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Issue 3, 2017
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Luminescence properties of La2W2−xMoxO9 (x = 0–2):Eu3+ materials and their Judd–Ofelt analysis: novel red line emitting phosphors for pcLEDs

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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

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Publication details

The article was received on 08 Jul 2016, accepted on 12 Aug 2016 and first published on 15 Sep 2016


Article type: Research Article
DOI: 10.1039/C6QM00118A
Citation: Mater. Chem. Front., 2017,1, 550-561
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    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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