Luminescent properties of deep red light-emitting phosphors NaGd(WO4)2:Pr3+ for blue LED

• Deep red phosphors Pr3+:NaGd(WO4)2 have been obtained via solid-state reaction.
• Pr3+:NaGd(WO4)2 can be efficiently excited by the commercial blue LED.
• Fluorescence concentration quenching of Pr3+:NaGd(WO4)2 was attributed to cross-relaxation energy transfer.
• Color coordinates of Pr3+:NaGd(WO4)2 can be tuned from deep red to light red.
• Pr3+:NaGd(WO4)2 exhibit great potential for use as deep red phosphors for white LEDs.

Pr3+-doped NaGd(WO4)2 phosphors with deep red emission in pure phase were prepared via high temperature solid-state reaction. Photoluminescence properties of those phosphors were investigated. Deep red emission bands with central wavelength at 649 nm were observed under the excitation of 430–500 nm, which is suitable for excitation of the blue LED chips. The optimum doping concentration of Pr3+ ions in NaGd(WO4)2 is 4.0 at.%. The fluorescence concentration quenching could be attributed to the phonon-assisted cross-relaxation energy transfer between the Pr3+ ions. The CIE color coordinates of Pr3+-doped NaGd(WO4)2 phosphors with different Pr3+ concentration can be tuned from deep red to light red. The present work suggests that Pr3+-doped NaGd(WO4)2 exhibit great potential for using as deep red phosphors for the blue LED.