Structure and electrical properties of BaCe1-xLaxO3-δ mixed conductors

In this study, BaCe1-xLaxO3-delta (x = 0.05, 0.10, 0.20, and 0.30) oxides synthesized using citrate-nitrate combustion method were calcined at 1100 degrees C for 5 h and subsequently sintered at 1550 degrees C for 5 h. Crystal structure, conductivity, and chemical properties were investigated via X-ray diffraction (XRD), alternating current (AC) impedance spectroscopy, and X-ray photoelectron spectroscopy (XPS). XRD analysis shows that all samples have orthorhombic perovskite-type structure, and lattice volume increases with increasing La content. XPS results show that Ba and La valence states are bivalent, and trivalent, respectively. Mixed Ce4+ and Ce3+ valence states can be identified in the samples. Furthermore, there are two types of O binding states in perovskite structure: (i) O-H groups/oxygen vacancies and (ii) lattice oxygen. AC impedance spectra reveal that all samples are proton-oxide ion-electron hole conductors at 400-800 degrees C in wet O-2 atmosphere and proton-electron conductors at 400-800 degrees C in wet Ar atmosphere. Among these samples, BaCe0.90La0.10O3-delta and BaCe0.95La0.05O3-delta display the highest conductivities at temperatures below and above 500 degrees C, respectively. Furthermore, BaCe0.95La0.05O3-delta exhibits the highest total conductivity of 1.06 x 10(-2) S cm(-1) at 800 degrees C under P-O2 approximate to 1 atm and P-H2O = 0.006 atm.

Automated summary

In this study, BaCe1-xLaxO3-delta oxides were synthesized and characterized for their crystal structure, conductivity, and chemical properties. The results showed variations in structure and properties among samples with different La content, with BaCe0.95La0.05O3-delta exhibiting the highest conductivity.