Ferroelectric behaviour and phase diagrams of SrTiO3-based solid solutions

Ceramic samples of Sr1-xCdxTiO3 and (1-x)SrTiO3–(x)KNbO3 solid solutions were investigated using a dielectric technique in the temperature range from 4.2 K to 300 K at frequencies of 1 kHz and 1 MHz. Phase diagrams of these systems are derived. It is shown that there are ferroelectric phase transitions in Sr1-x Cd x TiO3 for x values 0.01 ≤ x 0.05 and 0.85 ≤ x ≤ 1. In pure CdTiO3 the temperature dependence of the spontaneous polarization was obtained from ferroelectric hysteresis loops. At x value between x = 0.005 and x = 0.01, Sr1-x Cd x TiO3 undergoes a low-temperature transformation from the ferroelectric to a polar glasslike state. At low x, the transition temperature Tc varies as (x—x c)1/2 With x c ≈ 0.002 for Sr1-x Cd x TiO3 and x c ≈ 0.007 for (1-x)SrTiO3-(x)KNbO3. A polar state in (1-x)SrTiO3-(x)KNbO3 at x c ≤ x ≤ 0.2 has some features of a glasslike behavior.