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Article Dans Une Revue Scientific Reports Année : 2018

Thermal hysteresis measurement of the VO2 emissivity and its application in thermal rectification

Résumé

Hysteresis loops in the emissivity of VO 2 thin films grown on sapphire and silicon substrates by a pulsed laser deposition process are experimentally measured through the thermal-wave resonant cavity technique. Remarkable variations of about 43% are observed in the emissivity of both VO 2 films, within their insulator-to-metal and metal-to-insulator transitions. It is shown that: i) The principal hysteresis width (maximum slope) in the VO 2 emissivity of the VO 2 + silicon sample is around 3 times higher (lower) than the corresponding one of the VO 2 + sapphire sample. VO 2 synthesized on silicon thus exhibits a wider principal hysteresis loop with slower MIT than VO 2 on sapphire, as a result of the significant differences on the VO 2 film microstructures induced by the silicon or sapphire substrates. ii) The hysteresis width along with the rate of change of the VO 2 emissivity in a VO 2 + substrate sample can be tuned with its secondary hysteresis loop. iii) VO 2 samples can be used to build a radiative thermal diode able to operate with a rectification factor as high as 87%, when the temperature difference of its two terminals is around 17 °C. This record-breaking rectification constitutes the highest one reported in literature, for a relatively small temperature change of diode terminals.

Dates et versions

hal-04135112 , version 1 (20-06-2023)

Identifiants

Citer

C. Gomez-Heredia, J. Ramirez-Rincon, J. Ordonez-Miranda, O. Ares, J. Alvarado-Gil, et al.. Thermal hysteresis measurement of the VO2 emissivity and its application in thermal rectification. Scientific Reports, 2018, 8 (1), pp.8479. ⟨10.1038/s41598-018-26687-9⟩. ⟨hal-04135112⟩
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