Ba5Y12Zn[O(SiO4)]8: a novel non-centrosymmetric silicate with a short ultraviolet cut-off edge featuring [ZnSi4O16] and [SiO4] units

Abstract

A new non-centrosymmetric silicate Ba₅Y₁₂Zn[O(SiO₄)]₈ (BYZSO), the first compound of the Ba–Y–Zn–Si–O system, was synthesized by a high-temperature solution method in an open system, and its structure was identified using single-crystal X-ray diffraction data. Structural analysis indicates that it crystallizes in the noncentrosymmetric space group I2m (no. 121) with lattice parameters a = 18.7014(6) Å and c = 5.3640(2) Å corresponding to a tetragonal crystal system and is composed of isolated [ZnSi₄O₁₆] and [SiO₄] units. Meanwhile, the effect of the cation-to-silicon ratio on the Si–O framework was also studied by investigating the structures of barium-, yttrium-, and zinc-containing silicates found in the Inorganic Crystal Structure Database (ICSD). Experimental characterization demonstrates that it possesses a short ultraviolet cut-off edge of 204 nm (6.18 eV), a moderate second harmonic generation (SHG) response (0.3× KDP) at the maximum particle size, and excellent thermal stability. Besides, first-principles theoretical calculations were carried out to elucidate the relationship between the electronic structure and optical properties. In summary, this work is instructive for the synthesis and design of silicates with different dimensions in the Ba–Y–Zn–Si–O system.