Syntheses, structures, and physical properties of the new quaternary rare-earth chalcogenides RbNd2CuS4, RbSm2CuS4, CsLa2CuSe4, CsSm2CuSe4, RbEr2Cu3S5, CsGd2Ag3Se5, CsTb2Ag3Se5

Fu Qiang Huang*, James A Ibers

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Eight quaternary rare-earth chalcogenides, RbNd2CuS4, RbSm2CuS4, CsLa2CuSe4, CsSm2CuSe4, RbEr2Cu3S5, CsGd2Ag3Se5, CsTb2Ag3Se5, and Rb2Gd4Cu4S9, have been synthesized at 973 K with the use of a reactive flux of A2Q3 (A = Rb, Cs; Q = S, Se). All structural data were obtained at 153 K. The isostructural compounds ALn2CuQ4 (Ln =rare earth) crystallize with four formula units in the KGd2CuS4 structure type in space group Cmcm of the orthorhombic system; the isostructural compounds ALn2M3Q5 (M = Cu, Ag) crystallize with four formula units in the RbSm2Ag3Se5 structure type in space group Cmcm of the orthorhombic system; and Rb2Gd4Cu4S9 crystallizes with two formula units in space group C2/m of the monoclinic system. The cell dimensions of ALn2CuQ4 (a, b, c (Å)) are as follows: RbNd2CuS4, 4.0762(3), 13.954(1), 13.964(1); RbSm2CuS4, 4.0391(3), 13.815(1), 13.860(1); CsLa2CuSe4, 4.3129(6), 14.959(2), 14.798(2); CsSm2CuSe4, 4.2066(3), 14.6101(9), 14.5164(9). The corresponding R1 indices for the refined structures are 0.0264, 0.0196, 0.0258, and 0.0224. The cell dimensions of ALn2M3Q5 are as follows: RbEr2Cu3S5, 3.9283(3), 13.897(1), 16.348(1); CsGd2Ag3Se5, 4.2943(4), 15.424(1), 17.501(2); CsTb2Ag3Se5, 4.2779(4), 15.429(2), 17.426(2). The R1 indices are 0.0257, 0.0255, and 0.0241. The cell dimensions of of Rb2Gd4Cu4S9 (a, b, c (Å), β (°)) is 13.897(1), 3.9883(3), 16.054(1), 109.273(1), and the R1 index is 0.0199. All eight compounds have closely related three-dimensional tunnel structures. All alkali metal atoms in the tunnels are coordinated to eight Q atoms. Their anionic frameworks are built from LnQ6 octahedra and MQ4 tetrahedra. ALn2CuQ4 contains 1[CuQ3] chains of vertex-sharing tetrahedra; Rb2Gd4Cu4S9 contains 1[Cu4S8] chains of tetrahedra; and ALn2M3Q5 contains 2[M3Q5] layers of tetrahedra. Rb2Gd4Cu4S9 and RbEr2Cu3S5, which are paramagnetic, obey the Curie-Weiss law, and have effective magnetic moments of 7.9(2) μB for Gd3+ and 9.43(5) μB for Er3+. A band gap of 1.94 eV for Rb2Gd4Cu4S9 was deduced from its diffuse reflectance spectrum, and the typical 4f-4f optical transitions for Er3+ were found in RbEr2Cu3S5 at about 1.6, 1.9, and 2.5 eV.

Original languageEnglish (US)
Pages (from-to)299-306
Number of pages8
JournalJournal of Solid State Chemistry
Volume158
Issue number2
DOIs
StatePublished - Jan 1 2001

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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