A new rare-earth borate Na3-3δEu2+δ(BO3)3 (δ = 0.16): Synthesis, crystal structure, vibrational spectra, and luminescent properties

Abstract

A new rare-earth borate Na3-3δEu2+δ(BO3)3 (δ = 0.16) has been prepared using a high temperature flux method and structurally characterized by single-crystal X-ray diffraction analyses. The compound crystallizes in the orthorhombic space group Amm2 with a = 5.08902 (11) Å, b = 10.9754 (2) Å, c = 7.01996 (14) Å, V = 392.094 (14) Å3, and Z = 2. It features a three-dimensional framework constructed by interconnecting NaO6, EuO9, (Na/Eu)O8 distorted polyhedra, and BO3 planar triangles. Furthermore, IR, Raman, XPS, and UV–vis absorption spectra as well as photoluminescence properties of this compound were studied. Under near-UV excitation (396 nm), Na3-3δEu2+δ(BO3)3 (δ = 0.16) exhibits an intense reddish-orange emission centered at around 614 nm with the CIE coordinates of (0.637, 0.363), which can be assigned to the electric dipole 5D0→7F2 transition of Eu3+ ions. The phosphor shows the stable luminescence and color purity at elevated temperature. We may expect it to be a potential reddish-orange phosphor pumped by near-UV LED chips.