The role of fluorine in high quantum yield oxyfluoride glasses and glass-ceramics
Résumé
Oxyfluoride glass-ceramics is considered a great candidate for optical refrigeration. Their ability to form low-phonon fluoride crystals embedded in an oxide glass matrix presents great interest for the development of fluorescent efficient materials with good mechanical and thermal resistance. A better understanding of the material microstructure and its relations on properties is mandatory to achieve the required optical refrigeration values. In the present work, we discuss the effect of fluoride compound evaporations and their impacts on thermal, optical, crystallization, and luminescent properties. Using different melting temperatures, glass samples from the theoretical molar composition 37.6 SiO2-22.4 Al2O3-19 YF3-20 LiF-1 YbF3 are fabricated by the meltquenching method. The relation between composition and glass properties is assessed by measurement of glass transition, crystallization temperature, density, refractive index, and optical transmission. A detailed study of the crystallization behavior of the samples is conducted using scanning and transmission electron microscopies, and both classical and temperature in-situ x-ray diffractions. Finally, luminescent properties are measured, including quantum yield, and both steady-state and time-resolved spectroscopies.
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