A new rubidium europium polyphosphate, RbEu(PO3)4, was synthesized by the high-temperature solution reaction and studied by single-crystal X-ray diffraction (XRD) technique. RbEu(PO3)4 belongs to the monoclinic space group P21/n (Z=4) and characterizes a three-dimensional framework made up from double PO4 spiral chains, RbO11, and EuO8 polyhedra. The absorption spectrum indicates that the compound has no absorption above 320nm with insulator characteristic. In addition, the infrared spectroscopy was carried out.
Sodium holmium polyphosphate crystal, NaHo（PO3）4, has been synthesized by the high temperature solution reaction and characterized by X-ray diffraction analysis, EDX, IR, UV-vis-NIR, and PL spectra. The structure belongs to the monoclinic system, space group P21/n with Z = 4, α = 7.181（3）, b = 13.059（5） and c = 9.730 （4） ？. It is described as a three-dimensional （3D） architecture made up of [P4O12]4- anionic spiral chains and HoO8 polyhedra by corner-sharing. The 8-coordinated sodium atoms are located in infinite tunnels. The results of EDX and IR spectrum are in good agreement with the crystallographic analysis. In addition, NaHo（PO3）4 exhibits visible light emission in the solid state at room temperature.
The potassium terbium polyphosphate crystal KTb（PO3）4 has been synthesized using a high temperature solution reaction method. The structure and composition were characterized by single-crystal X-ray diffraction, powder X-ray diffraction and elemental analysis. The compound crystallizes in the monoclinic space group P21/n with a=10.3182（6）, b=8.9129（5）, c=10.7940（6） , β=105.993（1）o, V=954.3 3, Z=4, Mr=513.91, Dc=3.577 g/cm3, μ=8.585 mm（-1）, F（000）=960, S=0.955,（Δρ）max=1.380,（Δρ）min=–3.428 e/3, the final R=0.0301 and w R=0.0400 for 2301 observed reflections with I 〉 2σ（I）. In addition, pure powder of isostructural Rb Tb（PO3）4 was synthesized in order to investigate the optical property. Photoluminescence measurements show that both crystals ATb（PO3）4（A=K（1）, Rb（2）） are promising candidates to become solid-state visible green light-emitting sources.
