F anion dynamics in cation-mixed nanocrystalline LaF3: SrF2

Ion dynamics in nanocrystalline materials can be quite different compared to that in materials with μ m-sized crystallites. In particular, the substitution of iso- or aliovalent ions opens pathways to systematically control ion transport properties. Here we studied the incorporation of SrF 2 into th...

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Bibliographic Details
Published in:	Journal of materials science 2018-10, Vol.53 (19), p.13669-13681
Main Authors:	Breuer, S., Lunghammer, S., Kiesl, A., Wilkening, M.
Format:	Article
Language:	eng
Subjects:	Ball milling Characterization and Evaluation of Materials Chemistry and Materials Science Classical Mechanics Crystallites Crystallography and Scattering Methods Fluorides Ion currents Ion dynamics Ion transport Lanthanum fluorides Lattice strain Materials Science Mechanochemical Synthesis Nanocrystals Polymer Sciences Solid Mechanics Solid solutions Strontium fluorides Transport properties
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Summary:	Ion dynamics in nanocrystalline materials can be quite different compared to that in materials with μ m-sized crystallites. In particular, the substitution of iso- or aliovalent ions opens pathways to systematically control ion transport properties. Here we studied the incorporation of SrF 2 into the tysonite structure of LaF 3 and its effect on F - transport. High-energy ball milling directly transforms the binary fluorides in a structurally disordered, phase pure nanocrystalline ceramic. Compared to Sr-free LaF 3 , ionic conductivity could be increased by several orders of magnitude. We attribute this enhancement to the generation of lattice strain and the formation of F defect sites. In agreement with this increase, the activation energy E a of long-range ionic transport in the solid solution La 1 - x Sr x F 3 - x significantly decreases from 0.75 eV ( x = 0 ) to 0.49 eV ( x = 0.1 ).
ISSN:	0022-2461 1573-4803