Diffuse Phase Transition in Ferroelectric SbSe0.40S0.60I

Abstract

The pyroelectric effect is investigated in SbSe0.40S0.60I and the spontaneous polarization (Ps) and its derivative with respect to the temperature (λ) is deduced. The diffuse phase transition is analysed under the assumption of a non‐homogeneous composition through the sample. The good agreement between the theoretical predictions and experimental data allows the determination of the range where the selenium/sulfur ratio spreads.

Spontaneous polarization behaviour in ferroelectrics

“…From the experimental point of view the pyroelectric coefficient is determined by measuring the dc discharge current from a sample of known electrode area subjected to a controlled rate of temperature change. On the other hand, the pyroelectric coefficient is equivalent to the pyroelectric function which is given by the absolute value of the polarization derivative with respect to temperature [2], namely It is worthwhile to stress that the pyroelectric function allows us to determine the tail of the polarization with high precision. For this reason the approach based on thc pyroelectric coefficient measurements is fruitful in the analysis of diffuse phase transition effects.…”

“…The pyroelectric current is related to the change in the spontaneous polarization [2] so that the pyroelectric function can be defined as and can be expressed in the case of the scaling hypothesis as derived from (2.7) and (2.8) in the following forms: (2.10) (2.11) and respectively. We can see that the pyroelectric function is useful in order to find the exponent p which determines the spontaneous polarization in the direct way.…”