Enhanced luminescence in rare earth free fast sintering glass ceramic
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.
Optica