Synthesis and Study on Ionic Conductive (Bi1−x,Vx)O1.5−δ Materials with a Dual-Phase Microstructure

Homogeneous Bi2O3-V2O5 powder mixtures with different amounts of V2O5 content ( less than or equal to 15 mol%) were prepared by colloidal dispersion and sintering to high density. The sintered and annealed samples were studied by thermal analysis, quantitative X-ray diffraction and scanning electron microscopy. The electrical and ionic conductivities of the conductors were also measured by a four-probe direct current (DC) method. The results of the samples prepared at 600-800 degree C and annealed for as long as 100 h show that the sintered samples consisting of a pure gamma phase or delta + gamma binary phase perform differently in conductivity. The highly conductive delta phase in the composition of Bi0.92V0.08O1.5- delta enhances the electric conductivity 10-times better than that of the pure gamma -sample (Bi0.94V0.06O1.5- delta ) between 400 and 600 degree C. The compatible regions of the gamma phase with the alpha - or delta phase are also reported and discussed, so a part of the previously published Bi2O3-V2O5 phase diagram below 800 degree C is revised.