Competition between surface and volume crystallization in the Sr-Ti-Si-Na-Ca-O glass system
S. SATHA1 ; T. ZANIN1 ; M. GONON1 ; H. SATHA2, S ABDELOUHAB3
1 Materials science department, University of Mons
2 Materials science department, Université 8 mai 1945 Guelma, Algeria
3 Belgian Ceramic Research Center, Mons, Belgium
Email: Soufyane.Satha@student.umons.ac.be
The synthesis of glass-ceramics composed of pyroelectric strontium fresnoite crystals Sr2TiSi2O8 (STS) and a residual glass 0.8 SiO2 + (0.2 – x) Na2O + x CaO (with x = 0; 0.05; 0.10, 0.15) is investigated. The objective is to study the influence of the CaO/Na2O ratio on the parent glass properties and on the crystallization mechanisms.
The crystallization of the parent glass samples was operated by thermal treatment at 850°C, 900°C and 950°C with various holding time.
The observation of the cross-section of the sample after thermal treatment highlights that the competition between the surface and volume crystallization mechanisms is influenced by the CaO/Na2O ratio and the maximal temperature of the treatment. For CaO/Na2O = 0 and 0.33 the volume crystallization dominates at all the temperatures tested. Conversely, only the surface mechanism is observed for CaO/Na2O = 1 at 850°C, and 3 at 850°C, 900°C and 950°C.