Diffuse phase transition in Sr5RTi3Nb7O30 (R = La, Nd and Sm)

Polycrystalline samples of Sr5RTi3Nb7O30, (R=La, Nd and Sm) compounds were prepared by a high-temperature solid-state reaction technique. The formation and structure of the compounds were checked by preliminary X-ray studies. Detailed dielectric and electrical properties of the compounds as a function of frequency (1-100 KHz) and temperature (150-650 K) were studied. The temperature dependence of dielectric constant suggests that the compounds undergo ferro-paraelectric phase transition of diffuse type. Measurements of conductivity as a function of temperature suggest that the compounds have negative temperature coefficient of conductivity above 373 K. 16 refs.