Minimum emissivity limits given in the literature for high temperature selective surfaces may be too pessimistic. To reassess these limits, hypothetical bulk absorbing semiconductor–metal (SM) and semiconductor-insulator-metal (SIM) coatings were modeled using plausible high temperature semiconductor optical constants. Careful attention was paid to the positioning of the exponential region of the semiconductor absorption edge. Values of α/∊ near those of an ideal selective surface on copper were obtained with SIM surfaces, which use a dielectric refractive-index mismatch layer to reduce emittance. It is suggested that an ideal selective surface on copper (or silver) be regarded as the approachable limiting performances case for most applications. If favorable but extreme values of refractive index can be utilized, the ideal α/∊ may even be exceeded using interference effects to limit copper emissivity to below vacuum values.
© 1983 Optical Society of America
Original Manuscript: October 23, 1982
Published: October 15, 1983
David R. Mills and L. C. Botten, "Lower emissivity limits indicated for high temperature selective surfaces," Appl. Opt. 22, 3182-3190 (1983)