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Stacking fault energetics of alpha- and gamma-cerium investigated with ab initio calculations
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
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2016 (English)In: Physical Review B, ISSN 2469-9950, Vol. 93, no 9, 094103Article in journal (Refereed) PublishedText
Abstract [en]

At ambient pressure the element cerium shows a metastable (t(1/2) similar to 40 years) double-hexagonal close-packed beta phase that is positioned between two cubic phases, gamma and alpha. With modest pressure the beta phase can be suppressed, and a volume contraction (17%) occurs between the gamma and the alpha phases as the temperature is varied. This phenomenon has been linked to subtle alterations in the 4f band. In order to rationalize the presence of the metastable beta phase, and its position in the phase diagram, we have computed the stacking fault formation energies of the cubic phases of cerium using an axial interaction model. This model links the total energy differences between hexagonal closed-packed stacking sequences and stacking fault energetics. Total energies are calculated by density functional theory and by dynamical mean-field theory merged with density functional theory. It is found that there is a large difference in the stacking fault energies between the alpha and the gamma phase. The beta-phase energy is nearly degenerate with the gamma phase, consistent with previous third-law calorimetry results, and dislocation dynamics explain the pressure and temperature hysteretic effects.

Place, publisher, year, edition, pages
American Physical Society , 2016. Vol. 93, no 9, 094103
Keyword [en]
Generalized Gradient Approximation, Mean-Field Theory, Crystal-Structure, Electron-Gas, Metals, Transition, Energy, Phase, Ce, Transformation
National Category
Physical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-185363DOI: 10.1103/PhysRevB.93.094103ISI: 000372400100001ScopusID: 2-s2.0-84960955653OAI: oai:DiVA.org:kth-185363DiVA: diva2:921259
Funder
Swedish Research CouncilSwedish Foundation for Strategic Research Knut and Alice Wallenberg Foundation
Note

QC 20160420

Available from: 2016-04-20 Created: 2016-04-18 Last updated: 2016-04-20Bibliographically approved

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Östlin, AndreasVitos, Levente
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