Luminescence Properties Of Pr³⁺/Sm³⁺ Ions In Composite Oxides

In this paper,we mainly synthesized a series of new rare earth luminescent materials with garnet structure and YTa O₄ with M-type and M’-type structure by adjusting the synthesis conditions,and their structure,luminescent properties,temperature sensitive properties and mechanism were studied in detail.The research mainly includes three parts:（1）In this experiment,Pr³⁺ion doped Ca₂Lu Sc Ga₂Ge₂O₁₂ phosphors with garnet structure were prepared by high temperature solid state method.The structure and morphology of the samples were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,Fourier transform infrared spectroscopy（FTIR）and X-ray photoelectron spectroscopy（XPS）.The diffuse reflection and photoluminescence（PL）properties of the material were studied by UV-Vis spectrophotometer.Two interesting luminescence phenomena were found:one is that the ¹D₂ level quenching concentration of Pr³⁺ion is much lower than that of ³P₀ level;The other is that when the excitation wavelength is different,the quenching concentration of ³P₀ level will also be different.The concentration quenching mechanism of Ca₂Lu Sc Ga₂Ge₂O₁₂:Pr³⁺is discussed in detail.It is found that the luminescence color gamut of the luminescent material can be adjusted by changing the doping concentration of Pr³⁺ion.（2）The gallium germanate garnet Ca₂Lu Sc Ga₂Ge₂O₁₂:Pr³⁺fluorescent material prepared in this experiment was synthesized by high temperature solid state method.The crystal structure,apparent morphology and luminescence properties of the fluorescent material were studied by X-ray diffraction（XRD）,Scanning electron microscope（SEM）,Fourier infrared spectroscopy（FTIR）and Photoluminescence spectroscopy（PL）.The luminescence characteristics of Ca₂Lu Sc Ga₂Ge₂O₁₂:Pr³⁺Phosphor in the range of 80-500 K were studied.The results show that ³P₁ and ³P₀energy levels are thermally coupled energy level pairs of Pr³⁺,the two pairs of transitions ³P₀→³H₅ and ³P₁→³H₅ accord with the Boltzmann particle distribution,and the luminous intensity ratio is monotonous and continuous with the increase of temperature.At the same time,the non-thermally coupled energy levels ¹D₂→³H₄ and³P₀→³H₄ also show similar phenomena.By calculating the sensitivity value,it can be inferred that Ca₂Lu Sc Ga₂Ge₂O₁₂:Pr³⁺is a red phosphor with potential application value in the field of temperature sensing.（3）In this work,Nb⁵⁺,Sm³⁺single doped and Co-doped YTa O₄ phosphors were designed.YTa O₄ with M-type and M’-type structure can be obtained by adjusting the synthesis conditions.The structure and composition of the samples were characterized by X-ray diffraction（XRD）,Scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FTIR）.The photoluminescence properties of nbo43group and Sm³⁺ion in M-type and M’-type YTa O₄ matrix were studied.Due to the different thermal responses of Nb⁵⁺and Sm³⁺ions,the fluorescence intensity ratio between them can be used as a temperature detection signal.In the range of 77～500K,at 450 K,the maximum relative sensitivity of YTa O₄:Nb⁵⁺,Sm³⁺reaches 1.15%K^-1,indicating that the M-type YTa O₄ phosphor Co-doped with Nb⁵⁺and Sm³⁺can be used as an optical temperature sensor.This study can provide guidance for the temperature detection design of other rare earth doped luminescent materials.