Tuning of Optical Band Gaps:  Syntheses, Structures, Magnetic Properties, and Optical Properties of CsLnZnSe₃ (Ln = Sm, Tb, Dy, Ho, Er, Tm, Yb, and Y)

Abstract

Eight new quaternary selenides CsSmZnSe(3), CsTbZnSe(3), CsDyZnSe(3), CsHoZnSe(3,) CsErZnSe(3), CsTmZnSe(3), CsYbZnSe(3), and CsYZnSe(3) have been synthesized with the use of high-temperature solid-state experimental methods. These compounds are isostructural with KZrCuS(3), crystallizing with four formula units in the orthorhombic space group Cmcm. The structure of these CsLnZnSe(3) compounds is composed of [LnZnSe(3)(-)] layers separated by Cs atoms. The Ln atom is octahedrally coordinated by six Se atoms, the Zn atom is tetrahedrally coordinated by four Se atoms, and the Cs atom is coordinated by a bicapped trigonal prism of eight Se atoms. Because there are no Se-Se bonds in the structure, the oxidation state of Cs is 1+, that of Ln is 3+, and that of Zn is 2+. CsYbZnSe(3) exhibits an antiferromagnetic transition at 11 K, whereas CsSmZnSe(3) does not follow a Curie-Weiss law. The remaining rare-earth compounds are paramagnetic, and the calculated effective magnetic moments of the rare-earth ions agree well with their theoretical values. Optical absorption data on face-indexed single crystals of CsSmZnSe(3), CsErZnSe(3), CsYbZnSe(3), and CsYZnSe(3) demonstrate that the optical band gap changes by more than 0.75 eV with the composition and by as much as 0.20 eV with the crystal orientation. The optical band gaps range from 2.63 eV (CsSmZnSe(3), CsErZnSe(3)) to 1.93 eV (CsYbZnSe(3)) for the (010) crystal face and 2.56 eV (CsErZnSe(3)) to 1.88 eV (CsYbZnSe(3)) for the (001) crystal face. The difference in the optical band gap of the (010) face vs the (001) face varies from +0.05 eV (CsYbZnSe(3)) to +0.20 eV (CsSmZnSe(3)).

Cs2Bi2ZnSe5

“…coordination geometries, which result from the stereochemical activity of the 6s 2 lone pair of electrons of Bi 3+ , have often been observed in bismuth chalcogenides, for example in BaBi 2 Se 4 (Iordanidis et al, 2001) and CsBi 3 Se 5 (Iordanidis et al, 2003). Each Zn atom is coordinated by a tetrahedron of four Se atoms, with ZnÐSe distances ranging from 2.471 (1) to 2.5254 (6) A Ê , similar to those of 2.434 (1)±2.529 (1) A Ê in CsYbZnSe 3 (Mitchell et al, 2002).…”

Effect of lanthanide contraction on the Ln/Sb/Se/dien system: solvothermal syntheses and characterizations of lanthanide(III)-selenidoantimonate complexes with diethylenetriamine as a co-ligand

“…Chalcogenide-based lanthanide (Ln) compounds are traditionally prepared by reflux at high temperature or the extraction method in organic solutions of tetrahydrofuran, N,N-dimethylformamide, and dimethyl sulfoxide [31][32][33][34]. However, the oxygen and water sensitivity of these materials has hindered progress [35].…”

Solvothermal synthesis and optical property of novel lanthanide(III) coordination polymers involving inorganic tridentate μ-η1,η2-SbS4 S-donor ligand

“…The chemistry of chalcogenide-containing lanthanide (Ln) compounds is attracting much interest due to their structural diversity, and unusual optical and electrical properties [1][2][3]. These compounds are mainly prepared by the flux method at high temperature [4].…”

“…The syntheses of 1 and 2 show that the soft base S-donor [SbS 4 ] 3− ligand can coordinate to hard Lewis acidic lanthanide metals in the presence of amino chelating ligands of dien. The lanthanide selenidoarsenates 1 and 2 exhibit semiconducting properties with E g between 3.81 and 2.57 eV.The chemistry of chalcogenide-containing lanthanide (Ln) compounds is attracting much interest due to their structural diversity, and unusual optical and electrical properties [1][2][3]. These compounds are mainly prepared by the flux method at high temperature [4].…”