Hydrothermal Syntheses, Crystal Structures And Properities Of Novel Iodate Materials

Four novel nonlinear optical (NLO) compounds have been prepared by hydrothermal reactions at 170°C,including Ce(MoO2)(OH)(IO3)4,LiMoO3(IO3),NH4MoO3(IO3) and LiVO2(IO3)2. Single-crystal X-ray intensity data were collected on an automated Rigaku AFC7R four-circle diffractometer using monochromatized Mo Kαradiation. The crystal structures were solved by the SHELX-97 software, and physical properties of these compounds were investigated.A novel NLO compound, Ce(MoO2)(OH)(IO3)4 crystallizes in the polar space group P21 with a = 7.0144(8) , b = 14.1554(10) , c = 7.0969(6) ,β= 115.318(7)°, , Z = 2. The crystal structure of Ce(MoO2)(OH)(IO3)4 consists of a complex three-dimensional network formed by eight-coordinated Ce3+ cations, strongly distorted MoO66- octahedra, and bridging iodate anions.LiMoO3(IO3) crystallizes in the space group P21 with a = 5.4104(4) , b = 5.3158(3) , c = 9.0025(7) ,β= 106.863(6)°, Z = 2. LiMoO3(IO3) is a new layered material containing∞2 [MoO3(IO3)]- anionic layers separated by Li+ cations. DTA measurements demonstrate that LiMoO3(IO3) is stable up to at least 430oC. UV-vis diffuse reflectance spectrum of this compound shows a high degree of transparency from 1.1 to 2.8 eV and a band gap of about 2.8 eV. Second-harmonic-generation measurements on LiMoO3(IO3) display a response of about 4×KH2PO4, supporting the assignment of this structure in a noncentrosymmetric setting.NH4MoO3(IO3) crystallizes in a orthorhombic group Pna21 with a = 7.8167(6) , b = 10.2280(7) , c = 7.3466(4) , Z = 4. NH4MoO3(IO3) is isostructural with AMoO3(IO3) (A = Rb, Cs) and it has a three-dimensional (3D) framework in which strongly distorted octahedral Mo(VI) centers are connected to pyramidal IO3- groups.Li[VO2(IO3)2] crystallizes in space group P21/c, with all atoms occupying general positions, a = 9.994 (2) , b = 5.2020 (10) , c = 13.798 (3) ,β= 118.23°, Z = 4. The compound represents a new structure type in which distorted VO6...