A series of novel rare-earth bismuth tungstate compounds LnBiW2O9 (Ln = Ce, Sm, Eu, Er): Synthesis, crystal structure, optical and electronic properties

The structural, optical, and electronic properties of four rare-earth bismuth tungstate compounds, LnBiW(2)O(9) (Ln = Ce, Sm, Eu, Er), have been investigated by means of single-crystal X-ray diffraction, elemental analyses, and spectral measurements. For some of the compounds, the calculations of energy band structures and density of states have also been made by the density functional theory. The structure of CeBiW2O9 features a three-dimensional (BiW2O9)(3-) anionic framework with interesting channels where Ce atoms are located. The framework is constructed by one-dimensional BiO9 polyhedra chains and one-dimensional zigzag W2O9 chains via edge-and face-sharing. LnBiW(2)O(9) (Ln = Sm, Eu, Er) are isostructural and their structures feature a three-dimensional network based on alternating (BiO2)(-) layers and (Ln(2)W(2)O(12))(6-) layers connected by corner-linked chains of WO6 octahedra. Results of spectral measurements indicate that EuBiW2O9 exhibit the characteristic yellow-red light emission under excitation at 395 nm, and it will be a red phosphor in designing white light-emitting diode device. The calculated results of band structures by using the density functional theory (DFT) show that the solid-state compound CeBiW2O9 and SmBiW2O9 are indirect band gap materials.