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 ZnGa _2 O _4 . The temperature dependence of the thermal conductivity, diffusivity and specific heat capacity of as-grown, degenerated ZnGa _2 O _4 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 m ^2 s, the thermal conductivity is λ ≈ 22.9 W mK ^−1 and the specific heat capacity is C _V ≈ 537 J kgK ^−1 . 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.

Keywords

• zinc gallate ZnGa2O4
• thermal diffusivity
• thermal conductivity
• specific heat capacity
• boundary scattering
• umklapp scattering