The grain size and temperature dependence of the thermal conductivity of polycrystalline, tetragonal yttria-stabilized zirconia

The thermal conductivity of optically transparent, yttria-stabilized tetragonal zirconia having a range of grain sizes from 100 to 180 nm has been measured from just below its approximate Debye temperature up to 1000 degrees C. It is found that the grain size dependence is most marked at room temperature, decreasing with increasing temperature until being indistinguishable at the highest temperatures. The Kapitza thermal resistance of the grain boundaries is found to be almost independent of temperature, with a value of R(k) = 4.5 +/- 0.5 x 10(-9) m(2)K/W and an estimated grain boundary phonon transparency of similar to 0.9. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3593383]