A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor and preparation method thereof

Abstract

A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor and preparation method thereof, wherein the phosphor contains Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is x mol%, where x is greater than 0. The phosphor has obvious red light emission near 710 nm under the excitation of 432 nm blue-violet light, and its thermoluminescence peak temperature is around 366 K, proving the existence of shallow traps in the phosphor, and the luminescence wavelength is around 695 nm. At the same time, the phosphor has thermal broadening phenomenon, and the slow decay time of the afterglow is 687 s, and the fast decay time is 89 s. Therefore, the phosphor of the present invention has good chemical stability, high afterglow brightness, and long afterglow time, and can be used in fields such as lighting and medical imaging.

Description

Technical Field

[0001] The present invention relates to the technical field of near-infrared long afterglow phosphors, and in particular to a Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor and preparation method thereof. Background Art

[0002] In 2009, Dutta et al. developed ZGO:Dy 3+ ,Tb 3+ ,Mn 2+ Nano-phosphors show cold white light under ultraviolet excitation, providing a practical basis for designing white light sources. In 2011, Bessière et al. in France first reported ZGO:Cr with excellent near-infrared long afterglow performance. 3+ Near infrared afterglow material. ZGO:Cr 3+ Phosphors can emit high-purity and high-brightness red light with long afterglow under the excitation of ultraviolet light. In addition, ZGO matrix materials have the advantages of stable chemical properties, high voltage electric field resistance and good thermal conductivity, and have gradually become a research hotspot for long afterglow matrix materials.

[0003] In 2007, Chermont et al. first proposed the application of near-infrared long afterglow nanomaterials in in vivo imaging. Since then, near-infrared long afterglow materials have been widely studied. Long afterglow materials are substances that absorb specific energy and continue to emit light after the excitation stops. They are widely used in low-level lighting, medical fluorescent probes and other fields. The photoluminescence properties of ZGO can be adjusted by doping transition metals or rare earth ions. Eu 2+ 、Ce 3+ 、Eu 3+ , Tb 3+ And Dy 3+ Ions are several active ions that are currently being studied more. Among them, Tb 3+ Ionic 5 D3 → 7 F 5,4,3 The transition can emit blue light at 412, 438 and 467 nm. 5 D4→ 7 F 6,5 In addition, it can be found from different matrices that for dual-doped materials, Tb 3+ Often, the energy is transferred to another activated ion, enhancing its characteristic luminescence. 3+ Phosphor, Cr 3+ There are two emission modes: one is red emission at 70nm, attributed to 2 E→ 4 A2 spin forbidden transition; another due to4 T2→ 4 A2 spin-allowed transition causes broadband emission from 650nm to 1600nm.

[0004] In 2020, Qin Jin et al. found that compared with Yb 3+ , Er 3+ Other red long afterglow materials, doped with Cr 3+ The thermoluminescence intensity of the sample can be greatly improved, which is due to the Cr 3+ Doping can introduce more suitable defects to capture free electrons, but it still has the disadvantages of weak afterglow brightness and short afterglow time.

[0005] In order to overcome the problems of the above-mentioned prior art red long afterglow materials such as weak afterglow brightness and short afterglow time, a Cr 3+ , Tb 3+ It is necessary to dope ZnGa2O4 phosphor and its preparation method to solve the shortcomings of the prior art. Summary of the invention

[0006] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor. 3+ , Tb 3+ Doped ZnGa2O4 phosphor has the advantages of good chemical stability, high afterglow brightness and long afterglow time.

[0007] The above-mentioned purpose of the present invention is achieved by the following technical measures:

[0008] Provide a Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is x mol%, where x is greater than 0.

[0009] Preferably, the Cr 3+ Provided by Cr2O3.

[0010] Preferably, the Tb 3+ Provided by Tb4O7.

[0011] Preferably, the x is 0.1-5.

[0012] Preferably, the ZnGa2O4 is prepared from ZnO and Ga2O3.

[0013] The purpose of the present invention is to avoid the shortcomings of the prior art and provide a Cr 3+ , Tb 3+ Preparation method of ZnGa2O4 doped phosphor. 3+ , Tb 3+ The phosphor prepared by the preparation method of doped ZnGa2O4 phosphor has the advantages of good chemical stability, high afterglow brightness, long afterglow time and the like.

