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Journal of Materials Science

, Volume 29, Issue 18, pp 4866–4874 | Cite as

Evolution of the microstructure of undoped and Nb-doped SrTiO3

  • S. G. Cho
  • P. F. Johnson
Papers

Abstract

Undoped and Nb-doped SrTiO3 specimens with excess titania compositions were prepared by sintering in air at 1420 or 1480 °C. Large grains due to liquid-phase sintering were obtained for undoped specimens containing ⩾ 0.6 mol % excess titania and fired at 1480 °C. On the other hand uniform fine grains were observed for samples fired at 1420 °C, resulting from grain-growth inhibition due to exsolved TiO2 second phase. The solubility of excess titania seemed less than 0.2 mol% under our experimental conditions. The microstructural behaviour of Nb-doped SrTiO3 could be explained well by the Sr-vacancy compensation model. According to this model, the solubility of excess titania in SrTiO3 increased with Nb2O5 dopant concentration. Thus, for specimens which had high excess titania compositions and were sintered at 1480 °C, large grains were observed when the Nb content was low enough to retain sufficient excess titania-forming liquid phase. For specimens having the same compositions and fired at 1420 °C, uniform fine grains were obtained due to grain growth inhibition by the exsolved TiO2 second phase, when the Nb content was low. If the excess titania was less than the solubility determined by the amount of Nb dopant, Ruddlesden-Popper-type phases were believed to be formed and resulted in poor densification. Although excess titania was the major factor in determining the grain size of the specimens, the niobium dopant enhanced grain growth.

Keywords

Grain Size Microstructure TiO2 Titania Liquid Phase 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • S. G. Cho
    • 1
  • P. F. Johnson
    • 2
  1. 1.Department of Electronic Materials EngineeringGyeongsang National UniversityChinju, GyeongnamKorea
  2. 2.NYS College of CeramicsAlfred UniversityAlfredUSA

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