A photopyroelectric approach for electrocaloric effect characterization of polar materials

By means of the photopyroelectric method, we indirectly investigate the electrocaloric effect in polar materials by measuring the pyroelectric coefficient and the volumic heat capacity, as function of temperature. The influence of the heat capacity as function of the temperature on electrocaloric measurements is discussed. Measurements were performed on TriGlycine Sulfate single crystal. The compound showed a $\Delta T$ value of about 0.3 K upon a field change of 0.3 MV m⁻¹ near it's Curie temperature at 49 °C. Compared with repolarization current method where usually heat capacity is assumed as a constant value, the proposed technique provides an accurate way of calculating adiabatic temperature change of a ferroelectric material. (paper)