[0014] The above-mentioned purpose of the present invention is achieved by the following technical measures:

[0015] Provide a Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is prepared by the following steps:

[0016] S1. Weigh ZnO, Ga2O3, Cr2O3 and Tb4O7 into a container according to the stoichiometric ratio;

[0017] S2. Add anhydrous ethanol into a container and grind into powder to obtain a precursor;

[0018] S3, sintering the precursor in an air atmosphere to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor.

[0019] Preferably, the above S3 is specifically to first heat the precursor to 280°C to 320°C in an air atmosphere and keep it for 18min to 25min, then heat it to 980°C to 1020°C and keep it for 1.5h to 2.5h, then cool it to room temperature and grind it into powder to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor.

[0020] Preferably, the above S3 is specifically to first heat the precursor to 300°C in an air atmosphere and keep it for 20 minutes, then heat it to 1000°C and keep it for 2 hours, and then cool it to room temperature and grind it to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor.

[0021] In the step S3, the heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70min.

[0022] In the above-mentioned S2 and S3, both are ground into micron-sized powder.

[0023] The present invention provides a Cr 3+ , Tb 3+Doped ZnGa2O4 phosphor and preparation method thereof, wherein the phosphor contains Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is x mol%, where x is greater than 0. The phosphor has obvious red light emission near 710 nm under the excitation of 432 nm blue-violet light, and its thermoluminescence peak temperature is around 366 K, proving the existence of shallow traps in the phosphor, and the luminescence wavelength is around 695 nm. At the same time, the phosphor has thermal broadening phenomenon, and the slow decay time of the afterglow is 687 s, and the fast decay time is 89 s. Therefore, the phosphor of the present invention has good chemical stability, high afterglow brightness, and long afterglow time, and can be used in fields such as lighting and medical imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention is further described with reference to the accompanying drawings, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0025] Figure 1 This is a comparison chart of XRD between the ZGO:Cr and ZGO:Cr,Tb samples of the present invention and the standard card.

[0026] Figure 2 for Figure 1 A local enlarged image of the ZGO:Cr,Tb sample.

[0027] Figure 3 For ZGO: 1 mol%Cr 3+ ,x mol%Tb 3+ Emission spectrum under 432nm blue-violet light excitation.

[0028] Figure 4 ZGO:1mol%Cr 3+ ,0.5mol%Tb 3+ The excitation spectra were monitored at wavelengths of 546 nm and 698 nm.

[0029] Figure 5 ZGO: 0.5mol%Tb 3+ , ZGO:1mol%Cr 3+ and ZGO: 1mol%Cr 3+ ,0.5mol%Tb 3+ Emission spectrum of this material under 349 nm excitation.

[0030] Figure 6 TL3D spectrum of ZGO: 1 mol% Cr, 0.5 mol% Tb.

[0031] Figure 7 TL luminescence curve of ZGO: 1 mol% Cr, 0.5 mol% Tb.

[0032] Figure 8 This is the fluorescence decay curve of ZGO: 1 mol% Cr, x mol% Tb.

[0033] Fig. 9 This is the RL3D spectrum of ZGO:Cr,Tb.

[0034] Fig.10 This is the fluorescence decay curve of ZGO: 1 mol% Cr, x mol% Tb.

[0035] Fig.11 This is the normalized spectrum of RL and TL of ZGO:Cr, Tb luminescent material at 364K. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in conjunction with the following embodiments.

[0037] Example 1

[0038] A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is 0.1mol%, of which Cr 3+ Provided by Cr2O3; Tb 3+ Provided by Tb4O7. ZnGa2O4 is prepared from ZnO and Ga2O3.

[0039] The Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is prepared by the following steps:

[0040] S1. According to the stoichiometric ratio, ZnO, Ga2O3, Cr2O3 and Tb4O7 were weighed into an agate mortar, specifically 0.19378 g of ZnO, 0.44628 g of Ga2O3, 0.00044 g of Tb4O7 and 0.0018 g of Cr2O3;

[0041] S2. Add 3 ml of anhydrous ethanol into an agate mortar and grind into a powder with a particle size of micrometers to obtain a precursor;

[0042] S3, placing the precursor in a corundum crucible and sintering in a muffle furnace in an air atmosphere, heating to 300°C and maintaining for 120 minutes, then heating to 1000°C and maintaining for 2 hours, and then cooling to room temperature to a powder to obtain the phosphor. The heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70 minutes.

[0043] In both S2 and S3, the powder is ground into micron-sized powder.

