Electric Field Dependence of the Glasslike Thermal Conductivity of (Cd, Pb)2Nb2O7 at Low Temperatures

Abstract

Inorganic ferroelectrics display glasslike thermal and dielectric properties at low and ultralow temperatures. Fluctuations in the spontaneous polarization may provide the disorder mechanism, and this postulate was investigated by measuring the thermal conductivity of (Cd1-xPbx)2Nb2O7 at low temperatures under electric fields large enough (\\leqslant0.12 MV/cm) to influence the Ps fluctuations. The composition x=0.2 was selected to depress Ps while still insuring that the material was in the classical regime. Two thermal conductivity experiments were made: First, the thermal conductivity, 2–6 K, was measured at E=0, 60, and 117 kV/cm; and second, the thermal conductivity at 4.3 K was measured at 16 field levels up to 117 kV/cm. In both cases the thermal conductivity at 4.3 K was measured at 16 field levels up to 117 kv/cm. in both cases the theremal conductivity was E-field independent within the experimental uncertainty (±3%). It is concluded that fluctuations in Ps do not provide the disordering mechanism in ferroelectrics.