Effect of Hydrostatic Pressure on the Dielectric Properties of PMN-0.31PT Single Crystal

Abstract

[Pb(Mg _1/3 Nb _2/3 )O ₃ ] _0.69 (PbTiO ₃ ) _0.31 single crystal of composition close to the morphotropic phase boundary has been studied by dielectric spectroscopy in the frequency range of 1–1000 kHz under hydrostatic pressure (p) up to 0.6 GPa. At ambient pressure two successive phase transitions have been observed: the monoclinic-tetragonal transition at T ₁ = 346 K and the transition from the ferroelectric tetragonal to the cubic relaxor phase at T _C = 415.7 K. At elevated pressures the temperature range of the ferroelectric tetragonal phase diminished, while the relaxor phase evolved. The p-T phase diagram shows that pressure decreases linearly T ₁ and T _C , as well as the temperature T _m of the relaxor peak, but with different slopes: dT ₁ / dp = −(2.6 ± 1.6) K/GPa, dT _C/ dp = −(55.5 ± 0.2) K/GPa and dT _m (10 kHz)/ dp = −(48.7 ± 1.0) K/GPa.

Keywords:

• Relaxors
• pressure
• dielectric spectroscopy

Acknowledgment

The authors would like to thank Dr. H. Luo for the growth of the crystal. This work was supported by the Polish Committee of Scientific Research, Grant No. 1 P03B 110 27, and by the U.S. Office of Naval Research, Grant No. N00014-99-1-0738.

Paper originally presented at IMF-11, Iguassu Falls, Brazil, September 5–9, 2005