Structural Elucidation of Lithium Borate Glasses Using XRD, FTIR, and EPR Spectroscopy

Area of Science:

• Materials Science
• Solid State Chemistry
• Glass Science

Background:

• Lithium borate (LiB) glasses are crucial in various applications.
• Understanding structural modifications by glass modifiers is essential for material design.

Purpose of the Study:

• To investigate structural changes in LiB glass with lead(II) oxide and aluminum oxide modifiers.
• To elucidate the role of glass modifiers on the borate network and identify crystalline phases.
• To characterize the vibrational modes and local structure of the glass using spectroscopic and computational methods.

Main Methods:

• X-ray Diffraction (XRD) for crystalline phase identification.
• Fourier Transform Infrared (FTIR) and Electron Paramagnetic Resonance (EPR) spectroscopy for structural analysis.
• Differential Thermal Analysis (DTA) for thermal properties.
• Semiempirical modeling (PM3MM) for vibrational modes and geometry.

Main Results:

• Aluminum oxide incorporation led to a lithium aluminum boron oxide crystalline phase.
• Lead(II) oxide addition disordered the glass structure, forming a lithium tetraborate phase.
• Analysis revised the presence of BO4 units to distorted-trigonal BO3 groups with nonbridging oxygen (NBO) atoms.
• EPR spectroscopy correlated NBOs with a specific signal at g ≈ 4.2.

Conclusions:

• Glass modifiers significantly alter the structure of lithium borate glasses.
• The study provides a revised understanding of borate structural units and the role of NBOs.
• Spectroscopic and computational methods effectively characterize glass structure and modifier interactions.