Intriguing Dimensional Transition Inducing Variable Birefringence in K2Na2Sn3S8 and Rb3NaSn3Se8

Cd4InO(BO3)3: A New Nonlinear Optical Crystal Exhibiting Strong Second Harmonic Generation Effect and Moderate Birefringence

A new noncentrosymmetric cadmium indium borate, Cd4InO(BO3)3 (CIBO) has been successfully developed via a standard solid-state reaction. Its crystal structure was confirmed by the single crystal X-ray diffraction, which shows that CIBO belongs to the non-centrosymmetric and polar space group Cm. Its structure contains the distorted InO6 and CdOn (n = 6, 8) polyhedra, which link together by sharing an edge or corner to build a three dimensions framework with BO3 triangles accommodated in tunnels. Benefiting from the approximately parallel configuration of BO3 triangles, CIBO exhibited a strong second harmonic generation (SHG) effect (3 × KDP), and moderate birefringence of 0.077@1064 nm. Further optical and thermal characterizations suggest that CIBO possesses a wide transparent window and good thermal stability. Theoretical calculation reveals that the macroscopic SHG coefficients of CIBO results from the synergistic effect of the parallel arrangement of BO3 groups and d10 Cd2+ cation.

CsCu3SbS4: rational design of a two-dimensional layered material with giant birefringence derived from Cu3SbS4

By introducing Cs into known Cu3SbS4, we successfully obtained a novel thioantimonate, quaternary CsCu3SbS4 with an unprecedented 2D layered structure, which exhibits a giant birefringence (0.232 at 549 nm).

Ba6In2Ge2Te15: A THz Birefringent Material with an Intriguing Quasi-[Te5]4- Chain Possessing Giant Optical Anisotropy and Ultrawide Transmission Range

Exploring mid- and far-infrared (MFIR) and even terahertz (THz) birefringent crystal with a large optical anisotropy remains a great challenge. Herein, a novel THz birefringent material Ba6In2Ge2Te15, which contains the...

Designing A New Infrared Nonlinear Optical Material, β-BaGa2 Se4 Inspired by the Phase Transition of the BaB2 O4 (BBO) Crystal

Infrared nonlinear optical (IR NLO) crystals play a significant role in the development of IR laser technology. But rationally designing a new IR NLO crystal remains a huge challenge because of the unpredictability of inorganic structures. Herein, inspired by phase transformation of the famous BaB₂ O₄ (BBO) crystal, a temperature-induced centrosymmetric (CS) to noncentrosymmetric (NCS) transformation approach is employed in CS BaGa₂ Se₄ to uncover a new NCS ternary chalcogenide, β-BaGa₂ Se₄ which can exhibit the well-balanced NLO properties, including moderate phase-matching SHG response (≈0.6×AgGaS₂ ), high LDT (10×AgGaS₂ ), and large birefringence (Δn=0.18 in the visible region). Therefore, β-BaGa₂ Se₄ will be a promising IR NLO crystal. The analysis for the structure-property relationship shows that the excellent NLO properties of β-BaGa₂ Se₄ mainly originate from edge-sharing GaSe₄ tetrahedral chains, which are different from B₃ O₆ groups in β-BBO and respect a new direction for the design of IR NLO crystals. So, we believe that the current research provides not only a new IR NLO crystal but also some insights for the design of new IR NLO crystals.

Synthesis and Characterizations of Two Tellurides β-BaGa2Te4 and Ba5Ga2Ge3Te12 with Flexible Chain Structure

Demands for IR birefringent materials are increasing due to the rapid developments of IR laser applications. Herein, two new chain tellurides β-BaGa₂Te₄ and Ba₅Ga₂Ge₃Te₁₂ have been discovered. β-BaGa₂Te₄ crystallizes in the orthorhombic space group Imma (no. 74) with unit cell constants of a = 23.813(3) Å, b = 11.9673(19) Å, and c = 6.7215(9) Å, while Ba₅Ga₂Ge₃Te₁₂ crystallizes in the monoclinic space group P2₁/c (no. 14) with unit cell constants of a = 13.6540(3) Å, b = 9.6705(2) Å, and c = 23.1134(7) Å. The structure of β-BaGa₂Te₄ can be considered to be the antiparallel arrangement of one-dimensional (1D) [GaTe₂] chains formed by edge-sharing GaTe₄ tetrahedra, which are separated by Ba²⁺ cations. In the crystal structure of Ba₅Ga₂Ge₃Te₁₂, two kinds of 1D chains, namely chain 1 _∞¹[(GaGe)₃Te₈] and chain 2 _∞¹[(GaGe)₂Te₄], are stacked alternately and put together by the coulomb force with Ba²⁺ cations. In addition, First-principles calculations indicate that β-BaGa₂Te₄ has a large birefringence, ∼0.325 at 2050 nm, derived from the superposition of the polarizabilities of GaTe₄ tetrahedra, implying that it has potential as an IR birefringent material. This work may provide some guidance for exploring new IR birefringent crystals.

LaTeBO5: a new borotellurite with a large birefringence activated by the highly distorted [Te(iv)O4] group

A new borotellurite, LaTeBO₅, containing the highly distorted [Te^(iv)O₄] group has been synthesized. Interestingly, it exhibits a wide ultraviolet transmittance range and large birefringence (0.080@1064 nm). The response electron distribution anisotropy approximation and dipole moment calculation demonstrate that the synergistic effect of the highly asymmetric [Te^(iv)O₄] and BO₃ groups is conducive to its large birefringence.