Facile microwave-assisted synthesis of Cr2O3 nanoparticles with high near-infrared reflection for roof-top cooling applications

Hebbar, Deepak N and Choudhari, K S and Shivashankar, S A and Santhosh, C and Kulkarni, Suresh D (2019) Facile microwave-assisted synthesis of Cr2O3 nanoparticles with high near-infrared reflection for roof-top cooling applications. In: JOURNAL OF ALLOYS AND COMPOUNDS, 785 . pp. 747-753.

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Abstract

Microwave-assisted solution synthesis was employed for the preparation of Cr2O3 nanoparticles using Cr(acac)(3) and ethylene glycol. The optimum conditions for the completion of the reaction forming a green precipitate (yield-95%) were: irradiation for 40-60 min at 220 degrees C solution temperature. The as-prepared sample was barely crystalline; annealing in air at above 300 degrees C formed nanocrystalline Cr2O3, as shown by X-ray diffraction (XRD). High-resolution transmission electron microscopy (HRTEM) of the ``700 degrees C sample'' confirmed the well-crystallised Cr2O3 formation with similar to 37 nm average size. The asprepared powder (bluish-green) showed high near-infrared (NIR) reflectance, whereas the annealed samples showed bright-green reflectance, whose International Commission on Illumination L*a*b* (CIE L*a*b*) values shifted towards the green region. The higher D-q/B value (3.76), suggested that Cr3+ lies in a strong crystal field. Stainless steel blocks covered with the as-prepared (intermediate) material reduced heating under sunlight by 5 degrees C, indicating its suitability as an easily prepared tile coating for roof-top applications. The annealed samples are found suitable as an anti-dazzling coating for automobile windscreens and rear-view mirrors. (C) 2019 Elsevier B.V. All rights reserved.

Item Type:	Journal Article
Publication:	JOURNAL OF ALLOYS AND COMPOUNDS
Publisher:	ELSEVIER SCIENCE SA
Additional Information:	copyright for this article belongs to ELSEVIER SCIENCE SA
Keywords:	Cr2O3 nanoparticles; Microwave-assisted synthesis; Oxide materials; Ceramics; Chemical synthesis
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	27 May 2019 06:34
Last Modified:	27 May 2019 06:34
URI:	http://eprints.iisc.ac.in/id/eprint/62390

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