酸化チタンの導電率に及ぼす吸着水の影響

概要

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As a preliminary experiment to develop humjdity sensors applicable at 200-300℃, the electric conductivity of titanium oxides of rutne- and anataseform was measured in relation to the thermal desorption behavior of adsorbed water. Temperature programmed profiles of the conductivity showed a peak below 100℃ and two shoulders at 170-260℃ and 300-390℃, which corresponded to the desorption of physisorbed water, hydrogen-bonded water, and surface hydroxyls, respectively. Based on this result, the humidity-sensing properties of titanium oxides were measured for the 5 min introduction of about 17 Torr water-vapor pulse. At 20 and 80℃, the conductivity σt under water-vapor pulse was about ten times as large as the base conductivity σ0. Even at 200 and 300℃, a conductivity change of a σt/σ0=2-5 was observed, suggesting a possibility of titanium oxides as high temperature-type humidity sensors although the sensitivity was small. Addition of ammonium sulfate to titanium oxides enhanced their sensitivity of humidity detection at 20 and 80℃, but showed no improvement at 200 and 300℃.
長崎大学工学部,Faculty of Engineering, Nagasaki Universityの論文