Synthesis and investigation on stability and electrical conductivity of Ti-doped Ba3CaTa2-xTixO9 (0 <= x <= 1.0) complex oxides

Abstract

An attempt has been made here to synthesize Ba3CaTa2-xTixO9 (0 <= x <= 1.0) perovskite-type complex oxides and characterize with regard to structure, chemical stability and conductivity to develop electrolytes for proton conducting fuel cells. X-ray diffraction pattern shows the formation of single phase of double perovskite-type structure with lattice parameter lies in the range of 8.368-8.393 angstrom (+/- 0.004 angstrom) for x = 0-0.50 and decreases with titanium content (x). Fourier transform infrared spectra and X-ray diffraction data confirm improved stability of Ba3CaTa2-xTixO9 (0 <= x <= 0.5). in humid air (H2O exposed) and CO2 atmosphere at elevated temperatures. X-ray photoelectron spectra attributed to the presence of Ti3+ and Ti4+, bonding between Ba-O and O - (Ti/Ta). The electrical conductivity of electrolytes are analyzed in different atmospheres e.g., dry and wet air and argon. There is increase in conductivity in wet atmospheres, confirmed the proton conduction in Ba3CaTa2-xTixO9 (0 <= x <= 0.5). Among Ti-substituted materials, Ba3CaTa1.5Ti0.5O9 shows the highest conductivity. (C) 2018 Elsevier B.V. All rights reserved.