Dielectric response of disordered Pb(Sc_1/2Ta_1/2)O₃ single crystal under hydrostatic pressure

Abstract

The effect of hydrostatic pressure on the dielectric response of Pb(Sc_1/2Ta_1/2)O₃ single crystal with the degree of order S = 0.16 has been studied. At elevated pressures the dielectric anomaly characteristic of ferroelectric relaxors is shifted to lower temperatures, its amplitude decreases and the relaxor peak becomes more diffused. In the pressure range studied up to 0.75 GPa, the temperature dependencies of the characteristic relaxation time obey the Vogel–Fulcher law. It has been found that the Vogel–Fulcher temperature decreases with increasing pressure while the activation energy of the dipolar entities increases. This increase can be ascribed to the pressure-induced changes in the atom–atom and dipolar interactions, resulting in the increased energy barriers for dipolar fluctuations.

Keywords:

• ferroelectric relaxors
• lead scandium tantalite
• dielectric response
• hydrostatic pressure

Acknowledgements

The authors are grateful to Prof. R. Blinc for providing the PST crystal and Prof. A. Pietraszko for his help in determining the degree of the crystal order. This work was supported by the Polish Committee of Scientific Research, Grant No. 1 P03B 110 27.