B-site deficient hexagonal perovskites: Structural stability, ionic order-disorder and electrical properties

Mixed oxide ion–proton conductivity and the ionic migration mechanism in isolated tetrahedral LaVO4 by acceptor doping

“…3). This results in oxide ions becoming more disordered at high temperature, 9 reducing the trapping effect and allowing oxide ions to exchange more easily. The increased thermal energy enhances the mobility of oxide ions and possibly increases defect concentrations, facilitating a lower energy barrier for oxide ion conduction.…”

“…Solid-state oxide ion and proton conductors have received much attention due to their important applications as gas sensors and pumps, 1,2 in gas conversion, as permeation membranes, 3,4 as reformation catalysts, 5,6 and as electrolytes for solid oxide fuel cells. 7–9 Lowering the operating temperature for these devices requires high ion mobility at low temperatures, 10 which has stimulated extensive research into new solid-state ion conductors, alongside a deeper understanding of defect stabilization and the underlying mechanisms of ion conduction. Since the initial discovery of zirconia-type oxides by Nernst in the 19 th century, 11 a series of solid-state oxide and proton ion conductors have been reported, including, but not limited to perovskite-type LSGM, 12,13 BZY, 14,15 Ba 7 Nb 4 MoO 20 , 16,17 Ba 2 LuAlO 5 , 18 and tetrahedron-based structures encompassing apatites, 19–22 LAMOX, 23 LaBaGaO 4 , 24 melilites, 25 A 3 V 2 O 8 (A = Sr, Ba) 26 and scheelites.…”