Phonons in mixed superionic fluorites (BaF2)1–𝑥(LaF3)𝑥
In recent years, the fluorite-structured solid solutions with the general formula, (MF2)1–𝑥(RF3)𝑥 (M = Ca, Sr, Ba, Pb and R is a rare-earth element or Y), have been the subject of numerous experimental studies focussed on their superionic properties. The overall cubic crystal symmetry (space group 𝐹𝑚3𝑚) is conserved up to 𝑥 ≤ 𝑥max, where 𝑥max 0.4–0.5 depending on M and R. The zone centre phonons and phonon dispersion along three symmetry directions of the mixed superionic compound (BaF2)1–𝑥(LaF3)𝑥 have been investigated by applying de Launey angular force model for 𝑥 ≤ 𝑥max. The calculated results are compared and explained with available experimental results.
Volume 43, 2020
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