Dielectric and anharmonic behaviour of silver halides, thallous halides, alkaline earth fluorides, and lead fluoride crystals

Abstract

AbstractAn analysis is made of the dielectric behaviour and the anharmonic contribution to the dielectric constants of AgCl, AgBr, TlCl, TlBr, CaF2, SrF2, BaF2, and PbF2 crystals. The volume and temperature derivatives of static and electronic dielectric constants, and of the energy gap between bonding and antibonding states are derived from the experimental data using Phillips‐Van Vechten dielectric theory. The temperature derivatives of dielectric constants at constant volumes are used to estimate the magnitudes of anharmonic contributions. The effect of anharmonicity is discussed in terms of different theories. The volume derivatives of static dielectric constant are calculated using the Born‐Meyer theory of interionic potentials. The calculated quantities are compared with available experimental data. The applicability of the Mott‐Littleton theory of dielectric polarization is also discussed for the crystals under study.