Preparation and Properties of BaBiBO ₄ –SiO ₂ Glasses

Glasses in the new system (100− x ) BaBiBO ₄ – x SiO ₂ where x =10–50 (mol%) were prepared by the melt‐quench technique. The density of the glasses increases with an increase in BaBiBO ₄ content because of its higher molecular mass. T _g , T _d , and T _s decrease while coefficient of thermal expansion increases with the increase in BaBiBO ₄ content. Vis‐NIR spectra reveal that with increasing melting temperature transmission of the glasses decreases due to auto thermal reduction of Bi ³⁺ to Bi ⁰ as confirmed by transmission electron microscopy and selected area electron diffraction analyses. Fourier transform infrared reflection spectroscopic spectra of the glasses indicate the formation of BiO ₆ , BO ₃ , and BO ₄ structural units. Ferroelectric BaBiBO ₄ crystalline phase is obtained from these glasses by controlled heat treatment at 580°C. X‐ray diffraction analysis reveals its 45–66 nm crystallite size range. Whereas, the field‐emission scanning electron microscopy images show the formation of polycrystalline spherical grains of 89–194 nm along with single‐crystalline microrods of average diameter of 0.5–1.5 μm. Dielectric constant of the glasses increases with increase in BaBiBO ₄ content, which is attributed to the combined effects of high polarization and ionic refraction of both Bi ³⁺ and Ba ²⁺ ions. It is shown here that BaBiBO ₄ –SiO ₂ is a promising glass system for the synthesis of glass–ceramics of novel BaBiBO ₄ nonlinear optical crystal.