Nanograined Sc-doped BaZrO3 as a proton conducting solid electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs)

• BaZr0.75Sc0.25O3 is synthesized at low processing temperature (350 °C) with grain size < 10 nm.
• Different grain sizes of BaZr0.75Sc0.25O3 were studied and characterized.
• As-synthesized and heat treated samples show a simple BaZrO3 cubic perovskite-type structure.
• The 68.5 nm grains show the highest protonic conductivity almost comparable to Y-doped BaZrO3.

Nanograined 25 mol% Sc-doped BaZrO3, BaZr0.75Sc0.25O3 − δ, well-known as a proton conductor, has been successfully synthesized at low processing temperature with average grain sizes of 8.9 nm, 15.9 nm, and 68.5 nm, and the effect of grain size on the conductivity has been examined. X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns for these samples suggest a simple cubic perovskite type structure. The total DC conductivity, bulk and grain boundary contributions, of BaZr0.75Sc0.25O3 − δ as-pressed at room temperature (non-sintered) is 5.53 × 10− 6 S/cm (8.9 nm grains) at 500 °C, while values of 2.68 × 10− 5 S/cm and 1.27 × 10− 3 S/cm are observed at 500 °C for those samples post-annealed at 800 °C and 1250 °C with average grain sizes of 15.9 and 68.5 nm, respectively. The observed total DC conductivity for 68.5 nm grain size is almost comparable to that reported for benchmark Y-doped BaZrO3 with nanometer and micrometer grains.