Abstract
This study aims to elucidate the structural evolution of Ta5+ in the binary Li2O-Ta2O5 melts. The melt structure was characterized by using in situ high-temperature Raman spectroscopy. Combined with constructed Ta-O cluster models and quantum chemistry ab initio calculations to simulate Raman spectra, quantitative analysis of different coordination structures in melts was achieved by the deconvolution of the experimental spectra. Furthermore, the influence of Li2O content on melt microstructure was systematically investigated via high-energy X-ray scattering and empirical potential structure refinement simulations. Results reveal the coexistence of three coordination species ([TaO4], [TaO5], and [TaO6]) in melts. Their distribution exhibits a regular evolution with increasing Li2O content: the proportions of five- and six-coordinated Ta-O species gradually decrease, while the four-coordinated Ta-O species increases significantly. This work provides crucial theoretical support for establishing correlations between species with various coordination structures and physical properties in binary Li2O-Ta2O5 melts, as well as for optimizing interfacial dynamics through controlled crystal growth parameters.