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Abstract: The title compound was firstly synthesized by solid state reaction and its single crystals were successfully obtained using a selected flux. It is isotypic with the mineral buetschliite, K2Ca(CO3)2, and crystallizes in the trigonal space group R-3m with a = 5.4526(12) Å, c = 17.781(8) Å, Z = 3. In the structure, Ba and K atoms are disordered on a same site in the proportion of 0.492(4):0.508(4). The fundamental building units are YO6 octahedra and BO3 triangles. The structure consists of [YB2O6]∞ double layers constructed by corner-sharing YO6 and BO3 groups. Ba/K atoms occupy the spaces between these two layers and play the role of bridges. In addition, the luminescence properties of Eu3+ doped KBaY(BO3)2 were also studied. [Copyright &y& Elsevier]

Abstract: Tb3+ single-doped SiO2 (SiO2:Tb3+) and Tb3+, Ag co-doped SiO2 (SiO2:Tb3+–Ag) nanostructured luminescent materials were prepared by a modified Stöber method. Their microstructure and optical property were investigated using scanning electron microscopy, ultraviolet visible absorption and photoluminescence spectrophotometry. Results show that the samples are composed of well-dispersed near-spherical particles with a diameter about 50nm, the highest fluorescence intensity is obtained when the doping concentration of Tb3+ is 4.86mol%, the corresponding internal quantum efficiency is 13.6% and the external quantum efficiency is 8.2%. The experimental results indicate that Ag nanoparticles can greatly enhance the light absorption at 226nm and the light emission at 543nm of SiO2:Tb3+–Ag, and the fluorescence lifetime reduces with increasing Ag concentration in SiO2:Tb3+–Ag. Additionally, the present results indicate that fluorescence enhancement is attributed to the local field enhancement and the increased radiative decay rates induced by Ag nanoparticles. [Copyright &y& Elsevier]