A Crystal-Physical Model of Electrotransfer in the Superionic Conductor Pb1 – xScxF2 + x (x = 0.1)

Resumo

The frequency (ν = 10^–1–107 Hz) dependences of electrical conductivity σ(ν) of single crystals of superionic conductor Pb_0.9Sc_0.1F_2.1 (10 mol % ScF₃) with fluorite type structure (CaF₂) in the temperature range 153–410 K have been investigated. The static bulk conductivity σ_dc =1.5 × 10^–4 S/cm and average hopping frequency ν_h = 1.5 × 10⁷ Hz of charge carriers (mobile ions F⁻) at room temperature (293 K) have been defined from the σ_dc(ν) experimental curves. Enthalpies of thermoactivated processes of ionic conductivity σ_dc(T) (ΔH_σ = 0.393 ± 0.005 eV) and dielectric relaxation ν_h(T) (ΔH_h = 0.37 ± 0.03 eV) coincide within their errors. A crystal-physical model of fluorine-ion transport in a Pb_0.9Sc_0.1F_2.1 crystal lattice has been proposed. The characteristic parameters of charge carriers have been calculated: concentration n_mob = 2.0 × 10²¹ cm⁻³, the distance of the hopping d ≈ 0.5 nm and mobility μ_mob = 4.5 × 10⁻⁷ cm²/s V (293 K).