Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 15: Symposium SYCO of the divisions MM (leading), O, CPP, KFM and DS continued as topical session: Mechanically controlled electrical conductivity of oxides (joint session MM/CPP/O)
CPP 15.6: Vortrag
Montag, 1. April 2019, 18:00–18:15, H46
Influence of cation order and strain on Na diffusion in Na3Zr2Si2PO12: A computational study — •Lisette Haarmann and Karsten Albe — Technische Universität Darmstadt, Otto-Berndt-Str. 3 64287 Darmstadt
Na3Zr2Si2PO12 is a solid electrolyte which is part of the Na super ionic conductor (NASICON) family. Experimentally, only Si/P lattice positions can be determined, but not the distribution of P on these sites[1]. This distribution, however, plays a crucial role for the Na diffusion. A systematic study of different cation orders is conducted using Molecular Dynamics (MD) simulations. Due to the strong correlation of diffusion in this material, the calculation of Dσ is necessary to obtain the ionic conductivity from the Nernst-Einstein equation[2]. By calculating Dσ and the tracer diffusion coefficient Dtr, Haven ratios are determined. Additionally, a jump rate model was developed, which allows investigation of correlation between individual jumps.
Moreover, it has been reported that doping can strongly increase the diffusivity of Na in NASICON materials[3]. In many cases, this is attributed to enlarged bottlenecks of diffusion. These doping elements, however, do not only contract or dilate the lattice structure but alter the chemical environment of the Na ions as well. In an effort to study purely the effect of mechanical deformation, the strain dependence of Dtr and the activation energy EA is investigated.
[1] Boilot, J.P., et. al., Journal of Solid State Chemistry 73, (1988)
[2] Murch, G., Solid State Ionics 7, (1982)
[3] Guin, M., Tietz, F., Journal of Power Sources 273, (2015)