Adiabatic Thermal Changes in Barium Titanate Ceramic at Low Temperatures

The adiabatic thermal changes at 4\ifmmode^\circ\else\textdegree\fi{}K in barium titanate ceramic show a heating effect whether the the electric field is applied or removed. An interpretation of these result is that the polarization process is thermodynamically irreversible. The large temperature dependence of the dielectric constant at 4\ifmmode^\circ\else\textdegree\fi{}K may be understood as a result of the thermodynamically irreversible polarization. Quantitative results are given as to the temperature rise as a function of electric field strength and as a function of temperature.