Clustering and defect structure of Ca<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>crystals doped with Yb<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">F</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Booth, R. J.; Mustafa, M. R.; McGarvey, Bruce R.

doi:10.1103/physrevb.17.4150

Cited by 30 publications

(3 citation statements)

References 23 publications

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“…IJ,MJ) = 14,+4); 14,?3); 14,+2); 14,k I); (4,0) There is no agreement in the literature as to which of these five states is the ground state. The 14,?4), 14,+3), and 14,O) states have all been suggested as the ground state in uranocene.…”

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confidence: 89%

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Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

McGarvey¹

1984

Can. J. Chem.

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The paramagnetic shift resulting from f orbital covalency for lanthanide fluorides has been successfully treated theoretically in earlier studies. This theoretical method has been modified to calculate the paramagnetic shift for 13C and 1H in uranocenes. It is shown that the very large anisotropy in the magnetic moment makes the treatments in the literature incorrect. The so-called "contact shift" in 13C is in reality three terms: (1) a dipolar contribution from spin in the carbon pz orbital, (2) a dipolar contribution from spin in the nearest neighbor carbon pz orbitals, and (3) an induced Fermi contact term. Contribution (1) is the largest. For 1H there are contributions from the direct dipolar interaction of spin in the nearest carbon pz orbital and the induced Fermi contact term. Both terms are nearly equal in magnitude. The theory, however, predicts a much smaller magnitude and the incorrect sign for the shift as measured experimentally. The measured shift must, therefore, result from a polarization mechanism in which exchange interactions between the f electrons and electrons in filled orbitals cause spin delocalization into the ligand σ orbitals. It is argued that this polarization mechanism operates primarily through the overlap of the outer 6s and 6p orbitals of the uranium atom with the σ orbitals of the ligand making the observed nmr shifts insensitive to the nature of the bonding between the ligand and the uranium atom. We conclude, therefore, that the question of how much f orbitals are involved in covalent bonds between uranium and the ligands in uranocene cannot be answered by measuring the paramagnetic shift in 13C or 1H.

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confidence: 89%

“…[2] with the F functions of eq. [ 4 ] . It is these functions that will be used to calculate the contribution of covalent bonding between f orbitals and the IT orbitfls of COT to the paramagnetic shift.…”

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confidence: 99%

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

McGarvey¹

1984

Can. J. Chem.

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“…Various papers, involving Ti relaxation time measurements on the 19F nuclei, have been performed recently particularly on compounds with the fluorite structure : CaF2 [1], PbF2 [2], BaF2 [3] or on compounds with a derived structure such as PbSnF4 [4].…”

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19F nuclear relaxation in an ionic conductor : TlSn2F 5

Granier

Bernier²,

Dohri

et al. 1981

J. Phyique Lett.

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2014 Nous avons étudié la Résonance Magnétique Nucléaire du 19F sur le composé TlSn2F5, à différentes températures et fréquences. Alors que le T1 mesuré présente pour T 358 K un comportement classique, tel qu'il est généralement observé sur les conducteurs ioniques, un saut soudain est observé pour T ~ 358 K où intervient un changement de groupe d'espace du système. Pour des températures plus élevées, le comportement observé est caractéristique d'une très haute mobilité des fluors. Ces résultats sont comparés avec ceux obtenus par mesures de conductivité, qui montrent que ce composé est un des meilleurs conducteurs ioniques par ions F-. Abstract. 2014 We have studied the 19F NMR of the TlSn2F5 compound at various temperatures and frequencies. While the measured T1 shows a classical behaviour for T 358 K, as is generally observed in ionic conductors, it undergoes a sudden increase at T ~ 358 K corresponding to a change in the crystallographic space group. For higher temperatures, the observed behaviour is consistent with a very high mobility of the fluorine atoms. These results are compared with those obtained by conductivity measurements which make this compound one of the best ionic conductors via the F-ions.

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Far‐infrared absorption of BaF₂:Dy³⁺ versus concentration

Villermain-Lecolier¹,

Morlot²,

Roger³

et al. 1979

Physica Status Solidi (b)

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I n the BaF,: Dy3+ FIR spectrum the vibration frequencies of the interstitial compensation ion Fi is observed and the presence of some cluster types is revealed for concentrations equal t o or higher than 0.4 molyo. A 125 cm-l line is observed for the first time with Df+. I n BaF,:Nd3+ and BaF2:Ho3+ studies it is previously ascribed to the Fi vibration longitudinal mode in a trigonal site. Calculation gives 135 cm-l for the transversal mode vibration; experimentally it is observed for the first time. The 42 cm-l line previously ascribed to an electronic transition of Dy3+ in trigonal site disappears when the concentration increases.Le spectre infrarouge lointain de BaF2:Dy3+ permet d'observer les frbquences de vibration de ion de compensation interstitiel Fi. Cette btude rbvele la presence de plusieurs types de clusters pour des concentrations bgales ou supbrieures B 0,4 molyo. On observe pour la premiere fois avec le Dy3+ la raie A 125 cm-l que nous avons prbcbdemment attribube dans le cas de Nd3+ e t Ho3+ au mode longitudinal de la vibration de Fi dans un site trigonal. Un modhle laissait alors prbvoir la frbquence du mode transversal B 135 cm-l ; nous I'observons ici expbrimentalement pour la premiere fois. La raie A 42 cm-l prbcbdemment attribube B une transition blectronique de Dy3+ en site trigonal disparait quand la concentration augmente.

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Clustering and defect structure of CaF2crystals doped with YbF3

Cited by 30 publications

References 23 publications

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

19F nuclear relaxation in an ionic conductor : TlSn2F 5

Far‐infrared absorption of BaF₂:Dy³⁺ versus concentration

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Clustering and defect structure of CaF2crystals doped with YbF3

Cited by 30 publications

References 23 publications

Theory of 13C and 1H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Theory of 13C and 1H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

19F nuclear relaxation in an ionic conductor : TlSn2F 5

Far‐infrared absorption of BaF2:Dy3+ versus concentration

Contact Info

Product

Resources

About

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Theory of ¹³C and ¹H paramagnetic shifts in uranocene. Does it indicate f orbital covalency?

Far‐infrared absorption of BaF₂:Dy³⁺ versus concentration