Electronic structure and defects induced luminescence study of phase stabilized t-ZrO 2 nanocrystals.

Luminescent tetragonal-ZrO 2 nanocrystals were synthesized using an optimized combustion method without post-synthesis annealing and characterized using X-ray diffraction, electron microscopy, Raman, X-ray photoelectron spectroscopy, UV-Visible, photoluminescence spectroscopy, thermoluminescence and vibrating sample magnetometry. The as synthesized t-ZrO 2 nanocrystals have a band gap of 4.65 eV and exhibit defect assisted blue emission (CIE coordinates 0.2294,0.1984) when excited with 270 nm. The defect states were qualitatively and quantitatively analyzed using thermoluminescence (TL) after irradiating nanocrystals with gamma and UV radiation at various doses. The TL glow curves show intense emission in the high temperature region from 523-673 K for both UV and gamma irradiated samples; however, another less intense TL peak was also observed in the low temperature region from 333-453 K with gamma irradiation at higher doses, indicating the formation of shallow trapping states. The activation energies, frequency factor and order of kinetics were estimated through the computerized glow curve deconvolution method for the shallow and deep traps for γ and UV- irradiated samples. The present study shows that phase stabilized t-ZrO 2 nanocrystals are potential candidates for luminescence-based applications.