Correlations between magnetism, microstructure, crystallography, and phase stability in GdNi1−xCox alloys
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Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.
For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.
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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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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." Acta Materialia 92 (2015): 18-24. DOI: 10.1016/j.actamat.2015.03.049. Posted with permission.