Investigation on crystallization kinetics and microstructure of novel transparent glass ceramics containing Nd:NaYF4 nano-crystals

Nd3+-doped transparent oxyfluoride glass ceramics containing NaYF4 nano-crystals were prepared by melt-quenching and subsequent heating, and the crystallization kinetics of NaYF4 from the glass was investigated for the first time. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) investigation reveal that spherical NaYF4 nano-crystals are distributed homogeneously among the glassy matrix for the sample doped with 1% Nd3+ and heated at 620 °C for 2 h. The kinetics study indicates that the mean apparent activation energy Ea and Avrami exponent n of the crystallization are 315 kJ/mol and 1.77, respectively, suggesting the crystallization being a diffusion-controlled growth process of particles with decreasing nucleation rate. The XRD data demonstrate a durative lattice expansion of cubic NaYF4 with the increasing of Nd3+ content in the sample, indicating the incorporation of Nd3+ into the crystallites which is further verified by the energy dispersive X-ray spectroscopy (EDS) and absorption spectra analyses of Nd3+ in glass and glass ceramic.