Coated-PMMA microspheres consisting of poly (methyl methacrylate)(PMMA) core and barium titanate (BaTiO3) shell were synthesized by the modified sol-gel processing and then adopted as an electrorheological (ER) materials. The structure and morphology of coated powders were characterized by SEM and FT-IR; the shear stress of the suspensions of coated-PMMA particles and pure PMMA particles in silicone oil with a 20 vol% were investigated. The results show that the BaTiO3 coated PMMA microspheres based suspension in silicone oil exhibited typical ER behavior and stronger ER effects.
A new process to synthesize polycrystalline samples of Sr_(14)Cu_(24)O_(41)was presented.Firstly,dry gel powder of Sr_(14)Cu_(24)O_(41)was synthesized by the citrates sol-gel method,using Sr(NO_3)_2,Cu(NO_3)_2,ethylene glycol and citrate acid as raw materials.Then,polycrystalline samples of Sr_(14)Cu_(24)O_4 l were prepared by solid- state reaction.Thermal Gravimetric and Differential Thermal Analysis(TG-DTA)showed that the temperature for solid-state reaction is at 942℃.The samples are identified to be single phase by X-ray Diffraction(XRD) and Scanning Electron Microscopy(SEM).The SEM pictures showed that the first-step particles were at even size of about 100 nm by this technique.The electronic transport measurements showed that the doping compound were semiconductor with a crossover temperature T_p in the Arrhenius plot of the resistivity versus temprature.
WANG LiliWEI HuiHU NiXIONG RuiYU ZuxingTANG WufengSHI Jing
Nearly single-phase and polycrystalline charge-density-wave compound K_(0.3)MoO_3 have been prepared by using a simple method.In this work,K_2CO_3 and MoO_3 were used as starting materials and reacted by hot isostatic pressing(HIP)sintering.The product is nearly single phase K_(0.3)MoO_3 determined by X-ray powder diffraction (XRD)and energy dispersive spectroscopy(EDS).Measurement of temperature dependence of resistivity reveals that the transport property of polycrystalline K_(0.3)MoO_3 obviously differs from that of single crystal due to the grain boundaries and the anisotropic structure in this kind of compound.
dunfeng WANGRui XIONGNing SHUJing SHIZhengzhong dIN
