Low Thermal Conductivity in Garnets

Abstract

The thermal conductivity of dense, polycrystalline garnet ceramics with compositions of Y 3 Al x Fe (5−x) O 12 (x = 0.0, 0.7, 1.4, and 5.0) was measured in the temperature range 23° to 1000°C. The high‐temperature thermal conductivity of some of these garnets was found to be as low as 2.4 W·m ‐1 K ‐1 . The effects of temperature and composition on the observed thermal conductivity are discussed with reference to established theories of thermal conduction. The potential use of yttrium aluminum garnet or YAG (Y 3 Al 5 O 12 ), in particular, for a specific application of advanced thermal barrier coatings (TBCs) with improved durability is considered.