UV emission from Gd3+ ions in Gd3+-Pr3+ codoped YAlO3 perovskite

Gd3+-Pr3+ codoped YAlO3 perovskite was found to show an intense ultraviolet emission from Gd3+ ions under photo-excitation at 215 nm. The emission peak was observed at 314 nm with narrow peak width and assigned to the 4f-4f transition of 6P7/2-8S7/2 in Gd3+ ions. Three peaks at 245, 255 nm and 277 nm were observed in the excitation spectra of Gd3+ doped YAlO3 and they were attributed to the f-f transition of 8S7/2-6DJ or 8S7/2-6IJ in Gd3+ ions. In addition to the three peaks, an intense broad excitation band was newly observed at around 215 nm in the excitation spectra of Gd3+-Pr3+ codoped YAlO3. Taking account of the absorption spectra of Gd3+ doped and Gd3+-Pr3+ codoped YAlO3, the broad excitation band was ascribed to the 4f-5d transition in Pr3+ ions. The intensity of the UV emission from Gd3+-Pr3+ codoped YAlO3 was approximately 8 times larger than that from Gd3+ doped YAlO3 at optimal dopant concentration and excitation wavelength. It was considered that the intense emission in Gd3+-Pr3+ codoped YAlO3 was derived from the large absorption of excitation energy by Pr3+ ions and the energy transfer from Pr3+ to Gd3+ ions.