Synthesis, crystals structure and photoluminescence properties of a new rare-earth carbonate Na₃Eu(CO₃)₃6H₂O

A new sodium europium carbonate hydrate, Na₃Eu(CO₃)₃·6H₂O, has been prepared using the hydrothermal method, and its structure was determined by single crystal X-Ray diffraction analysis for the first time. It crystallizes in the polar hexagonal space group P63 with a = 11.382(9) Å, c = 5.989(5) Å, V = 672.06(9) ų , Z = 2, Mr = 509.06, Dc = 2.516 g/cm³ , F(000) = 492, μ(MoKa) = 4.84 mm^-1, R₁ = 0.015 and wR = 0.038. The structure features a three-dimensional(3D) framework composed of planar (CO₃)^2- triangles, Eu³⁺ ions and Na⁺ ions, which delimits 1D infinite chains with a hexangular star appearance along the c-axis. The IR spectrum and the self-activated photoluminescence properties were studied. Under the excitation of near UV light (395nm), it shows strong red emission at 618 nm with a lifetime of 348.7 μs. Present research indicates that Na₃Eu(CO₃)₃·6H₂O is a promising red phosphor for white light-emitting diodes