The Thermal Expansion of Solids

Abstract

From the theory of normal vibrations of a lattice, a practical means of obtaining the equation of state of an ionic solid is developed from which the thermal expansion can be derived. Using previous work by Kellermann, application is made to the case of sodium chloride and the results compared with experiment. Possible reasons for the discrepancy between theory and experiment, which is very large at 'high temperatures, are discussed. The variation with temperature of the specific heat at constant volume and the isothermal compressibility are also investigated.