Record Details

Title:
Synthesis, crystal structure, and magnetism of $A_{2}Co_{12}As_{7}$ (A=Ca, Y, Ce–Yb)
Topic:
Abstract:
Ternary intermetallics, $A_{2}Co_{12}As_{7}$ (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the $Zr_{2}Fe_{12}P_{7}$ structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of $A_{2}Co_{12}As_{7}$ is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for $Ce_{2}Co_{12}As_{7}$ and $Nd_{2}Co_{12}As_{7}$, respectively.
Imprint:
Orlando, Fla., Academic Press, 2016
Journal Information:
Journal of Solid State Chemistry, p. S0022459615301407 (2016)
ISSN:
0022-4596
1095-726X
External related publications:
10.1016/j.jssc.2015.08.038
WOS:000372672900020 (WOS)
Language(s):
English


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 Record created 2016-10-11, last modified 2017-08-31

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