In the system RbF–PbF2–SnF2 are formed solid solutions of the heterovalent substitution RbxPb0,86‑xSn1,14F4-x (0 < x ≤ 0,2) with structure of β–PbSnF4. At x > 0,2 on the X-ray diffractograms, in addition to the basic structure, additional peaks are recorded that do not correspond to the reflexes of the individual fluorides and can indicate the formation of a mixture of solid solutions of different composition. For single-phase solid solutions, the calculated parameters of the crystal lattice are satisfactorily described by the Vegard rule. The introduction of ions of Rb+ into the initial structure leads to an increase in the parameter a of the elementary cell from 5.967 for x = 0 to 5.970 for x = 0.20. The replacement of a part of leads ions to rubium ions an increase in electrical conductivity compared with β–PbSnF4 and Pb0.86Sn1.14F4. Insignificant substitution (up to 3.0 mol%) of ions Pb2+ at Rb+ at T<500 K per order of magnitude reduces the conductivity of the samples obtained, while the nature of its temperature dependence is similar to the temperature dependence of the conductivity of the sample β-PbSnF4. By replacing 5 mol. % of ions with Pb2+ on Rb+, the fluoride ion conductivity at T> 450 K is higher than the conductivity of the initial sample Pb0,86Sn1,14F4 and at temperatures below 450 K by an order of magnitude smaller. With further increase in the content of RbF the electrical conductivity of the samples increases throughout the temperature range, reaching the maximum values at x≥0.15 (σ573 = 0.34–0.41 S/cm, Ea = 0.16 eV and σ373 = (5.34–8.16)•10-2 S/cm, Ea = 0.48–0.51 eV, respectively). In the general case, the replacement of a part of the ions of Pb2+ with Rb+ to an increase in the electrical conductivity of the samples throughout the temperature range. The activation energy of conductivity with an increase in the content of RbF in the low-temperature region in the general case increases, and at temperatures above 400 K is inversely proportional decreasing. The nature of the dependence of the activation energy on the concentration of the heterovalent substituent and its value indicate that the conductivity of the samples obtained increases with an increase in the vacancies of fluoride ions in the structure of the solid solutions.
Gschwinda F., Rodriguez-Garciaa G., Sandbecka D.J.S., Grossa A., Weila M., Fichtner M., Hörmanna N. Fluoride ion batteries: Theoretical performance, safety, toxicity, and a combinatorial screening of new electrodes. Journal of Fluorine Chemistry. 2016. 182: 76.
Zhang L., Anji M. Reddy, Fichtner M. Development of tysonite-type fluoride conducting thin film electrolytes for fluoride ion batteries. Solid State Ionics. 2015. 272: 39.
Nakajima T., Groult H. Advanced Fluoride-Based Materials for Energy Conversion. (Elsevier, 2015). ISBN: 978-0-12-800679-5.
Rongeat C., Anji M. Reddy, Witter R., Fichter M. Nanostructured fluorite–type fluorides as electrolytes for fluoride ion batteries. The Journal of Physical Chemistry. 2013. 117: 4943.
Sorokin N.I., Sobolev B.P. Nonstoichiometric fluorides-Solid electrolytes for electrochemical devices: A review. Crystallography Reports. 2007. 52 (5): 842.
Sorokin N.I. SnF2-based solid electrolytes. Inorganic Materials. 2004. 40 (9): 989.
Sorokin N.I., Fedorov P.P. Superionic materials based on lead fluoride. Inorganic Materials. 1997. 33 (1): 1.
Yoshikado Sh., Ito Y., Réau J.M. Fluoride ion conduction in Pb1−xSnxF2 solid solution system. Solid State Ionics. 2002. 154-155: 503.
Vakulenko AM, Uksha E.A. Electrical conductivity of solid electrolyte PbSnF4. Soviet Electrochemistry. 1992. 28 (9): 1257.
Kanno R., Nakamura S., Kawamoto Y. Solid State Ionics. 1992. 51: 53.
Pogorenko Yu. V., Pshenichnyi R. N., Omel’chuk A. A., Trachevskii V. V. Electric conductivity of heterovalent substitution solid solutions of the (1–x)PbF2–xYF3–SnF2 system. Russian Journal of Electrochemistry. 2016. 52 (4): 374.
Pogorenko Yu. V., Pshenychnyi R. N., Omel’chuk A. O., Trachevskii V. V. Synthesis and conductivity properties of solid solutions Pb1-xLnxSnF4+x (Ln – La, Ce, Nd, Sm, Gd). Ukrainian Chemistry Journal. 2016. 82 (11): 33.
Pohorenko Yu.V., Pshenychnyi R.N., Pavlenko T.V., Omel’chuk A.O. Synthesis and conductivity of solid solutions the KxPb1 xSnF4-x and KxPbSn1 xF4-x. Ukrainian Chemistry Journal. 2018. 84 (11): 20.
The CRC handbook of solid state electrochemistry. Eds. P.J. Gellings, H.J.M. Bouwmeester. (CRC Press, Inc., 1997).
The Collaborative Computational Projects (CCPs). http://www.ccp14.ac.uk.
Ivanov-Shits A.K., Murin I.V. Solid state ionics. V.2. (St. Petersburg: Publishing House of St. Petersburg State University, 2010.[in Russian].
Kroger F.A., Vink H.J. Relations between the concentrations of imperfections in crystalline solids. Solid State Physics . Eds. Seitz. F., Turnbull D. (New York: Academ. Press, 1956). 3: 307.
Jonscher A.K. The “universal” dielectric response. Nature. 1977. 267: 673.
Jonscher A.K. The Interpretation of Non–Ideal Dielectric Admittance and Impedance Diagrams. Physica Status Solidi A. 1975. 32: 665.
Funke K. Jump relaxation in solid electrolytes. Progress in Solid State Chemistry. 1993. 22 (2): 111.