ChemInform Abstract: Large Scale Synthesis, Second‐Harmonic Generation, and Piezoelectric Properties of a Noncentrosymmetric Vanadium Phosphate, Li₂VPO₆.

Abstract

Large Scale Synthesis, Second-Harmonic Generation, and Piezoelectric Properties of a Noncentrosymmetric Vanadium Phosphate, Li2VPO6. -Phase pure Li2VPO6 is prepared by solid state reaction of a stoichiometric mixture of Li2CO3, V2O5, and NH4H2PO4 (Al2O3 crucible, 580°C, 36 h, cooling rate 10°C/h). The material crystallizes in the orthorhombic space group Pna21 with Z = 4 (powder X-ray and neutron diffraction) and exhibits a noncentrosymmetric layered structure which is composed of distorted VO6 octahedra and PO4 tetrahedra. The V 5+ cations are distorted either along the approximate [1 0 1] or [-1 0 1] directions attributable to the alignment of distorted VO6 octahedra, resulting in a polar structure. Powder second harmonic generation (SHG) measurements with 1064 nm radiation indicate that the material has a SHG efficiency of approximately 10 times that of α-SiO 2 and is not phase-matchable (type 1). Converse piezoelectric measurements for the material reveal a piezoelectric coefficient of 12 pm V -1 . -(LEE, E. P.; LEE, D. W.; CHO, Y.-H.; TRAN, T. T.; HALASYAMANI, P. S.; OK*, K. M.; J. Solid State Chem. 202 (2013) 22-26, http://dx.