A Cr against thermal quenching upconversion luminescence 3+ Scandium tungstate doped and applications thereof

Abstract

The present invention discloses a Cr-based luminescent material that is resistant to thermal quenching upconversion. 3+ Doped Scandium Tungstate and Its Application, Cr 3+ The chemical composition of scandium tungstate doped SWO:Yb / Cr is: Sc2(WO4)3:x%Yb 3+ / y%Cr 3+ , where 20≥x≥1, 0.1≥y≥10, where Yb 3+ is the sensitizer ion, Cr 3+ is the activator ion. 3+ Scandium tungstate (SWO):Yb / Cr) doped ratiometric fluorescence temperature sensor was constructed. Tests showed that the relative sensitivity of the ratiometric fluorescence temperature sensor constructed by the present invention reached 4% K. ‑1 , the absolute sensitivity reaches 7.4%K ‑1 , the temperature range is 300‑440K.

Description

Technical Field

[0001] The present invention relates to the field of luminescent materials and fluorescence sensing technology, and in particular to a Cr-based luminescent material that is resistant to thermal quenching upconversion luminescence. 3+ Doped scandium tungstate and its applications. Background Art

[0002] Cr 3+ It has many excellent optical properties, including a wide range of emission wavelengths, long fluorescence lifetime, and high quantum efficiency. 3+ The optical properties of Cr are affected by the local chemical environment, temperature, applied pressure or stress, external electric field and magnetic field. In addition, the matrix material, doping concentration and preparation process will affect the optical properties of Cr. 3+ Based on these special properties, Cr 3+ Doped fluorescent materials are widely used in solid lasers, photocatalysis, solar cells, long afterglow luminescent materials and optical sensors, especially Cr 3+ Down-transfer near-infrared luminescent materials as activators have become the focus of scientific researchers in recent years and have been widely studied and applied in many fields such as night vision and non-destructive imaging. 3+ / Cr 3+ Cr co-doped phosphor 3+ Ion upconversion luminescence is generally achieved through Yb 3+ The cooperative sensitization energy transfer process of ions is realized, and its excitation and emission wavelengths are both in the near-infrared band. It has the advantages of low background noise and high biological tissue penetration, and has excellent application prospects in the fields of optical sensing and deep tissue imaging.

[0003] Therefore, the new Cr 3+ The development and application of doped luminescent materials have very important research significance. However, like other types of luminescent materials, Cr 3+ Luminescence is also affected by thermal quenching of fluorescence, that is, the luminescence intensity decreases with increasing temperature. From the perspective of the design and application of fluorescent materials, the ability of fluorescent materials to resist thermal quenching is one of the key factors in evaluating their performance and is an important factor in determining their application prospects and applicability. 3+ The thermal quenching of luminescence seriously limits its research and application in high-power LEDs and some high-temperature environments. Therefore, it is urgent to develop Cr with good thermal quenching resistance. 3+ Although researchers have reported in the past that various methods such as matrix structure rigidity enhancement, band gap regulation, trap assistance, ion co-doping and multi-site occupancy can be used to improve the Cr 3+ However, the thermal stability of fluorescence achieved by the above methods is still very limited, and they all focus on Cr 3+ The down-shifted luminescence of Cr3+ Research on anti-thermal quenching upconversion luminescence.

[0004] Therefore, the prior art has defects and needs to be improved. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a kind of anti-thermal quenching upconversion luminescence Cr 3+ Doped scandium tungstate and its application to solve the problem of Cr 3+ Doped fluorescent powder anti-thermal quenching luminescence performance is limited and Cr 3+ Doped fluorescent powder anti-thermal quenching upconversion luminescence performance missing problem.The Cr 3+ Doped scandium tungstate material is a kind of anti-thermal quenching luminescence system based on Sc2 (WO4) 3 (SWO), which uses the energy compensation of energy bank in matrix material to active agent ion, realizes Yb 3+ Anti-thermal quenching luminescence, and Yb 3+ -Cr 3+ Synergistic sensitization energy transfer realizes the anti-thermal quenching upconversion luminescence of Cr 3+ , and develops the optical application of fluorescent temperature sensing based on this.

[0006] The technical scheme of the present application is as follows:

[0007] A kind of anti-thermal quenching upconversion luminescence Cr 3+ Doped scandium tungstate, Cr 3+ The chemical composition of doped scandium tungstate SWO:Yb / Cr is: Sc2 (WO4) 3: x%Yb 3+ / y%Cr 3+ , wherein 20≥x≥1, 0.1≥y≥10, wherein Yb 3+ Is a sensitizing agent ion, and Cr 3+ Is an active agent ion.

[0008] The anti-thermal quenching upconversion luminescence Cr 3+ Doped scandium tungstate, x=8, y=0.1.

