Mobility of Charge Carriers in a Single Crystal and Nanoceramic of the Superionic Pb1 – xSnxF2 Conductor (x = 0.2)

Abstract

A crystallophysical model of ion transfer in the superionic Pb_1 – xSn_xF₂ conductor with a fluorite (CaF₂) structure is proposed. The concentration dependence of the ionic conductivity of Pb_1 – xSn_xF₂ single crystals and poly- and nanocrystals is analyzed. The single-crystal form of the superionic conductor is characterized by the highest conductivity. The mobility and concentration of anionic charge carriers in a single crystal and ceramics of Pb_1 – xSn_xF₂ (x = 0.2) is calculated on the basis of structural and electrophysical data. The mobility of carriers μ_mob = 2.5 × 10^–6 cm²/s V (at 293 K) in a single crystal is seven times higher than in nanoceramic. The concentration of carriers n_mob = 1.7 × 10²¹ and 3.6 × 10²¹ cm³ (4.5 and 9.5% of the total number of anions) for a single crystal and nanoceramic, respectively. The comparison of isostructural Pb_0.8Sn_0.2F₂, Pb_0.67Cd_0.33F₂, and Pb_0.9Sc_0.1F_2.1 single crystals shows that anionic carriers have a maximum mobility in the β-PbF₂ and SnF₂ based solid solution.