Determination of Judd–Ofelt intensity parameters from the excitation spectra for rare-earth doped luminescent materials

Abstract

By utilizing the proportional relationship between the excitation and absorption spectra for some special excited multiplets of rare-earth (RE) ions that are followed by a very fast nonradiative relaxation to the monitored level, we propose a new approach to determine the Judd-Ofelt (JO) intensity parameters that are crucial to the evaluation of laser and luminescent materials via excitation spectra. To validate this approach, the JO parameters of NaGd(WO(4))(2) : Er(3+) and YLiF(4) : Nd(3+) crystals are calculated and compared through both the excitation and absorption spectra. The JO parameters derived from this approach are in good agreement with that determined from the conventional method (absorption spectra). Furthermore, the JO intensity parameters of Y(2)O(3) : Er(3+) nanocrystals are derived from the excitation spectra by taking into account the nano-size effects, which are comparable to the values of the crystal counterpart. The proposed approach is of particular importance for those powders or nanophosphors with low RE doping concentration that their quantitative absorption spectra are difficult to measure.

Judd–Ofelt analysis of ceramic La3Ga5.5Ta0.5O14 doped with Er3+

“…A similar method was previously used in [7], where the lifetime of 4 I 13/2 was used to calibrate the excitation spectrum of Er 3 þ in Y 2 O 3 nanocrystals. The large energy gap between 4 I 13/2 and 4 I 15/2 ($6000 cm À 1 ) assures a radiative decay of 4 I 13/2 level.…”

Judd–Ofelt analysis of Ho3+ doped in ceramic CaSc2O4

“…To overcome this difficulty, various methods to replace the usual absorption spectrum with some equivalents were proposed [3][4][5][6][7][8][9][10][11]. One method consists in embedding the powder in some diluent as transparent epoxy [3] or in KBr [4] and measuring the absorption spectrum.…”

“…One method consists in embedding the powder in some diluent as transparent epoxy [3] or in KBr [4] and measuring the absorption spectrum. Another method is based on measuring the excitation spectra and selecting the energy levels for which the excited multiplets relax very fast nonradiatively [5,6], but the spectra should be calibrated; for this, the lifetime of a level known to decay mainly radiatively ( 4 I 13/2 for Er 3 þ and 4 F 3/2 for Nd 3 þ ) was used. The diffuse reflectance spectra were also used [7]; to convert the diffuse reflectance spectra in absorption spectra, the authors applied the Kubelka-Munk theory for samples of various thicknesses.…”

Judd–Ofelt and energy-transfer analysis of Er3+ doped in CaSc2O4 ceramic samples

“…[8] we surveyed the methods used in the literature to replace the absorption spectrum with some 'equivalents': (i) using the excitation spectra [14,15], (ii) measuring diffuse reflectance spectra [16], (iii), dispersing the powder doped with rare-earth ions in KBr pellets and measuring the IR absorption spectra [17], (iv) embedding the nanocrystals powder in an epoxy [18], (v) measuring the photoacoustic spectra [19], (vi) using the emission spectrum 5 D 4 -7 F J of Tb 3 þ [20]. Known exceptions are Eu 3 þ -doped phosphors, where the presence of the pure magnetic dipole-transition 5 D 0 -7 F 1 allows the calibration of the 5 D 0 -7 F J luminescence spectrum [21][22][23].…”