Upconversion Optical Temperature Sensing of YbNbO4:Ho3+with Host Sensitization
A series of YbNbO4 phosphors doped with x%(ion concentration)Ho3+(x=1,2,5,10,15)were pre-pared by high temperature solid phase method.The synthesized sample was characterized by X-ray diffraction(XRD)and Fourier transform infrared spectroscopy(FT-IR),and the results showed that the synthesized fluorescent powder sample had a monoclinic phase structure with a space group of I2/a.At the same time,the electronic struc-ture(band and density of states)of the YbNbO4 matrix was calculated.YbNbO4 has a direct band gap with a band-gap width of 4.223 eV.Further investigation was conducted on the effect of Ho3+ions doping concentration on emis-sion spectra,and it was screened that a 2%Ho3+ions doping concentration had the best luminescence effect.In addi-tion,samples doped with 2%Ho3+were excited at different powers.By fitting the emission peak to the excitation light power,it was further concluded that the upconversion of Ho3+ions to red light at 666 nm(5F5→5I8)and green light at 543 nm(5S2/5F4→5I8)emission both belong to two-photon processes.In addition,based on the fluorescence intensity ratio(LIR)technique,the temperature dependent spectra of 2%Ho3+doped samples were measured in the tempera-ture range of 300-570 K,and the absolute sensitivity(Sa)and relative sensitivity(Sr)used to characterize the opti-cal temperature sensing performance were calculated.The results showed that the Sr of the samples reached a maxi-mum value of 0.36%·K-1 at 420 K.
upconversion luminescencehigh temperature solid phase methodfluorescence intensity ratiofirst principles calculation
万方数据
