THE NONCENTROSYMMETRIC ORTHOBORATE BAZN2(BO3)2

The new orthoborate BaZn2(BO3)2 has been synthesized and its structure determined by single-crystal X-ray methods. It crystallizes in an orthorhombic cell with dimensions a = 9.305(3), b = 12.128(1), and c = 4.9255(8) Å; the space group is P212121. The structure was determined from 876 independent reflections and refined to the final residuals R = 0.024 and Rw = 0.034. It exhibits a three-dimensional framework of vertex-sharing ZnO4 tetrahedra and BO3 triangles that isolates Ba atoms in channels extending along the c axis. The optical second harmonic signal generated from a 1064-nm fundamental and microcrystalline sample is approximately 10% of that observed from the frequency converter potassium dihydrogen phosphate (KDP). This result is consistent with the magnitude of the nonlinearity computed on the basis of the anionic group model. © 1992.