Lithium-inserted vanadium dioxide (LixVO2) thin films

Mohammad S. R. Khan

doi:10.1117/12.238123

8 April 1996 Lithium-inserted vanadium dioxide (Li_xVO₂) thin films

Mohammad S. R. Khan

Proceedings Volume 2780, Metal/Nonmetal Microsystems: Physics, Technology, and Applications; (1996) https://doi.org/10.1117/12.238123
Event: Metal/Nonmetal Microsystems: Physics, Technology, and Applications, 1995, Polanica Zdroj, Poland

Abstract

Thermochromic switching between a low-temperature and high-temperature less transparent state is possible in thin films based on vanadium dioxide (VO₂). The critical temperature T_c at which the transition takes place in VO₂ is on the order of 68 degrees Celsius which can be depressed towards a comfortable temperature by several techniques, including dopants. Dopants can be inserted by electrochemical means. This work is an exploratory study of the electrochromism of Li_xVO₂ with a view to 'smart window' applications. Thin films of Li_xVO₂ (0 less than or equal to x less than or equal to 0.43) were made by reactive sputtering and annealing electrolyte of LiClO₄ and propylene carbonate. A maximum lithium content of x equals 0.43 was accomplished. Optical spectral response at wavelength pertinent to solar radiation was reported. Lithium insertion increased the transmittance gradually and reversibly i.e. Li_xVO₂ showed electrochromism and bleached under Li insertion. Li_xVO₂ also showed thermochroism, although to a smaller degree than VO₂ and was most transparent at low temperature. Temperature- dependent electrical conductivity and thermoelectric power measurements were also performed. A conductivity transition by approximately 3 orders of magnitude was seen at approximately 60 degrees Celsius in VO₂. This transition decreased in proportion with the amount of Li intercalation and was less than one order of magnitude in Li_0.43VO₂. Lithiation also decreased T_c by a few degrees Celsius. The thermoelectric power showed a well defined increase when T_c was exceeded.

Citation Download Citation

Mohammad S. R. Khan "Lithium-inserted vanadium dioxide (Li_xVO₂) thin films", Proc. SPIE 2780, Metal/Nonmetal Microsystems: Physics, Technology, and Applications, (8 April 1996); https://doi.org/10.1117/12.238123

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