Regensburg 2016 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 11: Topical session: Integrated computational materials engineering for design of new materials III

MM 11.2: Talk

Monday, March 7, 2016, 16:15–16:30, H39

Ab initio analysis of the phase stability of Ce-based hard-magnetic materials — •Halil Ibrahim Sözen, Tilmann Hickel, and Jörg Neugebauer — The Max-Planck-Institut für Eisenforschung GmbH Max-Planck-Straße 1, 40237 Düsseldorf

In recent years, the development in electro-mobility, i.e. the progressive replacement of oil-based fuels in the transportation by electric motors, increased the demand of hard magnetic materials, which are composed of rare-earths (RE) and transition metals (TM). Recently, there are attempts to develop alternative hard magnets that lift the dependence on the small number of RE elements. For this purpose, ab initio high-throughput calculations have been performed with the focus on a few selected magnetic parameters. However, the decisive question of the phase stability of potential material systems is much less investigated. For example, for Ce-based alloys the magnetically interesting CeFe11Ti phase is thermodynamically competing with a CeFe2 phase. In order to predict phase stability, we perform ab initio calculations for the Helmholtz free energy F(T,V) taking vibrational, electronic, magnetic and configurational entropy contributions into account. We carefully investigate the performance of density functional theory (DFT) and its extensions to achieve these results and compare the results with Nd-based hard-magnetic materials. Based on these results we provide suggestions as to how the favourable magnetic phases can be stabilized.