Upconversion Luminescence Properties Of Rare Earth Doped Tungstate

Rare earth upconversion luminescence can realize the conversion of infrared to visible,even ultraviolet luminescence,which has important applications in biomedicine,fluorescence temperature measurement and so on.On the one hand,the upconversion luminescence performance depends on the doped rare earth ions,on the other hand,the matrix also plays an important role.The typical substrates are fluoride,sulfide,oxide and so on.Tungstate is a potential fluorescent matrix material because of its low phonon energy and stable physical and chemical properties.In this paper,the upconversion luminescence and temperature sensing properties of tungstate doped with Eu³⁺,Dy³⁺/Nd³⁺and Er³⁺were studied.The main research contents are as follows:(1)Zn WO₄:Eu³⁺/Yb³⁺phosphors were prepared by high temperature solid state method.The crystal structure,morphology and size of the phosphor were characterized by X-ray diffraction and scanning electron microscopy.The upconversion luminescence spectra of phosphor samples excited by 980 nm infrared light were analyzed,and the influence of Yb³⁺doping concentration on the luminescence properties was discussed.In addition,the temperature sensing characteristics of Zn WO₄:Eu³⁺/Yb³⁺Phosphor were studied based on the non thermal coupling energy level fluorescence intensity ratio technique.The maximum sensitivity of temperature measurement was 0.62%K^-1at 303 K.(2)Zn WO₄:Dy³⁺/Yb³⁺and Zn WO₄:Dy³⁺/Nd³⁺/Yb³⁺phosphors were prepared by high temperature solid state method.The crystal structure,morphology and size of the phosphor were characterized by X-ray diffraction and scanning electron microscopy.The upconversion luminescence spectra of Zn WO₄:Dy³⁺/Yb³⁺phosphors excited by980 nm infrared light were analyzed,and the effect of Yb³⁺doping concentration on the luminescence properties was discussed.In addition,the luminescence spectra of Zn WO₄:Dy³⁺/Nd³⁺/Yb³⁺phosphors were analyzed,and the influence of Nd³⁺Doping on the luminescence properties of the phosphors was discussed.Finally,the temperature sensing characteristics of Zn WO₄:Dy³⁺/Nd³⁺/Yb³⁺Phosphor were studied based on the non thermal coupling energy level fluorescence intensity ratio technique.The maximum sensitivity of the phosphor was 12.8%K^-1at 573 K.(3)Ba WO₄(Ca WO₄,Sr WO₄):Er³⁺/Yb³⁺phosphors were prepared by high temperature solid state method.The crystal structure,morphology and size of the phosphor were characterized by X-ray diffraction and scanning electron microscopy.The upconversion luminescence spectra of Ba WO₄(Ca WO₄,Sr WO₄):Er³⁺/Yb³⁺phosphors excited by 980 nm infrared light were analyzed,and the differences of luminescence properties of Er³⁺doped tungstate matrix materials were discussed.In addition,the temperature sensing properties of Ba WO₄(Ca WO₄,Sr WO₄):Er³⁺/Yb³⁺phosphors were studied based on the thermal coupling energy level fluorescence intensity ratio technique,which find that the maximum temperature sensitivity of luminescent materials is also different.The maximum sensitivity of Sr WO₄:Er³⁺/Yb³⁺phosphor is 1.66%K^-1at 548 K.