Specific heat data are reported on pure and varistor ZnO, 1.7ndash;25 K, and thermal conductivity data are reported on varistor ZnO, 1.7ndash;15 K. In pure ZnO interstitials give rise to an Einstein contribution (ohgr;E=84 cmminus;1) to the specific heat above 10 K and to a Schottky contribution (dgr;bartil;10minus;5eV) below 4 K due possibly to ordering. The calorimetric Debye temperature is 399.5 K. In varistor ZnO the specific heat is dominated below 20 K by compensating charge densities (sim;1018cmminus;3) on the interfacial barriers which give rise to two Schottky terms (dgr;=7times;10minus;4and 3times;10minus;3eV). All of these nonhyphen;Debye excitations are localized (do not carry heat). No evidence is seen in the thermal conductivity for Kapitzahyphen;resistance effects at the heavily doped grain boundaries.
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