Photoluminescence investigations of Li 2SiO 3:Ln (Ln=Er 3+, Eu 3+, Dy 3+, Sm 3+) phosphors
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2012
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Abstract
In this study, we report a comprehensive structural and photoluminescence (PL) study on lithium metasilicate (Li 2SiO 3) phosphor ceramics doped with four rare earth (RE) ions. X-ray diffraction (XRD) patterns show a dominant phase, characteristic of the orthorhombic structure Li 2SiO 3 compound and the presence of dopants has no effect on the basic crystal structure of the material. The first excited state Er 3+ luminescence at 1.54 μm arises from a sharp atomic-like radiative transition between the 4I 13/2 state and the 4I 15/2 state (ground level) under a 532 nm line of an Ar ion laser excitation. Sm doped samples showed Sm 3+ emission characteristics corresponding to the some 4G 5/2→ 6H j (j=5/2,9/2,11/2) transitions indicating a strong crystal-field effect. PL spectra of Eu doped material exhibited peaks corresponding to the 5D 0→ 7F j (j=0,1,2,3 and 4) transitions under 405 nm excitation. The dominant red color emission at 612 nm from the hypersensitive ( 5D 0→ 7F 2) transition of Eu 3+ indicates the inversion antisymmetry crystal field around Eu 3+ ion, which is favorable to improve the red color purity. Dy doped samples showed the Dy 3+ emission characteristic due to the 4F 9/2→ 6H 13/2 transition. Their relative intensity ratios also suggested the presence of a symmetric environment around the metal ion. We suggest that lithium metasilicate has enough potential candidates to be a phosphor material. © 2012 Elsevier B.V.
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Keywords
Crystal structure , Doping (additives) , Erbium , Europium , Iodine , Laser excitation , Light emission , Metal ions , Phosphors , Photoluminescence , Rare earths , Silicon compounds , Structural ceramics , X ray diffraction , Antisymmetries , Color emission , Color purity , Crystal field effects , Crystal fields , Doped materials , Doped sample , Emission characteristics , First excited state , Ground level , Ion laser excitation , Lithium metasilicate , Orthorhombic structures , Phosphor materials , Photoluminescence investigation , PL spectra , Radiative transitions , Rare earth ions , Relative intensity ratio , Solid state synthesis , Lithium