Influence of Ru doping on the conductivity of LaCrO₃ ceramic prepared by SPS and the feasibility of the doped ceramic for an inert anode of molten salt electrolysis

LaCrO₃ ceramic is a promising function material in areas such as high temperature piezoelectric materials and solid oxide fuel cells (SOFC). However, its practical applications are limited by fatal flaws including their low density and poor conductivity. To address these challenges, spark plasma sintering (SPS) was used to prepare the high-density LaCrO₃ ceramic. Additionally, Ru, a multivalent metallic element, was doped in the A site of the LaCrO₃ ceramic to investigate the conductivity of the La_1−xRu_xCrO₃ (x=0−0.25). X-ray power diffraction (XRD) results and scanning electron microscope images show that the sintered La_1−xRu_xCrO₃ ceramic has a single perovskite phase and high density. The characteristic peak shifting observed in the XRD pattern indicates that the Ru element has been successfully doped in the A site of the LaCrO₃ ceramic. Whereas, the results of the Energy dispersive spectrometer (EDS) prove that there is no obvious change in the Ru content before and after sintering by SPS, which indicates that no actual Ru loss can occur during the SPS process at 1600 °C. Moreover, the conductivity of the sintered La_1−xRu_xCrO₃ increases with increasing Ru content and temperature. The results also indicate that there is good linear relationship between ln(σT) and 1/T, demonstrating that the conductivity of the La_1−xRu_xCrO₃ obeys the Arrhenius law. The activation energy of the doped La_1−xRu_xCrO₃ ceramic is smaller than that of the LaCrO₃ ceramic. Lastly, the feasibility of the application of doped La_1−xRu_xCrO₃ ceramics as the inert anode of molten salt electrolysis in CaCl₂ melt has been investigated at the temperature of 800 °C. These findings demonstrate that the doped La_1−xRu_xCrO₃ ceramic has an excellent chemical corrosion-resistant property. However, it has poor thermal stability, which inhibits its application as an inert anode. Future studies focusing on the improvement of the heat-shock resistance and elucidating the corrosion resistance mechanism of La_1−xRu_xCrO₃ in CaCl₂ melt is recommended.