Ln3FeGaQ7: A new series of transition-metal rare-earth chalcogenides

Noncentrosymmetric rare-earth copper gallium chalcogenides RE3CuGaCh7 (RE=La–Nd; Ch=S, Se): An unexpected combination

“…They extend the transition-metal substitution in RE 3 MGaCh 7 , previously limited to M¼Mn-Ni [9,13,15]. The RE 3 CuGaCh 7 compounds were prepared by direct reaction of the elements at 1050 1C (sulfides) or 900 1C (selenides), under identical conditions used to synthesize other RE 3 MGaCh 7 compounds [15].…”

“…As in all other copper-containing La 3 CuSiS 7 -type compounds [3,5,23,29,30], Cu atoms occupy the site strictly centred within the plane of these triangles to attain a CN of 3. In other cases, it is the antiprismatic site located halfway between these triangles that is occupied by metal atoms in an octahedral geometry (CN6), as in RE 3 MGaCh 7 (M ¼Mn-Ni) [9,13,15], or it could be an intermediate site having an asymmetric coordination with three short and three long bonds, as experienced by deficient Al atoms in Ce 3 Al 0.67 AlS 7 [16].…”

Two new phases in the ternary RE–Ga–S systems with the unique interlinkage of GaS4building units: synthesis, structure, and properties

“…Recently, quaternary chalcogenides that contain a rare-earth metal together with a group 13 main-group metal (e.g., Ga and In) are of great interest due to their fascinating structural chemistry and interesting physical properties including magnetic, photo-response, photoelectric, and nonlinear optical (NLO) properties. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] For example, 1D infinite anionic chains containing the compound Ba 2 REMQ 5 (RE = rare-earth metal; M = Ga, In; Q = S, Se, Te) offer flexibility in band gap engineering by controlling the composition and show weak short-range antiferromagnetic interactions between the adjacent RE 3+ cations. 7,9,10 La 3 CuGaSe 7 contains interesting isolated [CuSe 3 ] 4− pyramids and [GaSe 4 ] 5− tetrahedra and exhibits interesting centrosymmetric photo-response behaviour.…”

Synthesis, Crystal and Electronic Structure, and Optical Property of the Quaternary Selenide: La3Sb0.33SiSe7

“…The ordered derivative of the Ce 3 Al 1.67 S 7 ‐type structure forms in the absence of disorder in both octahedral and tetrahedral sites, as in the case of RE 3 FeGa Q 7 ( Q = S, Se),32 RE 3 M InS 7 ( M = Fe, Co, Ni), RE 3 M Ga Q 7 ( M = Fe, Co, Ni; Q = S, Se),33 Y 3 NaSiS 7 ,34,35 and RE 3 NaGeS 7 ( RE = Ce, Nd, Sm, Gd, Yb) 36. When the atoms in octahedral sites are displaced from the center towards the triangular base, the coordination arrangement can gradually change from octahedral (CN = 6), to the extreme of trigonal planar (CN = 3), resulting in a closely related La 3 CuSiS 7 ‐type structure, such as RE 3 MN Q 7 ( RE = rare earth metal; M = Cu, Ag; N = Si, Ge, Sn; Q = S, Se) 37…”