Effect of aluminum oxide on the structure and conduction behaviors of silver borate glasses

Abstract

ABSTRACT. The current study focuses on glass preparation and characterization in the glass system of chemical formula xAl₂O₃ (35-x) Ag₂O.65B₂O₃ (0≤x≤35 mol%), where Ag₂O is replaced with Al₂O₃. To examine a wide range of both structure and morphology of the prepared glasses, nuclear magnetic resonance (NMR) of ²⁷Al nuclei, X-ray diffraction (XRD) spectroscopy, and transmission electron microscopy (TEM) are used. In Al₂O₃-rich glass, the well-formed AlO₆, AlO₅, and AlO₄ structural groups are the well-formed units. In samples of (20 and 30 mol % Al₂O₃), tetrahedral AlO₄ and traces from AlO₆ units could be detected. At lower concentrations of Al₂O₃ (10 mol%), the dominant forming unit is only AlO₄ groups containing non-bridging oxygen bonds (NBO). The XRD spectra confirm the amorphous nature of the glasses of Al₂O₃ ˂20 mol% while glasses of higher Al₂O₃ concentrations contain crystalline Ag₂Al₂B₂O₇ formed due to the higher oxygen packaging of the mixed AlO₅ and AlO₄ compared with that of glasses containing only AlO₄ species only. The morphology of crystalline units is confirmed from TEM to differ from that of an amorphous composition. The increase of activation energy and the hardness number of the glasses led to an increase in the durability of the investigated glasses.

KEY WORDS: Aluminum borate glass, NMR, Coordination of aluminum atom, Conductivity, Crystallization process

Bull. Chem. Soc. Ethiop. 2022, 36(3), 597-606.                                                              

DOI: https://dx.doi.org/10.4314/bcse.v36i3.9