Mechanism of texture development in <001> oriented (K, Na)NbO3-based ceramics

The development of grain orientation was examined for (K, Na)NbO₃-based ceramics using two kinds of platelike NaNbO₃ template powders made by single- and two-step molten salt synthesis (MSS) and four kinds of matrix powders to examine the factors controlling the degree of orientation. The template grains made by single-step MSS were dissolved in the matrix of a mixture of NaNbO₃ and KNbO₃ powders, leaving large voids. The template grains made by two-step MSS were not dissolved and gave high reproducibility in the degree of orientation. The effect of matrix species on the grain orientation was examined using the template powder made by two-step MSS and the matrixes of KNbO₃, NaNbO₃, and (K_0.5Na_0.5)NbO₃ powders and a mixture of KNbO₃ and NaNbO₃ powders. The extensive grain orientation developed only in (K_0.5Na_0.5)NbO₃ and a mixture of KNbO₃ and NaNbO₃ powders. The origin of the difference in the grain orientation behavior was examined by microstructure observation.