Upconversion luminescent material and preparation method and application thereof

Abstract

The present invention provides an upconversion luminescent material and its preparation method and application, which belongs to the field of luminescent materials. The present invention provides an upconversion luminescent material, which is a core-shell structure, wherein the core is Ho 3+ Ion doping AR2(BO4)4 or Ho 3+ Ion doped ABO4, shell is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doping ABO4; A is a divalent transition metal ion or a divalent main group metal ion; R is a trivalent rare earth metal ion; B is Mo 6+ or W 6+ The present invention converts Yb 3+ ions are doped into the matrix material and encapsulated with Ho 3+ The core layer doped with luminescent center ions increases the distance between the luminescent center and the surface defects of the upconversion nanoparticles, reducing the influence of surface defects and surface organic molecular vibration on upconversion luminescence; at the same time, the Yb 3+ The shell layer enhances the absorption of excitation light by the upconversion luminescent material.

Description

Technical Field

[0001] The present invention relates to the field of luminescent materials, and in particular to an up-conversion luminescent material and a preparation method and application thereof. Background Art

[0002] Tungsten molybdate materials have low phonon energy, so they can effectively suppress the non-radiative transition of excited state energy levels, which helps to improve the luminescence efficiency of rare earth ions. In addition, the material's unique ABO4 type (A = Ca, Sr, Ba, Mg, Pb, Zn, Mn, Ni, Fe, Co, etc.; B = Mo or W) tetrahedral structure has extremely high stability and application value when used as a luminescent matrix material.

[0003] However, the rare earth activating ions used in the up-conversion luminescent materials based on molybdate or tungstate are all Er. 3+ As the main research object, for example, Chinese patent CN104031644A discloses Er 3+ and Yb 3+ Doped ZnGd4Mo3O 16 , where Yb 3+ Ions act as sensitizers to increase Er 3+ The green light luminescence intensity is improved, but its luminescence performance is still poor. Summary of the Invention

[0004] The purpose of the present invention is to provide an up-conversion luminescent material and a preparation method and application thereof. The up-conversion luminescent material of the present invention has excellent luminescent properties.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides an up-conversion luminescent material having a core-shell structure, wherein the core is Ho 3+ Ion doping AR2(BO4)4 or Ho 3+ Ion doped ABO4, shell is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doping ABO4;

[0007] A is a divalent transition metal ion or a divalent main group metal ion;

[0008] R is a positive trivalent rare earth metal ion;

[0009] The B is Mo 6+ or W 6+ .

[0010] Preferably, the chemical formula of the upconversion luminescent material is AR 1.97-y (BO4)4:yYb3+ ,0.03Ho 3+ ;

[0011] The chemical formula of the nuclear layer is AR 1.97 (BO4)4:0.03Ho 3+ ;

[0012] The chemical formula of the shell is AR 2-y (BO4)4:yYb 3+ ;0.02≤y≤0.07.

[0013] Preferably, the transition metal ions include Zn 2+ 、Mn 2+ 、Ni 2+ 、Fe 2+ or Co 2+ ;

[0014] The main group metal ions include Pb 2+ , Ca 2+ Mg 2+ 、Sr 2+ Or Ba 2+ .

[0015] Preferably, the rare earth metal ions include Gd 3+ .

[0016] Preferably, the particle size of the up-conversion luminescent material is 45 to 60 nm; the thickness of the shell is 0 to 30 nm, and is not 0.

[0017] The present invention also provides a method for preparing the upconversion luminescent material described in the above technical solution, comprising the following steps:

[0018] The first solution containing A, the first solution containing R, the first solution containing B, the solution containing Ho 3+ A solution containing A, a first complexing agent and a first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material; or a first solution containing A, a first solution containing B, a solution containing Ho 3+ The solution, the first complexing agent and the first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material

[0019] The core layer material is mixed with a second solution containing A, a second solution containing R, a second solution containing B, a solution containing Yb 3+ The solution, the second complexing agent, and the second pH adjusting agent are mixed for a second time and then subjected to a second crystallization reaction to obtain the up-conversion luminescent material; or the core layer material is mixed with a second solution containing A, a second solution containing B, a solution containing Yb 3+ The up-conversion luminescent material is obtained by mixing a second solution, a second complexing agent, and a second pH regulator and then performing a second crystallization reaction.

[0020] Preferably, the ratio of the amount of A in the first A-containing solution to the mass of the first complexing agent and the ratio of the amount of A in the second A-containing solution to the mass of the second complexing agent are independently 0.01-0.02 mol:0.5 g.

