Low temperature thermal conductivity of OH − and OD −-doped LIF single crystals

Abstract

Thermal conductivity measurements between 0.1 and 70K of OH − and OD − doped LiF indicates resonant phonon scattering at 0.86cm − for OH − and 0.43cm − for OD −. Hydroxyl impurities trapped at divalent impurity sites do not scatter phonons resonantly and it is shown that inhomogenous distribution of strong scattering centers modify thermal conductivity curves considerably. A simple tunneling model for the isotope shift suggests an effect similar to the “polaron” model of paraelastic centers. A relaxation time for phonon scattering by OH − is derived, showing that the ground state may be understood in terms of a direct process, underlining that this system provides a connection between the theory of paraelectric/paraelastic impurities and Jahn-Teller systems.