Photoluminescence properties of sub-micron NaGd1−xEux(WO4)2 red phosphor for solid state lightings application: Derived by different synthesis routes

• Three different methods to used synthesized phosphor successfully.
• Single phase powder were synthesized at low temperature by sol-gel (700 °C) and combustion synthesized and solid state methods.
• Morphological and luminescence variations were studied with different synthesized methods.

A series of NaGd1−xEux(WO4)2 (NGEW) red emitting phosphors were synthesized by three different methods, like conventional solid state reaction method, sol-gel and combustion reaction method. Detail investigations were made in terms of structural, vibrational, morphological, and luminescence analysis to identify changes with respect to three different synthesized methods. The formations of scheelite phase were confirmed by x-ray powder diffraction in all the three different synthesis methods and dopant ions do not alter its structure. Raman analysis indicated tetrahedral and translation motion tungstate assembly vibrations of synthesized NGEW samples. Morphology and grain size changes were observed in the SEM micrographs with respect to synthesis methods. The concentration dependent luminescence was studied and highest emission Eu3+ concentration in NGW matrix was found to be 60 mol% and critical distance was estimated by using Blasse approximation. The CIE co-ordinates of different methods derived NaGd0.40Eu0.60(WO4)2 were calculated and these values were fall in red region in CIE diagram and also well matched NTSC standard value. The Judd-Ofelt parameters (Ω2 and Ω4) were calculated by using emission spectra, to conform the occupancy and site symmetry of the Eu3+ ions in NGW matrix. The size control and luminescence ability suggested that the sol-gel method was significant method to synthesis red phosphor for using the red component in future lightings and display applications.

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