Advanced Materials Research Vol. 412

Abstract: Quasi-monodispersed SnO₂ nanocrystal microspheres were successfully fabricated by a solvothermal route with the assistance of poly (ethylene glycol) (PEG, Mn=6000) template. The as-prepared SnO₂ microspheres were well characterized by XRD, SEM, TEM, and FT-IR. The photocatalytic activity for Rh B on the SnO₂ microspheres was also investigated under UV irradiation. The experimental results show that the quasi-monodispersed SnO₂ microspheres with diameter about 1.3µm are self-assembled by large quantity of crystallites less than 10 nm. The SnO₂ microspheres have a good photocatalytic property, as evidenced by the result that over 95% of the Rh B decomposed over the SnO₂ nanocrystal microspheres within 180 min. The high degradation rate of rhodamine B (Rh B) on the as-synthesized SnO₂ nanocrystal microspheres can be attributed to the small size of crystals.

Abstract: The walnut-like α-Ni (OH)₂ architectures have been successfully synthesized through a microwave-assisted hydrothermal method using urea as a hydrolysis-controlling agent and polyethylene glycol (PEG) as a surfactant. The NiO architectures with similar morphology were obtained by a simple thermal decomposition process of the precursor α-Ni (OH)₂. The as-obtained products were well characterized by XRD, SEM, TEM, and FTIR. The experimental results shown that walnut-like α-Ni (OH)₂ architectures with a diameter of 2-6 μm. The formation process of Ni (OH)₂ architectures was observed by SEM via different hydrothermal reaction times.

Abstract: Ultra-thin fibers of indium oxide (In₂O₃) were prepared by sol-gel processing and the electrospinning technique using polyvinylpyrrolidone (PVP) and indium nitrate as precursors. The fibers were characterized by the thermogravimetric analysis, scanning electron microscopy, X-ray diffraction and room temperature photoluminescence spectra. It was observed that the In₂O₃ nanofibers exhibited photoluminescence peaks centered at 526 and 590 nm, corresponding to the defeat-related deep-level emission.

Abstract: This paper studied affect of porous structure SnO₂/In₂O₃composites about sinter temperature and chemical content of SnO₂ by solid-phase reactive sintering method. It studied on the influence of different content of SnO₂ and sintering temperature to porous structure SnO₂/ In₂O₃ composites. The microstructure and phase were analyzed by SEM (Scanning Electron Microcopy) and XRD (X-ray diffraction). The results showed SnO₂/In₂O₃ composites had better porous structure as following conditions: the content was 10% SnO₂ in SnO₂/In₂O₃ composites and sintering temperature was 1300°C holding 3 hours after 600°C holding 1 hour, and then cooling to room temperature in the furnace.

Abstract: ZrO₂ spherical nanoparticles were prepared by rheological phase reaction. The crystal structure, morphology and formation mechanism were characterized with X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR) and scanning electron microscopy (SEM), etc. Then three-dimensional photonic crystal was synthesized by sol-gel method and using surfactant as template. The study showed that well-controlled spherical particle is helpful to preparation of photonic crystal with adjustable apertures. Mesoporous ZrO₂ was obtained with narrow pore size distributions.

Abstract: 3Y-TZP powder has been successfully synthesized by gel solid-state method. The structural phases of powder particles were analyzed by X-ray diffraction and the morphology was analyzed by scanning electron microscopy. The average size of grains was 230 nm. The sintering behavior, mechanical properties and microstructure of 3Y-TZP ceramics sintered by this powder were investigated. The experiment results showed that the mechanical properties of ceramics were excellent.

Abstract: Acicular mullite porous ceramics were synthesis by high-temperature sintering technique. In the present work, Kaolin and industrial aluminum hydroxide were selected as raw materials, AlF₃ used as catalyst. XRD and SEM were used to detect the crystal type and microstructure of prepared mullite ceramics, respectively. The influences of sintering temperature on the growth of crystal, the apparent porosity and compressive strength of the resulting porous ceramics were investigated. The results indicate when sintering temperature ranges from 1250 ~ 1400°C, much acicular mullite crystal appeared in the resulting ceramics. The apparent porosity, the compressive strength and the morphology of the mullite whisker changed obviously with the sintering temperature. When sintering temperature is 1400°C, the porous ceramics showed the maximum compressive strength of ~28 MPa and the maximum apparent porosity of ~63%.

Abstract: Platelet alumina powders have been synthesized by introducing AlF₃ as crystalline transformation additive. The influence of the additive contents on the phase transformation of the start material Al (OH)₃ was studied by SEM, the effect of calcination temperatures on the phase transformation and microstructure of alumina powder were investigated by TG-DSC, XRD and SEM. The results indicate that uniform platelet powders could be abtained while more than 15% AlF₃ was introduced. When the calcination temperature higher than 1100°C pure α-Al₂O₃ could be synthesized, comparing to the tranditional preparation of platelet alumina powders, the remarkable advantages of the method are low calsination temperature, small particle size and simple process.

Abstract: The MgO-Al₂O₃-SiO₂ (MAS) glass powders have been synthesized by low-temperature combustion technique using magnesium nitrate, aluminium nitrate, silicic acid as material, urea as fuel. The crystallization process, sintering behavior and dielectric properties were investigated by means of DTA, XRD, TMA and SEM techniques. The results showed that the glass powders could be sintered at lower than 1000°C. The μ-cordierite phase was first crystallized from glass and then transformed into α-cordierite phase during sintering process. The obtained cordierite-based glass-ceramics at 950°C and 1000°C have low dielectric constant (4.00 ~ 4.96 at 1 MHz), low dielectric dissipation factor (≈ 0.003) and high sintering density (which is above 98% of the theoretical density), which are used for electronic packaging.

Abstract: A new technology, gel solid-state reaction, for synthesis of SrTiO₃ ceramic composite powders is described in the present paper. This process, valuable for a great number of composite powders, is of great simplicity and has a relative low synthetic temperature of powders. The calcined lumped powder is porous and easy to grind. XRD and d-spacing-component figures of the solid solution powder demonstrated that the compounds were mutually miscible in the solid solutions, and SEM showed that they were uniform and substantially spherical with an average size of 1.0 μm in diameter. The remarkable advantages of the method are high yields, solvent-free, and environmental benign.