New Insight into Phase Formation of MxMg2Al4+xSi5−xO18:Eu2+ Solid Solution Phosphors and Its Luminescence Properties

Here we reported the phase formation of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) solid solution phosphors, where M(+) ions were introduced into the void channels of Mg2Al4Si5O18 via Al(3+)/Si(4+) substitution to keep the charge balance. XRD results revealed that the as-prepared phosphors with different M(+) contents were iso-structural with Mg2Al4Si5O18 phase. The combined analysis of the Rietveld refinement and high resolution transmission electron microscopy (HRTEM) results proved that M(+) ions were surely introduced into the intrinsic channels in Mg2Al4Si5O18. The emission peaks of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) phosphors with various x values performed a systematic red-shift tendency, which was ascribed to the elongation of [MgO6] octahedra. The temperature stable photoluminescence and internal quantum efficiency (QE) of MxMg2Al(4+x)Si(5-x)O18:Eu(2+) (M = K, Rb) phosphors were enhanced owing to the filling of M(+) in the void channels suggesting a new insight to design the solid solution phosphors with improved photoluminescence properties.