STRUCTURAL AND DIELECTRIC STUDIES OF SOME PEROVSKITE-TYPE TITANATES

Structural, dielectric and infrared spectral studies of mixed oxide systems of general formula (M12/La12/)xBa 1-xTiO3, where M=Li and K, and 0<or=x<or=1.0, have been reported. The extent of solid solubility can be represented as 0<or=x<or=0.5 for M=Li and 0<or=x<or=1.0 for the K-series. (Li 12/La12/)TiO3 crystallises with a tungsten bronze type (tetragonal) structure and exhibits an anomalously high dielectric constant (peak value: 37000) and simultaneous existence of both ferroelectric and antiferroelectric ordering. When M=K and x=0.3, the compound is a tetragonal perovskite showing a dielectric anomaly at approximately 400K. It does not produce any hysteresis loop in the polarisation versus electric field plots up to 5 kV.