Dielectric Properties of Spark-Plasma-Sintered (Na 0.5 K 0.5 )NbO 3 -PbTiO 3 Ceramics.

Dielectric properties of spark-plasma-sintered solid solution (1 - x )(Na 0.5 K 0.5 )NbO 3 - x PbTiO 3 were studied. Both the cubic-tetragonal and the tetragonal-orthorhombic phase transitions become more and more diffuse with increasing x . The strong deviation of the cubic-tetragonal phase transition temperature versus composition curve from the Vegard's law is observed. It is considered that (1) the introduction of heterovalence ions to both the perovskite A and B sites, and (2) the change of the mass difference between the perovskite B- and A-site, m B - m A , are two main factors responsible for the observations. [ABSTRACT FROM AUTHOR]