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Silver Exsolution-Enhanced Electrical Properties of Lanthanum-Based Perovskites



Author(s)

Rokas Sažinas and Kent Kammer Hansen

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DOI:10.17265/2161-6213/2019.5-6.004

Department of Energy Conversion and Storage, Technical University of Denmark, Roskilde DK-4000, Denmark

The effect of silver (Ag) exsolution on the electrical conductivity of strontium-doped lanthanum manganite (La_1-x-ySr_xAg_yMnO_3-δ, LSAM) and ferrite (La_1-x-ySr_xAg_yFeO_3-δ, LSAF) perovskites was investigated. The single-phase Ag-doped materials formed at 800 °C using modified Pechini method and revealed thermal stability in oxidizing atmosphere up to sintering temperature of the materials at 1,200 °C. The exsolution of the metallic Ag nanoparticles was performed at 420-500 °C in reducing atmosphere of 5% H₂/N₂. Scanning electron microcopy results exhibited the metallic Ag phase nanoparticles on the surface of the oxide backbone with a good contact of Ag to the surface of the perovskite after exsolution. The electrical conductivity of the materials was investigated in the temperature range of 50-900 °C in air and isothermally in 5% H₂/N₂ at 420 and 500 °C by means of four probe DC measurement method, and reached 80-230 S·cm^-1 for undoped and Ag-doped LSF and LSM. The electrical conductivity results showed improving conductivity in Ag-doped single-phase and Ag nanoparticle decorated perovskites after Ag exsolution. The results revealed the dependence of electrical conductivity on the atmosphere, temperature and Ag exsolution time.

Silver nanoparticles, exsolution, SOFC, cathodes, LSM, LSF, ceramics.