Morsy Mohamed A, Garrison Thomas F, Kessler Michael R, Mhareb Mohammad H A, El-Deen Hosny Zahr
Chemistry Department, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, Maryland 21218, United States.
ACS Phys Chem Au. 2025 Feb 11;5(2):227-238. doi: 10.1021/acsphyschemau.4c00106. eCollection 2025 Mar 26.
A detailed investigation of the structural changes of lithium borate (LiB) glass 25LiO-(75 - )BO was conducted in the absence and presence of lead(II) oxide or aluminum oxide ( = 10 mol %) glass modifiers. X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electron paramagnetic resonance (EPR) spectroscopy were used to explore the structural properties of LiB glass by incorporating trace amounts of manganese(III) oxide (0.00-0.25 mol %) as a probe. Differential thermal analysis and XRD results for the glasses and their ceramics confirmed the integration of aluminum atoms into the glass framework by forming a lithium aluminum boron oxide Li(AlBO) crystalline phase. Lead atoms were located interstitially, which disordered the borate glass structure and produced a lithium tetraborate crystalline phase. Semiempirical modeling of the glass structures was conducted to estimate the fundamental vibrational modes of the glass materials using a parametric method 3 (PM3MM) with molecular mechanics corrections to elucidate the geometry of the borate (BO) groups and their possible vibrational modes. Our analysis revised the conventional representation of the tetrahedral BO units, which were not observed, to "distorted-trigonal" BO groups and associated with nonbridging oxygen (NBO) atoms. EPR spectroscopy established a link between the NBO in oxides and the well-defined peak at -factor ∼4.2 in glass materials, which had been assigned to iron(III) ions according to the literature.
在不存在和存在氧化铅或氧化铝（=10摩尔%）玻璃改性剂的情况下，对硼酸锂（LiB）玻璃25LiO-(75 - )BO的结构变化进行了详细研究。通过加入痕量氧化锰（0.00 - 0.25摩尔%）作为探针，利用X射线衍射（XRD）、傅里叶变换红外（FTIR）和电子顺磁共振（EPR）光谱来探究LiB玻璃的结构性质。玻璃及其陶瓷的差示热分析和XRD结果证实，铝原子通过形成锂铝硼氧化物Li(AlBO)晶相融入玻璃骨架。铅原子位于间隙位置，这使硼酸盐玻璃结构无序，并产生了四硼酸锂晶相。利用具有分子力学校正的参数方法3（PM3MM）对玻璃结构进行半经验建模，以估计玻璃材料的基本振动模式，从而阐明硼酸盐（BO）基团的几何结构及其可能的振动模式。我们的分析将未观察到的四面体BO单元的传统表示形式修正为“扭曲三角”BO基团，并与非桥氧（NBO）原子相关联。EPR光谱在氧化物中的NBO与玻璃材料中g因子约为4.2处明确的峰之间建立了联系，根据文献，该峰曾被归属于铁（III）离子。
