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Layer structure compounds; ferroelectrics; piezoelectrics; impedance; dielectric properties

The system SrBi₄Ti_4−3xFe_4xO₁₅ belonging to bismuth layer structured ferroelectric (BLSF) materials withx = 0, 0.1 and 0.2 has been prepared through solid-state double sintering method. Increase of iron content in SrBi₄Ti₄O₁₅ resulted in densification of the samples. The normal puckering observed in the sample has been found to decrease and the lattice distortion increased. Dielectric measurements indicate the ferroelectric transition temperature of the samples to be 530°C, 560°C and 606°C. The increase of transition temperature with increasing iron content is correlated with lattice distortion. Conductivity measurements show two slopes and the activation energies have been found to increase with the iron content. Impedance spectroscopy measurements confirm insulating behaviour at lower temperatures. With increase in temperature the samples become conducting and show relaxational effects. The Cole-Cole plots at higher temperatures are found to be semicircles. The relaxation times decrease with the increase of iron content.

N Venkat Ramulu¹ G Prasad¹ S V Suryanarayana¹ T Bhima Sankaram¹

1. Department of Physics, Osmania University, Hyderabad - 500 007, India

Published

October 2000

Manuscript received

16 June 2000

Manuscript revised

10 July 2000