Actinide superconductivity

Because they exhibit interplay of magnetic and superconducting properties, the formation and crystal chemistry of MRgMy4B4 compounds have been examined. Ternary rare-earth and actinide (Th, U, Pu)-transition metal borides of the approxi-... 

Thus, the occurence of superconductivity and magnetism along the actinide series is now fairly well understood. 

For non-magnetic actinide metals, specific heat data have been employed very usefully to corroborate 5 f localization starting with Am, as indicated by the sudden drop in y values (ypu 12 mJ/mol K, yAm 2 mJ/mol K ). It allowed also the discovery of superconductivity in Pa and Am metals ... 

The lanthanides are rather rare on Earth and so were not used much in earlier technologies. However, today they are studied intensely, because superconducting materials often contain lanthanides (Fig. 1.52). The actinides are all radioactive elements. None of the elements following plutonium occurs naturally on Earth in any significant amount. Because they can be made only in nuclear reactors or particle accelerators, they are available only in small quantities. For example, only a few atoms of element 111 have ever been made. 

P. Thalmeier and G. Zwicknagl, Unconventional superconductivity and magnetism in lanthanide and actinide intermetallic compounds 135... 

The consequent increase in the nuclear charge and reduction of the shielding of the 6d- and 7s-electrons lead to a contraction of the atomic radius, similar to that previously discussed for the ionic radius. In Am and Cm, the 5f-electrons are localized in the core, which causes an expansion of the atomic radius. The differences in localization of f-electrons between light and heavy actinides are also illustrated by their different superconductive and magnetic behavior. The Th, Pa, and Am metals are superconductors Tc of 1.37, 0.42, and 0.79 K, respectively), whereas the heavier actinide metals are not superconductors but have larger magnetic moments at low temperatures. 

Superconductivity of actinides seems to be well understood (40) on the basis of recent progress in the calculation of their band structures and their vibrational spectra. Thorium and uranium are known to be superconductors. By using ac susceptibility techniques, superconductivity could be detected in both Am (41) and Pa (42). Vapour deposited Am was used as sample material ... 

UNCONVENTIONAL SUPERCONDUCTIVITY AND MAGNETISM IN LANTHANIDE AND ACTINIDE INTERMETALLIC COMPOUNDS... 

Superconductivity, magnetism and hidden order in lanthanide and actinide compounds pose an ongoing challenge. These compoimds serve as model systems to stutiy strong correlations in a broader context. 

This volume of the Handbook on the Physics and Chemistry of Rare Earths adds five new chapters to the science of rare earths, compiled by researchers renowned in their respective fields. Volume 34 opens with an overview of ternary intermetallic systems containing rare earths, transition metals and indium (Chapter 218) followed by an assessment of up-to-date understanding of the interplay between order, magnetism and superconductivity of intermetallic compounds formed by rare earth and actinide metals (Chapter 219). Switching from metals to complex compounds of rare earths, Chapter 220 is dedicated to molecular stmctural studies using circularly polarized luminescence spectroscopy of lanthanide systems, while Chapter 221 examines rare-earth metal-organic frameworks, also known as coordination polymers, which are expected to have many practical applications in the future. A review discussing remarkable catalytic activity of rare earths in site-selective hydrolysis of deoxyribonucleic acid (DNA) and ribonucleic acid, or RNA (Chapter 222) completes this book. 

Coqblin, B., E. Galleani d AgUano and R. Jul-lien, 1972, Superconductivity of Rare Earths and Actinides, in Douglass, D.H., ed.. Superconductivity in d- and f-Band Metals, AIP Conf. Proc. No. 4 (American Inst, of Physics-New York, 1972) p. 154. 

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