22.90% improvement of typical precursor with a PCE of 16.68%. In addition, crystal powder precursor receives obvious film stability in ambient condition (23 ℃, 65%~85% humidity) for 150 days and improved device storage stability in glove box within two months. This protocol using stock crystal powders for perovskite precursor formulation provides a relatively facile and reproducible device fabrication route for the commercialization of PSCs.
关键词： crystal powders,boosting performance,planar inverted,stability,perovskite solar cells
更新于2025-09-23 15:19:57
-
Preparation of SiC Powders by Carbonthemal Reduction Method at Low Temperature
摘要： The stable slurry was prepared by ball-milling with a certain proportion of silica fume as silicon source, glucose as carbon source and metal niobium (Nb) as additives mixed with alcohol water. After the slurry was dried and pulverized, put the powder into a tubular furnace heated to 650℃ for 2h under nitrogen atmosphere to prepare precursor, the heating rate was 5℃ /min. Treated the precursor under vacuum by carbothermal reduction method to prepare silicon carbide (SiC) powder. The effect of temperature and additive content on the morphology of synthesised silicon carbide and the impurity removal order on product purity were explored. After firing at 1300℃, 1400℃, 1500℃ for 2 h, the 3C-SiC powders are detected, and as the temperature increased, the crystallinity of the product become better. When the content of the additive is 1% of the quality of the silica fume, the particle size of the silicon carbide synthesized at the temperature of 1500℃ is even and the dispersion is better. As for the impurity removal order, removed SiO2 first, then removed C can effectively remove the impurities in the product.
关键词： metal niobium,carbothermal reduction,silica fume,glucose,SiC powders,low temperature
更新于2025-09-23 15:19:57
-
Measurement of effective diffusion coefficients in dairy powders by confocal microscopy and sorption kinetic profiles
摘要： A new method for the visualisation and determination of local diffusion coefficients in dairy powders is described based on real-time visualisation of penetration of fluorescent dyes into individual particles of spray-dried dairy powders including skim milk powder, milk protein concentrate and whey protein isolate. The rehydration process was controlled by adding polyethylene glycol (PEG) as a viscosity modifier to the aqueous phase in ratios of 1:0, 1:1, 1:3 and 1:4 aqueous rhodamine to PEG, respectively. Real-time effective diffusivity values were obtained from analysis of confocal laser scanning microscope images. Particle size was measured optically. Results indicated that for all dairy powders, rehydration rates were highly dependent on particle size. Effective diffusivity increased linearly with increasing particle size and average effective diffusivity of the liquid phase was calculated for all particle size distributions using this dependence. The Guggenheim-Anderson-de Boer (GAB) water sorption relationship was used to model water sorption isotherms over a broad range of water activities. Vapour phase systems had significantly higher effective diffusivity than liquid phase systems. The results obtained by this new method is broadly in agreement with previously published works, suggesting this new method may be used to measure the hydration of individual powder particles.
关键词： Microscopy,Food powders,Rehydration,Confocal,Diffusion
更新于2025-09-19 17:15:36