Effect of rare earth ions doping on the thermal properties of YAG transparent ceramics

Yttrium aluminium garnet doped with rare earth ions is one of the most common active media in solid state lasers. In high-power lasers, thermal management is crucial, requiring information on the thermal properties. In this work, the thermal diffusivity and conductivity of polycrystalline YAG ceramics doped with Yb and Er were measured by laser flash method at various temperatures ranging from room temperature to 900 degrees C. Transparent ceramic YAG samples were prepared by solid state reactive sintering of oxide powders under vacuum. Thermal diffusivity and conductivity showed similar trends, decreasing with increasing temperature as well as with the increase of dopant content from 0 to 20 at.%. The measured values were compared with literature data and empirical relations. Similar values were obtained both for Yb and Er doping. We thus suggest that the data of thermal diffusivity and conductivity of Yb:YAG may be used as a first approximation for Er:YAG.