Study On Temperature Sensing Characteristics Of Er³⁺(Tm³⁺)/Yb³⁺doped Upconversion Luminescent Materials

As a basic parameter of thermodynamic state,temperature plays a very important role in scientific research,industrial production,life medicine and even people's daily life.Rare earth doped upconversion luminescent materials have good color rendering,high conversion efficiency,good luminescence stability,can withstand the effects of high energy radiation,high temperature and high-power electron beams,so they are widely used in white LED lighting,PDP display,medical radiation and other fields.With its temperature characteristics,it can also be applied to non-contact temperature measurement research.In recent years,the non-contact optical temperature measurement by measuring the temperature-dependent luminescence intensity of rare earth ion doped upconversion luminescence materials,and establish the dependence of thermal coupling level fluorescence intensity ratio with temperature,has attracted widespread attention.As an optical temperature measurement method,the thermal coupling level fluorescence intensity ratio technology based on rare earth ions can achieve high-precision,wide-range temperature measurement,which is more convenient and flexible to meet the needs of production and life because it is not affected by the pump light source and the loss during optical signal transmission.SrWO₄has good thermal stability,high accuracy and low phonon energy,and is considered as a good upconversion luminescence host material.Er³⁺,Tm³⁺and Ho³⁺have thermally coupled energy level,which have potential applications in the study of optical temperature sensing characteristics.In this paper,three groups of Sr WO₄:Er³⁺(Tm³⁺,Ho³⁺)/Yb³⁺phosphor was prepared by high temperature solid-phase method,and the samples were characterized and tested.X-ray diffraction analysis,scanning electron microscope analysis,upconversion emission spectrum analysis,and upconversion luminescence mechanism analysis were performed on the samples.The structure characteristics and upconversion emission spectrum of the sample and the effect of Yb³⁺concentration on the luminescence intensity were analyzed.The upconversion emission spectra of three groups of phosphor were measured at different temperatures,and the temperature sensing characteristics of the three groups of phosphor were studied respectively.The thermal sensitivity of Sr WO₄:Er³⁺/Yb³⁺phosphor was reached a maximum of 0.013 K^-1at 513 K;the thermal sensitivity of Sr WO₄:Tm³⁺/Yb³⁺phosphor was reached to a maximum of 0.0012 K^-1at 303 K;the thermal sensitivity of Sr WO₄:Ho³⁺/Yb³⁺phosphor based on the thermal coupling energy level of Ho³⁺achieved a maximum value of 0.0077 K^-1at 303 K,and the thermal sensitivity of the non-coupling energy levels based on Ho³⁺was 0.0067 K^-1at303 K.This means that the acquired three materials of Sr WO₄:Er³⁺(Tm³⁺,Ho³⁺)/Yb³⁺can be applied and optical temperature measurement,which can provide accurate temperature measurement.