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A series of apatite-type phosphors Ba 4.97− x Sr x (PO 4 ) 3 Cl:Eu 2+ ( x = 0, 0.5, 1.0, 1.5, 2.0) were synthesized by the high temperature solid-state reaction method, and its luminescence properties were investigated in detail. It can be found that a red shift of the emission peak wavelength emerged from 439 to 462 nm with the continuous introduction of Sr 2+ into the crystal lattice which has been simulated by a crystal-field model. The red shift is explained by the distortion in the crystal structure through X-ray diffraction and the Rietveld refinement analysis. According to a recently raised structural model, Eu 2+ ions are surrounded by O atoms, PO 4 tetrahedrons and Ba/Sr ions. After introducing Sr 2+ into the lattice, the interatomic distance between Ba/Sr atoms and Eu 2+ was expected to become shorter, resulting in a distortion of the inner EuO n polyhedrons. Then the crystal field strength surrounding Eu 2+ was increased, finally resulting in the red shift. [ABSTRACT FROM AUTHOR]

Cyan-emitting LiBaBO 3 :Eu 2+ phosphor was synthesized by solid-state reaction at 800 °C. Structure refinement by Rietveld method reveals that LiBaBO 3 crystallizes in a monoclinic cell, space groups P 2 1 / c or P 2 1 / n . Upon 365 nm excitation, LiBaBO 3 :Eu 2+ shows a symmetric emission band peaking at 496 nm with full-width at half-maximum of 80 nm; when monitoring at 496 nm, a broad excitation band in the UV region (250–420 nm) is observed. The luminescence property of LiBaBO 3 :Eu 2+ is considerably different from LiSrBO 3 :Eu 2+ which holds the same space group. The local structures of the two hosts are compared to explain the different behaviors of Eu 2+ . [ABSTRACT FROM AUTHOR]