Cd₇SiAs₆, a Nonchalcopyrite Arsenide with a Strong Nonlinear-Optical Response

Abstract

A new arsenide, Cd7SiAs6, has been successfully synthesized and characterized. It is the first arsenide that adopts a nonchalcopyrite structure and possesses a strong nonlinear-optical (NLO) response. In the structure, the CdAs3 trigonal planar unit, a kind of π-conjugated planar NLO-active group, was identified for the first time. Furthermore, theoretical calculations reveal that the CdAs3 planar unit contributes more to the NLO effect than the CdAs4 tetrahedron does. The result may provide valuable insights for the future exploration of IR NLO materials, especially for application above 10 μm.

Second-Harmonic-Generation Effect and Giant Optical Birefringence in the Weyl Material CaAgAs

“…7 When the electronegative element becomes heavier, the vibration of the relevant bond and the lattice will be shifted to lower energy, and so the IR transparent range will be obviously red-shifted. 8 Hence, arsenide can cover the entire "8−14 μm" window, as shown by the traditional CdGeAs 2 crystal. 9 Furthermore, most arsenides have relatively small band gaps but large SHG coefficients, as shown by GaAs and CdGeAs 2 , which exhibit relatively smaller E g (∼1.519 and 0.57 eV) and larger d ij (∼170 and 236 pm/V) than ZGP.…”

“…Typically, ZnGeP 2 (ZGP), as an excellent commercial mid-IR NLO crystal, possesses a moderate band gap ( E g ∼ 1.8 eV) and a large second-harmonic-generation (SHG) effect ( d 36 ∼ 75 pm/V). , However, because ZGP has strong multiphonon absorption at 9 μm, it cannot be applied at longer wavelengths, especially the >10 μm part of the “8–14 μm” atmospheric transparent window . When the electronegative element becomes heavier, the vibration of the relevant bond and the lattice will be shifted to lower energy, and so the IR transparent range will be obviously red-shifted . Hence, arsenide can cover the entire “8–14 μm” window, as shown by the traditional CdGeAs 2 crystal .…”

Nonlinear Optical Phosphide CuInSi2P4: The Inaugural Member of Diamond-Like Family I–III–IV2–V4 Inspired by ZnGeP2

“…The UV−vis-NIR diffuse-reflection spectral data of CISP were processed by the Tauc Plot method, 40 and the optical band gap of CISP was detected as 0.81 eV (Figure S4), which are comparable with some reported NLO materials with narrow band gaps, such as CdGeAs 2 (0.57 eV), 41 Ba 4 AgGa 5 As 8 (0.8 eV), 42 CaAgAs (∼0.5 eV), 43 and Cd 7 SiAs 6 (0.36 eV). 44 Additionally, no significant absorption peaks from chemical bonds were observed in the IR spectrum of CISP (Figure S5). The investigation of the NLO properties of CISP was conducted due to its noncentrosymmetric (NCS) space group.…”

“…Powder X-ray diffraction (PXRD) was performed to verify the purity of the samples (Figure S3). The UV–vis-NIR diffuse-reflection spectral data of CISP were processed by the Tauc Plot method, and the optical band gap of CISP was detected as 0.81 eV (Figure S4), which are comparable with some reported NLO materials with narrow band gaps, such as CdGeAs 2 (0.57 eV), Ba 4 AgGa 5 As 8 (0.8 eV), CaAgAs (∼0.5 eV), and Cd 7 SiAs 6 (0.36 eV) . Additionally, no significant absorption peaks from chemical bonds were observed in the IR spectrum of CISP (Figure S5).…”

IrSi3As3: a first transition metal arsenide non-linear optical material

“…4 Among 5d transition metals, only a few metals were reported to form silicon arsenides with the common formula MSiAs but drastically different structures for M = Hf, Ta, and M = Au. [4][5][6][7] By using isovalent replacements of the pnictogen (P with As), the materials' properties can be adjusted. Novel metal silicon arsenides based on known metal silicon phosphides may be a successful approach to realize materials with symmetry-driven physical properties, such as second harmonic generation, topologically non-trivial phenomena, piezoelectricity, and superconductivity.…”