title: Synthesis, characterization, luminescence and defect centres in CaYAl3O7:Eu3+ red phosphor.
abstract: CaYAl(3)O(7):Eu(3+) phosphor was prepared at furnace temperatures as low as 550°C by a solution combustion method. The formation of crystalline CaYAl(3)O(7):Eu(3+) was confirmed by powder X-Ray diffraction pattern. The prepared phosphor was characterized by SEM, FT-IR and photoluminescence techniques. Photoluminescence measurements indicated that emission spectrum is dominated by the red peak located at 618 nm due to the (5)D(0)-(7)F(2) electric dipole transition of Eu(3+) ions. Electron Spin Resonance (ESR) studies were carried out to identify the centres responsible for the thermoluminescence (TL) peaks. Room temperature ESR spectrum of irradiated phosphor appears to be a superposition of two distinct centres. One of the centres (centre I) with principal g-value 2.0126 is identified as an O(-) ion while centre II with an isotropic g-factor 2.0060 is assigned to an F(+) centre (singly ionized oxygen vacancy). An additional defect centre is observed during thermal annealing experiments and this centre (assigned to F(+) centre) seems to originate from an F centre (oxygen vacancy with two electrons). The F(+) centre appears to correlate with the observed high temperature TL peak in CaYAl(3)O(7):Eu(3+) phosphor.
authors.affiliation: Mechanical Engineering Department, Chung-Ang University, Seoul, Korea. vijayjiin2006@yahoo.com
authors.forename: Vijay
authors.initials: V
authors.lastname: Singh
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
authors.forename: T K Gundu
authors.initials: TK
authors.lastname: Rao
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Kwak
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005063:Europium / Q000737:chemistry*; D049449:Luminescence; D008855:Microscopy, Electron, Scanning; D010758:Phosphorus / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D010758:Phosphorus; D005063:Europium