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Current issue   Ukr. J. Phys. 2014, Vol. 59, N 3, p. 246-253

    Paper

Kernazhitsky L.1, Shymanovska V.1, Gavrilko T.1, Naumov V.1, Fedorenko L.2, Kshnyakin V.3, Baran J.4

1 Institute of Physics, Nat. Acad. of Sci. of Ukraine
(46, Prosp. Nauky, Kyiv 03028, Ukraine; e-mail: kern@iop.kiev.ua)
2 Lashkaryov Institute of Semiconductor Physics, Nat. Acad. of Sci. of Ukraine,
(45, Prosp. Nauky, Kyiv 03028, Ukraine)
3 Sumy State University
(2, Rymsky-Korsakov Str., Sumy 40007, Ukraine)
4 Institute of Low Temperature and Structure Research, Polish Academy of Sciences
(2, Okolna Str., 50-950 Wroclaw, Poland)

Laser-Excited Excitonic Luminescence of Nanocrystalline TiO2 Powder

Section: Optics, lasers, and quantum electronics
Original Author's Text: English

Abstract: Titanium dioxide (TiO2) nanocrystalline powders were prepared by the thermal hydrolysis method in the form of pure anatase or rutile and were investigated by X-ray diffraction, Xray fluorescence, FT-Raman spectroscopy, optical absorption, and photoluminescence (PL) methods. PL spectra were studied under the intense UV laser excitation at 337.1 nm (3.68 eV) at room temperature. Some interesting features in the PL spectra including the well-resolved peaks of excitonic and band-band transitions in TiO2 were observed for the first time. It is shown that PL bands with peaks at 2.71–2.81 eV and its phonon replicas in anatase and rutile TiO2 arise from the excitonic e − ℎ+ recombination via oxygen vacancies. The excitonic peak at 2.91 eV is attributed to the recombination of self-trapped excitons in anatase or free excitons in rutile TiO2. The PL peaks within 3.0–3.3 eV in anatase TiO2 are ascribed to indirect allowed transitions due to the band-band e − ℎ+ recombination. The peaks at 3.03 and 3.26 eV are attributed to the free exciton emission near the fundamental band edge of rutile and anatase TiO2, respectively.

Key words: titanium dioxide, anatase, rutile, UV-vis spectroscopy, photoluminescence.