Misorientation dependence of Al2O3 grain boundary thermal resistance

The room-temperature thermal resistance of model low-angle (0001) twist bicrystal Al2O3 grain boundaries was measured as a function of misorientation angle using the 3ω thermal conductivity testing technique. The work yields interfacial thermal resistances of 0.44 × 10−8, 1.2 × 10−8, and 1.54 × 10−8 Km2 W−1 for the ∼1.3°, ∼8.0°, and ∼13° twist grain boundaries, respectively. The interfacial thermal resistance correlates with the grain boundary energy calculated from the Read-Shockley model. The results indicate significant anisotropy in the Kapitza resistance whose magnitude is dominated by local structural defects at the grain boundary rather than spectral mismatch between grains.