the effect of tio2 addition on the microstructure, crystallization and dielectric behavior of bao- al2o3- sio2 glass system

This study investigates the crystallization behavior, phase evolution, and dielectric properties of a bao-al2o3-sio2 glass system modified with 10 wt% tio2. thermal analysis revealed that tio2 addition reduced the glass transition temperature from 781.6°c to 779.4°c and the softening point from 838°c to 824.8°c, lowering the calculated nucleation temperature from 810°c to 800°c. differential thermal analysis indicated sluggish crystallization kinetics, with isothermal heat treatments identifying 1000°c as the optimal processing temperature. this led to the formation of a multiphase crystalline assemblage, including the target monoclinic ba3.75al7.5si8.5o32 phase, absent in the tio2-free glass, alongside celsian (baal2si2o8) polymorphs and barium titanate crystallites, as confirmed by x-ray diffraction. scanning electron microscopy revealed anisotropic crystal growth with lengths ranging from 1.14 to 1.52 μm. density measurements using the archimedes method showed that the titaniumcontaining glass had a density of 3.35 g/cm³, which increased to 3.85 g/cm³ after heat treatment at 1000°c for 48 hours. dielectric characterization in the ku-band (12.4–18 ghz) demonstrated enhanced properties, with the relative permittivity decreasing from 10.40 to 6.38 and the dielectric loss tangent improving from 0.3 to 0.2 postcrystallization. these enhancements, driven by the tailored crystalline phase assemblage facilitated by tio2, position this glass-ceramic system as a promising candidate for high-frequency microwave applications requiring low dielectric loss and stability. the role of tio2 as an effective crystallization modifier is highlighted, enabling optimized dielectric performance through controlled devitrification and targeted phase formation.