Judd−Ofelt Intensity Parameters and Spectral Properties of Gd₂O₃:Eu³⁺Nanocrystals

Abstract

Three nonequivalent centers of Cs (A, B, and C) in monoclinic phase and C2 and S6 centers in cubic phase were identified in the Gd2O3:Eu3+ nanocrystals with spectral techniques. Size dependence in the spectra indicated that the excitations from both host and charge-transfer band (CTB) for the 5D0 --> 7F2 transition of Eu3+ ions were nearly equal for a larger size of 135 nm of the cubic phase; however, with decreasing the size to or less than 23 nm, the excitations by the CTB dominated. The variation of excitation leading to the symmetry and energy change in the C2 and S6 sites was also observed for larger particle sizes. The Judd-Ofelt intensity parameters Omega(lambda) (lambda = 2, 4) for Gd2O3:Eu3+ nanoparticles were experimentally determined. The parameters Omega(lambda) were found to significantly change with the sizes of Gd2O3:Eu3+ from nanoparticles to bulk material. With decreasing the size from 135 to 15 nm, the quantum efficiencies for 5D0 reduced from 23.6% to 4.6% due to the increasing ratio of surface to volume.

Spectroscopic studies of Sm3+ and Eu3+ co-doped lithium borate glass

“…The standard procedure was employed in this case: the intensity of the 5 D 0 -7 F 1 magnetic dipole transition is host independent and its radiative transition probability for different hosts is reported to be between 30 and 60 s −1 [27][28][29][30][31][32][33][34][35][36][37]. Then it is possible to express the ratio of the radiative transition probabilities A R in terms of the ratio of areas S under corresponding emission curves [32,33]:…”

Effects of Phonon Confinement on Anomalous Thermalization, Energy Transfer, and Upconversion in Ln3+‐Doped Gd2O3 Nanotubes

“…[1][2][3][4] Ln 3þ -hydroxide and oxide (Ln ¼ Ce, Pr, Nd, Sm, Dy, Tb, Gd, Yb, Er) nanocrystals, Y 2 O 3 :Eu 3þ /Y 2 O 3 core-shell composites, Y 2 O 3 :Eu 3þ and Gd 2 O 3 :Eu 3þ nanotubes, and Gd 2 O 3 :Yb 3þ ,Er 3þ nanorods have received considerable attention [5][6][7][8][9][10][11][12][13][14] because they exhibit shape-specific and quantum-size effects. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] Size-dependent quantum confinement has important effects on the radiative and nonradiative electronic transitions in nanoparticles, and tuning the particles structure at the nanometer scale may result in novel optical properties for applications in 3D displays, [31][32] light-emitting devices, [33] and bioassays. [34,35] Due to the confinement effect in Ln 3þ -nanocrystals, the phonon density of states (PDOS) becomes discrete, with a cut-off on the low-energy side.…”

Judd–Ofelt Analysis of Eu³⁺ Emission in TiO₂ Anatase Nanoparticles

“…where Taking this value as a reference and with a well-known correction factor of (n/1.591) 3 , which can be derived from the general equations for the magnetic dipole transition probability rates 23,24) (here n = 2.49 is the refractive index of anatase), the 5 D 0 7 F 1 magnetic dipole transition radiative transition probability in our samples was estimated to be 220 s ¹1 . Such a method of evaluating the intensity parameters for Eu 3+ (the ³ 6 parameter cannot be estimated in this case, since the matrix elements of the ««U (6) «« operator for the considered transitions are zero) is widely used (Refs.…”