Sr-Substituted Barium Titanate Glass Ceramics from Oxide Glasses As Potential Material for Sensor Preparation
The present work reports on the synthesis of glasses in the system Na2O/Al2O3/BaO/SrO/TiO2/B2O3/SiO2/Fe2O3 from which, after appropriate thermal treatment, barium titanate and strontium-substituted barium titanate glass-ceramics are crystallized. The characteristic temperatures of the glasses are determined by differential scanning calorimetry DSC and show that higher alumina concentrations result in the stabilization of the glass network while an increasing Sr-concentration at constant alumina concentrations leads to a decrease of the glass transition temperature. The phase composition of the prepared materials was analysed by X-ray diffraction and shows precipitations of cubic barium titanate, BaTiO3 and strontium-substituted barium titanate, Ba1-xSrxTiO3. For isothermal treatments and longer annealing times, an additional crystalline phase occurs, i.e. fresnoite (Ba2TiSi2O8). The microstructure investigations of the glass ceramics by scanning electron microscopy witness the occurrence of globular bright crystals enriched in the heavier elements, here Ba, Sr and Ti.
KeywordsBarium-strontium titanate Glass-ceramics Phase separation Crystallization Sensors
This work is financially supported by contract NIS 11 663, Scientific sector of UCTM, Bulgaria and contract DN08/13, Bulgarian National Scientific Fund.
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