Etude structurale des oxysulfures de chrome(III) et de terres rares. I. Structure de l'oxysulfure LaCrOS2

Dugué, Jérôme; Voyan, T.; Villers, J.

doi:10.1107/s0567740880005948

Cited by 29 publications

(7 citation statements)

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“…These synthesis techniques employ various sulfur sources (elemental sulfur, H 2 S, or CS 2 ) as sulfidation agents. Some of them also involve a transition metal, producing not only bimetallic compounds, such as Ln 2 Ti 2 S 2 O 5 and LnCrOS 2 (Ln = La–Lu), − but also LaInOS 2 and La 5 In 3 S 9 O 3 …”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

et al. 2017

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Lanthanide oxysulfide nanoparticles have recently attracted interest in view of their potential applications, such as lighting devices and MRI contrast agents, which requires a good stability in air and a controlled surface. In order to address these issues, in this work, air-sensitive CeOS nanoparticles of hexagonal shape were successfully prepared and characterized under inert conditions. Bimetallic GdCeOS nanoparticles of similar shape and size were also synthesized for the whole composition range (y from 0 to 1). X-ray diffraction structural data are found to follow Vegard's law up to y = 0.4, which is attributed to the loss of stability in air of Ce-rich nanocrystals beyond this threshold. This picture is supported by X-ray absorption spectra taken at the S K-edge and Ce L-edge that show the partial oxidation of sulfide species and of Ce to Ce in the presence of air or water. A complementary near-ambient-pressure X-ray photoelectron spectroscopy study shows that at least two types of oxidized sulfur species form on the nanoparticle surface. Even in GdOS nanoparticles that are generally considered to be air-stable, we found that sulfide ions are partially oxidized to sulfate in air. These results unveil the physicochemical mechanisms responsible for the surface reactivity of lanthanide oxysulfides nanoparticles in air.

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Section: Introductionmentioning

confidence: 99%

Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

et al. 2017

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“…Most of the known examples incorporate an amazing range of compositions and involve the light lanthanides (La, Ce, Pr, Nd, Sm) and Group 4, 5, or 6 d-block metals. These include LnCrOQ 2 (Q = S and Ln = La, Ce, Pr, Nd, Sm − ; Q = Se and Ln = La, Ce, Nd), , Ln 5 V 3 O 7 S 6 (Ln = La, Ce, Pr, Nd), , Ln 2 Ta 3 O 8 Se 2 (Ln = La, Ce, Pr, Nd), La 6 Ti 2 O 5 S 8 , La 4 Ti 3 O 8 S 4 , Ln 20 Ti 11 O 6 S 44 (Ln = La, Ce), , La 14 Ti 8 O 6 S 33 , La 8 Ti 10 O 4 S 24 , La 8+ x Ti 8+ y O 4 S 24 ( x + y ⩽ 2), Sm 3 NbO 4 Se 3 , and Ln 2 Ti 2 O 5 S 2 (Ln = Pr, Nd, Sm) …”

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Three New Rare-Earth Titanium Oxyselenides: Ln_3.67Ti₂O₃Se₆ (Ln = Ce, Nd, Sm)

Tougait

Ibers

2000

Chem. Mater.

