Effect of Ti substitution on the electrochemical properties of LaCr_1−x Ti _x O_3+0.5x (x = 0–0.15)

Perovskite compound LaCr_1−x Ti _x O_3+0.5x (x = 0–0.15) was synthesized from an EDTA-chelating precursor solution at T < 800 °C, a temperature lower than that of the conventional solid-state method. Structural properties were determined at room temperature using X-ray powder diffraction and the lattice parameter decreased with increasing proportion of Ti. LaCr_1−x Ti _x O_3+0.5x was chemically stable under a H₂ atmosphere at 900 °C. Both electrical and ionic conductivity increased with increasing proportion of doped Ti, indicative of a p-type semiconductor. An Arrhenius-like behavior was observed, and the optimized bulk electrical conductivity was 0.107 S cm⁻¹ for LaCr_0.85Ti_0.15O_3.075 at 850 °C. X-ray photoelectron spectra indicate that the effect of the concentration of charge carrier on conductivity is closely related to the oxidation states of ions. The maximum power density reaches as high as 210 mW cm⁻² at 800 °C for SOFC with LaCr_1−x Ti _x O_3+0.5x (x = 0.15) anode.

Ti-substituted perovskite materials LaTi _x Cr_1−x O_3+0.5x (x = 0–0.15) show enhanced electronic and ionic conductivity with increasing proportion of doped Ti.