Photoluminescence and Raman spectroscopy studies of Eu³⁺-doped rutile TiO₂ nanocrystals at high pressures

Author： Zeng Q. G. Ding Z. J. Lei B. F. Sheng Y. Q. Zhang Z. M.

ISSN： 0895-7959

Source： International Journal of High Pressure Research, Vol.32, Iss.3, 2012-09, pp. : 412-418

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Abstract

Nanocrystal samples (particle size about 90 nm) of Eu³⁺-doped rutile titanium dioxide (TiO₂) nanocrystals (rutile Eu³⁺/TiO₂ nanocrystals) were synthesized by the sol–gel method with hydrothermal treatment. The pressure effect on photoluminescence (PL) and Raman spectra of the rutile Eu³⁺/TiO₂ nanocrystals was investigated with a diamond anvil cell under hydrostatic pressure condition. Raman spectra of the samples at high pressures indicated that the critical pressure for the transition from the rutile phase to a new baddeleyite-type phase was between 10 and 14.2 GPa. The position of Raman bands shifted to high wavenumbers and the PL intensity of ⁵D ₀→⁷F ₂ transition of Eu³⁺ decreased down to zero with the increase of pressure before the phase transition occurred. After releasing the pressure, the rutile phase was not recovered and a α-PbO₂-type phase was observed at ambient pressure.