CaCe(IO3)3(IO3F)F: a promising nonlinear optical material containing both IO3− and IO3F2− anions†
Abstract
The first noncentrosymmetric (NCS) rare earth fluoroiodate, CaCe(IO3)3(IO3F)F, has been hydrothermally synthesized through rational chemical substitution. Substituting one IO3− group with one IO3F2− unit and two Li+ cations with a Ca2+ cation in Li2Ce(IO3)4F2 transforms the symmetry from centrosymmetric (CS) to NCS. CaCe(IO3)3(IO3F)F crystallizes in the polar space group Pna21 and features a novel two-dimensional [Ce(IO3F)]2+ layer composed of Ce4+ cations bridged by IO3F2− units. Interestingly, the title compound exhibits a strong second-harmonic-generation (SHG) response of 5 times that of KDP, a wide optical transparent window (0.5–11 μm), a suitable birefringence of 0.071@1064 nm and a high laser-induced damage threshold (LIDT) (approximately 18.5 × AgGaS2), indicating that CaCe(IO3)3(IO3F)F is a potential material for visible to mid-infrared SHG applications. This work implies that the combination of IO3F2− and IO3− groups may be an efficient route to develop SHG materials based on metal iodates.