English

Abstract

The processing conditions, microstructure, and dielectric properties of strontium bismuthtitanate (SBT) were systematically studied. The specimen was synthesised by a mechano-chemicalprocessing route using a planetary ball mill. It is important that the action is vigorous enoughto break up loose aggregates and a fine particle size is obtained. The specimen was calcinedat 800 oC for 4 h. The calcined samples were subjected to cold isostatic pressing (CIP) processand finally sintered at 1200 oC for 2 h. A relative density 90 per cent of the theoretical densitywas obtained. Pellets having a diameter of 1cm and thickness of 1 mm were prepared from thesintered compacts for electrical measurements. X-ray diffraction showed that a single phase withthe layered perovskite structure of SBT was formed. Morphological studies were carried out bySEM analysis. Frequency dependence of impedance can provide additional insight intomechanisms controlling the electrical response. Resonance studies were made on poled samplein the frequency range 100 kHz – 20 MHz using an impedance analyser (HP-4294A) interfacedto a computer at room temperature. Dielectric measurements in the frequency range 100 Hz–1 MHz were made using an impedance analyser (HP-4192A) interfaced to a computer and themeasurements were carried out from room temperature to 550 oC. The ferroelectric hysteresis loopwas measured using a standard ferroelectric analyser based on Sawyer-tower circuit. Elasticcompliance (s33, s11) coupling factor (k33, k31)were also obtained. These materials can be utilisedin practical applications as substitutes for lead titanate and lead zirconate titanate (PZT)-basedceramics, where high temperature applications are foreseen.