Optimizing Lanthanum Chromite Interconnects for Solid Oxide Fuel Cells
Optimizing the composition of strontium substituted lanthanum chromites to minimize expansion is not straightforward and must be done carefully to avoid compromising sinterability, electrical conductivity, and mechanical strength. In this study, a variety of lanthanum strontium chromites were modified with V, Cu, and Mg to allow densification in air at 1500?C, and their materials properties were evaluated. Both additives (?5 mole % V and 2 mole% Cu) resulted in full densification of Sr substituted (10 and 15 mole%) lanthanum chromite. Of the compositions evaluated, only La0.85Sr0.15Cr0.95V0.05O3 appeared to be a promising interconnect material, showing <0.1% expansion at 10-16 atm. While the coefficient of thermal expansion was less than that of stabilized zirconia, small additions of Co (1 mole%) increased the CTE to 10.1 ppm ?C-1. The results of this study indicated that Cu acted as an acceptor when added to lanthanum chromite, increasing both the electrical conductivity and expansion upon reduction. The effect of vanadium additions were two-fold. First, it acted as a donor in the chromite lattice effectively reducing the overall acceptor concentration. Secondly, during sintering, V reacted with Sr to form Sr3(VO4)2, an effective sintering aid for lanthanum chromite, and further reduced the acceptor level by removing Sr from the perovskite lattice.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 974525
- Report Number(s):
- PNNL-SA-33987; AA2530000; TRN: US201007%%776
- Resource Relation:
- Conference: 6th International Symposium on Solid Oxide Fuel Cells (SOFC-VI), 99(19):706-715
- Country of Publication:
- United States
- Language:
- English
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