P7

Synthesis of a piezoelectric glass ceramic by the powder sintering route

S. Satha, M. Gonon

Materials science department, University of Mons, Belgium
Soufyane.SATHA@student.umons.ac.be

Glass-ceramics based on Sr₂TiSi₂O₈ fresnoite crystals are non-ferroelectric piezoelectric materials able to work at high temperature. Previous research has highlighted the high potential of these materials for the design of SAW devices.

The conventional route for the synthesis of the glass-ceramics is the controlled crystallization of a parent glass shaped at high temperature. However, this technology shows limitations in terms of the geometry of the desired object.

The objective of this communication is to present an alternative route based on the sintering and controlled crystallization of a green object made from a powder of the parent glass. This route would allow all the conventional and advanced shaping technics currently used in the ceramic industry (pressing, casting …).

However, in the case of the fresnoite glass-ceramics, the crystallization treatment must be operated on a fully dense parent glass. This requirement is due to the need of a surface crystallization mechanism to preferentially orient the non-ferroelectric crystals.

To achieve this goal, several grinding conditions of the parent glass were tested. The so obtained glass powders were used for shaping cylindrical samples by pressing or slip casting. Compactness of the green samples was characterized. The influence of the sintering conditions (heating rate, temperature on holding time of the plateau) on the densification and crystallization was then investigated.

At this stage of the work, it has not yet been possible to reach the full density before the beginning of the crystallization. The best results obtained are a 98.7% of relative density for pressing and 98.5% for casting. For a same relative density, crystallization is more extensive with pressing.

The go further, the compactness of the green body must be increased. This can be obtained by the control of the grain size distribution of the glass powder and the shaping parameters.

Reference

Dupla Florian, Renoirt Marie-Sophie, Gonon Maurice, Smagin Nikolay, Duquennoy Marc, Martic Grégory, Erauw Jean-Pierre, "A lead-free non-ferroelectric piezoelectric glass-ceramic for high temperature surface acoustic wave devices" in Journal of the European Ceramic Society, 40, 11, 3759-3765 (2020)