›› 2014, Vol. 23 ›› Issue (8): 84203-084203.doi: 10.1088/1674-1056/23/8/084203

• ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS • 上一篇    下一篇

Electronic and optical properties of TiO2 and its polymorphs by Z-scan method

S. Divya, V P N Nampoori, P Radhakrishnan, A Mujeeb   

  1. International School of Photonics, Cochin University of Science and Technology, Cochin, Kerala, India
  • 收稿日期:2013-07-31 修回日期:2014-01-01 出版日期:2014-08-15 发布日期:2014-08-15
  • 基金资助:
    Project supported by the Funds from the Department of Science and Technology (DST), India.

Electronic and optical properties of TiO2 and its polymorphs by Z-scan method

S. Divya, V P N Nampoori, P Radhakrishnan, A Mujeeb   

  1. International School of Photonics, Cochin University of Science and Technology, Cochin, Kerala, India
  • Received:2013-07-31 Revised:2014-01-01 Online:2014-08-15 Published:2014-08-15
  • Contact: S. Divya E-mail:divyasasi7@gmail.com
  • Supported by:
    Project supported by the Funds from the Department of Science and Technology (DST), India.

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摘要： TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable properties. TiO2 is known to exist in nature in three different crystalline structures: rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol-gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of χ(3) for amorphous, anatase, and rutile are also calculated and found to be 5× 10-19 m2/V2, 27× 10-19 m2/V2, 19× 10-19 m2/V2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

关键词: excitons, reverse saturable absorption (RSA), excitonic nonlinearity

Abstract: TiO2 is a material which has attracted considerable attention from the scientific community for its innumerable properties. TiO2 is known to exist in nature in three different crystalline structures: rutile, anatase, and brookite. Anatase and rutile TiO2 films have been widely characterized for their potential applications in solar cells, self-cleaning coatings, and photocatalysis. In the present report, the third-order nonlinear susceptibilities of TiO2 and its polymorphs, anatase, and rutile, prepared by the sol-gel technique followed by heat treatment are investigated using the Z-scan technique at a wavelength of 532 nm with a duration of 7 ns. Imaginary and real values of χ(3) for amorphous, anatase, and rutile are also calculated and found to be 5× 10-19 m2/V2, 27× 10-19 m2/V2, 19× 10-19 m2/V2, respectively. It is found that the values of the optical constants of amorphous TiO2 after heat treatment vary considerably. It is assumed that this could be due to the variation in the electronic structure of TiO2 synchronous with the formation of its polymorphs, anatase, and rutile. Amorphous TiO2 is marked by the localization of the tail states near the band gap, whereas its crystalline counterparts are characterized by completely delocalized tail states.

Key words: excitons, reverse saturable absorption (RSA), excitonic nonlinearity

中图分类号:  (Nonlinear optics)

  • 42.65.-k
42.70.Nq (Other nonlinear optical materials; photorefractive and semiconductor materials)