Advanced Materials Research Vol. 412

Abstract: The Bi-2223 powders were fabricated by the sol-gel technique. Metal nitrates were used as starting materials, and ethylenediamineteracetic acid was used as chelating agent. The solution was heated until it turns to gel. Then the organic was removed at a temperature of 240°C, and the nitrite was removed at 500°C. The powder was calcined at different temperature, varying the dwelling time. Experimental results show that the main phase of samples after heat treatment is Bi-2212 phase.

Abstract: Fused silica micro-powders with D₅₀ of 1.8μm were firstly prepared by ball milling. Effects of milling time on particle size distribution and microstructures of the powders were discussed. Then, the green compacts with volume density of 1.86g/cm³ was obtained by slip casting with lactic acid as dispersant. Effects of lactic acid content on apparent viscosity of the slurry, thickness and density of the green compacts were investigated. Finally, fused silica ceramics with thermal expansion coefficient of 0.56∙10^-6/°C, bending strength of 64MPa and volume density of 1.94g/cm³ were prepared.

Abstract: SnO-B₂O₃-SiO₂ glass powders, in which the different contents of SnO and B₂O₃ were 35% ~ 70%wt and 26% ~ 61% wt respectively, were prepared through high-temperature melting, water quenching and Ball milling. XRD showed that the performance of forming glass was very good and the range of extension was very wide. The effect of the contents of SnO and B₂O₃ on Tg, acidoresistant and density of prepared glass was studied. IR showed that it generates the heavy metal oxide generated glass. The density of glass powder decrease with increase of B₂O₃ content, but increase with increasing SnO content. SnO-B₂O₃-SiO₂ glass had excellent chemical stability. Differential thermal analysis (DTA) shown that, with increasing SnO content, glass transition temperature first lower and then decreased.

Abstract: The ultrafine bio-glass powder of Si-Al-Ca-P-F^- polynary system was prepared by sol-gel method with organic and inorganic compounds such as Si (OC₂H₅)₄, (C₂H₅)₃PO₄, Ca (NO₃)₂·4H₂O, Al (NO₃)₃·9H₂O and NH₄F. The powder was heat-treated at the different temperature in the range from 200 to 900°C and its crystallized transition was ascertained. The morphology, composition, structure state and crystallized behavior of the glassy powder were characterized by means of TEM, XRD, EDS, DSC-TG, FT-IR etc methods and compared with the glassy powder of the same system by melting-quenching and liquid precipitation. The results show that the powder containing elements Si, Al, Ca, P, F and O belongs to typical amorphous state, and is composed of the near spherical particles with the size from 100 to 400nm; The transition temperature of glass was about 580°C, and the crystallized phase CaF₂ precipitate firstly above 600°C; A series of crystallized phases Ca₅(PO₄)₃F and Ca₅(PO₄)₂SiO₄ were separated sequentially with increasing temperature; The network structure of glass is similar to that of melt-quenching or liquid precipitation glass.

Abstract: BiFeO₃ powders were prepared by sol-gel process and calcined at different temperatures. The DTA curve shows an obvious exothermic peak near 480.5°C, the temperature close to BiFeO₃ formation temperature, which is agreement with the XRD results (450°C). After calcining at 600°C for 1h, XRD spectra has the emergence of several sharp diffraction peaks, compared with the standard XRD spectrum of the crystal BiFeO₃. As the calcining temperature increased, the diffraction peak intensity of the XRD spectra of BiFeO₃ gradually increased and the diffraction peaks became sharply, indicating that the grain size gradually became larger. There is a clear endothermic peak near 825.1°C, which is the α phase to β phase transition from the knowledge of the phase diagram and in good agreement with the reported Curie temperature.

Abstract: The Y-type hexaferrite precursors was synthesized by co-precipitation, and the pivotal technological conditions, including pH value, temperature (T), rotate speed (R) and the flow velocity of salt solution (V) were discussed. The particles of precursors were studied by Laser particle size analyzer (LPS). The precursor calcined at 900°C was characterized via X-ray Diffraction (XRD), the vibrating sample magnetometer (VSM) and HP4291A impedance analyzer were used to investigated magnetic properties. The results showed that the particle sizes were around 3µm (D50) and the distribution range was from 2.28μm to 4.47μm, in the optimized technological conditions: pH = 10.50, T = 50°C, R = 300 rpm, V = 0.35 ml/min, SDBS = 0.3 g/L, the specific saturation magnetization, coercive force, residual magnetization, initial permeability and factor of quality of the sample were σ_s ≈ 29.72A·m²·kg^-1, H_c ≈ 4.11/kA·m^-1, σ_r ≈ 7.74 A·m²·kg^-1, μ_i ≈ 9 and Q ≈ 18 respectively.

Abstract: Because of aggregation and low chemical stability of nanomagnetic particles, we use Sol-Gel method as surface modification in this paper to improve the disperse ability and the chemical stability of Fe₃O₄ particles. At first, Fe₃O₄ were prepared by chemical-precipitation method. Then, the Sol-Gel method was used to modify the surface of the particles. Core-shell structural Fe₃O₄@ S iO₂ composite magnetic particles were prepared by hydrolysis and condensation of tetraethyl orthosilicate using Fe₃O₄ nanomagnetic particles as seeds. XRD,VSM were applied to characterize the composite magnetic particles. The effects of rotational speed and the quantity of TEOS on the performance of Fe₃O₄@ S iO₂ composite magnetic particles were investigated.

Abstract: For prepare magnetic liquids with good property, the authors prepared Magnetic Fe₃O₄ nanoparticles by co-precipitation in different temperatures including 60°C, 70°C, 80°C in this experiment and analyzed the product of Magnetic Fe₃O₄ nanoparticles by X-ray Diffraction Analysis, Transmission Electron Scanning, Saturation Magnetization Test and the result indicate that Magnetic Fe₃O₄ nanoparticles prepared at 70°C have good crystallinity and high saturation magnetization and suitable for prepare magnetic liquid.

Abstract: Spindle-like CdS structures were successfully synthesized via a simple one-step solvothermal process. The as-prepared products were characterization by X-ray powder diffractometer (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy (UV-vis). By discussing the captive indimediates, the formation process of the spindle-like CdS structure was proposed as the splitting and the Oswald growth mechanism. The optical property of the as-prepared CdS showed obvious blue shift relative to the bulk CdS materials.

Abstract: In this work, we fabricated indium hydroxide (In (OH)₃) nanocubes from In (NO₃)₃ and urea through hydrothermal method. NH₄OH form the hydrolysis of urea acts as the OH¯ provider. The resultant products were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), photoluminescence (PL) spectra and contact angle meter. It was observed that the In (OH)₃ nanocubes showed superhydrophobicity with water contact angle 161.9° after modified with fluoroalkylsilane (FAS, CF₃(CF₂)₇CH₂CH₂Si (OCH₃)₃), and exhibited PL peak at about 529 nm, corresponding to the deep level emission.