Correlations between magnetism, microstructure, crystallography, and phase stability in GdNi1−xCox alloys

Date
2015-06-15
Authors
Mudryk, Yaroslav
Paudyal, Durga
Prost, Timothy
Chumbley, L. Scott
Chumbley, L. Scott
Pecharsky, Vitalij
Gschneidner, K. A.
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Abstract

Relationships between the electronic structure, magnetostriction, and phase stability of the GdNi1−xCox system have been investigated. Increasing the concentration of Co in GdNi1−xCox (0 ⩽ x < 0.5) series leads to anisotropic changes of lattice parameters within the CrB-type crystal structure which are qualitatively similar to, but are stronger than, those observed upon the application of magnetic field to the Co-free, binary GdNi near its Curie temperature, TC. The magnetic field and temperature dependent X-ray powder diffraction study of GdNi0.85Co0.15 shows that the strong linear thermal expansion effects near TC are, however, absent. Density functional theory calculations show that hypothetical “GdCo” has positive formation energy, and density of states at the Fermi level indicates intrinsic instability of “GdCo” as opposed to GdNi. The enhanced exchange interaction energy of “GdCo” compared to GdNi supports the experimentally observed increasing Curie temperature of GdNi1−xCox with increasing x(Co).

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<p>This is a manuscript of an article published as Mudryk, Y., D. Paudyal, T. Prost, L. S. Chumbley, V. K. Pecharsky, and K. A. Gschneidner Jr. "Correlations between magnetism, microstructure, crystallography, and phase stability in GdNi1− xCox alloys." <em>Acta Materialia</em> 92 (2015): 18-24. DOI: <a href="https://doi.org/10.1016/j.actamat.2015.03.049" target="_blank">10.1016/j.actamat.2015.03.049</a>. Posted with permission.</p>
Keywords
Rare earth alloys, Magnetoelasticity, Magnetic properties, First principles
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