Growth and properties of single crystals of noncentrosymmetric Na ₃VO₂B₆O₁₁

A new nonlinear optical crystal, Na₃VO₂B ₆O₁₁, has been grown by the top-seeded solution growth method using a Na₂CO₃-V₂O₅ flux. The structure of the compound was determined by single-crystal X-ray diffraction. It crystallizesjn the noncentrosymmetric orthorhombic system, space group P2₁2₁2₁, with cell parameters a = 7.7359(9) Å, b = 10.1884(12) Å, c = 12.5697(15) Å, V = 990.7(2) ų, and Z = 4. Na₃VO₂B₆O ₁₁ has a three-dimensional structure consisting of hexaborate groups connected by VO₄ tetrahedra with the sodium atoms distributed in channels through out the three-dimensional network. The refractive indices have been measured by the minimum deviation technique and fit to the Sellmeier equations. Nonlinear optical measurements on the compound demonstrate that the material has second harmonic generation properties, with an efficiency approximately the same as that of KH₂PO₄.