The titanate and tungstate were exposed to O potential gradients at 1400 and 1100C, and were found to dissociate into their constituent oxides: NiO, TiO2, WO3, and NiO. This was consistent with the non-equilibrium phenomenon of kinetic decomposition. In the case of the titanate, at low O potentials, TiO2 was formed as sharp needle-like structures within the titanate matrix. At high O potentials, NiO was formed. On the other hand, NiO was formed at low O potentials in the case of the tungstate, while WO3 volatilized at high O potentials. It was concluded that W diffused faster than Ni in the tungstate. In both cases, there were significant macroscopic shifts (as established using Pt markers), of the oxide with respect to the original position, towards the high O potential side.

D.C.Azubike, A.Chrysanthou, B.S.Terry: Journal of Materials Science, 1994, 29[11], 2957-62