The crystal structure and luminescence of Ce3+, Tb3+ and Eu3+ in KBaLn3+(BO3)2 [Ln3+ = Sc, Y, Lu, Gd]

The structure of KBaLn(3+)(BO3)(2) [Ln(3+) = Sc, Lu, Gd] was solved by Rietveld refinement of the powder X-ray diffraction data. The materials crystallize with the mineral Buetschliite [K2Ca(CO3)(2)] structure. The lattice parameters of KBaLn(3+)(BO3)(2) [Ln(3+) = Sc, Lu, Gcl] increased with increasing ionic radius of the Ln(3+) cation. In this structure, the Ln(3+) cations are octahedrally coordinated. The phase formation region is dependent on the ionic radii of the Ln(3+) cation. The optical properties of Ce3+, Tb3+ and Eu3+ and their dependence on the host lattice composition are investigated and discussed. It is noteworthy that the optical properties of these ions are independent of the Ln(3+) cation in KBaLn(3+)(BO3)(2). It is concluded that in this family of materials, the crystalline field strength and the covalence at the rare earth site is independent of the host lattice composition. (C) 2015 Elsevier B.V. All rights reserved.