title: Laser excited long lasting luminescence in CaAl₂O₄: Eu³⁺/Eu²⁺+Nd³⁺ phosphor.
abstract: The europium and neodymium oxides doped nano-structured calcium aluminate phosphor samples have prepared through combustion technique and their luminescence properties are studied using laser excitations. Samples prepared in open atmosphere showed the presence of both Eu(3+) and Eu(2+) states and their ratio changes with calcination temperature. Single Eu(3+)/Eu(2+) ions doped sample has found to give broad emission at 450 nm without the persistence glow while the Eu(3+)+Nd(3+) ions codoped sample has shown persistence glow at 450 nm (Eu(2+)) on 355 nm laser excitation. Wavelength selective excitations show that 266 nm excitation gives the intense emissions from both Eu(3+) and Eu(2+) states with no afterglow but 355 nm excitation gives negligible emission from Eu(3+) ions and a strong afterglow at 450 nm wavelength. The mechanism of wavelength dependent phosphorescence has been discussed. Studies on Stark splittings and their relative intensities in emission spectra of Eu(3+) ions have shown that Eu(3+) ion can be used as excellent probe of crystal structure.
authors.affiliation: Department of Applied Physics, Indian School of Mines, Dhanbad 826 004, India. kumar.bhu@gmail.com
authors.forename: K
authors.initials: K
authors.lastname: Kumar
authors.forename: A K
authors.initials: AK
authors.lastname: Singh
authors.forename: S B
authors.initials: SB
authors.lastname: Rai
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry*; D017610:Calcium Compounds / Q000737:chemistry*; D005063:Europium / Q000737:chemistry*; D007834:Lasers; D049408:Luminescent Agents / Q000737:chemistry*; D008163:Luminescent Measurements; D049329:Nanostructures / Q000737:chemistry*; D009354:Neodymium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D049408:Luminescent Agents; D010087:Oxides; C035219:calcium aluminate; D009354:Neodymium; D005063:Europium