A radiation calorimeter makes it possible to measure the specific heat, the thermal conductivity, and the thermal diffusivity of a solid sample simultaneously and independently. Because three thermal quantities are not independent each other, the self-check of the reliability of obtained values can also be made from results. Measurements were performed for ferroelectric BaTiO_3 ceramics modified with small amount of Zr, Sn, and Hf in the temperature range from 300 to 450 K. The modifier content was changed from 2.5 to 12 mol% of Ti ion. Results indicate that the thermal conductivity decreases and the temperature dependence of thermal conductivity changes from crystalline-like to amorphous-like with an increase of the content.
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