Quasi-Equilibrium, Multifoil Platelets of Copper- and Titanium-Substituted Bismuth Vanadate, Bi2V0.9(Cu0.1−xTix)O5.5−δ, by Molten Salt Synthesis

Abstract

10% copper-substituted (BiCUVOX/Bi 2 V 0.9 Cu 0.1 O 5.5−δ ) and 5% copper/titanium double-substituted bismuth vanadate (BiCUTIVOX/Bi 2 V 0.9 (Cu 0.05 Ti 0.05 )O 5.5−δ ) platelets were formed by molten salt synthesis (MSS) using a eutectic KCl/NaCl salt mixture. The product was phase-pure within the limits of X-ray diffraction. The size and form of the platelets could be controlled by changing the heating temperature and time. The crystallite growth rate at a synthesis temperature of 650 • C and the activation energy for grain growth were determined for BICUTIVOX, which experienced inhibited growth compared to BICUVOX. Quasi-equilibrium, multifoil shapes consisting of lobes around the perimeter of the platelets were observed and explained in the context of relative two-dimensional nucleation and edge growth rates.

Ceramic Conductors

“…Proton conductivity may be observed in acceptor-doped perovskite oxides such as Ba 0.9 La 0.1 Zr 0.25 Sn 0.25 In 0.5 O 3−a , as studied by Skubida et al [2], and terbium-substituted lanthanum orthoniobate [3]. Oxygen ions are mobile charge carriers in materials such as substituted bismuth vanadate [4] and doped cerium oxide [5,6], as studied by Ring and Fuierer, and to a minor extent and at high temperature, they are also mobile charge carriers in ceramic proton conductors. Fluorine ions, the first mobile ions studied in solid-state ionic conductors, are present in SrF 2 -YF 3 solid solutions, as reported by Breuer et al [7].…”

“…On the other hand, the solid-state reaction route often does not allow the achievement of single-phase ceramics with expected properties. One of the interesting synthesis methods which may be used for manufacturing either fine ceramic powders [4] or even single crystals is molten-salt synthesis. Also, sol-gel self-combustion synthesis [5] and spray-pyrolysis [8] lead to the formation of nanosized ceramic powders.…”