Structure refinement and luminescence properties of a novel apatite-type compound Mn2Gd8(SiO4)6O2

The structural and luminescence properties of apatite-type compound Mn2Gd8(SiO4)6O2 have been investigated. The crystal structure of Mn2Gd8(SiO4)6O2 has been obtained from the X-ray diffraction data by Rietveld method in the hexagonal system, space group P63/m, a = 9.3851 Å, c = 6.7904 Å, V = 517.97 Å3, Z = 1. The Mn2Gd8(SiO4)6O2 phase contains two cationic sites, one site (4f site with point symmetry C3) is a distorted tricapped trigonal prismatic polyhedron formed by nine oxygen atoms, and other site (6h sites with point symmetry Cs) is an irregular polyhedron of pentagonal bipyramidal geometry with the coordination by seven oxygen atoms. It is found that the Mn2+ ions occupy only 4f sites with C3 point symmetry, that has been verified by photoluminescence spectrum and decay curves. This work provides an insight to the novel inorganic compound design and gives an impetus to discover new functional materials and develop new applications.