Thermal conductivity measurements of Yb:CaF_2 transparent ceramics using the 3m method

摘要

This paper reports on the measurement of the thermal conductivity of ytterbium doped CaF_2 transparent ceramics using the 3w method. Samples with different doping levels were studied in a temperature range of 10 K to 310 K. The results for doped samples are very similar to those obtained for Yb:CaF_2 single crystals with the same doping levels, which demonstrates an important improvement in the thermal properties of transparent ceramics. However, the results obtained for non-doped ceramics and single crystals differ for the maximum conductivity due to the presence of grain boundaries inside the ceramic. Theoretical calculations were also conducted using Callaway's model and are in a very good agreement with experimental results. The fitting parameters found tend to indicate that the introduction of a doping element in the lattice has more impact on thermal conductivity than the presence of grain boundaries in the material.