Magnetic susceptibility of californium ovides

Moore, J. R.; Nave, S.E.; Haire, R.G.; Huray, Paul G.

doi:10.1016/0022-5088(86)90529-1

Cited by 23 publications

(12 citation statements)

References 6 publications

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“…Examination of previously reported magnetic moments for Cf(III) compounds shows that values of ∼9.3 μ B are, in fact, the most commonly reported. However, most investigators have attributed these deviations from the calculated free-ion moment to experimental artefacts that result from the very small sample sizes employed in the measurements (∼1 μg of 249 Cf), and hence large errors in the masses of 249 Cf (refs 10 , 11 ). It should be pointed out, however, that the quantity of 249 Cf used in these prior studies was not determined by weighing, but rather by far more accurate radiation counting methods, and later studies conducted with tens of micrograms of 249 Cf yielded similar values as those with much smaller quantities 10 11 .…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, one of the hallmarks of the nuclear era was the maturation of ultramicrochemical techniques that had been perfected by the time californium became available in appreciable quantities. This enabled characterization of binary compounds such as halides and oxides 9 , and even in these systems peculiarities were observed that include abnormally broad f - f transitions in electronic absorption spectra, and consistently reduced magnetic moments with respect to that calculated for the free ion 10 11 . A testament to the unexpected features of californium compounds is that CfCp 3 (Cp=cyclopentadienyl) has a deep red colouration instead of the expected bright green 12 .…”

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Emergence of californium as the second transitional element in the actinide series

et al. 2015

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A break in periodicity occurs in the actinide series between plutonium and americium as the result of the localization of 5f electrons. The subsequent chemistry of later actinides is thought to closely parallel lanthanides in that bonding is expected to be ionic and complexation should not substantially alter the electronic structure of the metal ions. Here we demonstrate that ligation of californium(III) by a pyridine derivative results in significant deviations in the properties of the resultant complex with respect to that predicted for the free ion. We expand on this by characterizing the americium and curium analogues for comparison, and show that these pronounced effects result from a second transition in periodicity in the actinide series that occurs, in part, because of the stabilization of the divalent oxidation state. The metastability of californium(II) is responsible for many of the unusual properties of californium including the green photoluminescence.

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Section: Resultsmentioning

confidence: 99%

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Emergence of californium as the second transitional element in the actinide series

et al. 2015

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“…This is al arger decrease in average bond length between Am III to Cf III than expected; the contraction between neighboring fe lements is usually on the order of 0.01 .T hese shorter bond lengths could be an indicator of increased effects of covalency across the series. [37,38,[62][63][64][65][66][67][68][69] Support for californium representing the location in the actinide series at which a second break occurs (the first being between plutonium and Figure 6. Californium borate luminescence (left) and magnetic susceptibility (right).…”

Section: Solid-state Chemistry Of Californiummentioning

confidence: 99%

Contemporary Chemistry of Berkelium and Californium

White

Dan

Albrecht‐Schönzart

2019

Chemistry A European J

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The merging of small‐scale syntheses and rapid crystallization methods have provided access to crystalline samples of berkelium (Z=97) and californium (Z=98) coordination complexes and compounds that can be interrogated with a suite of spectroscopic tools and structural elucidation approaches that have come online over the last 20 years. The combination of this experimental data with relativistic theoretical methods that capture the effects of spin‐orbit coupling and scalar relativistic effects have allowed us to understand the electronic structure of berkelium and californium compounds at a level of detail that was not previously possible. The harbinger of this new era of post‐curium chemistry was the synthesis and characterization of [Cf{B6O8(OH)5}]. This compound possesses a structure type that is distinct from earlier actinide borates, a reduction in coordination number for californium, contracted Cf−O bond lengths, a substantially reduced magnetic moment with respect to the calculated free‐ion moment and, most importantly, vibronically coupled broadband photoluminescence. Ligand‐field analysis also showed that the splitting of the ground state was larger than typically found in the f‐block elements, and when taken together places its overall electronic structure as a hybrid of d‐ and f‐block components. The discovery of the unusual properties of this compound has led to the development of large families of 4f and 5f coordination complexes, in an effort to uncover the underlying origin of the electronic structure oddities, and whether there really is a sharp onset of these changes at californium. This in turn pushed the development of far more challenging berkelium chemistry (from a radiologic standpoint) because the half‐life of the isotopes decreases from 351 years for 249Cf to 330 days for 249Bk. This short review details some of the chemistry that has been reported over the last 15 years, and its consequences for understanding the periodic table.

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“…Indeed, this stoichiometry is found experimentally to be more stable than the dioxide for the later members of the actinide series, and actually only the sesquioxides have been observed for the actinides beyond californium. 31,35 Note that a calculation we performed on the hypothetical FmO 2 converged to a solution exhibiting nearly complete Fm 3+ character, even though it was initiated with the formal 4+ trial density. For comparison, most lanthanide species adopt the 3+ valence and the Ln 2 O 3 stoichiometry.…”

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Covalency in the actinide dioxides: Systematic study of the electronic properties using screened hybrid density functional theory

2007

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We present the first systematic study of the electronic properties of the AnO 2 series, An= Th-Es, using screened hybrid density functional theory. In contrast to local or semilocal functionals, this approach has been demonstrated to capture the strong electron correlation and localized Mott-insulating behavior observed in early dioxides such as UO 2 . One might expect later members of the series to show even more localized character as the f orbital radial extent decreases with increasing Z. However, we find two interesting features in the calculations: a 5f -O 2p orbital energy degeneracy, which leads to significant orbital mixing and covalency in the intermediate region ͑PuO 2 -CmO 2 ͒, and a strong Hund's rule exchange opposing spin-orbit coupling, which yields an unexpected ground state in CmO 2 .

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Magnetic susceptibility of californium ovides

Cited by 23 publications

References 6 publications

Emergence of californium as the second transitional element in the actinide series

Emergence of californium as the second transitional element in the actinide series

Contemporary Chemistry of Berkelium and Californium

Covalency in the actinide dioxides: Systematic study of the electronic properties using screened hybrid density functional theory

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