Evolution of Photoluminescence across Dimensionality in Lanthanide Silicates

The dehydratation process of layered lanthanide silicates K3[LnSi3O8(OH)2], Ln = Y, Eu, Tb, and Er, and the structural characterization of the obtained small-pore framework K3LnSi3O9, Ln = Y, Eu, Tb, and Er solids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-ray diffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electron microscopy, and 29Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 have been studied and compared with those of AV-22. Both materials have a similar chemical makeup and structures sharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution of the PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a single crystallographic Tb3+ site, PL spectroscopy indicates the presence of Ln3+ centers in regular framework positions and in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln3+ environment, namely, Eu3+ ions replacing K+ ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samples are of the same order of magnitude as those of standard Tb3+ green phosphors. For the samples K3(Y1-aEraSi3O9), a = 0.005−1, efficient emission and larger 4I13/2 lifetimes (ca. 7 ms) are detected for low Er3+ content, indicating that the Er3+−Er3+ interactions become significant as the Er3+ content increases

Evolution of Photoluminescence across Dimensionality in Lanthanide Silicates

The dehydratation process of layered lanthanide silicates K3[LnSi3O8(OH)2], Ln = Y, Eu, Tb, and Er, and the structural characterization of the obtained small-pore framework K3LnSi3O9, Ln = Y, Eu, Tb, and Er solids, named AV-23, have been reported. The structure of AV-23 has been solved by single-crystal X-ray diffraction (XRD) methods and further characterized by chemical analysis, thermogravimetry, scanning electron microscopy, and 29Si MAS NMR. The photoluminescence (PL), radiance, and lifetime values of AV-23 have been studied and compared with those of AV-22. Both materials have a similar chemical makeup and structures sharing analogous building blocks, hence providing a unique opportunity for rationalizing the evolution of the PL properties of lanthanide silicates across dimensionality. Although Tb-AV-23 contains a single crystallographic Tb3+ site, PL spectroscopy indicates the presence of Ln3+ centers in regular framework positions and in defect regions. PL evidence suggests that Eu-AV-23 contains a third type of Ln3+ environment, namely, Eu3+ ions replacing K+ ions in the micropores. The radiance values of the Tb-AV-22 and Tb-AV-23 samples are of the same order of magnitude as those of standard Tb3+ green phosphors. For the samples K3(Y1-aEraSi3O9), a = 0.005−1, efficient emission and larger 4I13/2 lifetimes (ca. 7 ms) are detected for low Er3+ content, indicating that the Er3+−Er3+ interactions become significant as the Er3+ content increases

Photoluminescent Layered Lanthanide Silicate Nanoparticles

The first examples of nanoparticles of pure layered Ln2(SiO4H)(OH)2(H2O)Cl (where Ln ) Eu, Gd, and Tb) and mixed microcrystalline layered lanthanide silicates containing different Eu/Gd and Tb/Gd ratios have been reported. The crystal structure of these silicates has been solved from synchrotron powder X-ray diffraction data. These materials display interesting and tuneable photoluminescence (PL) properties, such as energy transfer between different Ln3+ centers, illustrated here with the pairs Eu3+/Gd3+ and Tb3+/Gd3+. The PL properties of the mixed Eu3+/Gd3+ sample change upon F– for Cl- ion exchange, and this raises the possibility that this material may be exploited for sensing these ions

Synthesis, texture, and photoluminescence of lanthanide-containing chitosan-silica hybrids

Three different types of photoluminescent hybrid materials containing trivalent lanthanide (Ln3+ ) Eu3+, Tb3+) ions, chitosan, and silica have been prepared with different structural features. The different silica sources lead to diverse microstructures of hybrid materials, with silica being homogeneously dispersed in the chitosan materials (LnChS-H), or forming a core-shell morphology. Postsynthesis treatment is necessary for embedding the luminescent probe. The Ln3+-based materials have been investigated by photoluminescence spectroscopy (12-300 K). The chitosan-Eu3+-related local environment is maintained in the EuChS-H hybrid material. The emission features of the core-shell materials are characterized by the presence of two Eu3+ distinct local environments, one associated with the chitosan core and the other with the silica shell