Yb and Ho co-doped GBWO fluorescent powder and application as optical thermal material

Abstract

This invention provides a Yb and Ho co-doped GBWO phosphor and its application as a thermosensitive material. GBWO:0.2Yb phosphor was synthesized using a solid-state method. 3+ ,yHo 3+ (y=0.001,0.003,0.005,0.007,0.01,0.03) and GBWO:xYb 3+ 0.003Ho 3+ Upconversion phosphors in the series (x=0, 0.18, 0.24, 0.30, 0.32, 0.36) were observed in the 528 nm–560 nm and 630 nm–680 nm wavelength ranges under the action of a 980 nm laser. 3+ The weaker green emission peak ( 5 F4 / 5 S2~ 5 I8), and strong red light emission peak ( 5 F5 / ~ 5 I8). This sample can be used for optical temperature measurement, which is from Ho. 3+ of 5 F5 / ~ 5 I8 5 F4 / 5 S2~ 5 The I8 transition was confirmed in ratiometric fluorescence (FIR). Gd3BWO9:Yb 3+ Ho 3+ Ratio fluorescence (FIR) between non-thermally coupled energy levels (NTCELs) in phosphors has great application potential in the field of temperature measurement.

Description

Technical Field

[0001] This invention relates to a phosphor, specifically a phosphor based on molybdenum tungsten borate, its preparation method, and its application in optical and thermal sensitive materials. It belongs to the field of rare-earth luminescent materials technology. Background Technology

[0002] Rare-earth-doped upconversion materials convert low-energy, long-wavelength infrared light into high-energy, short-wavelength visible light by absorbing multiple photons. These upconversion emission materials possess remarkably tunable anti-Stokes luminescence properties and are widely used in cell imaging, optical anti-counterfeiting, temperature sensing, and solid-state lasers. This invention primarily studies the optical temperature sensing performance of phosphors.

[0003] Temperature is a crucial parameter in many fields, including industry, agriculture, biomedicine, and scientific research. Traditional contact temperature sensors are gradually being replaced by non-contact optical sensors because different fields require non-invasive temperature measurement of the substances being measured. Optical thermometry determines the temperature of a substance based on the fluorescence characteristics of luminescent ions. Among various optical thermometry methods, ratiometric fluorescence (FIR) based methods are widely studied due to their high accuracy, fast response, wide temperature range, absence of electromagnetic interference, and high spatial resolution. They can measure the surface and internal temperature of samples under high-temperature conditions.

[0004] Rare earth ions RE 3+ Having multiple outer electron shells, some electrons in the 4f energy level exhibit unique temperature sensitivity, a rarity in luminescent materials. In RE 3+ In the middle, Er 3+ Ho 3+ and Tm 3+ As a typical ion of upconversion emission, it is used in optical thermometry research. Among them, Er 3+ With Yb 3+ Double-doped substrate materials are the most studied in optical sensing because Er 3+ It has a rich energy level structure. 4 I 11 / 2 → 4 I 15 / 2 , 4 F 7 / 2 → 4 I 11 / 2 Energy level difference and Yb 3+ of 2 F 7 / 2 arrive 2 F 5 / 2 The wavelengths absorbed during energy level transitions are similar, which allows for efficient energy transfer between the two types of ions. However, Er 3+ The overlapping emission bands and narrow band gaps between the two elements can cause some errors in optical thermometers, so it is crucial to develop new optical thermometric materials doped with other lanthanide elements. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention employs GBWO tungstate material, which possesses nonlinear optical properties, good stability, and relatively low phonon energy, as a substrate, and investigates a series of GBWO:Yb... 3+ Er 3+ Based on the luminescent and optical thermometric properties of upconversion phosphors, this invention prepares a series of Ho... 3+ and Yb 3+ The double-doped GBWO phosphor, and the upconversion luminescence and thermometric properties of the prepared phosphor.

[0006] In this invention, Ho 3+ Because ions possess multiple broad, independent emission bands in their spectrum, Ho 3+ The absorption near 980 nm is weak, and the single-doped Ho 3+ The upconversion sample exhibited low emission intensity, therefore the sensitizer Yb was chosen. 3+ with Ho 3+ Co-doping can greatly improve the upconversion luminescence performance of doped phosphors.

