Structural and dielectric characteristics of Bi2O3 -TiO2-SrB4O7 glasses

Glasses of the composition 0.20 Bi₂O₃-0.30 TiO₂-0.50 SrB₄O₇ and 0.30 Bi₂O₃-0.45 TiO₂-0.25 SrB₄O ₇ have been fabricated by a conventional glass processing technique. These glasses have been characterized using X-ray powder diffraction (XRD), differential thermal analysis (DTA) and high resolution transmission electron microscopy (HRTEM). The frequency response of the dielectric constant and the loss tangent of these glasses has been studied. The formation of the crystalline bismuth titanate, Bi₄Ti₃O₁₂ (BiT) phase in the heat treated samples has been confirmed by XRD and HRTEM studies. The measured ε_τ of the glass-ceramics is found to be in good agreement with those predicted by the logarithmic mixture rule. Optical second harmonic generation (SHG) at 1064 nm has been observed in the heat treated samples and is attributed to the formation of the crystalline Bi₄Ti₃O₁₂ (BiT) phase in the SrB₄O₇ (SBO) matrix