Discovery of new nonlinear optical materials

Abstract

The phase pure large scale synthesis, second-harmonic generation, and piezoelectric properties of a vanadium phosphate, Li2VPO6 are reported. The material has been synthesized by a standard solid-state reaction using Li2CO3, V2O5, and NH4H2PO4 as reagents. The phase purity and crystal structure of the reported material have been confirmed by powder X-ray and neutron diffractions. The material crystallizes in orthorhombic space group Pna21 (no. 33) with a=10.32581(7) Å, b=4.63728(3) Å, c=8.56606(5) Å, and Z=4. The noncentrosymmetric layered structure is composed of distorted VO6 octahedra and PO4 tetrahedra. The V5+ cations distort 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 generating (SHG) measurements on Li2VPO6 using 1064 nm radiation, indicate the material has a SHG efficiency of approximately 10 times that of α-SiO2 and is not phase-matchable (type 1). Converse piezoelectric measurements for the material reveal a piezoelectric coefficient, d33, of 12 pm V−1.