Dielectric and Piezoelectric Properties of Non-Stoichiometric Sr_1-xBi_2+2x/3Ta₂O₉ Ceramics Prepared from Sol-Gel Derived Powders

Sr _1-x Bi₂₊₂ x/3Ta₂O₉ ceramics with x = 0, 0.15, 0.30, 0.45 having Sr-deficiency and Bi-excess have been prepared using sol gel derived powders. Sintering at, 1000°C produced a homogeneous single-phase material up to x = 0.15. The presence of an undesirable phase BiTaO₄ is detected with x > 0.15, and a higher sintering temperature of 1100°C prevents the appearance of this phase. Poling under a dc electric field of 3 kV/mm reduced the dielectric dispersion for ceramics with x = 0 to 0.30 and there was no effect of poling on x = 0.45. The piezoelectric constant d₃₃ increased linearly with x for samples with x = 0 to 0.30, but for x = 0.45 a low value has been obtained. The difference in the dielectric behavior with x = 0.45, and a sudden drop in d₃₃ are analyzed and it is inferred that samples with x = 0.45 still retain the BiTaO₄ phase which could not be easily identified from the X-ray diffraction analysis.

Keywords:

• Sol-gel
• non-stoichiometric phases
• SBT
• dielectric
• piezoelectric

Acknowledgments

The authors thank Department of Science and Technology, India.

Paper originally presented at AMF-4, Bangalore, India, December 12–15, 2003