La6Cd0.75Ga2Q11.5Cl2.5 (Q = S and Se): two new nonlinear optical chalcohalides with a large laser-induced damage threshold

Two new chalcohalides La6Cd0.75Ga2Q11.5Cl2.5 (Q = S and Se) with mixed-anionic functional groups were synthesized through a high temperature reaction using LaCl3 as reaction-flux. Both compounds crystalize in the non-centrosymmetric space group P63 with highly oriented tetrahedron [GaQ4] and one-dimension chain [CdQ/Cl6] (Q = S and Se). The La6Cd0.75Ga2S11.5Cl2.5 shows a large laser-induced damage threshold (LIDT) (18.6 × AgGaS2) and strong second harmonic generation (SHG) response (0.8 × AgGaS2). These results indicate that the introduction of halogens into chalcogenides is beneficial to achieve large LIDTs and SHG response.