Room temperature photoluminescence of anatase and rutile TiO2 powders

The optical absorption and photoluminescence of anatase and rutile TiO2 were studied at room temperature. TiO2 nanocrystalline powders were synthesized in the form of pure anatase or rutile. The samples were characterized by X-ray diffraction, X-ray fluorescence, Raman spectroscopy, optical absorpti...

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Bibliographic Details
Published in:Journal of luminescence 2014-02, Vol.146, p.199-204
Main Authors: Kernazhitsky, L., Shymanovska, V., Gavrilko, T., Naumov, V., Fedorenko, L., Kshnyakin, V., Baran, J.
Format: Article
Language:English
Subjects:
Anatase
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Cross-disciplinary physics: materials science
rheology
Electron states
Exact sciences and technology
Excitation
Excitation spectra
Excitons
Excitons and related phenomena
Materials science
Nanocrystalline materials
Nanoscale materials and structures: fabrication and characterization
Optical absorption
Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of bulk materials and thin films
Photoluminescence
Physics
Rutile
Spectra
Titanium dioxide
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Summary:The optical absorption and photoluminescence of anatase and rutile TiO2 were studied at room temperature. TiO2 nanocrystalline powders were synthesized in the form of pure anatase or rutile. The samples were characterized by X-ray diffraction, X-ray fluorescence, Raman spectroscopy, optical absorption and photoluminescence (PL) methods. The PL spectra were studied under the intensive UV (3.68eV) laser excitation. Some interesting features in the PL spectra including the well-resolved peaks of excitonic and band–band transitions in TiO2 were observed, to our knowledge, for the first time. It is shown that PL bands including peaks at 2.71–2.81eV and its phonon replicas in anatase and rutile TiO2 arise from the excitonic e−−h+ recombination via oxygen vacancies. The excitonic peak at 2.91eV is attributed to the recombination of self-trapped excitons in anatase or free excitons in rutile TiO2. The PL peaks within 3.0–3.3eV in anatase TiO2 are ascribed to indirect allowed transitions due to the band–band e−−h+ recombination. The peaks at 3.03eV and 3.26eV are attributed to the free exciton emission near the fundamental band edge of rutile and anatase TiO2, respectively. The influence of TiO2 crystal structure and calcination temperature on the PL spectra is discussed. •Well-resolved peaks of the exciton PL at room temperature were observed.•The peaks fine structure is caused by strong exciton–phonon interaction under laser excitation.•The PL intensity in anatase TiO2 powders increases when the specific surface area increases.•The PL intensity in rutile TiO2 powders depends on several competing factors.
ISSN:0022-2313
1872-7883
DOI:10.1016/j.jlumin.2013.09.068