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Characterization of perovskite-type cathode, La0.75Sr0.25Mn0.95− xCoxNi0.05O3+ δ(0.1 ≤ x ≤ 0.3), for intermediate-temperature solid oxide fuel cells

Journal of Power Sources
Publication Date
DOI: 10.1016/j.jpowsour.2008.10.136
  • Doped Lamno3
  • Cathode
  • Structure
  • Thermal Property
  • Electrical Conductivity
  • Earth Science


Abstract Phase evolution, structure, thermal property, morphology, electrical property and reactivity of a perovskite-type cathode system, La 0.75Sr 0.25 Mn 0.95− x Co x Ni 0.05O 3+ δ (0.1 ≤ x ≤ 0.3), are reported. The samples are synthesized using metal acetates by the Pechini method. A perovskite-type phase is formed after calcination at ∼700 °C and a rhombohedral symmetry of R – 3 c space group is stabilized at ∼1100 °C. An increase in x decreases the unit cell volume linearly, accompanying with a linear decrease in bond lengths and tilt angle. The differential thermal analysis suggests the phase stabilization for a temperature range, 50–1100 °C. The thermo-gravimetric, thermal expansion, and electrical and ionic conductivities studies suggest presence of a Jahn–Teller transition at ∼260–290 °C. The samples with x = 0.1 mol exhibit electrical conductivity of ∼55 S cm −1 at ∼600 °C, activation energy of ∼0.13 eV, coefficient of thermal expansion of ∼12 × 10 6 °C −1, crystallite size of ∼45 nm, Brunauer–Emmett–Teller (BET) surface area of 1.26 m 2 g −1 and average particle size of ∼0.9 μm. A fairly high ionic conductivity, 5–9 × 10 −2 S cm −1 makes the sample with x = 0.1 mole suitable for intermediate-temperature solid oxide fuel cell cathode applications. The experimental results are discussed with the help of the defect models proposed for La 1− x Sr x MnO 3+ δ .

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