Site selectively excited luminescence and energy transfer of X1-Y2SiO5:Eu at nanometric scale

Abstract

Two different types of structure called X 1 and X 2 are existing in Y 2 SiO 5 at normal conditions. In X 1 type, Y 3ϩ ions occupy two sites where they are surrounded respectively by nine and seven oxygen ions, while in X 2 structure, only six and seven oxygen ions are involved. Nanometric scale X 1 -Y 2 SiO 5 crystals were prepared by sol-gel method with particle size around 50 nm. Site selective excitation at low temperature has shown four different luminescent centers. Two of them belong to Eu 3ϩ embedded in X 1 -Y 2 SiO 5 , the other two are attributed to Y 2 O 3 :Eu phase and to a particular site on the surface. The occurrence of the latter site may be related to the nanometric size of the sample. A pronounced excitation energy transfer from site 2 to site 1 was also observed on excitation spectra. The energy transfer rate increases rapidly with increasing Eu 3ϩ concentration and for x ϭ0.7 in Y 2Ϫx SiO 5 :Eu x , no fluorescence takes place in site 2 at 15 K. The lifetimes of the 5 D 0 levels of Eu 3ϩ in the two sites were measured as a function of Eu 3ϩ concentration. The results have shown that the lifetime of the 5 D 0 level of Eu 3ϩ in site 2 decreases with increasing Eu 3ϩ concentration. The energy transfer rate dependence upon temperature was studied in detail and compared to a theoretical simulation.

Synthesis of Y2SiO5:Eu3+ nanoparticles from a hydrothermally prepared silica sol

“…As Eu 3+ and Y 3+ have very similar ionic radii, the site occupancy should be very close. Two peaks are observed at about 578.5 and 580.5 nm, in good agreement with the value reported in the literature for the two sites [15,16]. Emission at around 611.5 nm corresponds to the 5 D 0 → 7 F 2 electric dipole transition, which is very sensitive to the local environment around the Eu 3+ ion, and its intensity depends on the symmetry of the crystal field around the europium ion.…”

Size-dependent microstructure and europium site preference influence fluorescent properties of Eu3+-doped Ca10(PO4)6(OH)2 nanocrystal

“…Furthermore, the 7 F 0 and 5 D 0 state levels do not split. Therefore, the number of 5 D 0 -7 F 0 transition peaks will correspond to the number of C s or C n or C nv site in luminescent materials [7,19,24,25]. According to Fig.…”

Hydrothermal synthesis and luminescent properties of YBO3:Tb3+ uniform ultrafine phosphor

“…It is well known that hydrothermal method is a promising synthesis route, which can be better controlled from the molecular precursor to the reaction parameters, such as the reaction time and temperature to give highly pure and homogeneous materials. The technique allows low reaction temperatures, and controlled size and morphology of the products [9][10][11][12][13][14][15].…”