Phase Development during Mixed–Oxide Processing of a [Na0.5K0.5NbO3]1-x -[LiTaO3]x Powder
Powders of the solid solution series [Na0.5K0.5NbO3]1-x - [LiTaO3]x, with x = 0.06, are shown to transform from an orthorhombic to a tetragonal crystal system as calcination temperature is increased in the range 850 °C to 1100 °C. Addition of 3 wt% of each alkali carbonate prior to calcination allows retention of the orthorhombic phase to 1100 oC. The latter changes in phase content are attributed to a partial compensation of alkali oxide volatilisation losses. The approach of adding extra alkali carbonates lead to an increase in d33 coefficient in sintered ceramics.
Wei Pan and Jianghong Gong
T.A. Skidmore et al., "Phase Development during Mixed–Oxide Processing of a [Na0.5K0.5NbO3]1-x -[LiTaO3]x Powder", Key Engineering Materials, Vols. 368-372, pp. 1886-1889, 2008