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 (K0.5Na0.5)NbO3 powders and a mixture of KNbO3 and NaNbO3 powders. The extensive grain orientation developed only in (K0.5Na0.5)NbO3 and a mixture of KNbO3 and NaNbO3 powders. The origin of the difference in the grain orientation behavior was examined by microstructure observation.