engleski

Assessment of thin-films for thermochromic application using an in-operando approach

Thin-films for thermochromic application were tape-casted from pure vanadia, zirconium-doped vanadia and cerium-doped vanadia powders derived by wet chemistry synthesis from intermediate phase of vanadyl glycolate. We conceptualised a characterisation setup suitable for assessment of the thermochromic functionality reposing on in-operando grazing incidence synchrotron X-ray diffraction and Raman spectroscopy for structural evolution study of the films under isothermal conditions. The Materials Characterization by X-ray diffraction beamline goniometer demonstrated ideal performance combining flexible geometry, high resolution, and the possibility to accommodate the multi-channel equipment for in-operando characterisation, to continuously monitor the monoclinic to tetragonal transition in pure and doped vanadia phases, responsible for the transmission and reflection of light in the infrared part of the solar spectrum. Diffraction and spectroscopic results pointed out that the prepared films had a considerable level of chemical homogeneity, whereas spectroscopic results enhanced by a full-scale device allowed resolution suitable for thin-films with low-thicknesses. The fact that the transition temperature was lowered in average by 5°C suggests that metal ions doping in vanadia was successful from the structural point of view. Among doped samples, cerium-doped vanadia showed only minute phase separation, better tape casting and thermal treatment stability and consequently more favourable structure modification. Primarily on behalf of structural influence, the derived thin-films (especially cerium-doped vanadia) can derivatively be considered as candidates for materials with better thermochromic behaviour. Ultimately, the exploited diffraction/spectroscopic thermal in-operando setup enables comprehensive self-standing characterisation on nanoscale materials, including thermochromic films.

smart window, thermochromic transition, in-operando GIXRD-Raman-f(T) setup, multi-channel characterisation, vanadium dioxide, zirconium-doping, cerium-doping

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