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

Abstract Two new vanadium tellurites, VTeO 4 (OH) ( 1 ) and Ba 2 V 4 O 8 (Te 3 O 10 ) ( 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 Pca 2 1 (No. 29) while compound 2 crystallizes in the centrosymmetric space group C 2 /c (No. 15). The topography of compound 1 reveals a two-dimensional, layered structure comprised of VO 6 octahedral chains and TeO 3 (OH) zig-zag chains. Compound 2 , on the contrary, features a three-dimensional [V 4 O 8 (Te 3 O 10 )] 4- anionic framework with Ba 2+ ions filled into the 10-member ring helical tunnels. The [V 4 O 8 (Te 3 O 10 )] 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 (KH 2 PO 4 ) under 1064 nm laser radiation. Infrared spectroscopy, elemental analysis, thermal analysis, and dipole moment calculations have also been carried out.