New Layered Materials:  Syntheses, Structures, and Optical and Magnetic Properties of CsGdZnSe₃, CsZrCuSe₃, CsUCuSe₃, and BaGdCuSe₃

Abstract

Four new quaternary selenides CsGdZnSe3, CsZrCuSe3, CsUCuSe3, and BaGdCuSe3 have been synthesized with the use of traditional high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS3, crystallizing with four formula units in the orthorhombic space group Cmcm. Cell constants (A) at 153 K are CsGdZnSe3 4.1684(7), 15.765(3), 11.0089(18); CsZrCuSe3 3.903(2), 15.841(10), 10.215(6); CsUCuSe3 4.1443(7), 15.786(3), 10.7188(18); and BaGdCuSe3 4.1839(6), 13.8935(19), 10.6692(15). The structure of these ALnMSe3 compounds (A = Cs, Ba; Ln = Zr, Gd, U; M = Cu, Zn) is composed of 2 to infinity [LnMSe3(n-)] (n = 1, 2) layers separated by A atoms. The Ln atom is octahedrally coordinated to six Se atoms, the M atom is tetrahedrally coordinated to four Se atoms, and the A atom is coordinated to a bicapped trigonal prism of eight Se atoms. Because there are no Se-Se bonds in the structure, the oxidation state of A is 1+ (Cs) or 2+ (Ba), that of Ln is 3+ (Gd) or 4+ (Zr, U), and that of M is 1+ (Cu) or 2+ (Zn). CsGdZnSe3 and BaGdCuSe3, which are paramagnetic, obey the Curie-Weiss law and have effective magnetic moments of 7.87(6) and 7.85(5) muB for Gd(3+), in good agreement with the theoretical value of 7.94 muB. Optical transitions at 1.88 and 2.92 eV for CsGdZnSe3 and 1.96 eV for BaGdCuSe3 were deduced from diffuse reflectance spectra.

Synthesis, Structure and Properties of [Gd(c6n0(2)h5)3(h(2)0)2](2n)•(nh(5)0(2))(nzncl5)(2nzncl4)•(2nh(2)0) With Strong Fluorescence

“…7 The gradual slope of the optical absorption edge for 1 is indicative of the existence of indirect transitions. 8 The optical absorption of 1 is likely originated from the charge-transfer excitations mainly from the valence band of the chlorine atoms to the conduction band of the zinc center, similar to those reported in the references. 9 Fig.…”

A novel samarium complex with interesting photoluminescence and semiconductive properties

“…The steep slope of the optical absorption edges for complex1 is indicative of the existence of direct transitions [48]. It should be pointed out that the energy band gap of 3.60 eV of complex 1is obviously larger than those of CuInS 2 (1.55 eV), CdTe (1.5 eV), CuInSe 2 (1.04 eV), and GaAs (1.4 eV), all of them are highly efficient photovoltaic materials [49][50].…”

Preparation, Structure, Photoluminescent and Semiconductive Properties, and Theoretical Calculation of a Novel Cadmium Complex with Mixed Ligands

“…The slow slope of the optical absorption edge of complex 1 suggests that it must be an indirect transition. 32 The energy band gap of 3.25 eV of complex 1 is obviously larger than those of CuInS 2 (1.55 eV), CdTe (1.5 eV) and GaAs (1.4 eV), all of them are broadly applied as efficient photovoltaic materials. 33,34 …”