Structural variation and near infrared luminescence in Mn5+-doped M2SiO4 (M = Ba, Sr, ca) phosphors by cation substitution

Alkaline earth orthosilicates M2SiO4 (M = Ba, Sr and Ca) phosphors doped with Mn5+ ions have been prepared by the conventional solid-state reaction method. The crystal structures were verified by X-ray diffraction. By varying the host composition from Ba to Ca, the position shifting of photoluminescence emission bands corresponding to the E-1 -> (3)A(2) transition are induced by the increasing angular distortion and covalence. The nonradiative energy transfer becomes a dominant role in the photoluminescence process with substituting Ba2+ sites for smaller cations. The structural evolution and relevant luminescence mechanisms in (Ba1-xCax)(2)SiO4 phosphors also have been investigated in detail. It reveals that the chemical composition modification and structural variation can be an efficient approach to optimize the photoluminescence behaviors.