THE THERMAL-DIFFUSIVITY TENSOR AND LATTICE-DYNAMICS OF BETA-OXYGEN ATHIGH-PRESSURE

An experimental approach to the study of thermal transport in the diam ond-anvil high pressure cell is described and the elements of the ther mal diffusivity tensor of beta-oxygen are reported to a pressure of 9 GPa. The anisotropy in the thermal conductivity is found to be opposit e in sense to that in the velocity of acoustic waves. Results are inte rpreted in terms of a lattice dynamical model in which the strong inte ractions between an atom and its first-, second-, and third-nearest ne ighbors are treated in tensorial form with parameters evaluated direct ly from experiment. (C) 1996 American Institute of Physics.