Berlin 2024 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 16: Poster Ia
MM 16.2: Poster
Montag, 18. März 2024, 18:30–20:30, Poster E
Ab initio study of transition paths between (meta)stable phases of Nb and Ta-substituted Nb — •Susanne Kunzmann1,2,3, Thomas Hammerschmidt3, Gabi Schierning1,2,4, and Anna Grünebohm3,5 — 1Experimental Physics, Bielefeld University, Germany — 2Research Center Future Energy Materials and Systems (RC FEMS), University of Duisburg-Essen, Germany — 3Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-University Bochum, Germany — 4Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Germany — 5Center for Interface-Dominated High Performance Materials (ZGH), Ruhr-University Bochum, Germany
Despite being well-characterized, Niobium exhibits unexplained anomalies. To address this, we employ density functional theory to revisit the metastablephases of Nb and Nb with Ta impurities. We compare energies and groundstate volumes of selected crystal structures, explore potential transition paths to the bcc ground state and the energy landscape for tetragonal distortions. Additionally, we assess stability through phonon spectra and vibronic free energies. We discuss previously overlooked aspects: a new local energy minimum on the bcc to ω transition path, a flat energy landscape concerning uniaxial strainalong [111], and significant stabilization of the σ phase through Ta substitution.
Keywords: Martensitic phase transition; DFT; DFPT; Transition metals; Lattice dynamics