The temperature dependence of the static dielectric constant

Overview & Synopsis

It is shown that in alkali halides the increase of the static dielectric constant ε with temperature is exclusively due to anharmonic effects. A simple formula is given which permits the calculation of ε at any temperature if we know : (i) the dielectric constant at room temperature and (ii) the thermal variation of bulk modulus and of the lattice parameter. Furthermore Flynn's explanation for the high formation entropy per Schottky defect is discussed.