Arrhenius Behavior of the Bulk Na-Ion Conductivity in Na3Sc2(PO4)3 Single Crystals Observed by Microcontact Impedance Spectroscopy

Daniel Rettenwander*, Günther J. Redhammer, Marie Guin, Artur Benisek, Hannes Krüger, Olivier Guillon, Martin Wilkening, Frank Tietz, Jürgen Fleig

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
Pages (from-to)1776-1781
Number of pages6
JournalChemistry of Materials
Volume30
Issue number5
DOIs
Publication statusPublished - 13 Mar 2018

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cooperations

  • NAWI Graz

Fingerprint Dive into the research topics of 'Arrhenius Behavior of the Bulk Na-Ion Conductivity in Na<sub>3</sub>Sc<sub>2</sub>(PO<sub>4</sub>)<sub>3</sub> Single Crystals Observed by Microcontact Impedance Spectroscopy'. Together they form a unique fingerprint.

Cite this