The Reaserch On Photoluminescence Regulation And Temperature Sensing Characteristics Of Rare Earth Ions

The rare earth ions doped optical materials have good optical,electrical and magnetic properties.And because of their very important application value in the fields of petrochemicals,bio-imaging,fluorescence detection,there-dimensional display and military defense,they have attracted much attention.In recent years,due to the high sensitivity,high precision,and fast response time of rare earth ion doped optical materials,it has been affected by optical temperature sensing applications.Herein,some studies have been made to focus on the disadvantages of rare-earth ion-doped optical materials,such as low luminous efficiency,severe laser thermal interference and large optical signal transmission loss.A series CaMoO₄:Er³⁺/Yb³⁺phosphors doping with different alkali ions?Li⁺,Na⁺,and K⁺?were synthetized by high temperature solid-state reaction technique successfully.The X-ray diffraction,scanning electron microscopy,and Raman spectroscopy were used to analyze the crystallization and morphology of the samples.Under the excitation of 980 nm laser,the effects of alkali ions doping and the concentration changes on the upconversion fluorescence emission of CaMoO4:Er³⁺/Yb³⁺phosphors were studied in detail.Furthermore,the optical temperature sensing characteristics based on the thermal coupled energy levels²H_11/2 and ⁴S_3/2 of Er³⁺were systematically studied by using the fluorescence intensity ratio technique.Compared with the alkali ions-free sample,about 9.13-,18.73-,and 9.01-fold enhancements for green upconversion luminescence were obtained in CaMoO₄:Er³⁺/Yb³⁺codoped with the optimized contents of Li⁺,Na⁺,and K⁺,respectively.The temperature sensing characteristics of the prepared materials were studied,and their sensitivity values were calculated in the temperature range of 303-773 K.The maximum sensitivities of CaMoO₄:Er³⁺/Yb³⁺containing Li⁺,Na⁺,and K⁺were 1.226%K^-1 at 432K,1.3%K^-1 at 565K,and1.041%K^-1 at 649 K,respectively.A series of NaY?WO₄?₂:Ho³⁺/Er³⁺/Yb³⁺phosphors were prepared by high temperature solid-state reaction technique.The X-ray diffraction,scanning electron microscopy,and Raman spectroscopy were used to analyze the crystallization and morphology of the samples.The 980 nm laser was used as the pumping source,the near-infrared fluorescence properties of the samples were analyzed,and the fluorescence mechanism was analyzed by combining the upconversion fluorescence spectrum.In addition,the temperature dependence of the fluorescence of Ho³⁺at 1200 nm and Er³⁺at 1530 nm was studied,and the luminous intensity of 1200 nm decreased with increasing temperature,while the luminous intensity of 1530 nm increased as the temperature increases.At the same time,the near-infrared fluorescence temperature characteristics of samples with different concentrations of Er³⁺and different concentrations of Ho³⁺were studied,and the optical temperature sensing properties of Er³⁺:⁴I_13/2 and Ho³⁺:⁵I₆ were analyzed by fluorescence intensity ratio technique.In the temperature range of 303-773 K,the 2 mol%Ho³⁺/1 mol%Er³⁺/10 mol%Yb³⁺tridoped NaY?WO₄?₂ phosphor has a maximum sensitivity of 218.9×10^-3 K^-11 at 773 K.Since the 1200 nm and 1530 nm light has a small loss coefficient in the fiber,it can be used for the fiber temperature sensors.