Effects of H and D order on the thermal conductivity of ice phases

Thermal conductivities (λ) of nine ice phases were determined by the transient hot wire method in a temperature range of 100–300 K and under pressures up to 2.2 GPa. Pure D2O as well as D2O–H2O mixtures were found to have values of λ close to those of pure H2O, except in phase VIII. For this phase λ was found to be about 9% lower in the case of pure D2O as well as in 1:1 and 1:3 mixtures of D2O:H2O. The hydrogen ordered phases systematically exhibit higher λ than the disordered ones, and in particular the presence of ice VI′ could be detected by a change of slope at low T in the curve of ln λ versus ln T for phase VI. If the results are fitted to the function λ=CT−n, the values of n fall into two groups. One group with n<1 contains only paraelectric phases, whereas the other group, having higher values of n, contains antiferroelectric phases and phase Ih. The latter phase is exceptional in that λ has a negative pressure coefficient. The results are interpreted in terms of dynamic decoupling of the hydrogen atoms from the lattice and in terms of induced oxygen disorder.