ヘテロポリ化合物の湿度センサー特性

抄録

Characteristics of H₃PMo₁₂O₄₀ and its salts used as humidity sensor has been studied at 20°C. Comparatively rapid response was obtained for thin-films of Cs₃PMo₁₂O₄₀ and {(CH₃) ₂NH0_{} 3}PMo₁₂O₄₀. As the relative humidity changed from 0 to 90%, the impedance decreased by a factor of 10³. The resistance-humidity correlation is greatly changed by cation-substitution. Based on the comparison of these resistance-humidity correlations and adsorption (absorption) properties, it was revealed that the resistance depends on the amount of the adsorbed (absorbed) water and that there are three different mechanisms of water adsorption (absorption) : (1) Capillary condensation in micro and mesopores (e. g., Cs₃PMo₁₂O₄₀ and {(CH₃) ₂NH₂} ₃PMo₁₂O₄₀). (In this case the logarithm of impedance changed almost linearly with the relative humidity). (2) Adsorption without capillary condensation on hydrophilic surface (e.g., (NH4) ₃PMo₁₂O₄₀). (3) Absorption into the bulk (e. g., H₃PMo₁₂O₄₀ and Na₃PMo₁₂O₄₀).