[0007] Yb and Ho co-doped GBWO phosphor, using Gd3BWO9 as the matrix and Yb 3+ and Ho 3+ As an active ion, the chemical composition of Gd is obtained. 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ , where 0.001≤y≤0.05.

[0008] As a preferred embodiment, 0.001≤y≤0.03; more preferably, y is any one of 0.001, 0.003, 0.005, 0.007, 0.01, and 0.03.

[0009] Yb and Ho co-doped GBWO phosphor, using Gd3BWO9 as the matrix and Yb 3+ and Ho 3+ As an active ion, the chemical composition of Gd is obtained. 2.997-x BWO9:xYb 3+ 0.003Ho 3+ , where 0.1≤x≤0.5.

[0010] As a preferred embodiment, 0.18≤x≤0.4; more preferably, y is any one of 0.18, 0.24, 0.30, 0.32, and 0.36.

[0011] A method for preparing a Yb and Ho co-doped GBWO phosphor includes the following steps: (1) Gd2O3, Yb2O3, Ho2O3, H3BO3 and WO3 are mixed and heated to 500-600℃ for pre-calcination; (2) The product obtained after pre-calcination is ground and dispersed and then sintered at 1200-1300℃. After natural cooling, Yb and Ho co-doped GBWO phosphor is obtained.

[0012] Before pre-calcination, Gd2O3, Yb2O3, Ho2O3, H3BO3, and WO3 are heated to 700-800℃ and kept at that temperature for 10-20 hours to dehydrate.

[0013] The amounts of Gd₂O₃, Yb₂O₃, Ho₂O₃, and WO₃ are determined according to Gd 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ The phosphor obtained by weighing the stoichiometric ratios of each element in the range 0.001≤y≤0.05 is Gd. 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ , where 0.001≤y≤0.05.

[0014] Or according to Gd 2.997-x BWO9:xYb 3+ 0.003Ho 3+ In the case where the stoichiometric ratio of each element in the range 0.1 ≤ x ≤ 0.5 is measured by weight, the resulting phosphor is Gd. 2.997-x BWO9:xYb 3+ 0.003Ho 3+ Where 0.1 ≤ x ≤ 0.5; The amount of H3BO3 is 110%-120% of the molar amount of boric acid used in the raw materials for forming the Gd3BWO9 matrix, in order to compensate for the loss caused by the decomposition reaction of boric acid at high temperature.

[0015] In step (1), the pre-firing conditions are to raise the temperature to 500-600℃ at a rate of 10℃ / min-50℃ / min and hold it for 4-6 hours; In step (2), sintering is carried out by heating the temperature to 1200-1300℃ at a rate of 10℃ / min-50℃ / min and holding it at that temperature for 20-30 hours.

[0016] The application of Yb and Ho co-doped GBWO phosphor as an optical thermosensitive material.

[0017] An optical thermosensitive material comprising the Yb and Ho co-doped GBWO phosphor.

[0018] This invention synthesizes a series of GBWO:Yb using a high-temperature solid-state method. 3+ Ho 3+ Upconversion phosphor. The effects of GBWO:Yb on upconversion phosphor were investigated using X-ray diffraction, Raman spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. 3+ Ho 3+ The structure, upconversion emission, and energy transfer characteristics of the [structure / emission method] were investigated. Under 980 nm light, the upconversion emission intensity exhibited a dependence on the pump light power. Furthermore, the Ho [structure / emission method] was obtained using FIR technology. 3+ Non-thermally coupled energy levels (NTCLEs) 5 F5 and 5 S2 / 5 Temperature measurement performance between F4. In the range of 300~625 K, GBWO: 0.32Yb 3+ 0.003Ho 3+ S R and S A Both decrease with increasing temperature; at 300 K, S R and S A All reached their maximum values. Among them, S R（max） = 0.0073 K -1 S A（max） =0.0508 K -1 Subsequently, as the temperature continued to rise, S R and S A It continued to decrease, reaching its lowest value at 625 K, which was S. R = 0.0016 K -1 S A =0.0198 K -1 It should be noted that, compared with most samples reported in the literature, the Gd3BWO9:Yb synthesized in this invention... 3+ Ho 3+ It has 0.0508K -1 Rare absolute sensitivity; even at temperatures up to 625 K, the sample's S... A It remains at a relatively high level (0.0198 K). -1 Therefore, Gd3BWO9: Yb 3+ Ho 3+ Phosphors have great potential in optical temperature measurement. Attached Figure Description

[0019] Figure 1 The image shows the XRD patterns of the phosphor, where (a) and (c) represent GBWO: 0.2Yb. 3+ yHo 3+ (y=0.001,0.003, 0.005, 0.007, 0.01, 0.03) XRD patterns of phosphors; (b) and (d) are GBWO:xYb 3+ 0.003Ho 3+ XRD patterns of phosphors (x=0, 0.18, 0.24, 0.30, 0.32, 0.36).

