Syntheses, Structures, Physical Properties, and Electronic Structures of Ba₂MLnTe₅(M = Ga and Ln = Sm, Gd, Dy, Er, Y; M = In and Ln = Ce, Nd, Sm, Gd, Dy, Er, Y)

Abstract

The 12 new rare-earth tellurides Ba(2)MLnTe(5) (M = Ga and Ln = Sm, Gd, Dy, Er, Y; M = In and Ln = Ce, Nd, Sm, Gd, Dy, Er, Y) have been synthesized by solid-state reactions. The two compounds Ba(2)GaLnTe(5) (Ln = Sm, Gd) are isostructural and crystallize in the centrosymmetric space group P1, while the other 10 compounds belong to another structure type in the noncentrosymmetric space group Cmc2(1). In both structure types, there are one-dimensional anionic (1)(∞)[MLnTe(5)](4-) chains built from LnTe(6) octahedra and MTe(4) (M = Ga, In) tetrahedra, but the connectivity between the LnTe(6) octahedra and MTe(4) tetrahedra is different for the two structure types. On the basis of the diffuse-reflectance spectra, the band gaps are around 1.1-1.3 eV for these compounds. The Ba(2)MLnTe(5) (M = Ga and Ln = Gd, Dy; M = In and Ln = Gd, Dy, Er) compounds are paramagnetic and obey the Curie-Weiss law, while the magnetic susceptibility of Ba(2)InSmTe(5) deviates from the Curie-Weiss law. In addition, electronic structure calculation on Ba(2)MYTe(5) (M = Ga, In) indicates that they are both direct-gap semiconductors with large nonlinear-optical coefficients.

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.…”

K2Sn2ZnSe6, Na2Ge2ZnSe6, and Na2In2GeSe6: a new series of quaternary selenides with intriguing structural diversity and nonlinear optical properties

“…Examples include BaGa 4 S 7 , 8 BaGa 4 Se 7 , 9 BaGa 2 MSe 6 (M = Si, Ge; Q = S, Se), 10 Pb 4 Ga 4 GeQ 12 (Q = S, Se), 11 Ba 23 Ga 8 Sb 2 S 38 , 12 Cs 5 BiP 4 Se 12 , 13 Ln 4 GaSbS 9 (Ln = Pr, Nd, Sm, Gd−Ho), 14 and Ba 2 InYQ 5 (Q = Se, Te), 15,16 LiGaS 2 , 17 LiGaSe 2 , 18 Li 2 In 2 MS 6 (M = Si, Ge), 19 SnGa 4 Q 7 (Q = S, Se), 20 AAsQ 2 (A = Li,Na; Q = S,Se), 21 AZrPSe 6 (A = K, Rb, Cs) 1 and Na 4 MgM 2 Se 6 (M = Si, Ge). 22 Generally speaking, a large macroscopic NLO response originates from the cooperative arrangement of the microscopic NLO building units, including the MX 4 tetrahedra (M = Ga, In, Si, Ge, Sn etc.…”

Centrosymmetric to noncentrosymmetric structural transformation of new quaternary selenides induced by isolated dimeric [Sn2Se4] units: from Ba8Ga2Sn7Se18to Ba10Ga2Sn9Se22

“…Consequently, the nal R values were converged to R 1 ¼ 0.0415 and wR 2 ¼ 0.920 (Table 1, ESI Table S1a †). The nal charge-balanced formula was established as (Ba 18 . Meanwhile, all the subgroups of Pnma were checking.…”

“…Besides, different Ln cations lead to different crystal symmetries, like: controsymmetric Ba 2 LnGaTe 5 (Ln ¼ Sm or Gd) and noncentrosymmetric Ba 2 LnGaTe 5 (Ln ¼ Dy, Er, Y). 18 The family A/Ga/Sn/Q (A ¼ alkaline-earth metal; Q ¼ S, Se, Te) attracts our attention. One reason is that the asymmetric GaQ n units are able to build many noncentrosymmetric compounds, such as BaGa 4 Q 7 (Q ¼ S, Se), 19 BaGa 2 GeQ 6 (Q ¼ S, Se), 20 Ba 23 Ga 8 -Sb 2 S 38 , 15 Li 2 Ga 2 GeS 6 , 21 ACd 4 Ga 5 S 12 (A ¼ K, Rb, Cs), 22 Ba 2 Ga 8 MS 16 (M ¼ Si, Ge), 23 and Ln 4 GaSbS 9 (Ln ¼ Pr, Nd, Sm, Gd-Ho).…”