Related Experiment Video
Updated: Aug 20, 2025
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
AIB3IIC3IIIQ8VI: A New Family for the Design of Infrared Nonlinear Optical Materials by Coupling Octahedra and
Ling Luo1, Linan Wang1, Jianbang Chen1
1Research Center for Crystal Materials; CAS Key Laboratory of Functional Materials and Devices for Special Environments, Xinjiang Technical Institute of Physics & Chemistry, CAS, 40-1 South Beijing Road, Ürümqi830011, China.
Abstract:
Large second-harmonic generation (SHG) response and broad band gap are two important and competitive parameters. It is difficult to balance them out in one material. In this work, by coupling alkali earth metal (AEM) octahedra with large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap and nonlinear optical (NLO)-active tetrahedra units, nine noncentrosymmetric (NCS) compounds, belonging to a new quaternary chalcogenide family AIB3IIC3IIIQ8VI with unique windmill-like [Mg3M3IIIQ24] (MIII = Al, Ga; Q = S, Se) units constructed by alternated [MgQ6] octahedra and [MIIIQ4] tetrahedra, are rationally designed and fabricated. The compounds show a stable structural framework but adjustable optical properties. Among them, NaMg3Ga3Se8 shows a large SHG response (∼1 × AgGaS2 (AGS)), wide band gap (in selenide) (2.77 eV), high laser-induced damage threshold (LIDT) (∼2.3 × AGS), and suitable birefringence (0.079@546 nm). It should be a potential candidate for infrared (IR) nonlinear optical (NLO) materials. The results enrich the chemical diversity of chalcogenides and open an avenue for the development of new IR NLO materials through the octahedra and tetrahedra coupled strategy.
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:52Stereoisomerism
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:42Valence Bond Theory
01:27¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene...
02:42Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...