[0020] Figure 2 GBWO: 0.32Yb 3+ 0.003Ho 3+ SEM image.

[0021] Figure 3 (a) GBWO substrate and (b) GBWO:xYb 3+ 0.003Ho 3+ Raman spectra of (x=0, 0.32).

[0022] Figure 4 (a) GBWO: 0.2Yb 3+ yHo 3+ (y=0.001, 0.003, 0.005, 0.007, 0.01, 0.03) and GBWO: xYb 3+ 0.003Ho 3+ Upconversion emission spectra of a series of upconversion phosphors (x=0, 0.18, 0.24, 0.30, 0.32, 0.36) under pump light excitation at a wavelength of 980 nm.

[0023] Figure 5 GBWO:xYb 3+ 0.003Ho 3+ Color coordinates of (x=0.18, 0.24, 0.30, 0.32, 0.36).

[0024] Figure 6 GBWO: 0.32Yb 3+ 0.003Ho 3+ The temperature-varying upconversion spectrum is obtained from 300 K to 625 K, where the excitation wavelength is 980 nm.

[0025] Figure 7 GBWO: 0.32Yb3+ 0.003Ho 3+ A magnified view of a portion of the variable-temperature spectrum.

[0026] Figure 8 GBWO: 0.32Yb 3+ 0.003Ho 3+ Spectral comparison at 300 K and 625 K.

[0027] Figure 9 GBWO: 0.32Yb 3+ 0.003Ho 3+ Color coordinates at 300 K, 350 K, 400 K, 450 K, 500 K, 550 K, and 600 K.

[0028] Figure 10 For (a) FIR values ​​at different temperatures and (b) GBWO: 0.32 Yb 3+ 0.003 Ho 3+ Phosphors in the temperature range of 300~625 K (λ) ex S = 980 nm) R and S A value. Detailed Implementation

[0029] Example 1 The starting materials included Gd₂O₃ (Adamas, 99.99%), Yb₂O₃ (Adamas, 99.99%), Ho₂O₃ (Adamas, 99.99%), H₃BO₃ (Greagent, 99.5%), and WO₃ (Adamas, 99.99%). All required rare earth oxides were heated to 750°C and held for 15 hours to remove moisture from the raw materials.

[0030] Weigh the Gd3BWO9 substrate according to the stoichiometric ratio on a balance, and add an excess of 15% H3BO3 to compensate for the loss caused by the decomposition reaction of boric acid at high temperature. Then add Gd 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ The weights of Yb2O3 and Ho2O3 were 0.001, 0.003, 0.005, 0.007, 0.01, and 0.03, respectively.

[0031] (1) Gd2O3, Yb2O3, Ho2O3, H3BO3 and WO3 are mixed and heated to 500℃ at a rate of 50℃ / min, and held at the temperature for 4h for pre-calcination; (2) The product obtained after pre-calcination was ground and dispersed, then heated to 1200℃ at a rate of 50℃ / min, held at that temperature for 24h, and naturally cooled to obtain Yb and Ho co-doped GBWO phosphor. Based on the weighing of the different raw materials mentioned above, Gd was prepared separately. 2.799 BWO9:0.2Yb 3+ 0.001Ho 3+ Gd 2.797 BWO9:0.2Yb 3+ 0.003Ho 3+ Gd 2.795 BWO9:0.2Yb 3+ 0.005Ho 3+ Gd 2.793 BWO9:0.2Yb 3+ 0.007Ho 3+ Gd 2.790 BWO9:0.2Yb 3+ 0.01Ho 3+ Gd 2.77 BWO9:0.2Yb 3 + 0.03Ho 3+ .

