A series of K
2NiF
4-type compounds, La
2−xPr
xNiO
4 (
x = 0, 0.6, 1.0, 1.4, and 2.0), were synthesized by solid state reaction for use as cathodes in an intermediate-temperature (500–700°C) solid oxide fuel cell (IT-SOFC). La
2−xPr
xNiO
4 (
x = 0 and 0.6) crystallize in the
Fmmm space group, while La
2−xPr
xNiO
4 (
x = 1.0, 1.4, and 2.0) belong to the
Bmab space group. The electrical conductivity increased by Pr doping and La
2−xPr
xNiO
4 (
x = 0.6, 1.0, and 1.4) exhibited electrical conductivities similar to one another while Pr
2NiO
4 had the highest. Single test-cells consisting of samarium oxide doped ceria (SDC) as an electrolyte, Ni–SDC cermet as an anode and La
2−xPr
xNiO
4 as a cathode, were fabricated for measurements of cell performance at 500–700°C. Current interruption measurements revealed that the overpotential losses mainly decreased with increasing Pr content. Pr
2NiO
4 was found to exhibit the best cathode characteristics; maximum test-cell power densities of 14.1, 45.1, and 104.4 mW/cm
2 were obtained at 500, 600, and 700°C, respectively.
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