Thermal radiation properties of porous rare-earth garnet ceramics

Abstract

Yb3Al5O12 and Yb3Ga5O12 ceramics for emitters of thermophotovoltaic systems were made by solid-state reaction. Thermal radiation measurements revealed that the sufficiently porous ceramics had excellent selectivity regarding emission wavelengths. Generally, in spite of the narrow-band thermal emission of rare-earth ions, most ceramics do not present sufficient selectivity because of their transparency in the near infrared range. We discuss a mechanism for high selectivity from observing the microstructures of these developed ceramics.