Cathodoluminescence and Photoluminescence Studies of Undoped and Eu2+ Doped SrAl2O4 Phosphors Prepared by Combustion Method.

Undoped and Eu²⁺ doped strontium aluminate (SrAl₂O₄) nanosized phosphorescent powders were prepared by urea-nitrate solution combustion method at 500°C for 5 minutes. The average particle size of the powders was about 60 nm. The photoluminescent properties have been studied using the synchrotron radiation and electron excitation. The broad photoluminescence bands were observed in SrAl₂O₄: Eu²⁺ peaking at λ_max = 450 and 525 nm, which arise due to transitions from the 4 f⁶5d¹ to 4 f⁷ configuration of the Eu²⁺ ions situated in two sites with different symmetry. Three additional emission bands were also observed at 250, 370 and 403 nm in undoped as well as Eu-doped samples. The bands are attributed to the intrinsic emission of self-trapped excitons (band at 250 nm) and to extrinsic emission from complexes containing structural defects (bands at 370 and 403 nm). [ABSTRACT FROM AUTHOR]