[0009] The application of Cr 3+ Doped scandium tungstate in anti-thermal quenching upconversion luminescence.

[0010] The application of Cr 3+ Doped scandium tungstate in fluorescent temperature sensing.

[0011] The application is a composite fluorescent powder prepared by mixing SWO:Yb / Cr fluorescent powder and SWO:Er fluorescent powder uniformly; the anti-thermal quenching upconversion luminescence of SWO:Yb / Cr at 700-800 nm and the thermal quenching upconversion luminescence of SWO:Er at 510-570 nm have opposite intensity change trends with the increase of temperature; the intensity ratio of the two is selected as a temperature sensitive parameter to construct a ratio type fluorescent temperature sensing application.

[0012] The anti-thermal quenching upconversion luminescence: in the process of sample solid phase sintering, part of the intrinsic WO4 groups in the SWO matrix will be distorted into the interstitial gap to form extrinsic WO4 groups. The energy level coupling of intrinsic and extrinsic WO4 groups has the effect of energy storage pool. Under 976 nm excitation, Yb 3+ ions can absorb excitation light energy and transfer to the energy storage pool. After the energy storage pool absorbs and stores energy, it continuously compensates the doped Yb 3+ ions with energy at high temperature, so that Yb 3+ ions have anti-thermal quenching luminescence. Subsequently, Yb 3+ ions transfer energy to Yb 3+ -Cr 3+ ions through Yb 3+ ions, and the energy is continuously compensated to Cr 3+ ions through the cooperative sensitization energy transfer process, so that Cr -1 ions have anti-thermal quenching upconversion luminescence.

[0013] The application of the ratio type fluorescent temperature sensor shows that the relative sensitivity of the ratio type fluorescent temperature sensor constructed by the application reaches 4%K -1 , the absolute sensitivity reaches 7.4%K -1 , and the temperature measurement range is 300-440K. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 : X-ray diffraction data of SWO:8%Yb / 0.1%Cr.

[0015] Figure 2 : Scanning electron microscope and element analysis diagram of SWO:8%Yb / 0.1%Cr.

[0016] Figure 3 : Upconversion luminescence spectrum of SWO:8%Yb / 0.1%Cr under 980 nm excitation.

[0017] Figure 4 : Double logarithmic coordinate graph of luminescence intensity of SWO:8%Yb / 0.1%Cr changing with pump power.

[0018] Figure 5 : Yb 3+ -Cr 3+Two-photon upconversion luminescence process.

[0019] Figure 6 :The temperature-dependent near-infrared luminescence spectrum of SWO:8%Yb.

[0020] Figure 7 :SWO:8%Yb / 0.1%Cr in Yb 3+ Temperature-dependent near-infrared luminescence spectra.

[0021] Figure 8 :SWO:8%Yb / 0.1%Cr 3+ Temperature-dependent upconversion luminescence spectra.

[0022] Figure 9 :Temperature-dependent upconversion luminescence spectra of SWO:2%Er & SWO:8%Yb / 0.1%Cr composites

[0023] Figure 10 : Fluorescence intensity ratio I Cr / I Er (FIR) variation trend with temperature.

[0024] Figure 11 : Absolute sensitivity of ratiometric fluorescence thermometer.

[0025] Figure 12 : Relative sensitivity of ratiometric fluorescence thermometer. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to specific embodiments.

[0027] Example 1: Preparation of SWO:Yb / Cr (8 / 0.1 mol%)

[0028] First, based on a specific stoichiometric ratio, Sc2O3 (0.919mmol), Yb2O3 (0.08mmol), Cr2O3 (0.001mmol) and WO3 (3mmol) were weighed. Next, these raw materials were poured into an agate mortar, mixed and ground for 30 minutes in a dry state, and ethanol was added and continued to grind for 30 minutes until all the ethanol was evaporated to ensure that the various raw materials were fully mixed. Then, the mixed powder was transferred to an alumina crucible and placed in a muffle furnace. The temperature was raised to 800°C at a rate of 5°C per minute for about 160 minutes, and then raised to 1100°C at a rate of 3°C per minute for about 100 minutes, and kept at 1100°C for 6 hours. After the reaction was completed, the sample was taken out, cooled to room temperature, and then ground again for 30 minutes to obtain a fine and uniform fluorescent powder. Finally, the powder was collected in a 5ml small centrifuge tube for subsequent use.

[0029] The performance of the samples was tested and characterized using X-ray diffractometer, scanning electron microscope, Edinburgh FLS1000 instrument and Oxford DN2 variable temperature device. XRD data ( Figure 1 ), SEM images and EDS element scans ( Figure 2 ) all indicate that Cr 3+ Successfully doped into the SWO lattice.

