Papers by Author: Zhi Wei Yu

Abstract: Xerogel was prepared by the sol-gel method using ethyl ester orthosilicate, alcohol, carbamide and glucose with various contents as raw materials. The precursor powders were obtained after xerogel was solvothermally treated at 220oC for 2.5 h. IR analyses showed that the Si-O-Si and Si-O-NH2 bond are obtained in the precursors. XRD analyses indicated that the powders prepared by the solvothermal method are amorphous. Si3N4 powders are produced by heat-treating the precursors at 1400 oC in N2. It was proved that the synthesized powders are α–Si3N4 whiskers. With the increase of the glucose contents and the heat-treating temperature, the crystallization of Si3N4 is obviously improved.

Abstract: Bi2Fe4O9 nanoparticles were prepared at low temperature via a facile, one-step hydrothermal synthesis process using iron(III) nitrate nonahydrate (Fe(NO3)3•9H2O) and bismuth nitrate pentahydrate (Bi(NO3)3•5H2O) as starting materials and sodium hydroxide (NaOH) as precipitant and mineralizer. XRD results indicated that the as-prepared nanoparticles are pure orthorhombic Bi2Fe4O9. SEM images revealed that the as-prepared Bi2Fe4O9 nanoparticles have a sheet-like morphology. They are paramagnetic at room temperature demonstrated by the magnetic measurements.