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Three new compounds, Ln 3.67 Ti 2 O 3 Se 6 (Ln ) Ce, Nd, Sm), have been prepared from the reaction in stoichiometric ratios of Ln, TiO 2 , Ti, and Se in sealed fused-silica tubes at 950 °C. A KBr flux was used to promote the crystal growth. Single-crystal X-ray diffraction measurements show that these compounds are isostructural. They crystallize with four formula units in the monoclinic space group C2/m in a new structure type that contains four crystallographically independent Ln atoms with three different coordination geometries and three nonequivalent Ti atoms in octahedral geometry. The structure comprises infinite condensed slabs of composition ∞ 2 [Ln 4 Ti 2 O 4 Se 4 Se 5/2 ] alternating along the a axis with extended slabs of composition ∞ 2 [Ln 3.33 Ti 2 O 2 Se 3 Se 5/2 ]. To achieve charge balance, Ti 3+ and Ti 4+ cations must be present in equal numbers; these are randomly distributed over the Ti sites. Crystal data at -120 °C follow: Ce 3.67 Ti 2 O 3 Se 6 , a ) 28.315( 6) Å, b ) 3.8719(8) Å, c ) 11.271(2) Å, β ) 90.45(3)°, R(F) ) 0.0286; Nd 3.67 Ti 2 O 3 Se 6 , a ) 28.121(6) Å, b ) 3.8232(8) Å, c ) 11.179(2) Å, β ) 90.15(3)°, R(F) ) 0.0322; Sm 3.67 Ti 2 O 3 Se 6 , a ) 27.961(6) Å, b ) 3.7827(8) Å, c ) 11.128(2) Å, β ) 90.26(3)°, R(F) ) 0.0294. The magnetic susceptibilities of the Ln 3.67 Ti 2 O 3 Se 6 (Ln ) Ce, Nd, Sm) compounds are dominated by the trivalent rare-earth cations and display paramagnetic behavior down to 5 K.

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“…As a result, the crystal structure of CeCrS2O consists of layers ( Figure 6, right) built from two different octahedra that are edge-and vertex-sharing and are separated by Ce 3+ ions. The structural difference between the two chemically similar systems can be described as a coordination disproportionation: LaCrS2O contains only [CrS3/3S2/2O1/1] 3 entities [48] and CeCrS2O contains equal amount of [CrS4/2S2/3] 7/3 and [CrS4/3O2/1] 11/3 octahedra in an ordered fashion [54] (Figure 6). As it is clearly not a charge ordering phenomenon, this might be related to coordination order entropy that is rarely taken into consideration.…”

Section: Coordination Disproportionationmentioning

confidence: 99%

Anion Ordering in Bichalcogenides

Valldor

2016

Inorganics

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This review contains recent developments and new insights in the research on inorganic, crystalline compounds with two different chalcogenide ions (bichalcogenides). Anion ordering is used as a parameter to form structural dimensionalities as well as local-and global-electric polarities. The reason for the electric polarity is that, in the heterogeneous bichalcogenide lattice, the individual bond-lengths between cations and anions are different from those in a homogeneous anion lattice. It is also shown that heteroleptic tetrahedral and octahedral coordinations offer a multitude of new crystal fields and coordinations for involved cations. This coordination diversity in bichalcogenides seems to be one way to surpass electro-chemical redox potentials Further, the potential of the anion lattice is discussed as a parameter for future materials design.

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Etude structurale des oxysulfures de chrome(III) et de terres rares. I. Structure de l'oxysulfure LaCrOS2

Cited by 29 publications

References 4 publications

Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis and Characterization of Three New Rare-Earth Titanium Oxyselenides: Ln_3.67Ti₂O₃Se₆ (Ln = Ce, Nd, Sm)

Anion Ordering in Bichalcogenides

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Etude structurale des oxysulfures de chrome(III) et de terres rares. I. Structure de l'oxysulfure LaCrOS2

Cited by 29 publications

References 4 publications

Synthesis of Ce2O2S and Gd2(1–y)Ce2yO2S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis of Ce2O2S and Gd2(1–y)Ce2yO2S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis and Characterization of Three New Rare-Earth Titanium Oxyselenides: Ln3.67Ti2O3Se6 (Ln = Ce, Nd, Sm)

Anion Ordering in Bichalcogenides

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Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis of Ce₂O₂S and Gd_2(1–y)Ce_2yO₂S Nanoparticles and Reactivity from in Situ X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy

Synthesis and Characterization of Three New Rare-Earth Titanium Oxyselenides: Ln_3.67Ti₂O₃Se₆ (Ln = Ce, Nd, Sm)