Spectroscopic study of the role of alkaline earth oxides in mixed borate glasses - site basicity, polarizability and glass structure

Hosam Othman , Hagar Elkholy , Maria Rita Cicconi (1) , Dimitrios Palles , Dominique de Ligny , Efstratios I. Kamitsos , Doris Möncke

1 IPGP (UMR_7154) - Institut de Physique du Globe de Paris

The effect of alkaline earth ions on the structure and properties of borate glasses near the metaborate composition was studied for two glass series, 30MO-10Li₂O-10Al₂O₃-50B₂O₃ with M=Mg, Ca, Sr or Ba and xMgO-(30-x)BaO-10Li₂O-10Al₂O₃-50B₂O₃ series, for undoped and doped (0.5 mol% MnO or CuO) glasses. Thermal and optical properties, including the optical basicity, were correlated with structural variations. IR and Raman spectra showed the highest N₄ fraction for the high basicity glasses, decreasing for higher field strength ions (Ba>Sr>Ca>Mg). As determined from far IR bands the mixing of dissimilar cations affects M-O interactions. The glass transition temperature T_g correlates well to the average bond strength of the compared alkaline earth ions. The redox ratio of Mn²⁺/Mn³⁺ or Cu²⁺/Cu⁺ shifted to lower valences in low basicity glasses. The optical basicity probe ion Mn²⁺ gives consistently higher values compared to the average optical basicity, suggesting that Mn²⁺ ions seek out high basicity ligands.

Keywords: Borate glasses; Force constant; Raman and IR spectroscopy; Structure property correlation; Optical basicity

Domains: Sciences of the Universe [physics]

Hosam Othman, Hagar Elkholy, Maria Rita Cicconi, Dimitrios Palles, Dominique de Ligny, et al.. Spectroscopic study of the role of alkaline earth oxides in mixed borate glasses - site basicity, polarizability and glass structure. Journal of Non-Crystalline Solids, 2020, 533, ⟨10.1016/j.jnoncrysol.2020.119892⟩. ⟨insu-03584795⟩