Ferroelectric transitions in valence compensated Ba1− x La x Ti1− x Cr x O3 ceramics.

An attempt has been made to investigate the solid solubility limit between barium titanate, BaTiO₃ and lanthanum chromite, LaCrO₃. Compositions with x ≤ 0.15 have shown solid solution formation in the system Ba_{1− x} La _x Ti_{1− x} Cr _x O₃. Compositions with 0.01 and 0.05 are found to have a tetragonal structure, whereas those with x = 0.10 and 0.15 are found to have a cubic structure at room temperature. Dielectric measurements have been carried out at different frequencies in the temperature range 100–550 K. Plots of ε_r versus temperature for composition with x = 0.01 show dielectric anomalies at 376 K ( T _C-T) and 275 ( T _T-O) where T _C-T and T _T-O denote the temperature for cubic to tetragonal and tetragonal to orthorhombic transition. Dielectric anomaly corresponding to the ferroelectric to paraelectric transition has been found to shift to lower temperatures with increasing concentration of lanthanum and chromium. For compositions with x ≤ 0.05, T _C has been found to be frequency independent while for x = 0.10 and 0.15, T _C has been found to be frequency dependent in a manner similar to relaxor ferroelectrics. [ABSTRACT FROM AUTHOR]