New vanadium tellurites: Syntheses, structures, optical properties of noncentrosymmetric VTeO4(OH), centrosymmetric Ba2V4O8(Te3O10)

Abstract

Two new vanadium tellurites, VTeO4(OH) (1) and Ba2V4O8(Te3O10) (2), have been synthesized successfully with the use of hydrothermal reactions. The crystal structures of the two compounds were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the polar space group Pca21 (No. 29) while compound 2 crystallizes in the centrosymmetric space group C2/c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO6 octahedral chains and TeO3(OH) zig-zag chains. Compound 2, on the contrary, features a three-dimensional [V4O8(Te3O10)]4- anionic framework with Ba2+ ions filled into the 10-member ring helical tunnels. The [V4O8(Te3O10)]4- anionic network is the first 3D vanadium tellurite framework to be discovered in the alkaline-earth vanadium tellurite system. Powder second harmonic generation (SHG) measurements indicate that compound 1 shows a weak SHG response of about 0.3×KDP (KH2PO4) under 1064nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out.