Improvement of composite sol–gel process for manufacturing 40 μm piezoelectric thick films
✍ Scribed by A. Bardaine; P. Boy; P. Belleville; O. Acher; F. Levassort
- Book ID
- 104022828
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 560 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0955-2219
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✦ Synopsis
In this study, high performance piezoelectric thick films were prepared by depositing only a few sol-gel infiltrated composite layers on Si/SiO 2 /Ti/Pt wafers. Lead zirconate titanate (PZT) powder, binder and infiltration sol were synthesised from the same-laboratory made time-stable polymeric PZT sol. Adding coarse powder (50 wt%) to the sol precursor, crack-free coatings were prepared by dip coating in the 30-50 m thickness range in only 3-6 layers. The results showed that good performance can be achieved by controlling sol concentration, powder charge, composite sol ageing, number of infiltrations and heat treatments. The initial results showed that only a limited number of infiltrations are needed in the final stack to obtain high piezoelectric performance. For instance, a 40 m thick film was prepared with 6 composite layers with a 0.7 M PZT sol charged with 50 wt% PZT powder after 2 months' ageing. Poling was performed for 5 min under 15 V/m in an oil bath at 170 • C after 5 infiltrations and final annealing at 700 • C for 10 min in RTA. Despite substrate clamping, this coating reached an effective thickness coupling factor up of to 39% at a resonance frequency of 30 MHz. This result was obtained with a non-doped PZT powder.
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