Synthesis and photoluminescence studies of certain lanthanide ions dy3 eu3 sm3 activated phosphate based phosphors for pc wled applications

Abstract

In recent times, the superior characteristics and advantages of white light-emitting diodes (WLEDs) make them known as the next generation light source of the solid-state lighting (SSL) technology. The necessity of single phased pc-WLEDs drives the researchers interest to develop new phosphors with appropriate host matrices doped with suitable activators. In the recent past, the eulytite phosphate based host materials exhibiting superior properties have been studied widely by doping suitable lanthanide ions (Ln3+) which can give strong emission in the visible range corresponding to their 4f-4f, and 5d-4f transitions for N-UV/blue light excitation. Amid the several Ln3+ ions, the Dy3+ ions exhibiting the strong blue (B, 4F9/2and#8594;6H15/2) and yellow (Y, 4F9/2and#8594;6H13/2) emissions in the visible spectrum is found as a good candidate to obtain white light for a suitable Y/B ratio. And the red emitting Eu3+ and Sm3+ ions having strong optical absorption N-UV/blue region are also considered as promising activators. The weak red emission of the Dy3+ ions doped phosphors can be compensated by co-doping either the Sm3+ (orange-red) or the Eu3+ (red) ions at appropriate concentration to obtain white/warm white light-emission when excited by N-UV LEDs. newlineThe scope of this thesis is to synthesize near white/warm white emitting N-UV excitable phosphors for pc-WLEDs. The lanthanide ions (Dy3+, Eu3+, Sm3+) singly doped and co-doped NaMBi2-x(PO4)3 (M : Ca2+, Sr2+, Ba2+) phosphors were prepared by a simple solid state reaction method. The color tuning ability was studied by co-doping the red emitting lanthanides newline