Dielectric studies of phase transitions in the ferroelectric CdTiO3 and the Sr1−x CdxTiO3 solid solution

Temperature dependences of the permittivity and of the dielectric hysteresis loops in ceramic samples of nominally pure CdTiO3 and a Sr1−x CdxTiO3 solid solution were studied. At 76.5±0.5 K, CdTiO3 was established to undergo a ferroelectric phase transition close to the tricritical point. The temperature dependence of spontaneous polarization of CdTiO3 is described within the Landau theory of phase transitions with the critical order parameter exponent ≈0.25. The phase diagram of the Sr1−x CdxTiO3 solid solution was drawn in (T, x) coordinates, and the critical concentration x c =0.002, above which an induced polar state sets in the solid solution, was determined.