Estimation of Polarocaloric Contribution to Dielectric Loss in Oriented 0.92Pb(Zn_1/3Nb_2/3)O₃-0.08PbTiO₃ Single Crystals

This study estimates the contribution due to the polarocaloric effect (PCE) to the dielectric losses in 〈001〉, 〈110〉 and 〈111〉 oriented Pb(Zn_1/3Nb_2/3)O ₃-8%PbTiO₃ (PZN-PT) single crystals. The PCE is computed from the polarization-electric field curves measured under adiabatic conditions. The normalized magnitude of dielectric losses (χ″), given by χ̄″ = χ″/f(ω̄), where f(ω̄) is function of material parameters, constant electric field heat capacity and thermal conductivity, in the 〈100〉, 〈110〉 and 〈111〉 orientations at ferroelectric to paraelectric phase transitions are of the order 45, 55 and 25 respectively. This large magnitude of χ̄″ indicates that the PCE makes significant contribution to the dielectric absorption at high temperatures in poled state under applied electric field in this material. Further, the plot of PCE as a function of temperature traces the phase transformational characteristics of this system and clearly establishes the existence of intermediate ferroelectric orthorhombic phase in all the orientations.