Fluorine translational anion dynamics in nanocrystalline ceramics: SrF2-YF3 solid solutions

Stefan Breuer, Bernhard Stanje, Veronika Pregartner, Sarah Lunghammer, Ilie Hanzu, Martin Wilkening

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Nanostructured materials have already become an integral part of our daily life. In many applications, ion mobility decisively affects the performance of, e.g., batteries and sensors. Nanocrystalline ceramics often exhibit enhanced transport properties due to their heterogeneous structure showing crystalline (defect-rich) grains and disordered interfacial regions. In particular, anion conductivity in nonstructural binary fluorides easily exceeds that of their coarse-grained counterparts. To further increase ion dynamics, aliovalent substitution is a practical method to influence the number of (i) defect sites and (ii) the charge carrier density. Here, we used high energy-ball milling to incorporate Y3+ ions into the cubic structure of SrF2. As compared to pure nanocrystalline SrF2 the ionic conductivity of Sr1−x Yx F2+x with x = 0.3 increased by 4 orders of magnitude reaching 0.8 × 10−5 S cm−1 at 450 K. We discuss the effect of YF3 incorporation on conductivities isotherms determined by both activation energies and Arrhenius pre-factors. The enhancement seen is explained by size mismatch of the cations involved, which are forced to form a cubic crystal structure with extra F anions if x is kept smaller than 0.5.

Original languageEnglish
Article number122
JournalCrystals
Volume8
Issue number3
DOIs
Publication statusPublished - 5 Mar 2018

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Keywords

  • Aliovalent substitution
  • Ball milling
  • Binary fluorides
  • Cation mixing
  • Ionic conductivity
  • Nanocrystalline ceramics

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Inorganic Chemistry

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