Enhanced luminescence in rare-earth-free fast-sintering glass-ceramic

Abstract

[EN] One of the major challenges pursued in the luminescent materials community is to develop rare-earth-free phosphors in order to reduce the use of rare-earth elements, because of the lack of their availability and the environmental problems derived from their mining and processing. In this work, a rare-earth-free glass-ceramic-based phosphor with high photoluminescence has been designed. This novel phosphor rich in Na-rich plagioclase feldspar crystallizations presents high crystallinity, ~94%, and a dual micro-nanostructure provided by a fast-sintering processing route. Structural disorder in Si-Al distribution favors formation of luminescent centers in the glass-ceramic material, which results in an enhancement of both the UV-blue and the red luminescence regarding natural feldspars, 1 order of magnitude and 6 times, respectively. A microstructural and structural study by means of x-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, cathodoluminescence, and nuclear magnetic resonance evidence the important role of composition in the alteration of Si-Al ordering schemes. A strong correlation between Si-Al disorder and the presence of active luminescent centers is corroborated. Our research shows a sustainable, cost-effective, innovative, and scalable material that may be considered as an alternative to rare-earth phosphors for applications such as security markers or light-emitting glasses. This novel family of rare-earth-free glass-ceramics opens a new gate through structural tailoring to enhance and tune the intrinsic luminescent emissions displayed for relevant future optical applications.