Berlin 2018 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 16: Topical session (Symposium MM): Hydrogen in Materials
MM 16.5: Vortrag
Montag, 12. März 2018, 18:45–19:00, H 0107
Hydrogenation, dehydrogenation of α-tetragonal boron and its transition to δ-orthorhombic boron — Naoki Uemura1, Koun Shirai1, •Jens Kunstmann2, Evgeny A. Ekimov3, and Yuliya B. Lebed4 — 1Osaka University, Japan — 2TU Dresden, Germany — 3HPPI RAS, Troitsk, Russia — 4NR RAS, Troitsk, Russia
α-tetragonal boron (α-T) was recently added to the list of known boron allotropes. Experiments show that upon annealing of hydrogenated α-T boron (BnHm) the H release occurs non-continuous, in two steps, where the second one is associated with a structural change from α-T to δ-orthorhombic boron (δ-O) and full H release [1]. Our free energy calculations based on density functional theory reproduce the experimental trends well, explain the origin of the two-step transition, and show that the difference between α-T and δ-O boron lies in the ordering of interstitial boron atoms occupying 4c sites of the crystal structure. The latter implies an order-disorder transition. [1] Ekimov et al., J. Mater. Res. 31, 2773 (2016).