Hydrostatic pressure-induced phase transition in TGS monocrystal

Abstract

were the first to study the effect of hydrostatic pressure on the phase transition of TGS. They found a linear upward shift in Curie point with -3 growing pressure at a rate of dT / d d = 2 . 5~1 0 et al. (2) followed the effect of pressure on T and extended the result of (1) t o 3.3 kbar. Upward of this pressure, a deviation from linearity was found up to pressures of 5 kbar. Measurements by Zheludev et al. (3) resulted in a linear increase in T at a rate of dT / d d = 1 . 8~1 0 -~d e g / b a r up to 12 kbar. Samara (4) studied the effect of hydrostatic pressure on the electric permittivity of a TGS monocrystal up t o 17 kbar. In this paper, we report results on the influence of hydrostatic pressure up to 12 kbar on the phase transition of a TGS monocrystal. Moreover, in a modified thermodynamical theory taking into account the temperature and pressure dependence of the electromechanical coefficient, we determine the pressure-induced shift of the Curie point. deg/bar UP to 2.7 kbar. Leonidova C C C C The electric permittivity of the TGS monocrystal was measured a s a function of temperature at various values of the hydrostatic pressure, and a s a function of press u r e at various temperatures. The electric permittivity measurements were performed both during heating and cooling. The characteristic permittivity curves were observed to shift towards higher temperatures with growing pressure. At transition from the paraelectric phase to the ferroelectric phase the permittivity values observed in the Curie point are larger than those found for the ferropara transition.Permittivity versus pressure measurements performed at various temperatures showed that the higher the temperature the larger was the pressure required to obtain a phase transition. Fig. 1 shows a linear rise in Curie temperature a s a function of pressure up to 4 kbar, at a rate of dT / d d = deg/bar; at still higher pressures the dependence C

The effect of a DC bias field on the dielectric properties of trissarcosine calcium chloride

“…The effects of a DC bias field on the permittivity E and the transition temperature for the paralectric-tferroelectric (I+II) phase transition are interpreted in terms of phenomenological theory. The free energy F is expanded as functions of polarisation P and hydrostatic pressure p as follows (Fujimoto and Yasuda 1973, Klimowski et al 1973, Sorge and Straube 1979, Windsch and Schmidt 1980): F(p, P)=$ cp2+$ ( A + g p ) P + * ( P 4 + & 5 P 6 .…”