Dielectric and X-Ray Studies ofCaxBa1−xTiO3andCaxSr1−xTiO3

Abstract

Ceramics of ${\mathrm{Ca}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}\mathrm{Ti}{\mathrm{O}}_{3}$ and ${\mathrm{Ca}}_{x}{\mathrm{Sr}}_{1\ensuremath{-}x}\mathrm{Ti}{\mathrm{O}}_{3}$ have been prepared and their dielectric and structural properties investigated. Firing conditions were adjusted to obtain sharp x-ray back reflections. The Curie point of ${\mathrm{Ca}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}\mathrm{Ti}{\mathrm{O}}_{3}$ increases with Ca concentration up to 136\ifmmode^\circ\else\textdegree\fi{}C for $x=0.08$, and then decreases. Both the tetragonal-orthorhombic and the orthorhombic-rhombohedral transition points of ${\mathrm{Ca}}_{x}{\mathrm{Ba}}_{1\ensuremath{-}x}\mathrm{Ti}{\mathrm{O}}_{3}$ decrease monotonically with increasing Ca concentration. ${\mathrm{Ca}}_{x}{\mathrm{Sr}}_{1\ensuremath{-}x}\mathrm{Ti}{\mathrm{O}}_{3}$ solid solutions with $0.01<~x<~0.10$ are ferroelectric at very low temperatures. SrTi${\mathrm{O}}_{3}$ assumes a tetragonal structure below about 80\ifmmode^\circ\else\textdegree\fi{}K.