Improvement of piezoelectric properties of strontium Fresnoite glass-ceramics
Résumé
Most of piezoelectric sensors are made of ferroelectric ceramics. For high temperature applications, a problem occurs due to the depolarization of the ceramic at a temperature higher than its Curie temperature. To overcome this problem, pyroelectric non-ferroelectric ceramics can be used for these applications. However, the preferential orientation of the dipole moments needs to be induced during the fabrication process. It is possible through the glass ceramic synthesis process, which consists in crystallizing a parent glass to obtain a textured glass-ceramic. Strontium Fresnoite Sr2TiSi2O8 is a non-ferroelectric piezoelectric phase in which the dipole moment of the unit cell is oriented along the [00l] direction to induce a macroscopic polarization of the crystal phase in this direction. In the present research, crystallization within the glass-ceramic was achieved to study its piezoelectric properties and microstructure, by experimenting different crystallization temperatures. It was demonstrated that a thermal treatment at 1123 K leads to a finer microstructure and a better control of crystals orientation during the crystallization step. A tilt from (002) orientation to (201) orientation was also observed during this work