Non-centrosymmetric Selenides AZn<sub>4sub>In<sub>5sub>Se<sub>12sub> (A=Rb, Cs): Synthesis, Characterization and Nonlinear Optical Properties
文摘
Two new non-centrosymmetric polar quaternary selenides, namely, RbZn<sub>4sub>In<sub>5sub>Se<sub>12sub> and CsZn<sub>4sub>In<sub>5sub>Se<sub>12sub>, have been synthesized and structurally characterized. They exhibit a 3D diamond-like framework (DLF) consisting of corner-shared MSe<sub>4sub> (M=Zn/In) tetrahedra, in which the A<sup>+sup> ions are located. Both compounds are thermally stable up to 1300 K and exhibit large transmittance in the infrared region (0.65–25 μm) with measured optical band gaps of 2.06 eV for RbZn<sub>4sub>In<sub>5sub>Se<sub>12sub> and 2.11 eV for CsZn<sub>4sub>In<sub>5sub>Se<sub>12sub>. Inspiringly, they exhibit a good balance between strong second harmonic generation (SHG) efficiency (3.9 and 3.5×AgGaS<sub>2sub>) and high laser-induced damage thresholds (13.0×AgGaS<sub>2sub>). Theoretical calculations based on density functional theory (DFT) methods confirm that such strong SHG responses originate from the 3D DLF structure.