[0032] Weigh the different raw materials again and prepare Gd separately. 2.817 BWO9:0.18Yb 3+ 0.003Ho 3+ Gd 2.757 BWO9:0.24Yb 3+ 0.003Ho 3+ Gd 2.697 BWO9:0.30Yb 3+ 0.003Ho 3+ Gd 2.677 BWO9:0.32Yb 3+ 0.003Ho 3+ Gd 2.637 BWO9:0.36Yb 3+ 0.003Ho 3+ Gd 2.997 BWO9:,0.003Ho 3+ .

[0033] The PW3040 / 60X X-ray diffractometer (Netherlands) manufactured by Panalytical was used to collect GBWO: 0.2Yb 3+ yHo 3+(y=0.001, 0.003, 0.005, 0.007, 0.01, 0.03) and GBWO: xYb 3+ 0.003Ho 3+ XRD data (x=0, 0.18, 0.24, 0.30, 0.32, 0.36) were used to characterize the crystal structure (diffraction angle range 10-70°). The morphology and size of the upconversion phosphors were characterized using a Hitachi SU8010 SEM. Diffuse reflectance spectra of a series of phosphors in the wavelength range of 200–1200 nm were measured using a Shimadzu UV-2600 UV spectrophotometer (Japan). Room temperature upconversion emission spectra and variable power upconversion emission spectra were measured using a FluoroMAX-4 fluorescence spectrometer (Horiba, Paris), equipped with a laser capable of receiving an external 980 nm pump light. GBWO and GBWO:xYb 3+ yEr 3+ Fluorescence lifetime data of the phosphor were collected using an FLS-980 spectrometer (Edinburgh, UK) with a 980 nm excitation source. Temperature-dependent upconversion spectra were collected using an FLS-1000 fluorescence spectrometer (Edinburgh, UK) equipped with a tunable 980 nm laser and a temperature control system.

[0034] GBWO belongs to P 6 Space group 3 (hexagonal crystal system). Figure 1 It is a synthetic GBWO: 0.2Yb 3+ yHo 3+ (y=0.001,0.003, 0.005, 0.007, 0.01, 0.03) and GBWO: xYb 3+ 0.003Ho 3+ XRD patterns of a series of phosphors (x=0, 0.18, 0.24, 0.30, 0.32, 0.36). Figure 1 In (a), Yb is fixed. 3+ The doping ratio is 0.2, changing Ho 3+ The diffraction pattern was collected under conditions of Ho concentration. Different concentrations of Ho can be observed. 3+ The doped patterns all perfectly match the GBWO PDF card (No. 97-025-0417), indicating that the synthesized substances are all pure phases. Figure 1 (b) is the same Ho 3+ Different concentrations of Yb 3+The XRD patterns of all samples match those of card No. 97-025-0417. These results reflect Ho's... 3+ and Yb 3+ Doping with Yb will not introduce impurities into the system, even when Yb 3+ - Ho 3+ The concentration of dual doping reaches its maximum (Yb) 3+ 0.36, Ho 3+ (0.003), no diffraction peaks of impurities were observed in the XRD pattern. Figure 1 In the middle (c) and (d) are respectively Figure 1 Enlarged views of (a) and (b) (2θ range: 28.5~31). It can be seen that in the co-doped system, the diffraction peaks are all shifted to the right, and with the increase in Ho in the system... 3+ Concentration (y) and Yb 3+ The rightward shift becomes more pronounced as the concentration (x) gradually increases. This phenomenon is due to Yb 3+ and Ho 3+ The radii of the ions are all larger than those of Gd. 3+ Small, part of Yb 3+ and Ho 3+ Replacement of part of Gd 3+ This causes the interplanar spacing in the GBWO lattice to decrease, and the XRD pattern shifts in the direction of increasing angle.

[0035] This invention uses scanning electron microscopy to study GBWO: 0.32Yb. 3+ 0.003Ho 3+ The morphology was characterized, such as Figure 2 As shown in the SEM image, GBWO: 0.32Yb 3+ 0.003Ho 3+ The phosphor has an irregular particle shape with a size distribution of approximately 2 μm to 15 μm.

[0036] Figure 3 (a) shows the Raman spectrum of the GBWO substrate, revealing numerous characteristic Raman peaks with wavenumbers of 314.5, 389.6, 451.2, 545.4, 625.9, 696.6, and 836.2 cm⁻¹. -1 .pass Figure 3 (a) It can be known that the maximum phonon energy of the GBWO matrix is ​​836.2 cm⁻¹. -1 This also promoted Yb 3+ / Ho 3+ Upconversion transmission.

