Rb2CdSi4S10: novel [Si4S10] T2-supertetrahedra-contained infrared nonlinear optical material with large band gap

Infrared nonlinear optical (IR-NLO) materials with wide band gaps are important for generating high-power laser light for modern laser technologies. Herein, a wide band gap IR-NLO material, Rb2CdSi4S10, was rationally designed and fabricated by introducing a NLO-active [Si4S10] T2-supertetrahedron (ST) into the quaternary sulfide system. The Rb2CdSi4S10 shows the largest band gap (4.23 eV) among the quaternary chalcogenide IR-NLO materials reported, which results in a high laser-induced damage threshold (LIDT) of ∼5 × AgGaS2 (AGS) at 1064 nm. At the same time, it has a moderate second-harmonic generation (SHG) response (0.6 × AGS). Based on statistical analyses, the Rb2CdSi4S10 is the first compound to be discovered in the AI2BIICIV4QVI10 family, and also the first Si-rich sulfide IR-NLO material with a [Si4S10] T2-supertetrahedra. The results indicate that Rb2CdSi4S10 is a promising new IR-NLO material, and the NLO-active [Si4S10] T2-ST unit could be used for the exploration of IR-NLO material with excellent performances.