Optical properties and thermal degradation of NbB2/Nb(BNO)/Al2O3 spectrally selective tandem absorber

Kumar Poobalan, R and Pratap Singh, M and Basavaraju, U and Barshilia, HC and Basu, B (2022) Optical properties and thermal degradation of NbB2/Nb(BNO)/Al2O3 spectrally selective tandem absorber. In: Solar Energy, 247 . pp. 510-519.

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Abstract

The development of any new ceramic absorber demands the evaluation of different performance-limiting properties. In a recently published paper from our research group, we reported the development of NbB2-based new tandem absorber. In our efforts to investigate further potentiality for concentrated solar power applications, this study reports the optical and angular dependent reflectance properties of the NbB2/Nb(BNO)/Al2O3 spectrally selective absorber. The optical properties (extinction coefficient and refractive index) and the dielectric constants of the coatings were determined using spectroscopic ellipsometry analysis. Such analysis together with SCOUT simulation of the reflectance spectrum, confirms the refractive index gradient from the substrate to the top layer. The angular-dependent reflectance measurement demonstrates good solar absorptance (from 8 to 48°). More importantly, the coatings exhibited good thermal stability up to 200 h in vacuum at 500 °C. Extensive transmission electron microscopy analysis reveals the traces of oxygen in the layers. The moderate decrease in absorptance can be rationalised due to the compaction and formation of an oxide layer. Based on the obtained results and earlier published studies, the potential of the NbB2-based coatings as solar selective absorber for concentrated solar power applications is established.

Item Type:	Journal Article
Publication:	Solar Energy
Publisher:	Elsevier Ltd
Additional Information:	The copyright for this article belongs to Elsevier Ltd.
Keywords:	Coatings; Light transmission; Niobium compounds; Reflection; Refractive index; Solar absorbers; Solar energy; Spectroscopic analysis; Spectroscopic ellipsometry, Concentrated solar power; Optical property degradation; Optical-; Performance; Power applications; Property; Research groups; Simulation; Tandem absorber; Thermal degradation', High resolution transmission electron microscopy, degradation; inorganic compound; instrumentation; optical property; refractive index; simulated annealing; solar power
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	30 Dec 2022 10:19
Last Modified:	30 Dec 2022 10:19
URI:	https://eprints.iisc.ac.in/id/eprint/78644

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