[0037] Compared to the substrate, under the same test conditions, single-doped Ho 3+ GBWO is 836.2 cm-1 The peak intensity at Yb is significantly reduced, while the peak intensity at Yb is significantly reduced. 3+ The addition of [something] makes the peak here weaker. Figure 3 (b) Using Origin for GBWO matrix, GBWO: 0.003Ho 3+ and GBWO: 0.32Yb 3+ 0.003Ho 3+ At 836.2 cm -1 Integrating at the Raman peak at [location]. The resulting integrated areas are: GBWO (65770), GBWO: 0.003Ho. 3+ (37987), GBWO: 0.32Yb 3+ 0.003Ho 3+ (28957). Samples with higher phonon state density have lower fluorescence emission efficiency, which explains the introduction of Ho. 3+ After luminescence, at 836.2 cm⁻¹ -1 The peak intensity at that point decreases significantly, and the integral area decreases significantly. Introducing Yb... 3+ After being used as a sensitizer, the luminescence efficiency of the system was significantly enhanced, hence GBWO: 0.32Yb 3+ 0.003Ho 3+ The minimum integral area proves Yb 3+ with Ho 3+ There is efficient energy transfer between them.

[0038] Upconversion emission spectrum This invention tested GBWO:0.2Yb using a laser with a 980 nm pump light (pump power of 500 mW). 3 + yHo 3+ (y=0.001, 0.003, 0.005, 0.007, 0.01, 0.03) and GBWO: xYb 3+ 0.003Ho 3+ (x=0, 0.18, 0.24, 0.30, 0.32, 0.36) Phosphor upconversion spectra at room temperature in the 500-700 nm wavelength range (e.g.) Figure 4 (as shown in (a) and 4(b)). Figure 4 (a) is a fixed Yb 3+ The concentration was 0.2, and the Ho was changed. 3+ The concentration-measured spectra showed that all samples exhibited two Ho values ​​in the 528 nm–560 nm and 630 nm–680 nm wavelength bands. 3+ The emission peak, with the central peak at 540 nm, originates from Ho. 3+ Weaker green light emission ( 5F4 / 5 S2~ 5 I8), while the main emission peak at 653 nm is Ho. 3+ Strong red light emission ( 5 F5 / ~ 5 I8), they are Ho 3+ from 5 F4 / 5 S2 state and 5 F5 state return to 5 This is caused by electron transitions during the I8 ground state process. With Ho... 3+ As the concentration increases (y=0.001, 0.003, 0.005, 0.007, 0.01, 0.03), the intensity of the upconversion emission peak gradually increases, reaching a peak at y = 0.003 (GBWO: 0.20Yb). 3+ 0.003Ho 3+ The maximum value is reached when Ho... 3+ As the content increases further, a concentration quenching effect occurs, resulting in a decrease in emission intensity. Therefore, GBWO: 0.20Yb 3+ yHo 3+ (y=0.01, 0.015, 0.02, 0.025, 0.05) Ho in the sample 3+ The optimal ratio is y = 0.003.

[0039] Next, fix Ho. 3+ The concentration was 0.003, and Yb was changed. 3+ Further research will be conducted on the changes in emission intensity based on the concentration. Figure 4 (b) is GBWO: xYb 3+ 0.003Ho 3+ (x=0, 0.18, 0.24, 0.30, 0.32, 0.36) Upconversion room temperature emission spectrum of phosphor (excited by 980nm near-infrared light, spectral range: 500-700 nm). Figure 4 Display, change Ho 3+ or Yb 3+ The concentration of Yb does not change the position or shape of the upconversion emission peak. However, with the concentration of Yb 3+ The emission peak intensity at 540 nm and 653 nm varies differently depending on the content of Yb. The peak intensity at the 540 nm emission band changes with Yb. 3+ The effect increases with increasing concentration, as Yb 3+ The intensity of green light emission reaches its maximum when the content is x = 0.36, and the peak intensity in the 653 nm emission band increases with Yb. 3+ The concentration initially increases and then decreases with increasing concentration, when Yb3+ When the concentration is x = 0.32, the intensity of red light emission reaches its maximum value, and then the intensity decreases, resulting in a concentration quenching effect.

