New Antimony Lanthanide Disulfide Dibromides LnSbS
CeSbS{sub 2}Br{sub 2} (I), Ce{sub 1/2}La{sub 1/2}SbS{sub 2}Br{sub 2} (II), and LaSbS{sub 2}Br{sub 2} (III) have been synthesized at 700 C from a mixture of LnBr{sub 3}, Ln{sub 2}S{sub 3}, Sb, and S and characterized by single-crystal X-ray diffraction. The three phases are isostructural (space group P2{sub 1}/c, Z=4) and crystallize in a novel, dense, bidimensional structure with cell parameters a=8.709(3) {angstrom}, b=9.187(2) {angstrom}, c=17.397(5) {angstrom} {beta}=104.26(3) for I, a=8.739(7) {angstrom}, b=9.219(7) {angstrom}, c=17.41(2) {angstrom}, =104.3(1) for II, and a=8.785(1) {angstrom}, b=9.236(2) {angstrom}, c=17.372(3) {angstrom}, {beta}=104.09(2) for III. In these compounds, [Ln S{sub 5}Br{sub 4}] and [Ln S{sub 3}Br{sub 6}] (Ln=Ce, La) distorted tricapped trigonal prisms define infinite {sub {infinity}}{sup 2}[LnS{sub 2}Br{sub 2}] layers counterbalanced and capped by antimony cations. In good accordance with the structural features, the charge balance in these materials is to be written Ln{sup III}Sb{sup III}S{sup -II}{sub 2}Br{sup -I}{sub 2}. These compounds exhibit a yellow hue with a measured absorption threshold of 2.42(1), 2.55(1), and 2.72(1) eV for I, II, and III, respectively. In the two cerium containing bromothioantimonates I and II, the origin of the color is assigned to a Ce-4f{yields}Ce-5d electronic transition, which shifts to higher energy from I to II due either to a matrix effect (increase of the mean Ln-S distances under the substitution of Ce for La) or to an atomic ordering between Ce and La cations on the Ln(1) and Ln(2) crystallographic sites. In contrast, the electronic transition at play in III involves a charge transfer from the bromine and sulfur ions to the antimony ions, the latter contributing substantially to the lowermost levels of the conduction band.
- Research Organization:
- Institut des Materiaux Jean Rouxel, UMR 6502, Laboratoire de Chimie des Solides, Nantes (FR)
- Sponsoring Organization:
- None (US)
- OSTI ID:
- 784435
- Journal Information:
- Journal of Solid State Chemistry, Vol. 158, Issue 2; Other Information: PBD: 1 May 2001; ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ANTIMONY
ANTIMONY IONS
CATIONS
CERIUM
DISULFIDES
MIXTURES
RARE EARTHS
SULFUR IONS
X-RAY DIFFRACTION
ANTIMONY SULFIDES
LANTHANUM SULFIDES
CERIUM SULFIDES
ANTIMONY BROMIDES
LANTHANUM BROMIDES
CERIUM BROMIDES
CHEMICAL PREPARATION
MONOCLINIC LATTICES
SPACE GROUPS
LATTICE PARAMETERS
COLOR
ELECTRONIC STRUCTURE
LANTHANUM
EXPERIMENTAL DATA