“…K 2 CdGe 3 S 8 and K 2 CdGe 3 Se 8 are type-I phase-matching materials. K 2 CdGe 3 S 8 exhibits balanced NLO properties of a high SHG coefficient (2.1× AgGaS 2 , samples of particle size of 200–250 μm), high LDTs (6.2× AgGaS 2 ), and good air stability and is the record holder of best SHG properties in the II 2 II 1 IV 3 Ch 8 (II = K, Rb, Cs; II = Mn, Co, Fe, Zn, Cd; IV = Ge, Sn; and Ch = S, Se) family. − The superior SHG response of K 2 CdGe 3 S 8 is attributed to the chemical characteristics of Cd compared to Fe, which was studied in this work. A detailed study of crystal structures, electronic structures, optical properties, and density functional theory (DFT) calculations of K 2 TGe 3 Ch 8 (T = Fe, Cd and Ch = S, Se) is summarized in the present work.…”