Humidity sensitivity of Nb2O5-doped TiO2 ceramics

Katayama, Keiichi; Hasegawa, Kiyoshi; Takahashi, Yutaka; Akiba, T.; Yanagida, Hiroaki

doi:10.1016/0924-4247(90)80048-a

Cited by 58 publications

(15 citation statements)

References 8 publications

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“…Titanium dioxide (TiO 2 ) has been studied and utilized for a material for photo-catalyst [1], solar cells [2], bio-compatible elements [3], gas sensor [4] and pigments [5]. It is well-known that TiO 2 occurs in three crystalline modifications, rutile (stable phase), anatase (low-temperature phase) and brookite (metastable phase).…”

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confidence: 99%

Time-resolved luminescence spectra in colorless anatase TiO2 single crystal

Wakabayashi

Yamaguchi

Sekiya

et al. 2005

Journal of Luminescence

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Time-resolved luminescence was measured on a colorless anatase single crystal under pulsed-laser excitation. The time evolution of luminescence is composed of fast and slow components with time constants of 10 À6 and 10 À5 s, respectively. The fast component corresponds to a direct formation of STE. Some traps near the conduction band give a retardation effect on the slow component. The traps are occupied by conduction electrons at low temperatures and the trapped electron can be excited thermally at temperatures higher than 100 K. They compete with non-radiative recombination process. A possible model for the relaxation process is proposed. r

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mentioning

confidence: 99%

Time-resolved luminescence spectra in colorless anatase TiO2 single crystal

Wakabayashi

Yamaguchi

Sekiya

et al. 2005

Journal of Luminescence

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“…The process used to make the sensor here presented is somehow a new one: a low speed spin coating of a powder emulsion on an alumina substrate. The choice of titania, TiO 2 was due to the reported high sensitivity to humidity changes [11][12][13]. In order to determine the grain size and structural properties of the material X-ray diffraction (XRD), scanning electron microscopy, optical microscopy and porosimetry were used.…”

Section: Introductionmentioning

confidence: 99%

Humidity sensing properties of a thick-film titania prepared by a slow spinning process

Faia

Furtado

Ferreira

2004

Sensors and Actuators B: Chemical

128

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A ceramic thick film humidity sensor was produced from an emulsion of titania powders by a spin coating technique using a low speed. Electrical measurements were taken between interdigital electrodes obtained by depositing silver paste on the oxide, then cured at 500 • C for 15 min. Different relative humidities of a dynamic atmosphere were obtained by mixing dry and 23 • C saturated synthetic air in convenient proportions. Complex impedance spectra of the titania sensor at various relative humidities (RH) and different temperatures were measured and compared. The humidity sensing behaviour is due to surface water molecules adsorption and capillary condensation. The proposed sensing mechanisms, explaining the registered impedance spectra, are a combination of proton hopping, hydronium electrical drift and diffusion, and electrolytic conduction. In the frequency range 1-400 Hz, resistance and capacitive reactance show variations of three to four-order magnitude over the RH range 10-100%. The curves representing the variations of resistance and capacitive reactance versus RH show clearly the existence of two dominant electrical charge transport mechanisms. A parameter called characteristic humidity is defined to represent the sensitive response of the sensor. It was found that the sensitivity was highly dependent on the frequency. This work also shows that, for the same RH, both resistance and capacitive reactance vary with the atmosphere temperature.

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“…[6,7]. Additionally, they are able to detect a large category of harmful gases that affect the quality of life.…”

Section: Introductionmentioning

confidence: 98%