A NEW NONCENTROSYMMETRIC ORTHOBORATE [BA2ZN(BO3)2]

A new anhydrous, noncentrosymmetric orthoborate has been prepared and its crystal structure determined by X-ray diffraction of a single crys tal. The material crystallizes in the orthorhombic system with a = 15. 068(2), b = 8.720(2), and c = 10.128(3) angstrom; the space group is P ca2(1) and Z = 8. The final residuals were R = 0.083 and R(w) = 0.112 for 1140 reflections. The structure is composed of layers of ZnO4 tetr ahedra and BO3 triangles connected through shared oxygen vertices; the se layers are connected by additional interleaving BO3 triangles and b arium atoms. Calculations of the efficacy of the structure for second harmonic generation are discussed.