[0044] Example 2

[0045] A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is 0.5mol%, of which Cr 3+ Provided by Cr2O3; Tb 3+ Provided by Tb4O7. ZnGa2O4 is prepared from ZnO and Ga2O3.

[0046] The Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is prepared by the following steps:

[0047] S1. According to the stoichiometric ratio, ZnO, Ga2O3, Cr2O3 and Tb4O7 were weighed into an agate mortar, specifically 0.19378 g of ZnO, 0.44628 g of Ga2O3, 0.00222 g of Tb4O7 and 0.0018 g of Cr2O3;

[0048] S2. Add 4 ml of anhydrous ethanol into an agate mortar and grind into a powder with a particle size of micrometers to obtain a precursor;

[0049] S3, placing the precursor in a corundum crucible and sintering in a muffle furnace in an air atmosphere, heating to 300°C and maintaining for 120 minutes, then heating to 1000°C and maintaining for 2 hours, and then cooling to room temperature to a powder to obtain the phosphor. The heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70 minutes.

[0050] In both S2 and S3, the powder is ground into micron-sized powder.

[0051] Example 3

[0052] A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is 1mol%, of which Cr 3+ Provided by Cr2O3; Tb 3+ Provided by Tb4O7. ZnGa2O4 is prepared from ZnO and Ga2O3.

[0053] The Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is prepared by the following steps:

[0054] S1. According to the stoichiometric ratio, ZnO, Ga2O3, Cr2O3 and Tb4O7 are weighed into an agate mortar, specifically 0.19378 g of ZnO, 0.00445 g of Ga2O3, 0.00222 g of Tb4O7 and 0.0018 of Cr2O3;

[0055] S2. Add 4 ml of anhydrous ethanol into an agate mortar and grind into a powder with a particle size of micrometers to obtain a precursor;

[0056] S3, placing the precursor in a corundum crucible and sintering in a muffle furnace in an air atmosphere, heating to 300°C and maintaining for 120 minutes, then heating to 1000°C and maintaining for 2 hours, and then cooling to room temperature to a powder to obtain the phosphor. The heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70 minutes.

[0057] In both S2 and S3, the powder is ground into micron-sized powder.

[0058] Example 4

[0059] A Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is 5mol%, of which Cr 3+ Provided by Cr2O3; Tb 3+ Provided by Tb4O7. ZnGa2O4 is prepared from ZnO and Ga2O3.

[0060] The Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is prepared by the following steps:

[0061] S1. According to the stoichiometric ratio, ZnO, Ga2O3, Cr2O3 and Tb4O7 were weighed into an agate mortar, specifically 0.19378 g of ZnO, 0.022247 g of Ga2O3, 0.00222 g of Tb4O7 and 0.0018 g of Cr2O3;

[0062] S2. Add 4 ml of anhydrous ethanol into an agate mortar and grind into a powder with a particle size of micrometers to obtain a precursor;

[0063] S3, placing the precursor in a corundum crucible and sintering in a muffle furnace in an air atmosphere, heating to 300°C and maintaining for 120 minutes, then heating to 1000°C and maintaining for 2 hours, and then cooling to room temperature to a powder to obtain the phosphor. The heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70 minutes.

[0064] In both S2 and S3, the powder is ground into micron-sized powder.

[0065] Comparative Example 1

[0066] A Cr 3+ Doped ZnGa2O4 phosphor, Cr in ZnGa2O4 3+ The doping amount of Tb in this comparative example is 1 mol%. 3 + The doping amount is 0mol%, that is, no Tb is doped 3+ Cr 3+ Provided by Cr2O3. That is, ZnGa2O4 is prepared from ZnO and Ga2O3.

[0067] The preparation method of the phosphor is prepared by the following steps:

[0068] S1. According to the stoichiometric ratio, ZnO, Ga2O3 and Cr2O3 are weighed into an agate mortar, specifically 0.19378 g of ZnO, 0.022247 g of Ga2O3 and 0.0018 g of Cr2O3;

[0069] S2. Add 4 ml of anhydrous ethanol into an agate mortar and grind into a powder with a particle size of micrometers to obtain a precursor;

[0070] S3, placing the precursor in a corundum crucible and sintering in a muffle furnace in an air atmosphere, heating to 300°C and maintaining for 120 minutes, then heating to 1000°C and maintaining for 2 hours, and then cooling to room temperature to a powder to obtain a phosphor. The heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70 minutes. Grind to micron-sized powder in S2 and S3.

