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Effect of Doping of La in Pr Site and Cu/Fe in Ni site on Crystal Structure, Oxygen Non-stoichiometry level and Electrical Conductivity of Pr2NiO4 as Intermediate Temperature Solid Oxide Fuel Cell Cathode

Farhat, Pooneh | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51324 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Faghihi Sani, Mohammad Ali
  7. Abstract:
  8. Nowadays, one of the most important research goals is to develop intermediate-temperature solid oxide fuel cells (IT-SOFC) operated at 500–800 °C. However, the large cathode polarization resistance caused by the reduced temperature is a major barrier against such an urgent demand for commercialization. In this regard, it is necessary to select a proper material as a cathode working efficiently at reduced temperatures without losing its desired performance. Various mixed ionic electron conductors (MIECs), especially Ruddlesden–Popper-type oxides, are used to improve the cathode performance at intermediate temperatures. Among these layered oxides, Pr2NiO4 has been reported to possess the highest oxygen diffusion and surface exchange coefficient, and the largest amount of interstitial oxygen. In the present study, Pechini method was utilized to synthesis Pr2NiO4 powders with different quantities of La doped in Pr site and also different amounts of Fe/Cu in Ni site. XRD results showed that all the powders crystallized in single phase without any detectable impurities. Moreover, the effect of the type and the amount of the dopants on oxygen non-stoichoimetry level () and electrical conductivity was investigated. Results showed that by increasing the amount of La dopant in Pr site, both the above mentioned values decreased, whilst doping of Cu/Fe in Ni site led to increase of these values. Among the synthesized compounds, sample Pr1.9La0.1Ni0.7Cu0.25Fe0.05O4.31 showed the largest value of  together with the highest electrical conductivity: 81 S.cm-1 at the testing temperature of 500 °C for the latter and 0.31 at room temperature for the former
  9. Keywords:
  10. Doping ; Cathodes ; Solid Oxide Fuel Cell (SOFC) ; Stoichiometry ; Praseodymium Nickelate ; Crystalline Structure ; Pechini Method

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