White light tuning and temperature sensing of NaLu(WO 4 ) 2 :Ln 3+ up-converting phosphor.

NaLu(WO 4 ) 2 :Ln 3+ phosphors were synthesized via a hydrothermal method combined with subsequent calcination. Under excitation at 980 nm, 25%Yb 3+ , 0.5%Tm 3+ and 25%Yb 3+ , 1%Ho 3+ -doped phosphors produce blue, green and red emissions. Namely, NaLu(WO 4 ) 2 :25%Yb 3+ , 0.1%Ho 3+ , 0.1%Tm 3+ nanocrystals show suitable intensities of blue, green, and red (RGB) emission, resulting in the production of perfect and bright white light with CIE- x = 0.3299 and CIE- y = 0.3293, which is very close to the standard equal energy white light illumination ( x = 0.33, y = 0.33). Based on FIR theory, the temperature dependence of NaLu(WO 4 ) 2 :20%Yb 3+ , 1%Er 3+ was studied, and the maximum value of sensitivity was obtained as 1.38% K -1 at 543 K, which is better than that of previously reported temperature-sensing materials. It proves that the NaLu(WO 4 ) 2 :Ln 3+ phosphors have potential applications in white lighting, optical temperature measurement and other fields.