1. Effect of annealing under O2and H2on the piezoelectric parameters of the Ca12Al14O33single crystals
- Author
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Sébastien Fourcade, Rodolphe Decourt, Mario Maglione, Elias Castel, Encarnaçión García-Víllora, Kiyoshi Shimamura, and Tong Ik Shin
- Subjects
Crystal ,Permittivity ,Crystallography ,Materials science ,Piezoelectric coefficient ,Annealing (metallurgy) ,Surface acoustic wave ,General Physics and Astronomy ,Dielectric ,Conductivity ,Composite material ,Piezoelectricity - Abstract
Piezoelectric single-crystal ingots of Ca12Al14O33 were grown by Czochralski technique. Upon specific chemical reductions, this dielectric material can be turned into an oxygen solid electrolyte, a mixed conductor, or an electride. We followed the thermal evolution of the piezoelectric performances of as-grown samples and compared it with oxygen and hydrogen annealed ones. The structure of Ca12Al14O33 crystal was studied by powder x ray diffraction patterns, and the chemical processing efficiency was checked by optical transmittance measurements. The dielectric permittivity ɛ11 and piezoelectric coefficient d15 were found to be on the orders of 8–12 and 16–20 pC/N, respectively. This material exhibits good bulk shear wave coupling factor k14 about 0.34 and promising surface acoustic wave (SAW) velocities of 3500 m/s that render it suitable for SAW devices as a substrate. The piezoelectric response of crystals before and after annealing under H2 and O2 is maintained. The observed evolutions may be related to the conductivity of the material or the electrical transport properties, which are known to be sensitive to the oxygen and the hydrogen content.
- Published
- 2012
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