PREPARATION AND CHARACTERIZATION OF IONIC CONDUCTOR Bi_(23)V_4O_(44.5)

摘要

Bi_(23)V_4O_(44.5) was synthesized by solid state reaction and via ball milling process. In ball milling process, high-density, fine-grained powders with uniform grain-size distribution were obtained. Rietveld refinement results on powder data showed that Bi_(23)V_4O_(44.5) crystallized in the triclinic system, space group P-1, with cell parameters at room temperature, a = 11.570(5)A, b = 11.543(5)A, c = 20.638(7)A, α = 76.46(3)°, β = 87.69(4)°, γ = 119.98(3)°. Impedance data shows that the material is a good ionic conductor with conductivity as high as 1.34 x 10~(-4) ohm~(-1) cm~(-1) at 300°C. A phase transition was also observed at ～180°C. The existence of grain boundary effect was observed in Bi_(23)V_4O_(44.5), which could not be eliminated in dense material preparation via ball milling process. The discrepancy of electrical behavior in the materials prepared via solid state reaction and ball milling process was investigated. Further characterization using high precision inductance/capacitance/resistance (LCR) meter, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and Scanning Electron Microscopy (SEM) were carried out.