Interfacial Thermal Resistance and Thermal Conductivity in Nanograined SrTiO3

A series of nanograined dense SrTiO3 ceramics were examined for thermal conductivity, kappa, as a function of average grain size d. The kappa decreased gradually with decreasing d, primarily due to a significantly increased number of interfaces as heat transport barriers. Lowest kappa at 300 and 1000 K, obtained in a 55-nm-grained sample, were about 50 and 24% smaller than those of a bulk single crystal. The Kapitza-type interfacial thermal resistance was estimated, and the dependence of kappa on grain size was formalized, which shows the theoretical minimum kappa could be achieved at d of about 10 nm. (C) 2010 The Japan Society of Applied Physics