[0071] Experiment and testing

[0072] 1. XRD test

[0073] The phosphor of Example 1 and the phosphor of Comparative Example 1 were subjected to XRD test. Figure 1 and Figure 2 As shown. In the figure, ZGO:Cr 3+ The phosphor of comparative example 1, ZGO:Cr 3+ ,Tb 3+ The phosphor of Example 1.

[0074] from Figure 1 and 2 It can be seen that ZGO:Cr 3+ and ZGO:Cr 3+ ,Tb 3+ The diffraction peaks of the samples are basically consistent with those of the standard card (JCPDS No.71-0843), indicating that the two samples are not doped with Cr. 3+ , Tb 3+ Impurities change the crystal structure, and the sample purity is high. Figure 1 It can be seen that ZGO:Cr 3+ ,Tb 3+ The XRD diffraction spectrum of TbO2 shows a peak at about 28.9 degrees, which is the characteristic peak of TbO2. 3+ Effectively doped and incorporated into the crystal lattice.

[0075] 2. PL Spectrum

[0076] The phosphors of Examples 1 to 4 and the phosphor of Comparative Example 1 were subjected to PL spectrum testing. Figure 3-Figure 5 As shown. Where x=0 in the figure is the phosphor of comparative example 1, and x=0.1, 0.5, 1, 5 are the phosphors of examples 1-4 respectively. Figure 3 λ in the PL spectrum ex =432 nm. Figure 3 It can be seen that with the increase of Tb 3+ As the doping concentration increases, the shape and position of the emission peak remain basically unchanged, and the emission intensity increases first and then decreases. 3+ The red light emission of the sample is strongest when the doping concentration is 0.5mol%, and then a serious concentration quenching effect occurs as the doping concentration increases.

[0077] from Figure 4 and 5 It can be seen that ZGO:Tb 3+ ,Cr 3+ Tb was also found in the phosphor at 546nm 3+ The characteristic emission of ZGO:Cr 3+ ,Tb 3+ Cr in phosphor 3+ The characteristic luminescence is significantly stronger than that of ZGO:Cr 3+ , and ZGO:Cr 3+ ,Tb 3+ Tb 3+ The characteristic luminescence is significantly weaker than that of ZGO:Tb 3+ This may be due to Tb 3+ Substituting Ga in the octahedral lattice 3+ And as a sensitizer, it enhances the luminescence center Cr to a certain extent. 3+ The characteristic luminescence at 600-800nm ​​shows that Tb 3+ →Cr 3+ energy transfer.

[0078] 3. TL3D spectrum and TL luminescence curve

[0079] The phosphor of Example 2 and the phosphor of Comparative Example 1 were irradiated with 30 Gy of X-rays and their TL3D spectra and TL emission curves were measured. Figure 6 and Figure 7 shown.

[0080] from Figure 6 and 7 It can be seen that the thermoluminescence sensitivity of the phosphor of the present invention is relatively high, and the luminescence peak position is basically consistent with PL, both of which have obvious red light emission at 700nm, which is attributed to Cr 3+ of 2 E g → 4 A 2g transition, and Tb was not found in TL3D 3+ The characteristic emission of ZGO:Tb 3+ ,Cr 3+ Cr in the system 3+ The traps dominate.

[0081] 4. Photoluminescence decay curve

[0082] The ZGO:Cr phosphors of Examples 1 to 4 and Comparative Example 1 were excited at 365 nm for 60 seconds. 3+ The photoluminescence decay curve is as follows: Figure 8 In general, when the ultraviolet light excitation is stopped, the afterglow of the sample decays rapidly at first, and then the degree of afterglow decay gradually slows down as time goes by.

[0083] The phosphor ZGO:Cr can be calculated by the formula 3+ Samples doped with different Tb 3+ Ion concentration (Tb 3+ The doping amounts are 0 mol %, 0.05 mol %, 0.1 mol %, 0.5 mol % and 5 mol %), the slow decay times are 101s, 599s, 601s, 610s, 687s, and the fast decay times are 26s, 95s, 70s, 67s, 89s. 3+ The incorporation of ions can effectively improve the ZGO:Cr 3+ The average fluorescence lifetime of Tb 3+When the doping amount is 5%, the average fluorescence lifetime of the phosphor of Example 2 is the highest. When the Tb3+ doping amount is different, the afterglow attenuation variation trend is 0mol%<0.05mol%<0.5mol%<0.1mol%<5mol%.

