Abstract
The electron diffraction investigation of two-component phases in the systems MF2–RF3 (CaF2–ErF3, SrF2–LaF3) and components of the systems CaF2, SrF2, BaF2, and LaF3 is performed in a transmission electron microscope. The effect of electron irradiation, causing decomposition of metal fluorides with elimination of fluorine and transformation of the formed metal into oxide, is demonstrated. The crystal structure of the ordered tysonite (structural type LaF3) phase of the composition Er0.7Ca0.3F2.7, characterized by complete cation ordering and a low fluorine-ion conductivity, is identified. A nanostructured state of the tysonite phase La1 – ySryF3 – y (y = 0.10, 0.15), comprised of a tysonite matrix and lamellar interlayers of a phase enriched with strontium, is established. The formation of lamellar interlayers is responsible for the decrease in the ionic conductivity of the tysonite phases La1 – ySryF3 – y with an increase in the content of strontium after the conductivity peak at y = 0.05.
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Funding
This work was performed within State task no. 075-00355-21-00 (Institute of Microelectronics Technology and High Purity Materials, Russian Academy of Sciences) and a State task for the Federal Scientific Research Centre “Crystallography and Photonics” of the Russian Academy of Sciences.
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Translated by D. Churochkin
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Nikolaychik, V.I., Avilov, A.S. & Sobolev, B.P. The Electron Diffraction Investigation of the Phase Structures in the Systems MF2–RF3 (CaF2–ErF3, SrF2–LaF3). Crystallogr. Rep. 66, 608–611 (2021). https://doi.org/10.1134/S1063774521040167
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DOI: https://doi.org/10.1134/S1063774521040167