Thermal Stability and Electrical Properties of High-Pressure-Molded Nanocomposites Containing Fast Ion-Conductive...

The report presents the electrical, structural, and microstructural properties of high-pressure-high-temperature-treated (HPHT) composites composed of δ-like Bi₂O₃ nanograins embedded in an aluminosilicate glassy matrix. Nanocomposites were obtained by heat treatment of the Bi₂O₃-Al₂O₃-SiO₂ ternary glass system, followed by high-pressure molding (above 750 MPa). The total oxygen conductivity σ_t of the studied nanocomposites was high and approached a value of 4.5 × 10^-4 S/cm at 600 °C. Due to HPHT treatment, we could also determine the intragrain conductivity of δ-Bi₂O₃ nanocrystallites. In this case, the value of σ_δ was even higher and was equal to 1.3 × 10^-3 S/cm at 600 °C. It was also possible to study the temperature dependence of intragrain conductivity, showing two activation energies, which probably reflect the order-disorder transition within the sublattice of mobile O^2- ions. The obtained nanocomposites exhibited promising properties for applications in electrochemical devices operating in the intermediate temperature range from 300 to 600 °C.