[0030] Example 2Cr 3+ Characterization of upconversion luminescence performance

[0031] In order to characterize the upconversion luminescence performance of SWO:Yb / Cr, the luminescence spectrum of SWO:Yb / Cr was tested under 976nm excitation. As expected, under 976nm excitation light, Yb 3+ will absorb a near-infrared photon to reach the excited state, and then the two Yb 3+ ions can simultaneously transfer energy to Cr 3+ ions, namely the cooperative sensitization energy transfer process, which makes Cr 3+ After reaching the excited state, it emits a broad upconversion luminescence at 750 nm ( Figure 3 In order to further study the upconversion luminescence mechanism of SWO:Yb / Cr, the power dependence of upconversion luminescence under 976nm laser excitation was studied in detail. The emission intensity increased with the increase of excitation power. The slope of the variation of the near-infrared emission intensity of the sample with the pump power was about 1.8 after linear fitting. Figure 4 ), confirming the above Yb 3+ -Cr 3+ Two-photon cooperative sensitized upconversion luminescence process ( Figure 5 ).

[0032] Example 3 Characterization of the thermal quenching-resistant upconversion luminescence performance of SWO:Yb / Cr

[0033] In order to characterize the thermal quenching resistance of SWO:Yb / Cr, the temperature-dependent upconversion luminescence spectra of SWO:Yb and SWO:Yb / Cr were tested, respectively. The test temperature range was 300-500K. Under 976nm excitation, the luminescence intensity of SWO:Yb continued to increase with the increase of the test temperature ( Figure 6 ). When co-doped with Cr 3+ After ionization, Yb 3+ The fluorescence thermal enhancement effect was significantly suppressed ( Figure 7 ), prove that Yb 3+ Continuously transfer energy to Cr 3+ ions. Therefore, the Cr 3+ The anti-thermal quenching upconversion luminescence of Cr 3+The luminous intensity increases with the temperature, and the enhancement factor reaches 16 times at 460K ( Figure 8 ).

[0034] Example 4 Ratio-type fluorescence temperature sensing based on SWO:Yb / Cr & SWO:Er composite materials

[0035] Taking advantage of the fact that the upconversion luminescence intensity of SWO:Yb / Cr (8 / 0.1 mol%) increases with increasing temperature, a ratiometric fluorescence temperature sensing application can be designed. 3+ It is easier to measure temperature by changing the integral intensity of a single fluorescence peak with temperature. However, the luminous intensity of the fluorescent material will also be affected by various factors such as the external environment, instrument and human operation errors, and the structure and composition of the material itself may also undergo subtle changes. Therefore, we physically mixed SWO:2%Er phosphor and SWO:8%Yb / 0.1%Cr phosphor in a mass ratio of 2:1 to prepare a composite material. Under 976nm laser excitation, as the temperature continues to rise, the Cr in the composite material 3+ The up-conversion luminescence intensity (I Cr ) increases with increasing temperature, and Er 3+ The green light intensity (I Er ) continues to weaken( Figure 9 By monitoring the fluorescence intensity ratio of the composite material in the temperature range of 300-440K Cr / I Er (FIR)( Figure 10 ), achieving ratiometric fluorescence temperature sensing. The relative sensitivity of fluorescence temperature sensing reaches 4%K -1 ( Figure 11 ), the absolute sensitivity reaches 7.4%K -1 ( Figure 12 ).

[0036] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A Cr-based upconversion luminescent material with resistance to thermal quenching 3+ Doped scandium tungstate, characterized in that Cr 3+ The chemical composition of scandium tungstate doped SWO:Yb / Cr is: Sc2(WO4)3:x%Yb 3+ / y%Cr 3+ , where 20≥x≥1, 10≥y≥0.1, where Yb 3+ is the sensitizer ion, Cr 3+ is the activator ion.

2. The Cr-based luminescent material with thermal quenching resistance according to claim 1 3+ Doped scandium tungstate, characterized in that x=8, y=0.

1.

3. Cr according to claim 1 or 2 3+ Application of scandium tungstate-doped materials in thermally quenched upconversion luminescence.

4. Cr according to claim 1 or 2 3+ Application of scandium tungstate-doped materials in fluorescence temperature sensing.

5. The use according to claim 4, characterized in that: A composite phosphor was prepared by mixing SWO:Yb / Cr phosphor and SWO:Er phosphor. The thermally quenched upconversion luminescence of SWO:Yb / Cr at 700-800 nm and the thermally quenched upconversion luminescence of SWO:Er at 510-570 nm showed opposite intensity changes with increasing temperature. The intensity ratio of the two was selected as the temperature-sensitive parameter to construct a ratiometric fluorescence temperature sensing application.

Images