Synthesis, Fluorescence And Temperature Sensitive Properties Of Rare Earth Metal Ions Doped Polyoxometalate Compounds

Temperature is a thermodynamic parameter,and the accurate measurement of temperature is essential in many fields.Luminescence thermometers have the advantages of fast response speed and high spatial resolution.Optical parameters will change with temperature changes.Here,the change of fluorescence intensity with temperature is selected to confirm whether it has temperature-sensitive characteristics,and the strength of temperature-sensitive characteristics is compared by relative sensitivity.Using three luminescent rare earth metal ions(Ln³⁺=Eu³⁺,Dy³⁺,Sm³⁺)as the central ions,three rare-earth-based polyoxometalates(LnW₁₀,LnSiW₁₁,LnPW₁₁)are synthesized.Then the nine light-emitting rare-earth compounds are doped with rare earth metal ions(La³⁺/Gd³⁺).Obtained Ln_xLa_1-xW₁₀ series,Ln_xGd_1-xW₁₀ series,Ln_xLa_1-xSi W₁₁ series,Ln_xGd_1-xSi W₁₁ series,Ln_xLa_1-xPW₁₁ series and Ln_xGd_1-xPW₁₁series products.Use infrared spectroscopy,XRD,EDS energy spectroscopy,and fluorescence spectroscopy to analyze the structure,luminescence performance and temperature sensitivity of the product.Infrared spectroscopy showed that rare earth-based polyoxometalates(LnW₁₀,LnSiW₁₁,LnPW₁₁)had been successfully synthesized,and infrared spectroscopy and XRD spectra showed that rare earth metal ions(La³⁺/Gd³⁺)doping did not change the structure of Ln-POMs.EDS energy spectrum and elemental analysis show that doped rare earth metal ions(La³⁺/Gd³⁺)have successfully replaced part of Ln³⁺.Fluorescence spectra show that rare earth-based polyoxometalates(LnW₁₀,LnSiW₁₁,LnPW₁₁)all show characteristic emission peaks of Ln³⁺.Except for Eu_xGd_1-xW₁₀,a proper proportion of rare earth metal ions(La³⁺/Gd³⁺)doping has a fluorescence gain effect.In the temperature range of 50℃ to 100℃,the temperature sensitivity characteristics of rare earth-based polyoxometalates(LnW₁₀,LnSiW₁₁,LnPW₁₁)are analyzed.For rare earth metal ions(La³⁺/Gd³⁺)doped with Ln-POMs,use the Ln_xLa_1-xW₁₀ series,Dy_xGd_1-xW₁₀ series,Sm_xGd_1-xW₁₀ series,Ln_xLa_1-xSi W₁₁ series,Ln_xGd_1-xSi W₁₁ series,Ln_xLa_1-xPW₁₁ series and Ln_xGd_1-xPW₁₁ series products with the highest fluorescence intensity are analyzed for temperature-sensitive characteristics,while Eu_xGd_1-xW₁₀ series are followed by Increase the Gd³⁺doping ratio and analyze the temperature-sensitive characteristics;compare the relative sensitivity to the temperature-sensitive characteristics.For the rare-earth-based polyoxometalates with different rare earth luminescent central ions and the same building unit,Eu³⁺has the strongest temperature-sensitive characteristic,Dy³⁺secondly,Sm³⁺has the worst temperature-sensitive characteristics;for the rare earth polyoxometalates with the same the rare earth luminescence center ions and different building units,LnW₁₀ has the strongest temperature-sensitive characteristics,followed by LnPW11,and LnSiW11 has the worst temperature-sensitive characteristics;Appropriate amount of rare earth metal ions(La³⁺/Gd³⁺)doping can also enhance the temperature sensitivity.In the temperature range of 50℃ to 100℃,the relative sensitivity gradually increases as the temperature increases.