Synthesis, band structure, and optical properties of Ba2ZnV2O8

Abstract A novel compound Ba 2 ZnV 2 O 8 has been synthesized in high temperature solution reaction and its crystal structure has been characterized by means of single crystal X-ray diffraction analysis. It crystallizes in monoclinic system and belongs to space group P 2 1 / c with a = 7.9050 ( 16 ) , b = 16.149 ( 3 ) , c = 6.1580 ( 12 ) A , β = 90.49 ( 3 ) . It builds up from 1-D branchy chains of [ZnV 2 O 8 4− ] ∞ , and the Ba 2+ cations are located in the space among these chains. The IR spectrum, ultraviolet-visible diffuse reflection integral spectrum and fluorescent spectra of this compound have been investigated. The calculated results of energy band structure by the density functional theory method show that the solid-state compound of Ba 2 ZnV 2 O 8 is an insulator with direct band gap of 3.48 eV. The calculated total and partial density of states indicate that the top valence bands are contributions from the mixings of O-2 p , V-3 d , and Zn-3 d states and low conduction bands mostly originate from unoccupied antibonding states between the V-3 d and O-2 p states. The V–O bonds are mostly covalence characters and Zn–O bonds are mostly ionic interactions, and the ionic interaction strength is stronger between the Ba–O than between the Zn–O. The refractive index of n x , n y , and n z is estimated to be 1.7453, 1.7469, and 1.7126, respectively, at wavelength of 1060 nm for Ba 2 ZnV 2 O 8 crystal.