Abstract
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Highlights
1- The addition of 10 wt% TiO₂ to the BaO-Al₂O₃-SiO₂ glass system resulted in a notable reduction in the glass transition temperature (from 781.6°C to 779.4°C) and softening point (from 838°C to 824.8°C), consequently decreasing the calculated nucleation temperature (from 810°C to 800°C).
2- Isothermal heat treatments at 1000°C led to the development of a multiphase crystalline assemblage in the TiO₂-containing glass that beneficially included the target monoclinic Ba3.75Al7.5Si8.5O32 phase, which was absent in the TiO₂-free glass. X-ray diffraction analysis confirmed the presence of this phase, along with celsian (BaAl₂Si₂O8) polymorphs and barium titanate crystallites.
3-Dielectric characterization in the Ku-band (12.4-18 GHz) demonstrated significant property enhancements, with the relative permittivity decreasing from 10.40 to 6.38 and the loss tangent improving from 0.3 to 0.2 after crystallization.
4- These improvements in dielectric properties are attributed to the formation of the specifically tailored crystalline phase assemblage, including the desired Ba3.75Al7.5Si8.5O32 phase, and the controlled microstructure facilitated by TiO₂ addition.