Fabrication and optical property improvement of gasochromic switchable mirror based on Pd/MgNb2O5 thin film

Recently, the application of magnesium-based gasochromic switchable mirror has been baffled by the low optical dynamic range due to the insufficient conversion between Mg and MgH₂. Based on the excellent catalytic property of Nb₂O₅ for the magnesium-hydrogen reaction, we fabricated fluorocarbon (FC)/Pd/MgNb₂O₅ switchable films via magnetron sputtering and low-temperature inductively coupled plasma chemical vapor deposition technologies in this study, and the optical performance and microstructure of the films were investigated. The results show that the FC/Pd/Mg-3 mol% Nb₂O₅ film exhibits the higher dynamic ranges of the luminous (49.4%) and solar transmittance (54.7%), compared with most of reported Mg-based alloys and MgTiO₂ systems. The addition of Nb₂O₅ and covering a FC layer on the Pd/Mg film could effectively accelerate the switching response and improve such optical properties as transmittance at transparent state and dynamic range. The microstructural analysis reveals that the Nb₂O₅ and appropriate amount of ternary MgNbO phase in the Mg-based layer are supposed to facilitate rapid and sufficient hydrogen absorption and desorption. Furthermore, the high-valence Nb ions scattering around Mg atoms may act as a transfer station for catalyzing the reversible reaction between Mg and H. The excellent optical modulation performance and enhanced hydrophobicity of the FC/Pd/MgNb₂O₅ films signify an application prospect for gasochromic switchable mirror.