Formation of complete solid-solution and luminescence-evolution of cyclophosphates KMg(PO3)3 – KMn(PO3)3

Abstract

A series of red-emitting cyclophosphates KMg1-xMnx(PO3)3 (x = 0.01–1.0) were synthesized by the high-temperature solid-state reaction. The analysis of XRD structural Rietveld refinements prove that the complete solid solution is realized in the KMg(PO3)3 and KMn(PO3)3 system indexed to the hexagonal lattice with P6̅c2 (188) space group. And the formation of solid-solution was also verified via the luminescence-evolution of Mn2+ activator centers. The luminescence efficiencies, activator centers, and spectral profiles are discussed on the crystallographic surrounding of Mn2+ ions. Only one distinct Mn2+ center was confirmed showing red-emitting luminescence from the spin forbidden transition 4T1→6A1 in this solid-solution. Both UV and near-UV wavelength can effectively excite the phosphors, which could reach a maximum quantum efficiency of 30%. The dynamics luminescence is analyzed within the general energy transfer and migration processes by using the Inokuti-Hirayama and Yokota-Tanimoto models, respectively. The mechanism of energy transfer in lowly-doped KMg1-xMnx(PO3)3 (x=<0.5) is the diffusion-limited case with dominant dipole-dipole interaction and weak diffusion. While, there is the fast migration in Mn2+-heavily doped KMg1-xMnx(PO3)3 (x = 0.6–1.0). The phosphor shows a great interest for application in research on basic luminescence theories and lighting application.