A new neodymium-doped BaZr _0.8Y _0.2O _3-δ as potential electrolyte for proton-conducting solid oxide fuel cells

Chemically stable BaZr _0.8Y _0.2O _3-δ (BZY) oxide is limited to applications as an electrolyte for solid oxide fuel cells (SOFCs) because of its poor sintering behavior. This study attempts to improve the sinterability and conductivity of BZY using the partial substitution of Zr ⁴⁺ in BZY with Nd ³⁺. An oxide with the nominal composition of BaZr _0.7Nd _0.1Y _0.2O _3-δ (BZNY) is specifically investigated. Results from X-ray diffraction (XRD) demonstrate Nd ³⁺ is successfully doped into the lattice as anticipated and transmission electron microscopy (TEM) characterizations verify the morphology and crystal structure of the BZNY powder. Dilatometric measurement and scanning electron microscopy (SEM) observations provide verification that the sinterability of the oxide is effectively improved by introducing Nd ³⁺. XRD and CO ₂-TPD results demonstrate that BZNY is relatively stable with respect to the CO ₂ atmosphere. The total conductivity of BZNY in wet H ₂ is 2.76×10 ^-3Scm ^-1 at 600°C. An anode-supported thin-film BZNY electrolyte (~30μm) cell is fabricated, and the electrolyte layer is found to be well densified after co-sintering with the anode substrate at 1450°C for 5h. The cell delivers a peak power density of 142mWcm ^-2 at 700°C, higher than the reported values for a similar cell with BZY electrolyte.