Abstract
Four binary Li2O‐GeO2 crystals, Li4GeO4, Li6Ge2O7, Li2GeO3, and Li2Ge2O5, were synthesized through solid‐state sintering. In situ high‐temperature Raman spectroscopy, combined with theoretical calculations, was employed to qualitatively and quantitatively analyze the structure evolution from the crystalline to the molten state, as well as the melt microstructure. The study reveals that the melts of Li4GeO4, Li6Ge2O7, and Li2GeO3 are composed of [GeO4]4-, [Ge2O7]6-, and [GeO3]2- units, respectively, along with Li+ ions. In contrast, Li2Ge2O5 crystal undergoes a gradual transition from a three‐dimensional network structure formed by [GeO4]4- tetrahedra to smaller [Ge3O9]6- three‐membered rings as the temperature increases towards the melting point. The microstructure units and a series of model clusters have been designed, optimized, and calculated by quantum chemistry ab initio calculations. The computational simulation, in conjunction with the experiments, presents a novel method for correcting the experimental Raman spectra of the melts. By introducing the concept of delicate structure and employing Gaussian functions to deconvolute the stretching vibration band of non ‐ bridging oxygen in [GeO4]4- tetrahedra within Raman spectra, we quantitatively determined the distribution of structure units (Qi, where i denotes the number of bridging oxygens in each [GeO4]4- tetrahedron, i=0‐4) for these four crystals in their molten state.