Sr2TiSi2O8 (STS) Polar Glass-Ceramics: Effect of Na2O and CaO Additions in the Parent Glass on the Crystallization Mechanism and on the Piezoelectric Properties

Glass-ceramics containing pyroelectric Sr2TiSi2O8 (STS) crystals are produced from parent glasses of compositions STS + 0.8 SiO2 (0.2 − x) Na2O x CaO, with = 0; 0.05; 0.10; and 0.15. The aim this work is to investigate the effect additions stoichiometric composition on crystallization mechanisms piezoelectric properties glass-ceramic. DSC analyses evidence that glass transition temperatures Tg, onset temperature peak To Tc maximum increase CaO/Na2O ratio. On basis data, samples was operated by thermal treatment. observation cross-sections heat-treated highlights competition between surface volume influenced ratio temperature. For all samples, XRD performed surfaces as obtained after treatment evidenced a preferential orientation plans (00l) parallel surface. grinding show only crystallized layers preferentially oriented. Moreover, changes in (202) or (201) observed over depth, depending These influence polarization layer and, consequently, its charge coefficient d33. highest values d33 were measured glass-ceramic exhibiting mainly their thickness.