Dresden 2017 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 14: Various Topics II
DF 14.4: Talk
Wednesday, March 22, 2017, 16:00–16:20, GER 37
The work function for Li+-Ion Emission from Spodumene - a complete characterization of thermionic emission — •Martin Schäfer, Stephan Schuld, Mira Diekmann, and Karl-Michael Weitzel — Philipps-Universität Marburg
Experiments with ion beams have manifold applications, e.g. in surface structuring, in focused ion beam microscopy and micromachining, in micro-propulsion for space vehicles and for depth profiling in secondary ion mass spectrometry. Most of these applications rely on a strong and stable ion source. A classical means for generating strong ion beams is thermionic emission. In the current work [1], thermionic emission of Li+ from synthetic spodumene (LiAlSi2O6) has been investigated as a function of temperature and electric field. The data presented cover the entire range from space charge limited Child-Langmuir regime, to the Richardson-Dushman regime and finally the field assisted Schottky regime. From a self-consistent analysis of all data measured the work function for Li+ emission from synthetic spodumene is determined as (2.47 ± 0.015),eV. The thermionic currents exhibit a voltage offset of (1.7 ± 0.1) eV, which can be traced to a combination of the ionic work function of the emitter, the recombination energy Li+ + electron, the electronic work function of the detector and the contact potential between detector and filament. Fundamental differences between ion emission and electron emission and their relevance for properties of Li-electrolytes in battery materials are discussed. [1] S. Schuld, M. Diekmann, M. Schäfer, and K. M. Weitzel, J. Appl. Phys. 120, (2016) 185102