High-energy milled, Eu3Â +-doped fresnoite glass-ceramic powders: Structural characterization and luminescent properties

Fresnoite glass-ceramic powders were investigated as luminescent materials, due to their pronounced blue luminescence upon UV excitation. However, the luminescence intensity of mechanically milled luminescent materials decreases by reducing the particle size, because of the induced surface damage of the particles. Thus, the preparation of luminescent nano powders still represents a challenge in the processing of luminescent materials. In this work, different milling routes were carried out in order to achieve a submicron Eu3 +-doped Fresnoite (Ba2TiSi2O8) glass-ceramic powder, keeping sufficient luminescence intensity. The milling parameters studied were: milling medium, milling balls-to-powder mass ratio, rotation speed and time of milling. The microstructure of the powders was evaluated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The luminescence emission at UV excitation was recorded and related with the microstructure observed. The local environment of the Eu3 + ions changes with the particle size, as shown from the red-to-orange emission ratio. An optimized milling route is proposed, which enables to produce particles as small as possible with the highest possible emission intensity.