Na2Cd7B8O20: a new noncentrosymmetric compound with special [B3O7] units

Abstract

A new noncentrosymmetric compound, Na₂Cd₇B₈O₂₀, has been synthesized by solid-state reaction for the first time. The crystal structure has been determined from single crystal X-ray diffraction data. The compound crystallizes in the orthorhombic space group Fdd2 with a = 51.5597(7) Å, b = 58.6920(8) Å and c = 3.381 Å. The crystal structure is composed of CdO_n (n = 6, 7), Na–CdO_n (n = 5, 6) NaO_n (n = 4, 6) polyhedra, [B₃O₇] and [BO₃] units. The [B₃O₇] unit is built up of three [BO₃] groups via corner-sharing, rarely found in borate compounds. The IR spectrum, the optical diffuse reflectance spectrum and nonlinear optical properties of Na₂Cd₇B₈O₂₀ are reported.