2022-Sustainable Industrial Processing Summit
SIPS2022 Volume 1 Alario-Franco Intl. Symp Solid State Chemistry

Editors:F. Kongoli, F. Marquis, S. Kalogirou, B. Raveau, A. Tressaud, H. Kageyama, A. Varez, R. Martins.
Publisher:Flogen Star OUTREACH
Publication Year:2022
Pages:154 pages
ISBN:978-1-989820-34-6 (CD)
ISSN:2291-1227 (Metals and Materials Processing in a Clean Environment Series)
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    Fixing the Misuse of Cohesive-Energies in Modeling Transition Metals & Nanoalloys

    Micha Polak1; Leonid Rubinovich1;
    1BEN-GURION UNIVERSITY OF THE NEGEV, Beer-Sheva, Israel;
    Type of Paper: Regular
    Id Paper: 245
    Topic: 52

    Abstract:

    In spite of free-atom electronic-relaxation contributions to transition-metal cohesive-energies (Ecoh), numerous studies have misused the latter instead of using genuine interatomic bond-energies (Eb) in modeling bulk and surface properties [1-2], including atomistic-potential parametrization for nanoalloys. The required Ecoh modification consists of s to d electronic promotion energy plus the magnetic spin-polarization energy (in accordance with Hund’s first rule). The latter was computed [3] for the 3d, 4d and 5d series using the local spin-density approximation (LSDA), whereas the former was obtained from spectroscopic data.
    This work first reveals that eliminating these free-atom contributions from experimental cohesive-energies leads to highly accurate linear correlations of the resultant bond-energies with melting temperatures and enthalpies, as well as with inverse thermal-expansion coefficients, specifically for the fcc transition-metals. In addition, predictions of surface segregation phenomena in Cu-Pd and Au-Pd bulk alloys on the basis of the correct energetics are in much better agreement with reported LEISS experimental results. A distinctive demonstration of the problem and its solution involves the significant impact of the cohesive-energy modification on segregation (separation) phase transitions in Cu-Ni truncated-octahedron nanoalloys. In particular, without the correction destabilization of Janus configuration in favor of core-shell is erroneously obtained. Preliminary computations for Cu-Ni-Pd ternary nanoalloys reveal significant effects of Pd and of the fixed energetics on chemical-order and transition temperatures.
    Generally, the introduced correction procedure should be applicable also to other bond-energy related properties of any transition metals, alloys as well as nanoalloys.

    Keywords:

    Important classes of materials; Transition-metals; Thermal properties; Bond-energy; Nanoparticle Chemical Order

    References:

    REFERENCES:
    [1] R. Vardi, L. Rubinovich, M. Polak, Surf. Sci. 602 (2008) 1040-1044.
    [2] M. Polak and L. Rubinovich, J. Phys.: Condens. Matter 31 (2019) 215402.
    [3] M.S.S. Brooks and B. Johansson, J. Phys. F: Met. Phys. 13 (1983) L197-L202.

    Cite this article as:

    Polak M and Rubinovich L. (2022). Fixing the Misuse of Cohesive-Energies in Modeling Transition Metals & Nanoalloys. In F. Kongoli, F. Marquis, S. Kalogirou, B. Raveau, A. Tressaud, H. Kageyama, A. Varez, R. Martins. (Eds.), Sustainable Industrial Processing Summit SIPS2022 Volume 1 Alario-Franco Intl. Symp Solid State Chemistry (pp. 133-134). Montreal, Canada: FLOGEN Star Outreach