A DFT-based model to the interpretation of DC conductivity in transition metals doped zinc phosphate glass

Ternary zinc–sodium–phosphate glasses doped with transition metal of the composition Na2MxZn1−xP2O7(x = 0, 1, 2 and 5 mol %) (where M = Ni, Cu and Co) were prepared by the traditional quenching method. The ac conductivity measurements at different temperatures for the prepared glasses have been investigated, and the activation energy for dc conduction has been determined in each transition metal doped sample. The results showed that the evolution of the activation energy of the conductivity depends on the nature of the dopant ions. A model based on formal density functional theory concept in which the electrical charge exchanged between the transition-metal cations and the surrounding material surface is proposed. The outcome is a “simplified” formula which allows us to explain the evolution of the ionic dc conductivity activation energy as a function of the doped ion in interaction with the cation and the surface.

Three-Dimensional High Spatial Localization of Efficient Resonant Energy Transfer from Laser-Assisted Precipitated Silver Clusters to Trivalent Europium Ions

We report on the 3D precipitation, using a direct laser writing approach, of highly fluorescent silver clusters in a Eu3+-doped silver-containing zinc phosphate glass. Micro-spectroscopy of fluorescence emission shows the ability to continuously adjust the local tri-chromatic coordinates in the CIE (Commission Internationale de l’Éclairage) chromaticity diagram between red and white colors, thanks to the laser-deposited dose and resulting tunable combination of emissions from Eu3+ and silver clusters. Moreover, continuous-wave and time-resolved FAST-FLIM spectroscopies showed a significant enhancement of the fluorescence emission of Eu3+ ions while being co-located with UV-excited laser-inscribed silver clusters. These results demonstrate the ability to perform efficient resonant non-radiative energy transfer from excited silver clusters to Eu3+, allowing such energy transfer to be highly localized on demand thanks to laser inscription. Such results open the route to 3D printing of the rare earth ions emission in glass.