[0040] For Yb 3+ The effect of doping concentration on emission color was plotted using the CIE plugin in Origin based on spectral data, and the sample GBWO:xYb was plotted. 3+ 0.003Ho 3+ A color coordinate graph of (x=0.18, 0.24, 0.30, 0.32, 0.36), as shown below. Figure 5 As shown in the figure. Points 1, 2, 3, 4, and 5 in the figure represent Yb respectively. 3+ Data with contents of 0.18, 0.24, 0.30, 0.32, and 0.36. When x = 0.18, 0.24, 0.30, 0.32, and 0.36, the corresponding CIE coordinates are 1 (0.43211, 0.55854), 2 (0.4235, 0.56784), 3 (0.4105, 0.58053), 4 (0.42413, 0.56745), and 5 (0.40605, 0.58514), respectively. When Yb 3+ As the content gradually increases, the emission moves from the yellowish region to the yellow-green region. When x=0.32, the emission returns to the yellowish region, and when x=0.36, it shifts back to the yellow-green region. Optical temperature measurement characteristics For GBWO: 0.32Yb 3+ 0.003Ho 3+ The optical thermometry characteristics were investigated, and the upconversion temperature-varying spectrum was measured over an experimental temperature range from 300 K to 625 K. The excitation wavelength was 980 nm, the pump power was approximately 500 mW, and the temperature variation step was 25 K. Figure 6 As shown, in the spectral region of 500-700 nm, GBWO: 0.32Yb 3+ 0.003Ho 3+ Ho 3+ from 5 F4 / 5 S2, 5 The F5 energy level returns to the ground state. 5 I8 produced two emission peaks centered at 540 nm and 653 nm.

[0041] When the temperature increases from 300 K to 625 K, the peak shape and position in the spectrum remain unchanged. When the temperature increases from 300 K to 325 K and then to 350 K, the red emission intensity increases slightly. However, as the temperature increases from 350 K to 625 K, the emission intensities of both green and red continuously decrease (the decrease in green emission intensity is not as significant as that of red). This may be due to the fact that at low temperatures, Yb... 3+ -Ho 3+ The energy transfer efficiency is greater than that of phonon-assisted nonradiative relaxation, resulting in enhanced fluorescence intensity. As the temperature continues to rise, the nonradiative relaxation of electrons between energy levels gains the upper hand in the competition, and the thermal quenching effect further leads to a decrease in fluorescence intensity. Figure 7 The changes in emission intensity reflecting the partial temperature variation spectrum at 653 nm were clearly understood.

[0042] from Figure 6 and 7 The study found that the red emission band at 653 nm consists of two split peaks (centered at 654 nm and 662 nm, respectively). This is due to... 5 The F5 level is formed by the return of two different Stark sub-levels to the ground state. Close observation reveals different evolutionary trends for these two peaks. As temperature increases, the intensity of the peak at 662 nm gradually decreases, and its proportion in the entire red emission band also gradually decreases. Conversely, the peak at 654 nm exhibits the opposite trend. This is because there is an effective non-radiative process between the two closely adjacent Stark sub-levels. When the temperature rises, the lower sub-level (at 662 nm) can be thermally excited to fill the higher sub-level (at 653 nm), indicating that the two Stark levels are thermally coupled.

[0043] To observe this phenomenon more clearly, data at 300 K and 625 K were used to plot a locally magnified spectrum. Figure 8 ).

[0044] Based on the measured temperature-varying spectrum, the CIE coordinates (e.g., ...) within the temperature range of 300 K–600 K were calculated. Figure 8 The seven dots 1-7 represent GBWO: 0.32Yb respectively. 3+ 0.003Ho 3+ The chromatic coordinates at 300 K, 350 K, 400 K, 450 K, 500 K, 550 K, and 600 K are (0.52985, 0.46509), (0.545, 0.45026), (0.5529, 0.44251), (0.56358, 0.43207), (0.57166, 0.42416), (0.57994, 0.41603), and (0.58464, 0.41141), respectively.

[0045] from Figure 9 As the temperature rises, the color emitted by the sample changes from orange to dark orange and finally to red. At room temperature, 5 S2, 5 The green emission produced by the F4→5I8 transition is greater than... 5 F5 → 5 The red emission produced by the I8 transition is weak, and red emission is dominant over green emission, resulting in orange emitted light. As temperature increases, the color coordinates gradually shift towards the deeper orange region, and at 600K, the emitted light is red.

