LUMINESCENCE PROPERTIES AND ENERGY-TRANSFER OF EU2+ DOPED CA8MG(SIO4)4CL2 PHOSPHORS

The synthesis and luminescence characteristics of Eu2+ activated calcium magnesium chlorosilicate, Ca8Mg(SiO4)4Cl2, have been reported and analyzed. The emission spectrum of Eu2+ is composed of two separate bands with peaks at 507 and 428 nm, which result from the Eu2+ centers in different crystallographic sites. At room temperature, the excitation spectrum of the very strong 507 nm emission shows not only the broad 4f7-4f(6)5d excitation bands, but also the fine structure resulting from the splitting of 4f6 configuration in the 4f(6)5d excited state. This structure is explained by the high covalency degree of the cation-anion bonds in this system. Efficient energy transfer between the two inequivalent Eu2+ centers has been evaluated quantitatively.