Ask for a reprint
email :
* Give your email
2022
ACL
|
M.Cholin, C.Genevois, P.Carles, J.Cornette, S.Chenu, M.Allix, G.Delaizir, P.Thomas, V.Couderc, J.R.Duclère, 'Highly transparent bismuth borotellurite glass-ceramics: Comprehension of crystallization mechanisms', J. Non-Cryst. Solids 598 121953 (2022) doi:10.1016/j.jnoncrysol.2022.121953
Understanding the mechanism at play during the partial crystallization of a parent glass remains crucial for controlling the optical properties of the final glass-ceramics. In this work, we study the crystallization of bismuth borotellurite glasses, where a specific investigation on the 60TeO2–20B2O3–20Bi2O3 composition is reported. Under adapted heat treatment conditions, highly transparent glass-ceramics can be obtained: the crystallization of the unique anti-glass Bi2Te4O11 phase is evidenced by X-ray diffraction and Raman spectroscopy data confirm its disordered nature. While the quenched glass appears homogeneous, the observation of the early stages glass-ceramic samples by transmission electron microscopy reveals the formation of isolated polycrystalline Bi2Te4O11 entities scattered in a predominant glassy matrix. However, longer heat-treatment of samples induce some chemical demixtion of the residual glass matrix, where two separate amorphous regions of a different composition coexist. The resulting material is finally constituted of the aforementioned Bi2Te4O11 polycrystalline clusters dispersed within a majority of regions with a Te/Bi ratio larger than the nominal 1.5 ratio, separated by tiny “venules” strongly impoverished in tellurium and also likely containing boron element. Photoluminescence properties of Eu3+-doped samples indicate that tiny spectral and temporal modifications happen with the crystallization, reflecting the persistent disordered surrounding of the rare-earth ions.
|
|
|