Journal of Materials Science

, Volume 24, Issue 10, pp 3478–3482 | Cite as

The effect of aluminium on the electrical and mechanical properties of BaTiO3 ceramics as a function of sintering temperature

Part 2 Mechanical properties
  • T. V. Parry
  • H. M. Al-Allak
  • G. J. Russell
  • J. Woods


The effect of aluminium additions on the mechanical behaviour of BaTiO3 positive temperature coefficient of resistance ceramics sintered in air at temperatures ranging between 1220 and 1400° C has been investigated. Tensile strength has been measured indirectly by the diametral compression of lapped discs using concave loading anvils. Values of ∼ 85 and ∼ 110 MPa for samples fired near their optimum sintering temperature were determined for two batches of material, the latter of which contained additions of Al2O3 (0.55 mol%). Strength did not vary systematically with grain size and appeared to be controlled by near surface defects. The size of these cavities, which were generally crescent shaped, was consistent with the material having a bulk fracture toughness of ∼1.3 MPam1/2. The higher mechanical strength of samples which contained Al2O3 additions was attributed to the enhanced “healing up” of these cavities by the liquid phase giving a smaller inherent critical defect size rather than by increasing the bulk toughness of the ceramic.


Al2O3 Tensile Strength Fracture Toughness BaTiO3 High Mechanical Strength 
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Copyright information

© Chapman and Hall Ltd. 1989

Authors and Affiliations

  • T. V. Parry
    • 1
  • H. M. Al-Allak
  • G. J. Russell
  • J. Woods
  1. 1.Applied Mechanics and Applied Physics Groups, School of Engineering and Applied ScienceUniversity of Durham, Science LaboratoriesDurhamUK

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