Thermal Wave Measurements with a Mirage Detection for Investigation of Thermal Diffusivity of GdCa4O(BO3)3 Single Crystals

Single crystals of GdCa4O(BO3)3 were examined to determine their thermal properties. Samples were grown by the Czochralski pulling technique. There were three types of samples: a pure crystal, the crystal doped with neodymium (4 at.% of Nd), and the third one doped with ytterbium (7 at.% of Yb). All samples were rectangular prisms with edges parallel to the axes of the optical indicatrix X, Y , Z (principal axes). The thermal diffusivity was determined by means of the thermal wave method with the optical detection of the temperature disturbance based on a mirage effect. Experimental results showed anisotropy of the thermal diffusivity. The thermal diffusivity along Y direction has the highest value while values obtained in X and Z axes are much lower. Dopants cause decrease in the thermal diffusivity for all investigated directions.