Structure, thermal stability, optoelectronic and electrophysical properties of Mg- and Na-codoped bismuth niobate pyrochlores: Experimental and theoretical study

Low‐temperature dielectric behavior of Sc‐ and In‐doped bismuth titanate pyrochlores

“… 15,16 The location of the dopant atoms in one of the cationic positions can affect the properties of the pyrochlore solid solutions. Moreover, atomic displacements from the ideal pyrochlore positions ( A from 16 c to 96 h or 96 g ; O′ from 8 a to 32 e or 96 g ) are known to be characteristic of the Bi‐based pyrochlores 15,16,28,43 . Here, we carefully performed Rietveld refinement of the XRD patterns (Figure 1).…”

“…Moreover, atomic displacements from the ideal pyrochlore positions (A from 16c to 96h or 96g; O′ from 8a to 32e or 96g) are known to be characteristic of the Bibased pyrochlores. 15,16,28,43 Here, we carefully performed Rietveld refinement of the XRD patterns (Figure 1). The occupations of the atomic sites in the refined models were kept frozen based on the initial chemical composition of the compounds.…”

Effect of Li and Li-RE co-doping on structure, stability, optical and electrical properties of bismuth magnesium niobate pyrochlore

“…The proton transport of defect pyrochlores makes them attractive for use in proton-conducting membranes. A defect pyrochlore can be formed by acceptor doping [13][14][15][16][17][35][36][37] and/or the adjustment of the initial defect composition [38]. These procedures result in the formation of oxygen vacancies.…”

“…In a humid atmosphere, the adsorbed water on the surface of the oxide material dissociates into a hydroxide ion and a proton, fills in the oxide ion vacancies, and then forms a covalent bond with the lattice oxygen [35]. The corresponding bulk proton transport proceeds through ambipolar diffusion of V ⋅⋅ O and OH ⋅ O as a supplement to the oxygen transport in the oxide material [35][36][37]. The temperature range of the presence of proton conductivity is defined by the initial pyrochlore matrix: up to 360-400 • C for doped magnesium bismuth niobates [36,37], up to 500-700 • C for doped bismuth titanates [38] and up to 650 • C for Ca-doped La 2 Zr 2 O 7 [14,15].…”

“…The corresponding bulk proton transport proceeds through ambipolar diffusion of V ⋅⋅ O and OH ⋅ O as a supplement to the oxygen transport in the oxide material [35][36][37]. The temperature range of the presence of proton conductivity is defined by the initial pyrochlore matrix: up to 360-400 • C for doped magnesium bismuth niobates [36,37], up to 500-700 • C for doped bismuth titanates [38] and up to 650 • C for Ca-doped La 2 Zr 2 O 7 [14,15].…”