Microwave Dielectric Properties and Defect Behavior of xTiO(2)-(1-x)SiO(2) Glass.

xTiO(2)-(1-x)SiO(2) (x = 2.9~8.2 mol%) glass specimens were synthesized using the flame hydrolysis technique. This study aimed to elucidate the influence of TiO(2) incorporation on the optical characteristics, defect behavior, and microwave dielectric performance of these materials. UV-vis and near-infrared spectroscopic analyses were employed to investigate the hydroxyl and optical bandgap properties. Electron paramagnetic resonance (EPR) and AC impedance spectroscopy were utilized to examine oxygen vacancies, Ti(3+) defects, and their respective behaviors. The findings revealed that, with increasing TiO(2) content, the generation and migration of defects became more favorable, consequently leading to higher dielectric losses. The imaginary component of the electric modulus experimental data was fitted using the modified Kohlrausch-Williams-Watts (KWW) function, while the frequency-dependent AC conductivity was analyzed using the Jonscher power law. The calculated activation energy exhibited a decreasing trend with increasing TiO(2) content, consistent with the characteristics of doubly ionized oxygen vacancies, suggesting the involvement of identical charge carriers in the relaxation and conduction mechanisms. Notably, the 8.2TiO(2)-91.8SiO(2) glass specimen demonstrated exceptional microwave dielectric performance, exhibiting ε(r) = 4.13, Q × f = 57,116 GHz, and τ(f) = -4.32 ppm/°C, rendering it a promising candidate for microwave substrate applications.