Abstract(s) :

(Anglais) This work is part of a project that aims at developing high-temperature pressure Surface Acoustic Waves sensors. For this purpose, piezoelectric glass-ceramics containing fresnoite crystals have been developed and successfully tested up to 800°C. However, parent glass crystallization needs to be further studied in order to control the glass-ceramic microstructure and properties. The glass-ceramic contains a crystalline pyroelectric and non-ferroelectric phase. Macroscopic piezoelectric properties are obtained if the crystallization leads to a preferential orientation of the c crystal’s polar axis (c-axis). The parent-glass composition is 2SrO-TiO2-3.3SiO2-0.1Al2O3-0.2K2O and the crystallization of this specific glass composition leads to a glass-ceramic composed of 70 vol% of Sr2TiSi2O8 crystals and 30 vol% of residual glass. Crystallization is performed by heating the parent glass plate up to a temperature ranging between 850°C and 950°C. For all temperatures, a surface nucleation mechanism leads to a crystallization front propagating from the surface into the bulk over time. Velocity of the front increases with temperature. XRD analyses show that a strong (002) planes preferential orientation is observed for low depth. After 100μm, a tilt to (201) planes is sometimes observed. However, its origin is not yet understood, and it was impossible, during this research, to relate this tilt to the different processing conditions.