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Investigation of Sintering Behavior of BaTiO3 Nanoparticles Synthesized Via Hydrothermal Method

Soroush, Soheil | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 40254 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Nemati, Ali; Simchi, Abdolreza
  7. Abstract:
  8. In the present work, Barium Titanate nanoparticles were synthesized by a facile hydrothermal method at 180oC for 4 hours and their sintering behavior was studied. The characterization tests illustrated that the obtained powder was BaTiO3 single phase with excess Ti content from stoichiometric composition. The average particle size of about 50 nm and a narrow particle size distribution was noticed. SEM investigations showed that the samples sintered at temperatures less than 1250oC had plate-like grains. This behavior resulted from twin plates existed in the grains and facetted grain boundaries. At the temperatures more than 1250oC, the grains became polygonal due to the formation of trace elements eutectics. Therefore, grain boundaries were altered from facetted boundaries to rough ones. The grain growth of the samples which were sintered between 1250 and 1300oC was studied kinetically and the grain growth exponent and activation energy for grain growth were calculated to be 2.8 and 950±54 kJ mol-1, respectively. Based on the calculated grain growth exponent and studying the SEM results, the grain growth mechanism was proposed to be Ostwald ripening. A comparison between the calculated activation energies of grain growth and defects which favorably formed in the BaTiO3 system, a mechanism was proposed to control the grain growth mechanism. The formation of schottky defect (Oxygen vacancy and Barium vacancy) and diffusion of Barium vacancies are found to be responsible for the observed phenomenon.

  9. Keywords:
  10. Barium Titanat ; Sintering ; Grain Growth ; Hydrothermal Synthesis

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