Mechanism of highly sensitive and fast response Cr doped TiO2 oxygen gas sensor

Sharma, Ramavtar; Bhatnagar, M.C.; Sharma, Govind

doi:10.1016/s0925-4005(97)00295-5

Cited by 127 publications

(57 citation statements)

References 14 publications

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“…The aforementioned promotion of anatase-to-rutile transformation observed from the XRD is, however, evidence for substitutional doping of Cr in the coatings, justifying our DFT treatment of substitutional doping. 50 The band gaps of the pure and doped coatings were compared by plotting Tauc plots, using both Ultraviolet-visible (UV-Vis) spectroscopy and ellipsometry data, as depicted in Fig. 6.…”

Section: Resultsmentioning

confidence: 99%

Influence of doping on the photoactive properties of magnetron-sputtered titania coatings: Experimental and theoretical study

et al. 2012

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The UCD community has made this article openly available. Please share how this access benefits you. Your story matters! (@ucd_oa) Some rights reserved. For more information, please see the item record link above. PHYSICAL REVIEW B 86, 115306 (2012) Influence of doping on the photoactive properties of magnetron-sputtered titania coatings:Experimental and theoretical study Titanium dioxide (TiO 2 ) thin films, doped with chromium (Cr) and codoped with chromium-carbon (Cr, C) and chromium-nitrogen (Cr, N) of various concentrations, were deposited using magnetron sputtering. Postdeposition thermal treatments were carried out at 450• C for 5 h to change the as-deposited amorphous coatings to their crystalline form. The crystalline phase was found to be dependent on the amount and type of dopant present. Ultraviolet-visible (UV-Vis) absorption data and band gap energies calculated by spectroscopic ellipsometry showed that, on increasing Cr concentration, a shift of the absorption edge towards visible light and a reduction of the band gap occurred. This was further improved by codoping of Cr with either N or C, with the latter case exhibiting more photo-activity towards visible light. In addition, hybrid density functional theory (DFT) calculations were performed for Cr-, N-. and C-monodoping, together with Cr-C and Cr-N codoping, in both rutile and anatase phases of crystalline titania. Using this method, absorption coefficients and band gaps were determined to explore photo-activity. Very good, semiquantitative agreement was found between the DFT and experimental approaches for these quantities, underlining the key role of state-of-the-art quantum calculations in interpreting and guiding experimental studies of doping in metal oxides.

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Section: Resultsmentioning

confidence: 99%

Influence of doping on the photoactive properties of magnetron-sputtered titania coatings: Experimental and theoretical study

et al. 2012

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“…According to Ref. [5], the temperature for Cr doped into the lattice of TiO 2 is 1300 K by solid state reaction because of the good stability of TiO 2 . For the powder prepared through sol-gel route, no Cr 2 O 3 diffraction peak is detected in 3 at.% Cr doped powder sintered at 923 K (see Fig.…”

Section: Resultsmentioning

confidence: 99%

Electrical characterization of TiO2-based ceramics for VOCs

Wang

Xiao

et al. 2008

J Electroceram

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Cr doped TiO 2 and TiO 2 /Cr 2 O 3 powders are prepared by sol-gel technique and solid state reaction respectively. The structural and electronic properties of these powders are investigated. The responses of the materials made from the powders to benzene and formaldehyde vapors are studied. The research results show that Cr 3+ can enter into the lattice as substitutional metal dopant by sol gel route at lower temperature. The segregation of Cr 2 O 3 happens when Cr content exceed 8 at.%. The resistance of TiO 2 can be remarkable decreased by doping Cr 3+ as substitutional metal dopant. Besides Cr 3+ , the segregation of Cr 2 O 3 also contributes to the alteration of conduction from n-to p-type. With some other catalyzer, both of Cr doped TiO 2 -based and Cr 2 O 3 /TiO 2 -based ceramics can detect benzene and formaldehyde vapors at 21 ppm.

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“…[11][12][13][14][15] Figure 3 illustrates the variation in the sensor resistance over the course of a typical analysis cycle. Initially, the chamber was vacuumed down to a pressure of 0.665 Pa.…”

Section: Materials Analysis and Resistance Detectionmentioning

confidence: 99%

Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO<SUB>2</SUB>/TiO<SUB>2</SUB> Film

Lee

Hwang

2005

Mater. Trans.

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This paper investigates the effect of photocatalysis on the sensitivity of oxygen sensors constructed with SnO 2 /TiO 2 thin films. An R.F. magnetron sputtering system is employed to fabricate SnO 2 /TiO 2 double-layer films. The thin films are deposited with SnO 2 /TiO 2 thickness ratios of 250/50, 200/100, 150/150, 100/200, and 50/250 nm, respectively. During deposition, the Ar:O 2 flow rate is fixed at 4:1. To stabilize the material properties, the films are annealed for four hours at a temperature of either 550 or 650 C. The increase in sensitivity of the SnO 2 / TiO 2 thin films when irradiated by UV light with a wavelength of 365 nm is investigated. The results indicate that the annealed samples have higher oxygen sensitivities than the as-deposited samples. The sensitivity of the non-annealed samples increases from 0.70 to 1.15 under UV irradiation, while the sensitivity of the annealed samples increases from 7.17 to 10.60. Therefore, it is clear that UV irradiation causes the sensitivity of the SnO 2 /TiO 2 thin films to increase significantly. Finally, it is found that the oxygen sensitivity of the SnO 2 /TiO 2 thin films increases as the SnO 2 /TiO 2 ratio is reduced.

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Mechanism of highly sensitive and fast response Cr doped TiO2 oxygen gas sensor

Cited by 127 publications

References 14 publications

Influence of doping on the photoactive properties of magnetron-sputtered titania coatings: Experimental and theoretical study

Influence of doping on the photoactive properties of magnetron-sputtered titania coatings: Experimental and theoretical study

Electrical characterization of TiO2-based ceramics for VOCs

Enhancing the Sensitivity of Oxygen Sensors through the Photocatalytic Effect of SnO<SUB>2</SUB>/TiO<SUB>2</SUB> Film

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