[0084] 5. RL3D Spectrum

[0085] Fig. 9 and 10 ZGO:Cr 3+ ,Tb 3+ RL3D spectrum of the phosphor under X-ray excitation. It can be seen from the RL3D spectrum that with the increase of temperature, the emission peak position remains basically unchanged, the luminescence intensity first increases and then decreases, the luminescence is strongest when the temperature is 350 K, and then shows obvious thermal quenching as the temperature increases. The increase in RL luminescence intensity with increasing temperature is closely related to the traps in the phosphor. At the same time, the existence of shallow traps in the phosphor is further confirmed based on the TL spectrum.

[0086] In addition, from Fig.10 It can be seen that with the increase of temperature, obvious thermal broadening phenomenon occurs. This broadening is uniform and the peak position does not shift. This may be because the lattice field around the activated ions embedded in the crystal will affect the position of their energy levels. The lattice vibration makes the activated ions in the lattice field that changes with time. The energy corresponding to the energy level of the activated ions changes within a certain range, thus causing the spectral line to broaden. The higher the temperature, the more intense the vibration and the wider the spectral line.

[0087] Fig.11 With TL3D spectrum ( Figure 6 ) compared, it can be clearly seen from the normalized spectra at 364K that the N2 line of both is dominant, but the relative intensity of the Stokes PSB luminescence peak is somewhat different, and the Stokes PSB relative intensity of the R line of RL is stronger than that of TL. This difference is due to the presence of two different types of Cr in gallate 3+ Ion, untwisted Cr n 3+ Shows little X-ray-induced persistent phosphorescence, while Cr dis 3+ Associated with strong delayed emission.

[0088] The present invention Cr 3+ , Tb 3+ When the ZnGa2O4 phosphor is excited by 410 nm blue-violet light, the emission peak is around 710 nm with obvious red emission, which is attributed to the Cr 3+ of 2 E→ 4 A2 transition, the study found that a certain concentration of Tb3+ , can enhance ZGO:1mol%Cr 3+ The PL spectrum intensity of the phosphor is due to the presence of Tb 3+ →Cr 3+ Energy transfer, when x is 0.5, the sample has the highest luminescence intensity. From the TL3D spectrum, it can be seen that the main luminescence peak temperature of the phosphor is at 364K, indicating that there are shallow traps in the sample, and the luminescence wavelength is around 695 nm, proving that the phosphor of the present invention has potential application value in the application field of red long afterglow materials, such as lighting and medical imaging. Based on the RL3D spectral distribution, which is basically consistent with PL and TL, with the increase of temperature, the luminescence intensity first increases and then decreases, and the luminescence is strongest at around 350 K; adding a certain amount of Tb is beneficial to improve the fluorescence lifetime, Tb 3+ The average lifespan is best when the doping amount is 5%. The above results show that ZGO:Cr 3+ ,Tb 3+ It is a new type of phosphor with excellent performance.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A Cr 3+ , Tb 3+ The preparation method of doped ZnGa2O4 phosphor is characterized by: Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor is Cr in ZnGa2O4 3+ The doping amount is 1mol% Tb 3+ The doping amount is x mol%, where x is 0.1 to 5; Cr 3+ Provided by Cr2O3, Tb 3+ Provided by Tb4O7; ZnGa2O4 is prepared from ZnO and Ga2O3; Prepared by the following steps: S1. Weigh ZnO, Ga2O3, Cr2O3 and Tb4O7 into a container according to the stoichiometric ratio; S2. Add anhydrous ethanol into a container and grind into powder to obtain a precursor; S3, sintering the precursor in an air atmosphere to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor; Specifically, the precursor is heated to 280°C to 320°C in an air atmosphere and maintained for 18 min to 25 min, then heated to 980°C to 1020°C and maintained for 1.5 h to 2.5 h, then cooled to room temperature and ground into powder to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor.

2. The preparation method according to claim 1, characterized in that: Specifically, the precursor is heated to 300° C. in an air atmosphere and maintained for 20 min, then heated to 1000° C. and maintained for 2 h, and then cooled to room temperature and ground to obtain the Cr 3+ , Tb 3+ Doped ZnGa2O4 phosphor.

3. The preparation method according to claim 2, characterized in that: In the step S3, the heating rate from 300°C to 1000°C is 10°C / min, and the heating time is 70min.

4. The preparation method according to claim 3, characterized in that: In the above-mentioned S2 and S3, both are ground into micron-sized powder.

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