Neutron Diffraction Study of YbC2 at 300–2°K

Atoji, Masao; Flowers, R.H.

doi:10.1063/1.1672965

Cited by 21 publications

(5 citation statements)

References 8 publications

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“…This fact, coupled with the similarity in phase shift between C and O ͑in acac͒ as a near-neighbor scattering atom, 8 indicates that the heated Yb 2.75 C 60 sample is a mixture of three components: ͑1͒ ϳ10-20 % of crystalline, asgrown Yb 2.75 C 60 , ͑2͒ ϳ60-70 % of disordered ͑amorphous͒ Yb 2.75 C 60 , and ͑3͒ ϳ20% of a form of Yb carbide with Yb in the trivalent state. Indeed, analysis of the difference data using Yb͑Cp͒ 3 as a model gives a Yb-C distance of 2.41 Ϯ0.04 Å, a value identical to the Yb-C distance in YbC 2 , 13 where Yb is mainly in the Yb͑III͒ state.…”

Section: Resultsmentioning

confidence: 89%

Distorted and inequivalently chargedC60anions inYb2.75

Citrin¹,

Ozdas²,

Schuppler³

et al. 1997

Phys. Rev. B

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Near-edge x-ray absorption measurements from single-phase Yb 2.75 C 60 establish that all of the Yb cations are divalent, meaning that the average negative formal charge of the C 60 anions is 5.5. Extended x-ray absorption fine structure ͑EXAFS͒ and Raman measurements also reveal that the C 60 anions are distorted in shape, despite their well-ordered local structure around the Yb cations. These findings are combined with a model to show that the charge transferred from Yb to C 60 is both anisotropically distributed on the anions and inequivalently partitioned among them within the unit cell. In the model, the inhomogeneously distributed transferred charge ͑which arises from the comparatively greater electron affinity of the C 60 pentagonal faces͒ interacts strongly with the divalent cations and leads to significant anion distortions. The redistribution of transferred charge is traceable to the three crystallographically different types of C 60 anions that are surrounded by 8, 10, or 12 Yb cations, a situation similar to the inequivalently coordinated and charged O anions in the high-T c compound YBa 2 Cu 3 O 7 . Additional EXAFS and Raman data from Yb 2.75 C 60 heated above 670°C show the removal of local order around the Yb cations and the production of an amorphous carbidic phase containing Yb͑III͒. Our collective results, along with comparisons to analogous fulleride and organometallic compounds, provide insight into the distinctive structural features of Yb 2.75 C 60 and its unique distribution of anion charge. They also have general implications for a variety of other metal-doped fullerides.

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Section: Resultsmentioning

confidence: 89%

Distorted and inequivalently chargedC60anions inYb2.75

Citrin¹,

Ozdas²,

Schuppler³

et al. 1997

Phys. Rev. B

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“…The calculated C-C dimer distances in YbC 2 with various Hubbard U remain almost unchanged and reach the experimental value of 1.293 Å. 17 Moreover, it is noteworthy that the C-C dimer distance in other Pu 2 C 3 -and CaC 2 -type rare-earth carbides is approximately 1.3 Å, such as 1.298 Å in Y 2 C 3 , 34 1.2942 Å in La 2 C 3 , 35 1.2888 Å in YC 2 , 36 and 1.303 Å in LaC 2 . 37 This result indicates that the C-C dimer distance shows a weak dependence on the choice of metal atoms in these crystals.…”

Section: Equilibrium Structural Propertiesmentioning

confidence: 55%

“…16 Similar to lightweight rare-earth carbides, YbC 2 assumes a tetragonal CaC 2 -type structure. 17 Surprisingly, the lattice parameters of YbC 2 are different from other rareearth dicarbides. The lattice parameters of rare-earth carbides decrease regularly with increasing of atomic number of metal atoms, by contrast, the lattice parameters of YbC 2 lie between those of HoC 2 and ErC 2 .…”

Section: Introductionmentioning

confidence: 99%

Effect of carbon content and electronic strong correlation on the mechanical and thermodynamic properties of ytterbium carbides

et al. 2015

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“…This is comparable to the Yb−C distance of 2.404−2.647 Å found in YbC 2 (which has a C 2 unit in an octahedral site), as well as the Yb−C distance of 2.501 Å found in cubic Yb 2 C (which has a single C atom in an octahedral site). 23,24 Counterintuitively, the addition of C reduces the Yb−Yb distances from 3.911 Å in hcp Yb to 3.61(2) Å in Yb 2 CH x . This is very similar to the Yb−Yb distance found in YbC 2 (3.63 Å).…”

Section: ■ Experimental Proceduresmentioning

confidence: 99%

Metal Flux Growth of Lanthanide Carbide Hydrides Using Anthracene

Larson,

Wix,

Chen

et al. 2023

Inorg. Chem.

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Reactions of anthracene in Ln/T eutectic mixtures (Ln = La, Yb; T = Ni, Cu) have produced crystals of new complex lanthanide carbide hydride phases. The thermal decomposition of anthracene provides a source of both carbon and hydrogen. LaCH x forms in space group Pnma with unit cell parameters a = 7.2736(4) Å, b = 3.7218(2) Å, and c = 13.0727(7) Å. Yb2CH x forms in space group P-3m1 with unit cell parameters a = 3.5659(4) Å and c = 5.8000(8) Å, with a structure related to that of Ho2CF2. The presence of hydride in interstitial sites is supported by the formation of different compounds in the absence of hydrogen and by comparison to known hydride structures. 1H nuclear magnetic resonance (NMR) spectra collected on LaCH x show two unique hydride resonances, in agreement with the two available interstitial sites. Density of states calculations show that filling the tetrahedral sites in LaCH x with hydrogen increases metallic behavior, while adding hydrogen into the tetrahedral sites in Yb2CH x induces the formation of a band gap.

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Neutron Diffraction Study of YbC2 at 300–2°K

Cited by 21 publications

References 8 publications

Distorted and inequivalently chargedC60anions inYb2.75

Distorted and inequivalently chargedC60anions inYb2.75

Effect of carbon content and electronic strong correlation on the mechanical and thermodynamic properties of ytterbium carbides

Metal Flux Growth of Lanthanide Carbide Hydrides Using Anthracene

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