Solid state synthesis and luminescence properties of Eu3+ doped NaYGeO4 phosphors

A series of Eu3+ undoped/doped germinate phosphors NaY1_xEuxGeO4 (0 <x < 1) were synthesized by a solid-state reaction at high-temperature. Their phase structures and luminescence properties were examined by powder X-ray diffraction method, Rietveld structure-refinements and photoluminescence measurements. Under 300 nm excitation, with increasing doping concentration of Eu3+, these as-prepared phosphors showed adjustable luminous color from blue to red, which was induced by Eu3+-concentration-dependent energy transfer behavior from host to Eu3+. Upon excitation with 464 nm, the optimal-component NaY0.5Eu0.5GeO4 phosphor presented characteristic red luminescence resulting from dominant 5D0 -> 7F2 transition of Eu3+, which was with millisecond-level lifetime and excellent thermal stability. Finally, on the basis of the current NaY0.5Eu0.5GeO4 phosphor, a red LED device was fabricated, emitting bright red light driven by certain voltage and current. The results showed the as-prepared NaYGeO4:Eu3+ red phosphor have possible application prospect in the field of solid state lighting.