The Reaserch On Luminsescence And Temperature Sensing Properties For Rare Earth Ions Doped Optical Materials

With the advancement of technology,rare earth doped optical materials have attracted much attention because of their unique characteristics in optical,electrical and magnetic,and have important application values in petrochemical,power industry,fluorescence detection and three-dimensional display.It has become the focus of research at home and abroad.In many studies of the rare earth doped luminescent materials,the technology of temperature measurement with rare earth fluorescence has attracted the attention of researchers,because of its high precision,high sensitivity and fast response.However,there are still many problems in the current research,including lower luminous efficiency,severe laser thermal interference and obvious spectral overlap,which greatly limited the development of technology of temperature measurement with rare earth fluorescent.In this paper,the rare earth doped luminescent materials were taken as the research target,and three aspects of photoluminescence enhancement,anti-Stokes fluorescence design and non-thermal coupling level temperature measurement are studied.CaWO₄:Nd³⁺/Yb³⁺phosphors were prepared by high temperature solid phase method,and enhanced near-infrared fluorescence radiation was obtained by doping with different concentrations of Li⁺ions.Studies have shown that the incorporation of Li⁺ions can improve the crystallinity of the matrix and reduce the probability of non-radiative transitions.It can also cause the distortion of the matrix lattice structure,thereby improving the crystal field environment around the rare earth ions and enhancing the near-infrared fluorescence radiation.In addition,the temperature measurement behavior of near-infrared fluorescence in Nd³⁺ions was studied.Through the temperature dependence experiment of near-infrared fluorescence in Nd³⁺ions,it is observed that the near-infrared fluorescence intensity is further enhanced with the increase of temperature with the aid of Li⁺ions.In addition,the temperature measurement performance of a pair of new thermal coupling energy levels in Nd³⁺ions is also explored.The research shows that the thermal coupling energy levels have excellent temperature measurement in accuracy and sensitivity.Er³⁺/Yb³⁺co-doped glass-ceramics were prepared by melt quenching.The green upconversion fluorescence of Er³⁺ions was studied by fluorescence intensity comparison technique under 980 and 106 4 nm laser excitations.The upconversion mechanism of Er³⁺ions was analyzed.The temperature sensing characteristics of the band were discussed by changing the power.The results show that the resonant excitation process using 980 nm lasers as the pumping source promotes the generation of thermal effect when the power increases,which makes the calibration process of measurement parameters dependent on the power.Therefore,the stability of temperature measurement is affected by the power changed.The non-resonant excitation process using 1064 nm laser as pumping source can annihilate phonons through phonon-assisted anti-Stokes excitation mechanism,effectively avoiding the influence of thermal effect.Finally,the above mechanism was validated by rate equation and fluorescence time-resolved curve.The results show that the thermal effect can be effectively avoided under 1064 nm laser excitation,and the temperature measurement stability of Er³⁺ions green up-conversion light is enhanced.The NaY?WO₄?₂:Yb³⁺/Er³⁺phosphor samples were prepared by high temperature solid phase method.The 1064 nm laser was used as the pumping source.The luminescence properties and temperature dependence of the near-infrared fluorescence of Er3+ions in the 1530 nm band were analyzed.The luminous intensity of this band increases as the temperature increases.At the same time,the laser is used as the reference light and the fluorescence is the signal light.The temperature measurement characteristics of the non-thermal coupling level are studied.It is found that the spectral error can effectively avoid the measurement error caused by spectral overlap.In the temperature range of 323 K-773 K,the temperature sensitivity is the largest at 323 K,and the maximum sensitivity is 16.3×10^-33 K^-1.It can therefore be used for the sensing elements in fiber optic temperature sensors.