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Preparation and Characterization of BaFe2As2 Superconductor by Solid State Reaction

khezripour, Ramin | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46718 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Khosroabadi, Hossien; Akhavan Farshchi, Mohammad
  7. Abstract:
  8. The discovery of Iron-based superconductors with maximum transition temperature of 56 Kelvin and High critical magnetic field of the order of 50T at temperature 20K has created evolution in different fields of superconductivity including practical issues. BaFe2As2 family is one of the most important compounds of Iron-based superconductors and with different doping elements for instanse elements of the first column like Potassium inters superconducting state with critical temperature of 36K.
    The purpose of this thesis is to localize the technology of making this compound in Iran which no project has been done in this field in the country before. In this thesis manufacturing, Optimization and characterization of BaFe2As2 sample is done which its Crystal and electonic structure is determined by Density Functional Theory (DFT) in Advanced Materials Physics Laboratory of Physics Department. Raw materials for making this compound are Iron, Arsenic and barium with purity higher than 99%. In this thesis polycrystalline samples of the compound are made in different conditions such as the final temperature of thermal processes and duration of heating. Using various method presented in the thesis we conclude that polycrystalline sample of BaFe2As2 with standard solid-state method with precursors BaAs and Fe2As has the most quality and Single-phase structure. We made tablets of precursors BaAs and Fe2As by pressing iron, Arsenic and Barium powders with appropriate stoichiometric ratio and put tablets inside a quartz tube afterwards which was closed at one end. Then we closed the open end while vacuumed inside of the tube and after that increased temperature to 400 ° C and 800 ° C respectively. Using these precursors with appropriate stoichiometric ratio, BaFe2As2 compound was made by performing the above steps and increasing the temperature to 850 ° C. In order to prevent oxidation of barium, all processes except thermal processes were done in glove box under argon atmosphere.
    Characterization experiments such as XRD، SEM، EDX و ICP are done for the sample. XRD experiment shows that BaFe2As2 is single-phased. Crystal structure and lattice parameters of this compound are determined by analysis of the experimental data by available computational software. To study the formation of grains SEM experiment is done which shows that the grains have a uniform distribution with a size of about 1-5μm. EDX experiment is used to determine the elemental composition of some of composed sample grains and stoichiometry of the compound obtained. ICP experiment is done for this compound to complete EDX experiment and it was found that the compound Ba1Fe1.5As1.3 comprises more than 94 percent of the total composition. These experiments are in good agreement with references reported in this thesis
  9. Keywords:
  10. Construction ; Iron Based Superconductor ; Characterization ; Determine Phases Formed

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