Structural and optical studies on Dy3+ doped Gd2Ti2O7 pyrochlore as white light emission

Abstract

A series of Dy3+ trivalent ion embedded into the GTO pyrochlore (Gd2-xDyxTi2O7 (x = 0.5, 1.0, 1.5, 2.0, and 2.5 mol%)) have been synthesized through standard solid state reaction technique. The single phasic nature with Fd3m space group was determined through XRD, Raman spectroscopy, and photoluminescence spectroscopy. Rietveld refinement analysis results confirm that the substitution is not going to disturb the crystallographic structure as well unit cell dimensions. From Raman deconvoluted spectrums, it was found that all the vibrational bands show a very small blue shifting on Dy3+ substitution. The photoluminescent EM-spectra for all the samples were examined under the excitation wavelength 347 nm gives two high intense emission bands centered around 484 nm (blue) and 581 nm (yellow) due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions respectively, and less intense band appeared at wavelength of 456 nm arising due to the 4I13/2 → 6H13/2 transition of Dy3+ ions. For the optimum Dy3+ concentration (2.0 mol%), the Y/B ratio is found to be 0.8753 which is close to unity hence combination of both yellow and blue emission bands emits white light as validated by CIE chromaticity coordinates calculated values are (x = 0.34959, y = 0.35381). Therefore, the results reveal that Dy3+ substituted GTO pyrochlore samples could be used as luminescent material for wLEDs application.