Accession Number : AD0622801

Title :   QUANTUM EFFECTS AT ABSOLUTE ZERO IN PURE CRYSTALS AND ISOTOPIC MIXTURES. PART V.

Descriptive Note : Technical rept.,

Corporate Author : BRUSSELS UNIV (BELGIUM)

Personal Author(s) : Prigogine,I. ; Bingen,R.

Report Date : 1955

Pagination or Media Count : 54

Abstract : The influence of the anharmonicity of motion is studied, in connection with the properties at very low temperatures of solids such as H2, He and their isotopes, which are sufficiently light to display large quantum effects. The properties of pure crystals at absolute zero are studied. The volume, the free energy and the Debye temperature are calculated as functions of de Boer's quantum parameter. The mass effect in solid isotopic mixtures, i.e. the influence of the spatial distribution of the two isotopes upon the zeropoint energy is studied. The volume effect is discussed, i.e. the volume change and the corresponding variation of zero-point energy which occur when two isotopes are mixed. This volume effect is more important than the mass effect, at least for light substances. It is first evaluated in the case of one-dimensional crystals. The calculations are then extended to real three-dimensional crystals, showing that the excess free energy is always positive.

Descriptors :   (*CRYSTALS, QUANTUM THEORY), (*STATISTICAL MECHANICS, IRREVERSIBLE PROCESSES), (*ISOTOPES, SOLIDIFIED GASES), HYDROGEN, HELIUM, CRYOGENICS, THERMODYNAMICS, KINETIC THEORY, PHASE STUDIES, CRYSTAL LATTICES, MOTION

Distribution Statement : APPROVED FOR PUBLIC RELEASE