Na2BaMg(PO4 )2:synthesis, crystal structure and europium photoluminescence properties

Na2 BaMg(PO4)2 was synthesized and characterized by X-ray diffraction,differential thermal analysis(DTA),31P NMR spectroscopy and photoluminescence measurements.This compound crystallized in the P3m1 space group of the trigonal system with the parameters of equivalent hexagonal cell a=0.5305(1) nm and c=0.6986(3) nm.The structure showed a perfect isotipysm with the mineral glaserite K3 Na(SO4)2.Thus,it exhibited a lamellar framework which could be described as the stacking along the [001] direction of [MgP2 O8 4-] layers of corner sharing MgO6 polyhedra and PO4 tetrahedra.The Ba2+cations were located within the interlayer space,while the Na+ones were found in large cavities bound to the layers.The DTA analysis showed that this compound melt congruently at 1385 K.The31P NMR spectrum was consistent with the presence of a single phosphorus site in the structure.Optical properties were investigated for the 5% doped Eu3+and Eu2+phases.The trivalent europium was used as a local probe,replacing barium while the divalent europium was used to examine whether this material could be used as an optical applications.