Field Dependent Thermal Conductivity of SrTiO3, BaTiO3 and KTaO3 Ferroelectric Perovskites

–Expressions are obtained for the thermal conductivity of some ABO3 type displacive ferroelectrics in paraelectric phase, using Kubo formalism and double time thermal Green’s function technique. The total thermal conductivity obtained for these perovskites which is sum of two terms contributed by optical and acoustical phonons, is in agreement with the experimental results of Steigmeier. The variation of thermal conductivity with temperature and external electric field is discussed, for the case of SrTiO3, BaTiO3 and KTaO3 in presence of anharmonicity. Thermal conductivity decreases with increase of temperature in the cases of all these three perovskites. Also the total thermal conductivity which is the sum of two terms contributed by optical and acoustical phonons is seen to increase with the applied electric field, which is in agreement with the experimental results of Steigmeir. Around the Curie temperature, the thermal conductivity shows an anomalous behaviour and soft mode is held responsible for it. Keywords––Anharmonicity, ferroelectric crystals, paraelectric phase, perovskites, soft mode, thermal conductivity.