Measurement of the hysteretic thermal properties of W-doped and undoped nanocrystalline powders of VO2

Gomez-Heredia, C L and Ramirez-Rincon, J A and Bhardwaj, D and Rajasekar, P and Tadeo, I J and Cervantes-Lopez, J L and Ordonez-Miranda, J and Ares, O and Umarji, A M and Drevillon, J and Joulain, K and Ezzahri, Y and Alvarado-Gil, J J (2019) Measurement of the hysteretic thermal properties of W-doped and undoped nanocrystalline powders of VO2. In: SCIENTIFIC REPORTS, 9 (1).

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Abstract

Hysteresis loops exhibited by the thermal properties of undoped and 0.8 at.%W-doped nanocrystalline powders of VO2 synthesized by means of the solution combustion method and compacted in pellets, are experimentally measured by phototherma I radiometry. It is shown that: (i) the W doping reduces both the hysteresis loops of VO2 and its transition temperature up to 15 degrees C. (ii) The thermal diffusivity decreases (increases) until (after) the metallic domains become dominant in the VO2 insulating matrix, such that its variation across the metal-insulation transition is enhanced by 23.5% with W-0.8 at.% doping. By contrast, thermal conductivity (thermal effusivity) increases up to 45% (40%) as the metallic phase emerges in the VO2 structure due to the insulator-to-metal transition, and it enhances up to 11% (25%) in the insulator state when the local rutile phase is induced by the tungsten doping. (iii)The characteristic peak of the VO2 specific heat capacity is observed in both heating and cooling processes, such that the phase transition of the 0.8 at.%W-doped sample requires about 24% less thermal energy than the undoped one. (iv) The impact of theW doping on the four above-mentioned thermal properties ofVO(2) mainly shows up in its insulator phase, as a result of the distortion of the local lattice induced by the electrons of tungsten. W doping at 0.8 at.% thus enhances the VO2 capability to transport heat but diminishes its thermal switching efficiency.

Item Type:	Journal Article
Publication:	SCIENTIFIC REPORTS
Publisher:	NATURE PUBLISHING GROUP
Additional Information:	Copyright of this article belongs to NATURE PUBLISHING GROUP
Keywords:	PHASE-TRANSITION HYSTERESIS; CHEMICAL-VAPOR-DEPOSITION; THIN-FILMS; ELECTRICAL-PROPERTIES; INSULATOR-TRANSITION; OPTICAL-PROPERTIES; VANADIUM; TEMPERATURE; COATINGS; NANOPOWDERS
Department/Centre:	Division of Chemical Sciences > Materials Research Centre
Date Deposited:	28 Nov 2019 09:27
Last Modified:	28 Nov 2019 09:27
URI:	http://eprints.iisc.ac.in/id/eprint/63828

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