Novel redox reversible oxide, Sr-doped cerium orthovanadate to metavanadate

Abstract

A-site substituted cerium metavanadates, Ce_1−xSr_xVO₃, were synthesised by solid-state reactions from single-phase powders of the corresponding orthovanadates. All samples were found to exhibit an orthorhombic perovskite structure of space groupPnma (62) with a = 5.5181 (3), b = 7.7853 (2) and c = 5.5155 (4) Å for Ce_0.85Sr_0.15VO₃. Conductivity measurements were performed in air and in dry 5% H₂–Ar with conductivity values at 700 °C ranging from 0.1 to 2.5 S cm⁻¹ with peaking at 6 S cm⁻¹ in reduced atmosphere. X-Ray diffraction patterns and thermal analyses have shown that the reduction of Sr-doped CeVO₃ from the equivalent orthovanadate is redox phase reversible without formation of parasitic phases while the undoped CeVO₄ is not.