Pressure-induced ionic to mixed ionic and electronic conduction transition in solid electrolyte LaF3.
Phys Chem Chem Phys
; 22(45): 26306-26311, 2020 Nov 25.
Article
em En
| MEDLINE
| ID: mdl-33175931
ABSTRACT
The ionic transport properties of solid electrolyte LaF3 were systematically studied under high pressures up to 30.6 GPa with alternate-current impedance spectra measurements and first-principles calculations. From the impedance spectra measurements, LaF3 was found to transform from pure ionic conduction to mixed ionic and electronic conduction at 15.0 GPa, which results from the pressure-induced structural phase transition from a tysonite-type structure to an anti-Cu3Ti-type structure. F- ion migration can be suppressed by pressure, causing a decrease of the ionic conductivity of LaF3. By first-principles calculations, the pressure-dependent diffusion behaviors of the F- ions can be understood. The increased overlap of electron clouds at the interstitial site between rigid La3+ and liquid F- lattices leads to the appearance of electronic conduction in anti-Cu3Ti-type structured LaF3.
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MEDLINE
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2020
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Article