I have observed some changes in optical performance of TiO2 while irradiated with high energy electron beam.
What changes have you observed? Can you show the spectra before/after irradiation?
While measuring absorbance spectra using UV Visible spectrofotometer, slight increse in band gap observed for irradiated samples. Also PL specrum shows larger peak for irradiated samples and a small blue shift.
May be during radiation the change of phase occurs or the mixture of various phases takes place. May be a new phase appears in some regions of the crystal. In this case, you investigate a mixture of different phases with different values of bandgap.It is possible originally you had a phase rutile with a band gap of 3.0 eV. As a result of irradiation, other phase (anastase) with band gap 3.2 eV also appears. The mixture of these phases will lead to an effective increase in band gap. Other case : may be during irradiation a high concentration of defects appears in the crystal lattice. However, in this case the band gap must decrease.What is a crystalline phase of investigated TiO2 ? It is possible that the optical properties of TiO2 may be reversible by high-temperature annealing.
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