Research On Preparation Of Novel Up/Down Conversion Sr₃La₂Ge₃O₁₂ Fluorescent Materi-Als And Temperature Measuring Performance

Temperature measurement technology based on fluorescence intensity ratio has attracted much attention because of its fast and accurate response.There are three kinds rare earth doped Sr₃La₂Ge₃O₁₂luminescent materials were designed and prepared,and their structure,up-down conversion luminescence characteristics and temperature sensing performance were systematically investigated.Sr₃La₂Ge₃O₁₂:Bi³⁺,Eu³⁺phosphors were prepared by high temperature solid state method in air.Under the same UV excitation,Sr₃La₂Ge₃O₁₂:Bi³⁺,Eu³⁺phosphors show Bi³⁺（³P₁→¹S₀）blue emission peak and Eu³⁺（⁵D₀→⁷F₂）red emission peak,with good separation and good signal resolution.The energy transfer behavior is proved by the overlap of the emission band of Bi³⁺and excitation band of Eu³⁺.In addition,the increase of Eu³⁺concentration results in the decay of Bi³⁺lifetime,which further verifies this conclusion.The maximum absolute sensitivity of Sr₃La₂Ge₃O₁₂:Bi³⁺,Eu³⁺is 0.00079 K^-1at 573 K,and the maximum relative sensitivity is 0.831%K^-1at 473 K.It is proved that Sr₃La₂Ge₃O₁₂:Bi³⁺,Eu³⁺phosphors have good performance in optical temperature measurement and have potential in the field of temperature measurement.Sr₃La₂Ge₃O₁₂:Bi³⁺,Sm³⁺phosphors were prepared by high temperature solid state method in air.Under the excitation of external excitation light,the emission peaks of Bi³⁺and Sm³⁺hardly overlap.As the temperature rises,the different response characteristics of the two kinds of ion emission to the changing temperature.The blue emission of Bi³⁺and the red emission of Sm³⁺ions were converted into fluorescence intensity ratio signals to measure the temperature.The maximum absolute and relative sensitivities at 573 K were 0.00085 K^-1and 0.814%K^-1,respectively,indicating that the phosphor is suitable for use in high temperature regions.Sr₃La₂Ge₃O₁₂:Yb³⁺,Er³⁺upconversion phosphors were prepared by high temperature solid-state method in air.Under the excitation of 980 nm,the Er³⁺of this series of samples emit strong green light.After adding Yb³⁺as sensitizer,the up-conversion emission intensity is greatly enhanced,and the fluorescence lifetime of Er³⁺is greatly increased.Based on the fluorescence intensity ratio of thermally coupled energy levels,the maximum relative sensitivity of Sr₃La₂Ge₃O₁₂:Yb³⁺,Er³⁺is 1.15%K^-1at 293 K.According to the calculation formula,it has high sensitivity in low temperature region.The optical properties and temperature sensing properties of phosphors can be controlled by changing the composition ratio of the matrix.The Sr²⁺gradually replaced with Ca²⁺,a change in physical properties and optical properties of sample,and the relative sensitivity to 1.38%K^-1.