Thermal conductivity, diffusivity and specific heat capacity of as-grown, degenerate single-crystalline ZnGa₂O₄.

Abstract This work provides the first experimental determination of the low-temperature thermal properties for novel highly pure single-crystalline ZnGa2O4. The temperature dependence of the thermal conductivity, diffusivity and specific heat capacity of as-grown, degenerated ZnGa2O4 single crystals is measured using the 2 ω -method between T = 27 K and room temperature. At room temperature the thermal diffusivity is D ≈ 6.9 · 10−6 m2s, the thermal conductivity is λ ≈ 22.9 W/mK and the specific heat capacity is C V ≈ 537 J/kgK. The thermal conductivity increases with decreasing temperatures due to reduced phonon-phonon Umklapp scattering down to T = 50 K. For lower temperatures the thermal conductivity is limited by boundary scattering.