Issue 3, 2017

Luminescence properties of La2W2−xMoxO9 (x = 0–2):Eu3+ materials and their Judd–Ofelt analysis: novel red line emitting phosphors for pcLEDs

Abstract

A series of novel red emitting La1.95Eu0.05W2−xMoxO9 (x = 0–2, in steps of 0.1) and La2−yEuyW1.6Mo0.4O9 (y = 0–2, insteps of 0.2) phosphors were prepared by a conventional solid state reaction. Powder XRD analysis of La1.95Eu0.05W2−xMoxO9 (x = 0–2, in steps of 0.1) reveals a phase transition from a triclinic to a cubic structure with increasing Mo6+ concentration (x ≥ 0.2). All the compositions show a broad charge transfer (CT) band due to CT from O to W/Mo and red emission (due to Eu3+ ions). In order to obtain the strongest red emission, concentration variation of Eu3+ was performed in La2−yEuyW1.6Mo0.4O9 (x = 0–2, insteps of 0.2). The Eu1.6La0.4W1.6Mo0.4O9 composition shows a high red emission intensity (∼8.2 times) compared to a commercial red phosphor with very good CIE chromaticity coordinates (x = 0.67, y = 0.33). A selected composition has also been synthesized by simple co-precipitation method. The emission intensity of the Eu1.6La0.4W1.6Mo0.4O9 phosphor synthesized by co-precipitation technique is ∼1.78 times higher than that of the phosphor synthesized by the solid state reaction. Phonon sideband spectrum analysis has been carried out for Eu3+ activated La2M2O9 (M = W and Mo). The temperature dependent photoluminescence studies reveal that the Eu1.4La0.6W1.6Mo0.4O9 compositions loses 30% of its efficiency up to 400 K (compared to ∼80% for CaS:Eu2+) and the Judd–Ofelt parameters were also calculated for the Eu3+ ions.

Graphical abstract: Luminescence properties of La2W2−xMoxO9 (x = 0–2):Eu3+ materials and their Judd–Ofelt analysis: novel red line emitting phosphors for pcLEDs

Supplementary files

Article information

Article type
Research Article
Submitted
08 Jul 2016
Accepted
12 Aug 2016
First published
15 Sep 2016

Mater. Chem. Front., 2017,1, 550-561

Luminescence properties of La2W2−xMoxO9 (x = 0–2):Eu3+ materials and their Judd–Ofelt analysis: novel red line emitting phosphors for pcLEDs

K. S. and S. V., Mater. Chem. Front., 2017, 1, 550 DOI: 10.1039/C6QM00118A

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