Structural studies on the low-melting boron frits modified with bismuth (III) oxide

Abstract

This work elucidated the effect of the addition of bismuth (III) oxide on the structure of low-melting boron frits applied for the production of ceramic roof tiles. Three commercial frits differing in the content of either alkali or glass forming/modifyng oxide (SiO2/B2O3/Al2O3), were modified with 5 or 10 wt% of Bi2O3. X-Ray Diffraction (XRD) analysis and spectroscopic studies (Fourier Transformed Infrared Spectroscopy – FTIR and Raman spectroscopy) proved the important role of Bi2O3 on the structure of both low-alkali and high-boron frits. Biincorporated in the form of distorted [BiO6] octahedral units, acted as a typical glass modifier, inducing NBOs’ (B-O−) formation. Moreover, such a low Bi2O3 addition yielded enhanced boron anomaly, thereby severe depolymerization of borate network explaining the beneficial improvement in technological properties of the investigated frits. However, it occurred only in case of the sufficiently high content of Al2O3, which stabilized amorphous network and introduced Bi3+ cations.