Phase transitions and glasslike behavior in Sr1-xBaxTiO3

A dielectric and ultrasonic study of phase transitions in Sr1-xBaxTiO3 with x ranging from 0.0 to 1.0, is reported. Both ceramic samples and single crystals were studied. The full phase diagram is derived from dielectric measurements for ferroelectric phase transitions and from ultrasonic measurements for structural phase transition. The cubic-tetragonal ferroelectric phase transition which is of the first order in pure BaTiO3 (x=1.0) transforms to the second order phase transition at x close to 0.2. The transition temperature T-c is a linear function of x at x values from 0.2 to 1.0. For x<0.2 the transition temperature is proportional to (x-x(c))(1/2), where x(c)=0.035. For x<x(c) a glasslike behavior is observed. The structural phase transition temperature T-a goes down as compared to pure SrTiO3 when x increases and levels off near x=0.05.