Ferroelectric and piezoelectric properties of non-stoichiometric Sr1−xBi2+2x/3Ta2O9 ceramics prepared from sol–gel derived powders
✍ Scribed by Rajni Jain; Vinay Gupta; Abhai Mansingh; K. Sreenivas
- Publisher
- Elsevier Science
- Year
- 2004
- Tongue
- English
- Weight
- 188 KB
- Volume
- 112
- Category
- Article
- ISSN
- 0921-5107
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✦ Synopsis
Ceramic compositions of strontium bismuth tantalate (SBT) [Sr 1Àx Bi 2+2x/3 Ta 2 O 9 ] with x = 0.0, 0.15, 0.30, 0.45 prepared from a sol-gel process have been studied. Stoichiometric and non-stoichiometric phases stable within the series have been investigated for their structural, dielectric, ferroelectric, and piezoelectric properties. Sintering at 1000 8C produces a single homogeneous phase up to x = 0.15. With x > 0.15 an undesirable BiTaO 4 phase is detected and a higher sintering temperature (1100 8C) prevents the formation of this phase. The ferroelectric to paraelectric phase transition temperature (T c ) increases linearly from 325 to 455 8C up to x = 0.30, and with x > 0.30, it tends to deviate from the linear behavior. At x = 0.45 a broad and a weak transition is observed and the peak value of dielectric constant (e 0 max ) is significantly reduced. The piezoelectric coefficient (d 33 ), remnant polarization (2P r ), and coercive field (2E c ) values increase linearly up to x = 0.30. The degradation in the electrical properties for x > 0.30 are attributed to the presence of undesirable BiTaO 4 phase, which is difficult to identify by X-ray powder diffraction analysis (XRD) due to the close proximity of the peaks positions of BiTaO 4 and the SBT phase.