%0 Journal Article
%A Rettenwander, Daniel
%A Redhammer, Günther J.
%A Guin, Marie
%A Benisek, Artur
%A Krüger, Hannes
%A Guillon, Olivier
%A Wilkening, Martin
%A Tietz, Frank
%A Fleig, Jürgen
%T Arrhenius Behavior of the Bulk Na-Ion Conductivity in Na 3 Sc 2 (PO 4 ) 3 Single Crystals Observed by Microcontact Impedance Spectroscopy
%J Chemistry of materials
%V 30
%N 5
%@ 1520-5002
%C Washington, DC
%I American Chemical Society
%M FZJ-2018-04619
%P 1776 - 1781
%D 2018
%X NASICON-based solid electrolytes with exceptionally high Na-ion conductivities are considered to enable future all solid-state Na-ion battery technologies. Despite 40 years of research the interrelation between crystal structure and Na-ion conduction is still controversially discussed and far from being fully understood. In this study, microcontact impedance spectroscopy combined with single crystal X-ray diffraction, and differential scanning calorimetry is applied to tackle the question how bulk Na-ion conductivity σbulk of sub-mm-sized flux grown Na3Sc2(PO4)3 (NSP) single crystals is influenced by supposed phase changes (α, β, and γ phase) discussed in literature. Although we found a smooth structural change at around 140 °C, which we assign to the β → γ phase transition, our conductivity data follow a single Arrhenius law from room temperature (RT) up to 220 °C. Obviously, the structural change, being mainly related to decreasing Na-ion ordering with increasing temperature, does not cause any jumps in Na-ion conductivity or any discontinuities in activation energies Ea. Bulk ion dynamics in NSP have so far rarely been documented; here, under ambient conditions, σbulk turned out to be as high as 3 × 10–4 S cm–1 at RT (Ea, bulk = 0.39 eV) when directly measured with microcontacts for individual small single crystals.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:29606799
%U <Go to ISI:>//WOS:000427661500038
%R 10.1021/acs.chemmater.8b00179
%U https://juser.fz-juelich.de/record/850868