Synthesis of monodisperse spherical core-shell SiO₂-SrAl₂Si₂O₈: Eu²⁺phosphors by hydrothermal homogeneous precipitation method

Abstract

Nanocrystalline SrAl 2 Si 2 O 8 : Eu 2+ phosphor layers were coated on nonaggregated, monodisperse and spherical SiO 2 particles using a hydrothermal homogeneous precipitation. After annealing at 1100 • C, core-shell SiO 2 @SrAl 2 Si 2 O 8 : Eu 2+ particles were obtained. They were characterized with x-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy and photoluminescence techniques. XRD analysis confirmed the formation of SiO 2 @SrAl 2 Si 2 O 8 : Eu 2+ particles; it indicated that the SrAl 2 Si 2 O 8 : Eu 2+ shells on SiO 2 particles consisted of hexagonal crystallites. The core-shell phosphors obtained are well-dispersed submicron spherical particles with a narrow size distribution. The thickness of the coated layer is approximately 20-40 nm. Under ultraviolet excitation (361 nm), the particles emit blue light at about 440 nm due to the Eu 2+ ions in their shells.

Lanthanide-Activated Phosphors Based on 4f-5d Optical Transitions: Theoretical and Experimental Aspects

“…These special synthetic conditions significantly affect the diffusion behaviors of the starting materials as well as the way single nanoclusters coalesce, which could be very different under normal atmospheric conditions. This means that lanthanide-activated phosphors with high purity and homogeneity can be achieved under such an extraordinary environment. − , …”

“…This means that lanthanide-activated phosphors with high purity and homogeneity can be achieved under such an extraordinary environment. [113][114][115][116][117][118]130 A distinct feature of hydro(solvo)thermal treatment is the utilization of chelating ligands to regulate the nucleation kinetics in order to control the growth of the particles during synthesis and prevent the aggregation of the phosphors in solutions. The chelating ligands bound to the phosphor surface can also impart the phosphors with a versatile function for bioconjugation and immobilization.…”

Structure and Photoluminescence of Eu2+Doped Sr2Al2SiO7Cyan-Green Emitting Phosphors

“…Some rare-earth doped M-Al-Si-O phosphors have been synthesized and studied. [3][4][5] The reported luminescent materials combined the unique luminescence characteristic from 5d to 4f transitions of rare-earth ions and the thermal and chemical stability of the host materials.…”

UV, Blue, Green, Yellow, Red, and Small: Newest Developments on Eu2+-Doped Nanophosphors

“…As previously explained, core–shell preparation methods allow the combination of different properties in a single nanocomposite, e.g., magnetism, biocompatibility, or luminescence, or also for enhancing the monodispersity. Moreover, this approach has been also used for improving, e.g., SrAl 2 O 4 :Eu 2+ ,Dy 3+ , GaN:Eu 2+ , CaSi 2 O 2 N 2 :Eu 2+ , and SrAl 2 Si 2 O 8 :Eu 2+ nanomaterials, enhancing, for example, their size distribution and stability. ,,, Similarly as in the template-assisted synthesis, nanospheres consisting of, e.g., SiO 2 are often used as hard patterns in core–shell preparation methods due to their ability to generate ideally spherical nanoparticles and to allow the easy control of size and size distributions, in addition to the improved thermal stability. However, the SiO 2 nanospheres remain in the form of compact SiO 2 cores and are not totally consumed as reactant for the formation of a new product or removed after the synthesis as by the template-assisted technique. , For producing SiO 2 @SrSi 2 O 2 N 2 :Eu 2+ nanoparticles, SiO 2 nanospheres are coated subsequently with SrCO 3 :Eu 3+ and BN.…”