Second-Harmonic-Generation-Active Oxyhalides: CuSb2O3X (X = CI, Br)

Metal oxyhalides have attracted broad interest recently because of their diverse structures and versatile properties. Her; two oxyhalides, CuSb2O3Cl (1) and CuSb2O3Br (2), were studied by focusing on their nonlinear-optical properties. They are crystallized in the noncentrosymmetric monoclinic Cc structure, and the layered structures could be derived from a 1:1 combination of CuX- (X = CI, Br) and Sb2O3 -type slabs. Their energy gaps were determined to be 2.76 and 2.64 eV. The second-harmonicgeneration (SHG) test suggests that they are nonlinear-optical-active, and the effects are ascribed to the contribution of CuX3O units. Meanwhile, the SbO3 units' arrangement has a small contribution to the SHG effects. This work is the pioneer SHG investigation of the M-I-M-III-O-X (M-I = Cu, Ag; M-III = trivalent As, Sb, Bi; X = halogen) family.