Dependence of luminescence properties of CaTiO₃: PR³⁺ on different TiO₂ polymorphs

CaTiO₃ is widely used in the ceramic industry, and when it is doped with Pr³⁺ it glows with a single red emission at a wavelength of 613nm upon ultraviolet or electron beam irradiation. The red emission is attributed to the ¹D₂→³H₄ radiative transition of Pr³⁺. The compound was prepared by using either rutile or anatase polymorphs of TiO₂ to investigate their effects on the luminescence properties. X-ray diffraction patterns of CaTiO₃:Pr³⁺ phosphor prepared with rutile polymorph show that the phosphor was successfully synthesized without any additional phases, whereas the patterns for the phosphor prepared with anatase polymorph show unreacted TiO₂ phases. The unreacted phases resulted in lowered luminescence intensity of the phosphor prepared with the anatase TiO₂. The cathodoluminescence stability of the phosphor was also investigated by exposing it to a prolonged electron beam irradiation. The persistent emission lifetimes increased with an increase in the synthesis temperature, with that of the anatase polymorph lasting longer. The energy distribution of the electron trapping centers was also determined.