Crystallophysical Model of Ion Transport in Single-Crystal Ba1 – xLaxF2 + x and Ca1 – xYxF2 + x Superionic Conductors

• Published in: Physics of the solid state 2021-12, Vol.63 (12), p.1821-1832
• Main Authors: Sorokin, N. I., Karimov, D. N.
• Format: Article
• Language: English
• Subjects: Chemical compounds; Conductors; Crystals; Current carriers; Directional solidification; Electrolytic cells; Fluorite; Ion transport; Mechanical properties; Physics; Physics and Astronomy; Single crystals; Solid solutions; Solid State Physics
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S106378342110036X

A crystallophysical model of ion transport is proposed based on the electrical and structural data for Ba 1 –   x La x F 2 +   x and Ca 1 –   x Y x F 2 +   x superionic conductors (sp. gr. ), in which charge carriers are mobile interstitial ions formed as a result of heterovalent substitutions of [M 8 R 6 F 69 ] structural clusters (R = La or Y) for [M 14 F 64 ] fluorite fragments (M = Ca or Ba). Single crystals of Ca 1 –   x Y x F 2 +   x (0.02 ≤ x ≤ 0.16) and Ba 1 –   x La x F 2 +   x ( x = 0.31) solid solutions are prepared using directional solidification. Mobilities of ion carriers in Ba 0.69 La 0.31 F 2.31 , Ca 0.84 Y 0.16 F 2.16 , Pb 0.67 Cd 0.33 F 2 , and Pb 0.9 Sc 0.1 F 2.1 isostructural superionic conductors are compared. Ba 1 –   x La x F 2 +   x and Ca 1 –   x Y x F 2 +   x crystals with improved conductometric and mechanical characteristics are promising for replacement of conventional electrolyte CaF 2 in galvanic cells for thermodynamic studies of chemical compounds.