Crystal growth and optical properties of lithium–lanthanide oxides: LiLnO2 (Ln = Nd, Sm, Eu, Gd and Dy)

Single crystals of LiLnO2 (Ln = Nd, Sm, Eu, Gd, Dy) were grown out of a high temperature hydroxide melt. The crystal structures were determined by single crystal X-ray diffraction. These oxides crystallize in the space groups P21/c (Nd, Sm – δ-type) and Pnma (Eu, Gd, Dy – γ-type) as a function of the lanthanide cation size. The structure of the δ-type (Nd, Sm) contains lithium in approximately trigonal bipyramidal coordination environments that connect to form rings around two lanthanide atoms, where the rings interconnect to form zig-zag layers. The structure of the γ-type (Eu, Gd, Dy) contains lithium in a distorted tetrahedral coordination environment, where two edges are shared to generate infinite chains separated by the rare earth cation. LiGdO2 and LiEuO2 luminesce in the visible range with emission maxima at 610 and 609 nm respectively.

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