LXXXV. The specific heats of lithium fluoride, sodium chloride and zinc sulphide at low temperatures

Abstract

The specific heats of lithium fluoride, sodium chloride and zinc sulphide have been measured within the temperature range 2°k to 30°k using a calorimeter of a novel type, upon which the crystal specimens were stuck with silicone grease. Ideally, these three substances have only a lattice contribution to their specific heats so that a direct comparison of the results with the theoretical predictions of the lattice theory of specific heats is possible. Good agreement between theory and experiment is found. The existence of a ‘T ³’ region extending up to a temperature of about 20°k is shown clearly in the case of lithium fluoride.