The origin of highly efficient selective emission in rare-earth oxides for thermophotovoltaic applications

• Published in: Nature materials Vol. 3; no. 9; pp. 632 - 637
• Main Authors: Lomascolo, M, Torsello, G, Licciulli, A, Diso, D, Tundo, S, Mazzer, M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 01-09-2004
• Subjects: Absorption; Computer Simulation; Earth; Electric Power Supplies; Electricity; Electrochemistry - instrumentation; Electrochemistry - methods; Emissions; Emissivity; High temperature; Hot Temperature; Materials Testing; Metals, Rare Earth - chemistry; Metals, Rare Earth - radiation effects; Models, Chemical; Oxides - chemistry; Oxides - radiation effects; Photochemistry - instrumentation; Photochemistry - methods; Power Plants; Thermal radiation
• ISSN: 1476-1122; 1476-4660
• DOI: 10.1038/nmat1197

Rare-earth oxide materials emit thermal radiation in a narrow spectral region, and can be used for a variety of different high-temperature applications, such as the generation of electricity by thermophotovoltaic conversion of thermal radiation. However, because a detailed understanding of the mechanism of selective emission from rare-earth atoms has so far been missing, attempts to engineer selective emitters have relied mainly on empirical approaches. In this work, we present a new quantum thermodynamic model to describe the mechanisms of thermal pumping and radiative de-excitation in rare-earth oxide materials. By evaluating the effects of the local crystal-field symmetry around a rare-earth ion, this model clearly explains how and why only some of the room-temperature absorption peaks give rise to highly efficient emission bands at high temperature (1,000-1,500 degrees C). High-temperature emissivity measurements along with photoluminescence and cathodoluminescence results confirm the predictions of the theory.