Nickel and titanium doubly doped lanthanum strontium chromite for high temperature electrochemical devices

Lanthanum chromite based materials are promising candidate for use as electrochemical components in high temperature electrochemical devices. In this study, nickel and titanium doubly doped lanthanum strontium chromites are developed and the effects of nickel and titanium co-doping of the chromite perovskite La0.85Sr0.15Cr1-2yNiyTiyO3-delta (0.05 <= y <= 0.3) on the electrical conductivity, chemical stability, microstructure, density, thermal expansion and electrochemical performance are measured. Density and the electrical conductivity increases with nickel concentration whereas Sr-segregation on the surface of La0.85Sr0.15Cr1-2yNiyTiyO3-delta has been observed for y >= 0.2 and is associated with reduction in the electrical conductivity. For y = 0.1, La0.85Sr0.15Cr1-2yNiyTiyO3-delta shows the highest electrical conductivity in air and reducing atmosphere (PO2 similar to 10(-24) atm). The conductivity of La0.85Sr0.15Cr1-2yNiyTiyO3-delta (y = 0.1) in reducing atmosphere (3.58 S cm(-1) at 950 degrees C) also remains higher than the most widely investigated compositions such as (La0.75Sr0.25)(0.95)Cr0.5Mn0.5O3-delta (2.81 S Cm-1) and (La0.75Sr0.25)(0.95)Cr0.7Fe0.3O3-delta (1.41 S cm(-1)). Smaller deviation in the oxygen stoichiometry is similarly observed for La0.85Sr0.15Cr0.8Ni0.1Ti0.1O3-delta (delta = 0.011) when compared to La0.75Sr0.25CrO3-delta (delta = 0.091), La0.75Sr0.25Cr0.5Mn0.5O3-delta (delta = 0.175) and La0.75Sr0.25Cr0.5Mn0.5O3-delta (delta = 0.148) at 1000 degrees C and similar to 10(-24) atm. Highest electrochemical performance and structural interfacial stability is obtained for new composition La0.85Sr0.15Cr0.8Ni0.1Ti0.1O3-delta (LSCNT0.1) when mixed with 8YSZ in both oxidizing and reducing atmosphere.