Luminescence of Eu3+ in LnAlO3 (Ln = Gd, Y) under UV and VUV excitation

Single phases of LnAlO(3): Eu3+ (Ln = Gd, Y) were obtained by the process of evaporation of their nitric acid solution, and then pyrolysis of their nitrate salts. On monitoring by 613 nm emission, broad bands at around 270 and 170 nm were observed in the excitation spectrum of Gd0.95Eu0.05AlO3. These peaks could be assigned to charge transfer (CT) transitions of Eu3+-O2- and Gd3+-O2- respectively. All the transitions observed in Gd0.95Eu0.05AlO3 are faithfully reproduced in the Y0.95Eu0.05AlO3, but with an exception of the (S7/2-->6I11/2)-S-8 transition of Gd3+. The 153 nm broad band could be the CT transition of Y3+-O2-. Accordingly, the efficiency luminescence of (Gd, Y)BO3: Eu3+ was explained as a result of CT transitions of Gd3+-O2- and Y3+-O2- under 147 nm excitation. Under VUV excitation, Gd0.95Eu0.05AlO3 exhibits a bright red luminescence with CIE chromaticity coordinates of (0.623, 0.335) with a PL intensity of 30 of the commercial phosphor (Gd, Y)BO3: Eu3+ (KX-504A). The PL spectrum of Y0.95Eu0.05AlO3 is similar to that of Gd0.95Eu0.05AlO3. Calculation of the color coordinates gives x = 0.636, y = 0.340 with a PL intensity of 50 of the (Gd, Y)BO3: Eu3+ (KX-504A) for Y0.95Eu0.05AlO3, and confirms that it has the appearance of pure spectral red, corresponding approximately to 608 nm. It can be concluded that LnAlO(3): Eu3+ is a promising red VUV phosphor.