A new quaternary rare-earth sulfide,Cs0.75(6)Er4.43(5)In3.32(6)S12(1),is discovered by high temperature solid state reactions with a slight excess of CsCl flux.The structure is characterized by single-crystal X-ray diffraction data,while crystallizes in hexagonal space group P63/m(No.176)with a=12.0329(6),c=3.8693(5),V=485.18(7)3,Z=1,Mr=1606.57,Dc=5.499 g/cm3,μ=25.457 mm-1,F(000)=752,the final R=0.0337 and wR=0.0904 for 328observed reflections with I>2σ(I).Its structure features a three-dimensional framework with hexagonal channels that are centered by Cs cations.Such channels are formed by double chains of edge-sharing M(1)S6(M(1)=Er(1)/In(1))octahedra and single chains of Er(2)S6triprism interconnected by corner-sharing.The syntheses,single-crystal analyses,optical band gap and magnetic property are reported.
Nanoscale tetragonal BiOCl samples have been synthesized using Bi[SC12H25]3 and CHCl3 as bismuth and chlorine sources by solvothermal reactions. The structure, morphology, and formation process have been investigated by SEM, TEM, HRTEM, XRD, and EDX analyses. The layered crystal structure feature of BiOCl may induce the growth of nano plates, which can subsequently aggregate into 3D spherical or flower-like microstructures under the presence of ethanol. The reaction temperature and the identity of secondary solvent influence the morphology. The yield of BiOCl depends on the completeness of the reaction and the degree of a competition reduction of BiOCl to Bi by ethanol. The as-synthesized 3D quasi-spherical BiOCl sample has an optical band gap of 3.15 eV, and shows much better photocatalytic performance on the degradation of methyl orange than that of commercial P25.
Well defined BiOI nanolamellas and BiSI nanorods have been synthesized by a solventless method. The phase identity, morphology, growth orientation, and conversion from lamella to rod have been investigated. Several experimental facts suggest that the growth orientations of BiOI nanolamellas and BiSI nanorods are guided by their corresponding crystal structure motifs. The optical band gaps of BiOI and BiSI are measured to be 1.97 and 1.61 eV, and the visible light photocatalytic activity of BiOI lamellas is primarily measured.
In order to explain the opposite phase matchability of two types of newly discovered chalcogenides, AX_2MQ_6 vs AX_4M_5Q_(12) belonging to the same R3 space group, the linear and nonlinear optical properties are calculated. The calculated Electron Localization Function(ELF) show the acentricity of the bonds on the Q^(2-) ions with sp^3 hybridization is the main origin of the optical anisotropy. To quantify such an acentricity, a geometric parameter, the dihedral angle between the tetrahedral undersides and the xy-planes is defined. And the calculated birefringence depends on the above defined geometric parameter and the ion radius. This correlation reasonably explains the opposite phase matchability of two closely related chalcogenide families of AX_2MQ_6 and AX_4M_5Q_(12) and is shedding useful light on further exploration on phase matchable IR-NLO crystals.
