Related Experiment Video
Updated: Jul 13, 2026
08:46
Determining the Ice-binding Planes of Antifreeze Proteins by Fluorescence-based Ice Plane Affinity
Published on: January 15, 2014
When Octahedra Learn to Be Prisms: Unlocking a Record Deep‑UV NLO Crystal
Qi Gao1, Hongping Wu1, Zhanggui Hu1
1State Key Laboratory of Crystal Materials, Tianjin Key Laboratory of Functional Crystal Materials, Department of Functional Crystals, Tianjin University of Technology, Tianjin, China.
Angewandte Chemie (International Ed. in English)
|July 11, 2026
Summary
Researchers developed a new deep ultraviolet (DUV) nonlinear optical (NLO) crystal, NCCBF, by altering cation geometry. This crystal offers superior performance for DUV lasers, overcoming limitations of existing materials.
Area of Science:
- Materials Science
- Optics and Photonics
- Solid State Chemistry
Background:
- Deep ultraviolet (DUV) lasers require high-performance nonlinear optical (NLO) crystals.
- Existing NLO crystals like KBe2BO3F2 (KBBF) have limitations including toxicity and growth challenges.
- Current crystal design often relies on octahedral coordination, limiting optimization.
Purpose of the Study:
- To propose a new design paradigm for DUV NLO crystals by optimizing π-conjugated ring arrangements.
- To synthesize and characterize a novel DUV NLO crystal based on triangular prismatic geometry.
- To overcome the performance trade-offs and growth limitations of conventional NLO crystals.
Main Methods:
- Challenged conventional octahedral coordination preference in NLO crystal design.
- Proposed steering cation-centered polyhedra toward triangular prismatic geometry.
- Synthesized Na2CsCa2(B3O6)2F (NCCBF) and grew centimeter-sized single crystals using top-seeded-solution-growth.
Main Results:
- Synthesized NCCBF, a new DUV NLO crystal with a large second harmonic generation response (5.5 × KDP).
- NCCBF exhibits a short UV cut-off edge (180 nm), suitable birefringence (0.090 @ 532 nm), and low refractive index dispersion.
- Achieved the shortest phase-matchable wavelength among all known [B3O6]-based crystals.
Conclusions:
- NCCBF is a promising candidate for high-power DUV laser applications.
- Established a new structural design principle for π-conjugated borate NLO crystals.
- Promoting octahedral distortion toward trigonal prismatic geometry unlocks potential in NLO materials.
Related Concept Videos
01:24The Seven Crystal Systems: Overview
Crystals with various point group symmetries belong to different crystal classes, which are synonymous terms. Despite being in the same class, crystals may have distinct shapes, like cubes and octahedra. There are 32 three-dimensional point groups, all of which are systematically divided into seven crystal systems.The basic cubic crystal system, exemplified by NaCl, features orthogonal vectors (α = β = �� = 90°) of equal lengths (a = b = c). When specific requirements are not imposed on the...
02:22Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
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...
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
Tetrahedral 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,...
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,...
01:18Unit Cells
A crystal's internal structure is an orderly array of atoms, ions, or molecules, and the details of this array significantly influence the solid's properties. In a crystal, periodically repeating 'structural motifs' - which could be atoms, molecules, or groups thereof - create a 'space lattice.' This is essentially a three-dimensional, infinite array of points, each surrounded by its neighbors in an identical way, forming the basic structure of the crystal.A 'unit cell' is a theoretical...
01:27Symmetry Elements in a Crystal
Crystal symmetry operations are isometric transformations that map objects onto indistinguishable copies while preserving distances, angles, and volumes. The simplest symmetry operation is translation, which shifts the entire infinite crystal lattice parallelly by a translation vector.Crystallographic rotations involve rotations by an angle of 2π/n around an axis without changing the positions of points on the axis. It is called the rotational axis of the symmetry, denoted by n. The combination...