Plasma-spray coated rare-earth oxides on molybdenum disilicide – High temperature stable emitters for thermophotovoltaics

Selective emitters for thermophotovoltaics consisting of intermetallic alloy MoSi2 substrate with plasma-spray coated rare-earth oxides ytterbium oxide Yb2O3, Yb-doped garnet Yb1.5Y1.5Al5O12, and erbium oxide Er2O3 have been successfully tested till 1650 °C. The emitters are fully operable in an oxygen containing atmosphere, are highly thermal shock stable, and show good selective emitting properties. Shielding the high out-of-band emittance of the MoSi2 substrate with a 4 μm thick Pt intermediate layer has resulted in reduced radiation power and emittance of the rare-earth oxide film due to multiple reflections at the interfaces. The novel technique of vacuum plasma-spray coated rare-earth oxide films on MoSi2 is a promising way for the production of effective and high temperature stable selective thermophotovoltaic emitters.