Berlin 2018 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 15: Battery Materials
MM 15.3: Vortrag
Montag, 12. März 2018, 18:00–18:15, H 0106
Antimatter meets defects: positron annihilation spectroscopy combined with two-component density functional theory to investigate Li4Ti5O12 (LTO) — •C. Grosu1,2, M. Schuderer2, P. Jakes1, C. Hugenschmidt3, R.A. Eichel1, K. Reuter2, and C. Scheurer2 — 1IEK-9, FZJ Jülich — 2Chair for Theor. Chemistry, TU Munich — 3Heinz Maier-Leibniz Zentrum, TU Munich
LTO is a well-established anode material with several advantageous electrochemical properties. These depend sensitively on the crystallographic structure and are influenced by the presence of defects within the structure. In fact, defects are purposefully introduced into the structure by tailored synthesis and sintering protocols to increase LTO’s electronic conductivity. Little is known to-date about the true nature of these defects and their exact mechanistic influence. Positron annihilation (PA) is one of the few techniques available to study defect distribution and chemical nature in solid materials experimentally. We perform positron lifetime calculations for bulk spinel LTO using two different self-consistent schemes within the framework of two-component density functional theory. An increased annihilation lifetime on the order of 200 ps is obtained for a positron in a neutral or formally negative defect. In contrast, for positrons in positively charged vacancies we compute lifetimes very close to the 180 ps as for defect-free LTO, likely rendering this type of defect invisible for PA. We discuss these findings in combination with lifetimes and positron coincidence Doppler broadening spectroscopy recently measured at the Garching positron source.