Reaserch In The Up-conversion Luminescence From Er³⁺/Yb³⁺ Co-doped Tungstate And The Corresponding Application

With the increasingly progress of science and technology, rare earth doped luminescence materials due to its excellent abilities have attracted many attention. It is a hot research both at home and abroad. With the development of rare earth elements, it has been widely applied in many fields, such as petrochemical, power industry, scientific research, environmental protection, agricultural and military defense and et al. The fluorescence spectra properties of rare earth doped up-conversion materials not only related with matrix material but also related with the temperature of samples. In this paper, Ca WO4 phosphor is taken as matrix material, Ca WO4: Yb3+/Er3+ was made by high temperature solid phase method. Under 980 LD, researching the samples’ up-converted fluorescence properties depend on different sintering temperature, Er3+ concentration and Yb3+ concentration. At the same time, the temperature properties and fluorescent temperature sensor application of material were shown by fluorescence intensity ratio and fluorescence lifetime two methods.Using high temperature solid phase method made some samples, through X-ray diffraction analysis the crystal structure of the samples, the result shows that they keep good Ca WO4 lattice structure. Excited by a 980 nm diode laser, the two up-conversion green characteristics fluorescence belt of Er3+ at 531 nm and 552 nm have been successfully obtained, respectively from energy level 2H11/2 and 4S3/2 to the ground state. Discussed the effect of different sintering temperature, doped concentration and pump power for the samples’ luminescence property. As the influence of synthesis condition to the fluorescence intensity and relative intensity of the centre wavelength. Based on the variation of emission intensities with the pumping powers, the UC mechanisms of Er3+/Yb3+ codoped Ca WO4 has been discussed. Moreover, the fluorescence lifetime of the sample was discussed at room temperature to get the effect to inherent physics mechanisms of Er3+ up-conversion fluorescence.According to the fluorescence intensity ratio method, temperature property of different synthetic process were studied. Under 980 nm diode laser, using the energy levels 2H11/2 and 4S3/2 as the thermally coupled levels, temperature property of this sample which Er3+/Yb3+ molar ratio was 0.5mol%/3mol% was studied between 307 K and 773 K. At the same time, the parameters A and ΔΕ of fluorescence intensity ratio based on sintering temperature, doped concentration of sample was discussed. It is resulting to the change of fluorescence intensity ratio curves and relative sensitivity curves. While, the fluorescence temperature properties of the samples was changed. Finally using fluorescence lifetime method to measure temperature property of a sample, we obtained lifetime curves and relative sensitivity at different temperature. And discussing the application of it using in temperature sensor.