Greenish‐Yellow Emission from Dy³⁺‐Doped Y₂O₃ Nanophosphors

Abstract

Trivalent dysprosium‐doped cubic yttrium oxide (Y2O3) nanophosphors were prepared by combustion synthesis using glycine as fuel. The resulting products were characterized by Raman and FT‐IR spectra to evaluate the vibrational features of the samples. X‐ray diffraction patterns confirmed the formation of a pure cubic phase of Y2O3. The morphology and selective area electron diffraction measurements were carried out using transmission electron microscopy (TEM) and field‐emission scanning electron microscopy. From TEM, it is observed that as‐prepared particles have average crystallite sizes of around 23 nm. The luminescent and dynamic properties of Y2O3:Dy3+ were examined as a function of temperature and different concentrations of Dy3+. The luminescence study reveals that these phosphors predominantly exhibit greenish‐yellow emission due to strong 4F9/2→6H13/2 transition at 575 nm and a feeble 4F9/2→6H15/2 transition at 488 nm. These results show that the relative luminescence intensity of emission bands changes with different heating temperatures, while the greenish yellow color luminescence as well as Commission International d'Eclairage chromaticity coordinates extracted from the emission spectra were not affected significantly. The strong greenish‐yellow emission of Y2O3:Dy3+ phosphor may be useful for applications in solid‐state white lamps for general illumination purposes.

Ion beam induced luminescence studies of sol gel derived Y2O3:Dy3+ nanophosphors

“…These characteristic emissions are attributed to the luminescence centers associated with Dy 3 þ ions. Emission peaks at 488, 584 and 670 nm are slightly broadened because of several stark levels of 4 F 9/2 and 6 H J (J¼15/2, 13/2, 11/2) and then split into Jþ 1/2 Stark levels due to Dy 3 þ ion (Kramer's ion) in the lower symmetry site [7]. Similar results on Mg 2 SiO 4 :Dy 3 þ are reported by Lakshminarasappa et al [35].…”

“…8(a) shows the PL excitation spectrum of Y 2 O 3 :Dy 3 þ recorded in the range 300-400 nm at an excitation of 573 nm. A sharp peak at 349 nm is attributed to the hypersensitive transition 6 H 15/2 -4 M 15/2 þ 6 P 7/2 and other bands with peaks at 331, 363, 383 nm are attributed to 6 H 15/2 -4 M 17/2 , 6 H 15/2 -4 I 11/2 and 6 H 15/2 -4 I 13/2 transitions, respectively [7]. PL emission is recorded under 349 nm excitation.…”

“…It confirms the presence of Y, O, Dy elements in the synthesized sample. [7,29]. The intensity of these modes decreases with ion irradiation due to loss of crystallinity and/or due to destruction of Y-O stretching bond, which indicates change in chemical composition.…”

“…Another feeble emission with peak at 488 nm corresponds to the 4 F 9/2 -6 H 15/2 (blue region) transition, which belongs to a magnetic dipole transitions and located at the inversion center (C 3i ) symmetry sites which is less sensitive to the host. Further, weak emissions with peak at 670 nm (Red region) and 767 nm (NIR region) are attributed to 4 F 9/2 -6 H 11/2 and 4 F 9/2 -6 H 9/2 þ 6 H 11/2 transitions of Dy 3 þ respectively [7,36]. The IL intensity depends on various factors such as ion species, ion fluence, energy, luminescence activators, quenchers and surrounding environment around the Dy 3 þ ion.…”

“…Y 2 O 3 possess high melting point ( $ 2600°C), wide transparency range, high thermal conductivity, high chemical stability with a band gap (5.72 eV) and low cut of phonon energy (380 cm À 1 ), which reduces the multiphonon relaxation process and leads to high luminescence efficiency [6]. Trivalent dysprosium ion (Dy 3 þ ) has been extensively studied in various hosts due to its unique spectral properties [7]. Dy 3 þ doped Y 2 O 3 exhibit excellent greenish yellow luminescent properties.…”