Abstract
X-ray diffraction, optical absorption and photoluminescence were measured for anatase titanium dioxide under high pressures using a diamond anvil cell. Pressure dependence of the lattice constants was determined. Absorption spectra revealed that the absorption edge of anatase shifts at a rate of 10 meV/GPa. A broad luminescence band at 2.3 eV shows a blue shift at a rate of 33 meV/GPa. The difference in these rates indicates that pressure effect on the Stokes shift energy of the exciton is larger than that on the band gap. On the phase transition, the absorption edge jumps to lower energy side. The broad luminescence band almost disappears and a weak, but sharp band appears at 1.5 eV. The difference in luminescence spectra between anatase and high-pressure phase strongly suggests that the broad emission band of anatase is due to recombination of the self-trapped exciton.
Published Version
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