Dielectric and X-Ray Studies of CaxBa1−xTiO3 and CaxSr1−xTiO3

Abstract

Ceramics of ${\mathrm{Ca}}_x{\mathrm{Ba}}_{1-x}\mathrm{Ti}{\mathrm{O}}_3$ and ${\mathrm{Ca}}_x{\mathrm{Sr}}_{1-x}\mathrm{Ti}{\mathrm{O}}_3$ 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 ${\mathrm{Ca}}_x{\mathrm{Ba}}_{1-x}\mathrm{Ti}{\mathrm{O}}_3$ increases with Ca concentration up to 136°C for $x=0.08\mathrm{}$, and then decreases. Both the tetragonal-orthorhombic and the orthorhombic-rhombohedral transition points of ${\mathrm{Ca}}_x{\mathrm{Ba}}_{1-x}\mathrm{Ti}{\mathrm{O}}_3$ decrease monotonically with increasing Ca concentration. ${\mathrm{Ca}}_x{\mathrm{Sr}}_{1-x}\mathrm{Ti}{\mathrm{O}}_3$ 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°K.