Several orthorhombic perovskite products with nominal chemical formula BaCe0.85Gd0.15O3–δ (BCGO), doped with variable amounts (0–5 mol%) of CuO and characterized by high total ionic conductivities, were synthesized by a sol-gel method followed by a calcination step at 1200 °C to induce the formation of a perovskite single phase. The products were characterized by X-ray Diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Raman spectroscopy and Electrochemical Impedance Spectroscopy analysis (EIS). The powders were sintered into highly dense bodies (greater than 99 % for the best sample) through a relatively mild sintering process, i.e. 1350 °C for 6 h. The positive effect of copper as a sintering aid was revealed when a threshold content value (around 2 mol%) was e. Indeed, beyond such a limit, by calcination at 1200 °C, a secondary phase, a mixed oxide of Cu, Ba and Gd (very likely with chemical formula GdBa4Cu3O9.18) appears in the precursor powders strongly enhancing the densification process, reasonably via partial liquid-phase sintering. Finally, remarkable grain growth also occurred, enhancing the overall conductivity of BCGO due to the positive effect of the reduction of grain boundary dimensions.
On the role of copper as a sintering aid in proton conducting Gd-doped barium cerate (BCGO)
Spiridigliozzi L.;
2023-01-01
Abstract
Several orthorhombic perovskite products with nominal chemical formula BaCe0.85Gd0.15O3–δ (BCGO), doped with variable amounts (0–5 mol%) of CuO and characterized by high total ionic conductivities, were synthesized by a sol-gel method followed by a calcination step at 1200 °C to induce the formation of a perovskite single phase. The products were characterized by X-ray Diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Raman spectroscopy and Electrochemical Impedance Spectroscopy analysis (EIS). The powders were sintered into highly dense bodies (greater than 99 % for the best sample) through a relatively mild sintering process, i.e. 1350 °C for 6 h. The positive effect of copper as a sintering aid was revealed when a threshold content value (around 2 mol%) was e. Indeed, beyond such a limit, by calcination at 1200 °C, a secondary phase, a mixed oxide of Cu, Ba and Gd (very likely with chemical formula GdBa4Cu3O9.18) appears in the precursor powders strongly enhancing the densification process, reasonably via partial liquid-phase sintering. Finally, remarkable grain growth also occurred, enhancing the overall conductivity of BCGO due to the positive effect of the reduction of grain boundary dimensions.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
