Laura Fernández-Rodríguez

Sm ³⁺ ‐doped and Sm ³⁺ /Dy ³⁺ codoped SiO ₂ –SrO–MgO glasses were prepared by conventional melt quenching and Sr ₂ MgSi ₂ O ₇ based glass–ceramics from sintering and crystallization of the glass powders. The thermal, structural, and optical properties of the glasses and glass–ceramics were investigated as a function of the dopant concentration. The optical characterization includes the photoluminescence spectra and the lifetimes of the ⁴ G _5/2 (Sm ³⁺ ) and ⁴ F _9/2 (Dy ³⁺ ) excited states. In Sm ³⁺ single‐doped samples, the emission intensity increases up to a concentration of 0.3 mol% Sm ³⁺ ions and then decreases due to nonradiative energy transfer processes. The emission spectra in the glass–ceramics show a more resolved structure and higher intensity compared to the glass samples, suggesting a different and crystalline environment for the Sm ³⁺ ions. The non‐radiative processes also influence the experimental decays of the glass samples which deviate from a single exponential with lifetimes decreasing as Sm ³⁺ concentration increases. The emission and excitation spectra of the codoped samples do not show significant energy transfer between Sm ³⁺ and Dy ³⁺ ions. Different emitting colors can be obtained in the codoped glasses by changing the excitation wavelength. The studied glass–ceramics could be applied as enamels on ceramic or metallic substrates.

In this study, glass-ceramics based on Sr₂MgSi₂O₇ phosphor co-doped with Eu/Dy were obtained from the sintering and crystallisation of glass powders. The glasses were melted in a gas furnace to simulate an industrial process, and the dopant concentration was varied to optimise the luminescence persistence times. The doped parent glasses showed red emission under UV light excitation due to the doping of Eu³⁺ ions, while the corresponding glass-ceramics showed persistent blue emission corresponding to the presence of Eu²⁺ in the crystalline environment. The dopant concentration had a strong impact on the sintering/crystallisation kinetics affecting the final glass-ceramic microstructure. The microstructures and morphology of the crystals responsible for the blue emission were observed by scanning electron microscopy–cathodoluminescence. The composition of the crystallised phases and the distribution of rare-earth (RE) ions in the crystals and in the residual glassy phase were determined by X-ray diffraction and energy dispersive X-ray analysis. The emission and persistence of phosphorescence were studied by photoluminescence.