Formation, structure, and optical properties of copper chromite thin films for high-temperature solar absorbers
Formation, structure, and optical properties of copper chromite thin films for high-temperature solar absorbers
Krause, M.; Sonnenberg, J.; Munnik, F.; Grenzer, J.; Hübner, R.; Garcia Valenzuela, A.; Gemming, S.
Abstract
CuCr2O4 thin films grown by physical vapour deposition were studied in order to evaluate their potential as absorber material for the next generation of concentrated solar power plants. A series of Cu-Cr-O thin films was deposited by reactive ion beam sputtering. The Cr/Cu ratio in the sputter target is demonstrated as the most important parameter to achieve the intended film stoichiometry. In-air annealing at 800 °C leads to structural transformations of the as-deposited films and results in phase compositions according to those expected from the ternary Cu-Cr-O phase diagram. Tetragonal CuCr2O4 with 98.6 at.% phase purity regarding the solid film constituents is obtained for the appropriate Cr/Cu ratio in the sputter target. CuCr2O4 thin films absorb light in the entire solar spectral range from 300 nm to 2500 nm. Their energy gap is found to be < 0.5 eV, and their solar absorptance is estimated to be (0.85 +/- 0.03). The dense microstructure with good thermal conductivity, full adhesion to the substrate, and a relatively low surface roughness are discussed as technological advantages of CuCr2O4 thin films grown by physical vapour deposition.
Keywords: solar absorber; spinels; sputtering; phase transformations; optical materials
Involved research facilities
- Ion Beam Center DOI: 10.17815/jlsrf-3-159
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- DOI: 10.17815/jlsrf-3-159 is cited by this (Id 32809) publication
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Materialia 18(2021), 101156
DOI: 10.1016/j.mtla.2021.101156
Cited 6 times in Scopus
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