[0046] RE 3+ The FIR spectrum follows the Boltzmann distribution. If two emission peaks are close to each other, their spectra will often partially overlap. Considering this, the formula for calculating the FIR spectrum is as follows: (1) In the formula, I, N, ω, , g, ΔE, and T represent the integral of fluorescence intensity, ion population, frequency, emission cross-section from TCL / NTCL level to ground state, level degeneracy, band gap, and absolute temperature, respectively. A is a constant, C is the newly added compensation factor, and K B Let be the Boltzmann constant. According to formula (1), we calculated GBWO: 0.32Yb 3+ 0.003Ho 3+ The FIR values ​​of the sample in the 300-625 K region were then used as a function of temperature to plot a temperature vs. FIR curve, as shown below. Figure 10 As shown in (a), the fitted equation is FIR = 20.65 × exp(-653.38 / T) + 4.63, with a goodness of fit of 0.995. The slope of the fitted curve is ΔE / k. It can be seen from the figure that the FIR value increases with increasing temperature. Meanwhile, the calculated value of ΔE is 454 cm⁻¹. −1 , satisfying the requirement of 200 cm −1 -2000 cm −1 Scope requirements.

[0047] In addition, relative sensitivity (S R ) and absolute sensitivity (S A The performance of the temperature sensor can be determined by formulas (2.6) and (2.7), and GBWO: 0.32Yb can be calculated. 3+ 0.003Ho 3+ S in the range of 300 ~ 625 K R and S A Value (e.g.) Figure 10(b) shown). GBWO: 0.32Yb 3+ 0.003Ho 3+ S R and S A Both decrease with increasing temperature; at 300 K, S R and S A All reached their maximum values. Among them, S R（max） = 0.0073 K -1 S A（max） =0.0508 K -1 As the temperature rises to 625 K, S R and S A They dropped to S respectively R = 0.0016 K -1 S A =0.0198 K -1 Table 1 summarizes some typical Ho 3+ and Yb 3+ Sensitivity values ​​of dual / multi-doped phosphors.

[0048] Table 1 Yb 3+ Ho 3+ S of co-doped upconversion phosphor R With S A

[0049] with Ba 0.77 Ca 0.23 TiO3: Yb 3+ Ho 3+ (S) R（max） =0.53% K -1 KLu(WO4)2: Yb 3+ Ho 3+ (S) R（max） =0.38% K -1 Y2O3:Yb 3+ Ho 3+ ,Ge 3+ (S) R（max） =0.62%K -1 Y2O3: Yb 3+ Ho 3+ Zn 3+ (S) R（max） =0.23%K -1 Compared to oxides such as 0.32Yb, GBWO: 0.32Yb 3+ 0.003Ho 3+ S of fluorescent powder R（max） It is at a relatively high level. Although GBWO:Yb3+ Ho 3+ With Ca2MgWO6: Yb 3+ Ho 3+ (S) R（max） =2.45%K -1 ) and Bi4Ti3O 12 Yb 3+ Ho 3+ (S) R（max） =2.11%K -1 S of oxides R（max） It is slightly inferior in comparison, but it has a very large S A（max） (5.08%K) -1 GBWO: 0.32Yb of this invention. 3+ 0.003Ho 3+ S of the sample A（max） The S of all temperature measuring materials in the table A（max） The value is 5 to 10 times higher. In summary, Gd3BWO9: Yb 3+ Ho 3+ Phosphors have great potential for application in optical temperature measurement.

[0050] GBWO:0.2Yb was synthesized using a solid-state method. 3+ yHo 3+ (y=0.001, 0.003, 0.005, 0.007,0.01, 0.03) and GBWO: xYb 3+ 0.003Ho 3+ For the upconversion phosphor series (x=0, 0.18, 0.24, 0.30, 0.32, 0.36), the optimal double-doped sample is GBWO: 0.32 Yb. 3+ , 0.003 Ho 3+ Under the action of a 980 nm laser, wavelengths from Ho were observed in the 528 nm–560 nm and 630 nm–680 nm bands. 3+ The weaker green emission peak ( 5 F4 / 5 S2~ 5 I8), and strong red light emission peak ( 5 F5 / ~ 5 I8), they are Ho 3+ from 5 F4 / 5 S2 state and 5 F5 state return to 5The emission is generated by electron transitions during the I8 ground state process. Measurements of the emission spectrum with varying power confirmed that the green emission at 540 nm and the red emission at 653 nm are both two-photon processes. Furthermore, this sample can be used for optical thermometry, which is derived from Ho... 3+ of 5 F5 / ~ 5 I8 5 F4 / 5 S2~ 5 The I8 transition was confirmed in the FIR. The GBWO: 0.32Yb was calculated by testing the upconversion temperature-varying spectra in the 300 K–625 K range. 3+ 0.003Ho 3+ The FIR values ​​of the sample in the 300–625 K region were further calculated to obtain S. R and S A At 300 K, S R and S A All reached their maximum values, namely S R（max） = 0.0073 K -1 S A（max） =0.0508 K -1 Therefore, Gd3BWO9: Yb 3+ Ho 3+ The FIR between NTCELs in phosphors has great application potential in the field of temperature measurement.

