Noncentrosymmetric (KBa0.5)In2Se4 and (K0.58Ba0.71)(Ga0.89In1.11)Se4 derived from centrosymmetric BaIn2Se4 via partial cation substitution: structural chemistry and nonlinear optical activity

Two new noncentrosymmetric multinary selenides, (KBa0.5)In2Se4 (1) and (K0.58Ba0.71)(Ga0.89In1.11)Se-4 (2), have been synthesized using a high-temperature flux method at 1123 K. They crystallize in the tetragonal noncentrosymmetric space group 14cm with cell parameters: a = 8.0277(2), c = 6.7654(3) angstrom, V = 435.99(3) angstrom(3) for 1; a = 8.0296(4), c = 6.5403(9) angstrom, V = 421.68(7) angstrom(3) for 2 vs the orthorhombic centrosymmetric space group Fddd for BaIn2Se4. Their one-dimensional structures are constructed by [(MSe2)(-)](n) (M = Ga, In) chains composed of MSe4 tetrahedra via sharing edges, and K+/Ba2+ cation occupying the interchain cavities. They both show moderate second-harmonic generation responses about 0.5 x AgGaS2@2.1 mu m. UV-vis-NIR diffuse reflectance spectroscopy measurement shows that the optical band gaps of 1 and 2 are about 2.60 and 2.34 eV, respectively. Theoretical calculations are also carried out to analyze their electronic structures and optical properties. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

Two new noncentrosymmetric multinary selenides have been successfully synthesized via a high-temperature flux method, showing moderate second-harmonic generation responses. UV-vis-NIR spectroscopy measurements indicate optical band gaps of approximately 2.60 and 2.34 eV for the two compounds.