Structural study of the Eu3+ environments in fluorozirconate glasses: Role of the temperature-induced and the pressure-induced phase transition processes in the development of a rare earth's local structure model
Estudio de la correlación entre la estructura de los entornos locales del ion Eu3+ en un vidrio fluorozirconato y sus propiedades ópticas.The correlation between the optical properties of the Eu3+ ions and their local structures in fluorozirconate glasses and glass-ceramics have been analyzed by means of steady-state and time-resolved site-selective laser spectroscopies. Changes in the crystal-field interaction, ranging from weak to medium strength values, are observed monitoring the luminescence and the lifetime of the Eu3+ ions in different local environments in the glass. As key roles in this study, the Eu3+ luminescence in the thermally-induced crystallization of the glass and the pressure-induced amorphization of the crystalline phase of the glass-ceramic experimentally states the existence of a parent local structure for the Eu3+ ions in the glass, identified as the EuZrF7 crystalline phase. Starting from the ab initio single overlap model, crystal-field calculations have been performed in the glass and the glass-ceramic. A simple geometrical model based on a continuous distortion of the parent structure is proposed for the distribution of local environments of the Eu3+ ions in the fluorozirconate glass.