Dielectric study of Ti-doped Bi2VO5.5 solid electrolyte

Abstract

Synthesis and characterization of Bi2V1−xTixO5.5−(x/2)−δ (0 ≤ x ≤ 0.150) was done. For the present system, the lower limit of Ti required for near-complete tetragonal phase stabilization has been found to be x = 0.125. The optimum values of ionic conductivity were obtained for the compositions; Bi2V0.875Ti0.125O5.4375 and Bi2V0.9Ti0.1O5.45 at 300 °C and 600 °C, respectively. Interestingly, two peaks have been observed in frequency versus dielectric loss spectra for parent compound, which is in α-orthorhombic phase, as well as for tetragonal phase stabilized specimens with compositions x ≥ 0.125 at temperatures below 300 °C. No such peaks have been found in β-orthorhombic (x = 0.085) as well as in mixed tetragonal and orthorhombic (x = 0.1 and 0.1125) phases. Thus, we propose that frequency-dependent dielectric loss spectra can be used to qualitatively distinguish α and γ-phases from β-phase in BITIVOX system and it is the central result of this work.