Preparation of novel transparent glass-ceramics containing fluoride crystals

Transparent glass-ceramics containing YLiF4 nano-crystals were synthesized by controlled heat-treatments of LiF-YE3-Al2O3-SiO2 glass. The crystallite size estimated to be about 8 nm was much less than the wavelength of the visible light. The transmittance of the glass-ceramic with a thickness of 2 mm was more than 85% at 400 nm and as high as 95% in the infrared region. The fluorescence centered around 1000 nm was hardly observed from Er3+-doped precursor glass under 800 nm excitation, while the emission with the Stark spitting was clearly observed for the Er-doped glass-ceramic. The phonon sideband of the F-7(0)-> D-5(2) excitation spectra of Eu3+ reveals that Eu3+ doped in precursor glass is in silicate network while Eu3+ doped in the glass-ceramic is in not only silicate framework but also fluoride framework. These results indicate that rare-earth ions such as Er3+ and Eu3+ could be successfully incorporated into YLiF4 nano-crystals in the glass-ceramics. (C) 2011 Elsevier B.V. All rights reserved.