Spontaneous Polarization in Sn2P2S6 Ferroelectric Single Crystals

Abstract

Spontaneous polarization P s (T) was measured as a function of temperature in the Sn2P2 S 6 single crystals. The coefficients α, β and γ of the thermodynamic potential were determined. The order parameter critical index β′ is 0.297. Discontinuity of the heat capacity ΔC p and pressure dependence of the quantity ΔC p (p)·β(p) were also calculated. In this dependence two anomalies connected with the tricritical point and transition into the IC phase are clearly seen at pressures p1 ≈ 0.1 GPa and p2 ≈ 0.2 GPa, respectively.