Tysonite Type Nanocrystalline Solid Solutions R1 – xScxF3 (R = La, Pr): Synthesis and Electrical Conductivity

Abstract

The single-phase nanocrystalline R0.9Sc0.1F3 solutions (R = La, Pr) were synthesized by soft chemistry methods as transparent xerogels with the tysonite structure (space group). The ionic conductivity of ceramic samples prepared from these materials was 4.5 × 10–4 and 2.1 × 10–3 S/cm at 773 K for R = La and Pr, respectively. The activation energy of the ion transfer in ceramic samples was 0.43 (R = Pr) and 0.48 eV (R = La) in the high-temperature segment and 0.56 eV (R = Pr) in the low-temperature segment. It was shown that the isovalent replacement of La3+ (Pr3+) cations in the R0.9Sc0.1F3 tysonite solid solutions with Sc3+ leads to 3–4-fold decrease in the conductivity of the ceramic electrolytes.