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

Na2BaMg(PO4)(2) was synthesized and characterized by X-ray diffraction, differential thermal analysis (DTA), P-31 NMR spectroscopy and photoluminescence measurements. This compound crystallized in the P (3) over bar m1 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 K3Na(SO4)(2). Thus, it exhibited a lamellar framework which could be described as the stacking along the [001] direction of [MgP2O84-](infinity) 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. The P-31 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.