Extensive research of conductivity in the fluorite-like KLn4Mo3O15F (Ln = La, Pr, Nd) rare earth molybdates: theoretical and experimental data

Ekaterina I Orlova; Yelizaveta A Morkhova; Anastasia V Egorova; Artem A Kabanov; Egor D Baldin; Elena P Kharitonova; Nikolay V Lyskov; Vasiliy O Yapaskurt; Olga A Alekseeva; Valentina I Voronkova; Daniil V Korona

doi:10.1039/d3cp06134e

Extensive research of conductivity in the fluorite-like KLn₄Mo₃O₁₅F (Ln = La, Pr, Nd) rare earth molybdates: theoretical and experimental data

Phys Chem Chem Phys. 2024 Feb 28;26(9):7772-7782. doi: 10.1039/d3cp06134e.

Authors

Ekaterina I Orlova^{1

2}, Yelizaveta A Morkhova³, Anastasia V Egorova^{4

5}, Artem A Kabanov⁶, Egor D Baldin⁷, Elena P Kharitonova^{1

2}, Nikolay V Lyskov^{8

9}, Vasiliy O Yapaskurt¹⁰, Olga A Alekseeva², Valentina I Voronkova¹, Daniil V Korona^{4

5}

Affiliations

¹ Lomonosov Moscow State University, Faculty of Physics, Moscow 119991, Russia. agapova@polly.phys.msu.ru.
² Shubnikov Institute of Crystallography of Federal Scientific Research Centre 'Crystallography and Photonics' of Russian Academy of Sciences, Moscow 119333, Russia.
³ Samara State Technical University, Samara 443100, Russia.
⁴ Ural Federal University, Yekaterinburg 620075, Russia.
⁵ Institute of High Temperature Electrochemistry, Ural Branch Russian Academy of Sciences, Yekaterinburg 620219, Russia.
⁶ P. N. Lebedev Physical Institute of the Russian Academy of Sciences, Samara 443011, Russia.
⁷ N.N. Semenov Federal Research Center for Chemical Physics RAS, Moscow 119991, Russia.
⁸ Federal Research Center for Problems of Chemical Physics and Medical Chemistry of the Russian Academy of Sciences, Chernogolovka 142432, Russia.
⁹ HSE University, Moscow 101000, Russia.
¹⁰ Lomonosov Moscow State University, Faculty of Geology, Moscow 119991, Russia.

PMID: 38374775
DOI: 10.1039/d3cp06134e

Abstract

The conductive properties of fluorite-like structures KLn₄Mo₃O₁₅F (Ln = La, Pr, Nd: KLM, KPM, KNM) have been studied theoretically and experimentally. Theoretical studies included the geometrical-topological analysis of voids and channels available for migration of working ions; bond valence site energy calculations of the oxygen ions' migration energy; quantum-chemical calculations for the estimation of the oxygen vacancies formation energy. Experimental measurements of conductivity were made using impedance spectroscopy and as a function of oxygen partial pressure. The total conductivity was ∼10^-3 S cm^-1 for KLM and ∼10^-2 S cm^-1 for KPM and KNM at 800 °C. Measurements with changes in partial pressure proved the mixed nature of electric transport in KLM, KPM, and KNM phases, with predominantly ionic conductivity. The measured ion transference numbers in air reached approximately 0.9 at 800 °C for the KPM and KNM ceramics. Also, evaluated proton transfer numbers were less than 10%, indicating a small contribution to the total conductivity.