Synthesis, structure and property studies of a new series of rare earth (Ce, Tb) bismuth silicates

A new series of rare earth bismuth silicates has been synthesized by flux method and solid state reaction. LnBiSiO5 (Ln = Ce, Tb) crystallizes in a triclinic space group P-1 with cell parameters a = 5.6763(2) angstrom, alpha = 105.591(3)degrees b = 6.7922(3) angstrom, beta = 110.551(3)degrees c = 6.9593(2) angstrom, gamma = 99.733(3) degrees, Z = 2. They exhibit a novel three-dimensional structure consisting of zig-zag chains of edge-sharing Ce/TbO8 polyhedra that are further linked by SiO4 units and Bi2O8 clusters. The optical band gap (E-g) of TbBiSiO5 was estimated to be 3.84 eV from UV-Vis-IR diffuse reflectance spectra. Photoluminescence measurements suggest that due to the cooperative interaction of Bi and Tb the excitation bands monitored at 544 nm are shifted towards longer wavelength which may favor commercial UV diode excitation. The magnetic measurements show that TbBiSiO5 exhibits paramagnetic behavior without magnetic transitions down to 1.8 K.

Automated summary

A new series of rare earth bismuth silicates were synthesized, exhibiting a novel crystal structure and potential optical and magnetic properties for commercial UV diode excitation.