Temperature and pressure dependence of dielectric properties of iodinated trissarcosine calcium chloride

Abstract

The dielectric properties such as the permittivity epsilon , the dielectric loss tangent and the spontaneous polarisation Ps of iodinated trissarcosine calcium chloride were measured at various pressures up to 9 kbar. The peak of epsilon is depressed and broadened by the large internal bias field Eb. The P-E hysteresis loop is highly biased. With increasing I concentrations x, both the peak value of epsilon and the value of Ps decrease rapidly. The ferroelectric transition temperature Tc(x) decreases with increasing x according to the relation (Tc(x)/Tc(0))2=(1-x/xc) where xc is the critical concentration and is estimated as 0.25. The Tc increases greatly with increasing p while the Ps is almost independent of p. The triple point (paraelectric-ferroelectric-new phase) shifted towards higher pressures and lower temperatures with increasing x. The effect of substitution of I for Cl on the dielectric properties is more remarkable than that of Br for Cl.