XPS study of Nb-doped oxygen sensing TiO2 thin films prepared by sol-gel method

Atashbar, Massood Z.; Sun, Hong‐Tao; Gong, Bin; Włodarski, W.; Lamb, Robert N.

doi:10.1016/s0040-6090(98)00534-3

Cited by 232 publications

(143 citation statements)

References 13 publications

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“…However, some contradictory report also exists. 36 In order to have a better insight we have performed the near edge x-ray absorption fine structure (NEXAFS) spectroscopy study to understand the Nb doping induced modifications in local electronic structure of NTO films and reduction of Ti valance states. The sensitivity and capability of this technique is quite well known.…”

Section: Resultsmentioning

confidence: 99%

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

Gautam

Singh

et al. 2015

AIP Advances

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The effect of Niobium doping and size of crystallites on highly transparent nano-crystalline Niobium doped Titanium Dioxide (NTO) thin films with stable anatase phase are reported. The Nb doping concentration is varied within the solubility limit in TiO2 lattice. Films were annealed in controlled environment for improving the crystallinity and size of crystallites. Elemental and thickness analysis were carried out using Rutherford backscattering spectrometry and cross sectional field emission scanning electron microscopy. Structural characteristics reveal a substitutional incorporation of Nb+5 in the TiO2 lattice which inhibits the anatase crystallites growth with increasing the doping percentage. The micro-Raman (MR) spectra of films with small size crystallites shows stiffening of about 4 cm−1 for the Eg(1) mode and is ascribed to phonon confinement and non-stoichiometry. In contrast, B1g mode exhibits a large anomalous softening of 20 cm−1 with asymmetrical broadening; which was not reported for the case of pure TiO2 crystallites. This anomalous behaviour is explained by contraction of the apical Ti-O bonds at the surface upon substitutional Nb5+ doping induced reduction of Ti4+ ions also known as hetero-coordination effect. The proposed hypotheses is manifested through studying the electronic structure and phonon dynamics by performing the near edge x-ray absorption fine structure (NEXAFS) and temperature dependent MR down to liquid nitrogen temperature on pure and 2.5 at.% doped NTO films, respectively.

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Section: Resultsmentioning

confidence: 99%

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

Gautam

Singh

et al. 2015

AIP Advances

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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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“…Metal oxide semi conducting materials appear to be one of the best candidates for gas sensing, as they operate reversibly and usually have stable chemical and thermal properties over extended periods of use [1]. TiO 2 thin films are popular for such applications, where changes in the film electrical conductivity can be related to the physisorption and chemisorption of oxygen atoms [2,3].Titanium dioxide has many excellent physical properties such as a high dielectric constant, a strong mechanical and chemical stability, as well as good insulating properties.…”

Section: Introductionmentioning

confidence: 99%

Structural, Dielectric and Optical properties of Sputtered TiO2 nano-films

Thaidun¹

2013

IOSR-JAP

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XPS study of Nb-doped oxygen sensing TiO2 thin films prepared by sol-gel method

Cited by 232 publications

References 13 publications

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

Anomalous behavior of B1g mode in highly transparent anatase nano-crystalline Nb-doped Titanium Dioxide (NTO) thin films

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

Structural, Dielectric and Optical properties of Sputtered TiO2 nano-films

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