Low-Temperature Synthesis of Materials in the SrF₂–ScF₃ System and a Study of Their Electrical Conductivity

Nanocrystalline (100−x)SrF₂⋅xScF₃ (3 ≤ х ≤ 33 mol %) samples with an average grain size of ~20 nm have been synthesized by the “soft chemistry” method (precipitation of HF from aqueous solutions of strontium chloride SrCl₂ and scandium chloride ScCl₃). Using a 95SrCl₂⋅5ScCl₃ solution, a single-phase Sr_0.97Sc_0.03F_2.03 solid solution with a fluorite structure (CaF₂-type, space group F \(m\bar {3}m\) ) with a unit cell parameter of a = 5.7959 ± 0.0016 Å has been formed. For a ceramic sample prepared from the solid solution by cold pressing and heated to a temperature of 831 K, the ionic conductivity in the cooling mode has been measured; it has been found to be 6.4 × 10⁻⁶ S/cm at 673 K. The activation energy for ion transfer is 1.13 ± 0.04 eV. The electrical conductivity of nanocrystalline Sr_0.97Sc_0.03F_2.03 is 3.5 times higher than that of a single crystal of the same composition and ~10 times lower than the electrical conductivity of a Sr_0.92Sc_0.08F_2.08 single crystal.