KCaEr₂CuS₅:  A New Pentanary Rare-Earth Layered Chalcogenide without Substitutional Disorder

Abstract

A new pentanary rare-earth chalcogenide without substitutional disorder, KCaEr2CuS5, was obtained from reaction of the Er-Ca-Cu-S precursor with KBr flux by either a two-step flux method or a direct reaction of the mixture of the binary components (1Cu2S:2Er2S3:3CaS) with excess KBr as flux. KCaEr2CuS5 crystallizes in the orthorhombic space group Cmcm (No. 63) with a = 3.9327(5) A, b = 13.410(2) A, c = 17.042(2) A, V = 898.8(3) A(3), Z = 4, R = 0.0632, and Rw = 0.0627. The KCaEr2CuS5 structure consists of four different building units: ErS6 octahedra, CaS6 octahedra, CuS4 tetrahedra, and KS6 trigonal prisms; it is characterized by [Er2CuS5]3- layers that are formed by the interconnection of double ErS6 octahedral chains with CuS4 tetrahedral chains in the a-c plane. K+ and Ca2+ cations are located in the cavities defined by S2- anions between the [Er2CuS5]3- layers. KCaEr2CuS5 is a semiconductor with an estimated band gap of 2.4 eV and shows a Curie-Weiss paramagnetic behavior in the 5-300 K range.

NaIn3S5, a new compound from the CaS–In2S3/NaBr system

“…Non-centrosymmetric chalcogenides containing alkaline or alkaline-earth elements have been investigated as new NLO materials with high laser-damage threshold for infrared applications, examples include LiGaQ 2 (Q = S, Se, Te) [30,72], LiInS 2 [73], LiInSe 2 [74], Li 2 CdGeS 4 [75], Li 2 CdSnS 4 [75], and BaGa 4 S 7 [76]. During our attempt to search for the analog of acentric NaIn 3 Se 5 (space group P3 2 ) [63] via a reactive halide flux method [52,[77][78][79][80][81][82][83], a new compound NaIn 3 S 5 has been obtained in the CaS-In 2 S 3 /NaBr system. We present here the synthesis, single crystal structure, experimental band gap and electronic structure calculation of NaIn 3 S 5 .…”

New Quaternary Rare-Earth Chalcogenides BaLnSn2Q6 (Ln = Ce, Pr, Nd, Q = S; Ln = Ce, Q = Se): Synthesis, Structure, and Magnetic Properties

“…Rare-earth chalcogenides have exhibited not only rich structures resulting from the diverse geometry of the Ln -centered coordination polyhedra and the flexible connectivity among them, but also fascinating magnetic, transport, and optical properties related to the 4f electrons. , Recently, rare-earth chalcogenides that also contain the p-block main group elements have received increasing attention. − Among them, Na 1.515 EuGeS 4 contains a three-dimensional (3D) framework structure with empty nanotubules constructed by mixed valence Eu (II/III) cations; K 2 Ln 2 As 2 Se 9 ( Ln = Sm, Gd) is the first series of quaternary rare-earth selenoarsenate compounds with a 3D framework containing chairlike As 2 Se 4 units; ZnY 6 Si 2 S 14 , Y 3 GaS 6 , La 2 Ga 2 GeS 8 , Eu 2 Ga 2 GeS 7 , La 4 GaSbS 9 , and Ba 2 YInS 5 show strong second-harmonic generation (SHG) responses in the middle IR. In earlier studies, we carried out systematic investigation in the quaternary A/M/ Ln /Q (A = alkaline-earth metal; M = group IIIA metals Ga or In; Ln = rare-earth element; Q = chalcogen) system, hoping that the introduction of alkaline-earth metal would help to increase the band gap and hence to increase the laser damage threshold for IR nonlinear optical (NLO) materials and avoid the two-photon absorption of the conventional 1 μm pumping source.…”

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)

“…Extensive efforts in the synthesis and characterization of rare-earth chalcogenides have led to the discovery of many new multinary rare-earth chalcogenides with intriguing structures and interesting magnetic, electronic, luminescent, thermoelectric, and nonlinear-optical (NLO) properties. − One subset of rare-earth chalcogenides that have received increasing attention are those containing the combination of a rare-earth metal and a main-group p-block element. For example, ZnY 6 Si 2 S 14 , La 2 Ga 2 GeS 8 , Eu 2 Ga 2 GeS 7 , La 4 InSbS 9 , Sm 4 GaSbS 9 , and Ba 2 InYSe 5 compounds, especially the latter four, were reported to exhibit strong second-harmonic-generation (SHG) responses in the middle IR.…”