Abstract
Frequency-dependent electric and dielectric properties of the porous Sm0.5Sr0.5CoO3−δ cathode prepared through conventional combustion synthesis technique were studied in the temperature range 298 K–973 K. The crystal symmetry, space group, and unit cell dimensions were confirmed by analyzing XRD pattern. XRD analysis indicates the formation of a single-phase orthorhombic structure with space group Pnma 62. Scanning electron microscopy technique was used to examine the morphology of the sample. Scanning electron microscopy study showed the formation of porous structure with an average grain size about 850 nm. From the electrical study, it is observed that the conduction in Sm0.5Sr0.5CoO3−δ sample takes place through the hopping mechanism and follows the inverse universal power law. The correlated barrier hopping model was employed successfully to explain the mechanism of charge transport in Sm0.5Sr0.5CoO3−δ. Further, the ac conductivity data was used to evaluate the minimum hopping length and apparent activation energy. The minimum hopping length was found to be ~10−4 times smaller than the grain size of Sm0.5Sr0.5CoO3−δ. The peaking behaviour of the real part of dielectric constant with frequency was explained using the Rezlescu model. This study helps to confirm that the charge transportation in Sm0.5Sr0.5CoO3−δ is due to two types of charge carriers.
Highlights
Recent worldwide interest in building a decentralized, hydrogen-based energy economy has refocused attention on the solid oxide fuel cell (SOFC) as a potential source of efficient, environmental friendly, fuel-versatile electric power generation [1, 2]
Performance of the solid oxide fuel cell mostly depends on properties of the electrolyte, anode, and cathode materials
Strontium-doped samarium cobaltate, Sm0.5Sr0.5CoO3−δ (SSC), with x = 0.5 is being investigated as a cathode material to replace the conventional La1−x SrxMnO3−x (LSM) material. This is due to the high catalytic activity of SSC for the oxygen reduction reaction (ORR) as well as its excellent ionic and electronic conductivity over a wide range of temperatures
Summary
Recent worldwide interest in building a decentralized, hydrogen-based energy economy has refocused attention on the solid oxide fuel cell (SOFC) as a potential source of efficient, environmental friendly, fuel-versatile electric power generation [1, 2]. From the last 20 years, scientific community is trying to understand the SOFC materials in terms of their chemical, thermal, catalytic, structural, morphological, and transport properties and their effect on performance of solid oxide fuel cell [3,4,5,6]. Strontium-doped samarium cobaltate, Sm0.5Sr0.5CoO3−δ (SSC), with x = 0.5 is being investigated as a cathode material to replace the conventional La1−x SrxMnO3−x (LSM) material. This is due to the high catalytic activity of SSC for the oxygen reduction reaction (ORR) as well as its excellent ionic and electronic conductivity over a wide range of temperatures. The dielectric data has been explained in the light of Rezlescu model to understand the charge transportation
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