Claims

1. A Yb and Ho co-doped GBWO phosphor, characterized in that, Using Gd3BWO9 as the matrix, with Yb 3+ and Ho 3+ As an active ion, the chemical composition of Gd is obtained. 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ , where 0.001≤y≤0.

05.

2. The Yb and Ho co-doped GBWO phosphor according to claim 1, characterized in that, The condition 0.001≤y≤0.03 is mentioned.

3. The Yb and Ho co-doped GBWO phosphor according to claim 1, characterized in that, The value of y is any one of 0.001, 0.003, 0.005, 0.007, 0.01, and 0.

03.

4. A GBWO phosphor co-doped with Yb and Ho, characterized in that, Using Gd3BWO9 as the matrix, with Yb 3+ and Ho 3+ As an active ion, the chemical composition of Gd is obtained. 2.997-x BWO9:xYb 3+ 0.003Ho 3+ , where 0.1≤x≤0.

5.

5. The Yb and Ho co-doped GBWO phosphor according to claim 4, characterized in that, The condition 0.18 ≤ x ≤ 0.4 is mentioned.

6. The Yb and Ho co-doped GBWO phosphor according to claim 5, characterized in that, The x value is any one of 0.18, 0.24, 0.30, 0.32, and 0.

36.

7. A method for preparing a Yb and Ho co-doped GBWO phosphor, characterized in that, Includes the following steps: (1) Gd2O3, Yb2O3, Ho2O3, H3BO3 and WO3 are mixed and heated to 500-600℃ for pre-calcination; (2) The product obtained after pre-calcination is ground and dispersed and then sintered at 1200-1300℃. After natural cooling, Yb and Ho co-doped GBWO phosphor is obtained. The chemical composition of the Yb and Ho co-doped GBWO phosphor is Gd 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ Where 0.001≤y≤0.05 or Gd 2.997-x BWO9:xYb 3+ 0.003Ho 3+ , where 0.1≤x≤0.

5.

8. The method for preparing Yb and Ho co-doped GBWO phosphor according to claim 7, characterized in that, Before pre-calcination, Gd2O3, Yb2O3, Ho2O3, H3BO3, and WO3 are heated to 700-800℃ and kept at that temperature for 10-20 hours to dehydrate.

9. The method for preparing Yb and Ho co-doped GBWO phosphor according to claim 8, characterized in that, The amounts of Gd₂O₃, Yb₂O₃, Ho₂O₃, and WO₃ are determined according to Gd 2.8-y BWO9:0.2Yb 3+ ,yHo 3+ The stoichiometric ratios of each element in the range 0.001≤y≤0.05 are weighed. Or according to Gd 2.997-x BWO9:xYb 3+ 0.003Ho 3+ The stoichiometric ratios of the elements in the range 0.1 ≤ x ≤ 0.5 are weighed. The amount of H3BO3 is 110%-120% of the molar amount of boric acid used in the raw materials for forming the Gd3BWO9 matrix.

10. The method for preparing Yb and Ho co-doped GBWO phosphor according to claim 9, characterized in that, In step (1), the preheating conditions are to raise the temperature to 500-600℃ at a rate of 10℃ / min-50℃ / min and hold it for 4-6 hours; In step (2), sintering is carried out by heating the temperature to 1200-1300℃ at a rate of 10℃ / min-50℃ / min and holding it at that temperature for 20-30 hours.

11. The application of the Yb and Ho co-doped GBWO phosphor according to any one of claims 1-6 as an optical thermosensitive material.

12. An optical thermosensitive material, characterized in that, Includes the Yb and Ho co-doped GBWO phosphor according to any one of claims 1-6.

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