[0021] Preferably, the first complexing agent and the second complexing agent independently comprise polyethylene glycol and / or EDTA.

[0022] Preferably, the temperature of the first crystallization reaction and the second crystallization reaction are independently 170-175° C., and the time is independently 18-20 h.

[0023] The present invention also provides applications of the up-conversion luminescent material described in the above technical solution or the up-conversion luminescent material prepared by the preparation method described in the above technical solution in the fields of astronomical observation instruments, solid-state lasers, lighting products or flat-panel displays.

[0024] The present invention provides an up-conversion luminescent material having a core-shell structure, wherein the core is Ho 3+ Ion doping AR2(BO4)4 or Ho 3+ Ion doped ABO4, shell is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doping ABO4;

[0025] A is a divalent transition metal ion or a divalent main group metal ion;

[0026] R is a positive trivalent rare earth metal ion;

[0027] The B is Mo 6+ or W 6+ .

[0028] The present invention uses Yb as a sensitizer 3+ ions are doped into the matrix material and in the form of a shell with rare earth Ho 3+ The core layer doped with luminescent center ions is wrapped, which can effectively increase the distance between the luminescent center of the upconversion nanoparticles and the surface defects, reduce the influence of surface defects and surface organic molecular vibration on the upconversion luminescence, and thus enhance the luminescent performance of the upconversion luminescent material; at the same time, the Yb 3+ The shell layer enhances the absorption of excitation light by the upconversion luminescent material, thereby further enhancing the luminescence performance of the upconversion luminescent material. The results of the embodiment show that under 0.6W, 990nm excitation light, the upconversion luminescent material of the present invention has a green luminescence peak intensity of 1377.397 and a red luminescence peak intensity of 483.291 in the range of 530-650nm, a color purity of 99.6%, and a quantum yield of 1.8%.

[0029] Yb in the up-conversion luminescent material of the present invention 3+ and Ho 3+ It has a unique 4f electron layer structure and can achieve efficient red and green light emission in the range of 540 to 660 nm under the excitation of an external excitation light source, and has high luminous intensity, high color purity, and high quantum yield. When used in astronomical observations, the up-conversion luminescent material provided by the present invention is used to prepare the original device of the observation equipment, which can respond to the long-wavelength light source in the non-visible light region (970-990 nm) of cosmic rays and emit red and green dual light. Therefore, compared with the luminescent material using short-wavelength excitation, the up-conversion luminescent material provided by the present invention can significantly improve the observation range of the observation equipment and has higher application value; at the same time, the up-conversion luminescent material of the present invention can also further improve the capabilities of high-quality flat-panel displays, the efficiency of solid-state lasers and high-performance lighting products.

[0030] Furthermore, the present invention further reduces the influence of surface defects and surface organic molecular vibration on up-conversion luminescence by adjusting the thickness of the shell layer, and improves the absorption of excitation light, thereby further enhancing the luminescence performance of the up-conversion luminescent material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a structural diagram of an upconversion luminescent material;

[0032] Figure 2 The normalized excitation spectra at 650nm and 540nm of the products obtained in Examples 1 to 4 are shown when excited by 0.6W, 990nm excitation light. DETAILED DESCRIPTION

[0033] The present invention provides an up-conversion luminescent material having a core-shell structure, wherein the core is Ho 3+ Ion doping AR2(BO4)4 or Ho 3+ Ion doped ABO4, shell is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doping ABO4;

[0034] A is a divalent transition metal ion or a divalent main group metal ion;

[0035] R is a positive trivalent rare earth metal ion;

[0036] The B is Mo 6+ or W 6+ .

[0037] In the present invention, the chemical formula of the up-conversion luminescent material is preferably AR 1.97-y (BO4)4:yYb 3+,0.03Ho 3+ The chemical formula of the core layer is preferably AR 1.97 (BO4)4:0.03Ho 3+ ; The chemical formula of the shell is preferably AR 2-y (BO4)4:yYb 3+ ; 0.02≤y≤0.07; the particle size of the up-conversion luminescent material is preferably 45-60 nm, more preferably 48-50 nm; the thickness of the shell is preferably 0-30 nm, and not 0, more preferably 5-15 nm, and further preferably 8-12 nm.

[0038] In the present invention, the structure of the up-conversion luminescent material preferably includes a tetragonal lattice structure.

[0039] In the present invention, the transition metal ions preferably include Zn 2+ 、Mn 2+ 、Ni 2+ 、Fe 2+ or Co 2+ ;

[0040] The alkaline earth metal ions preferably include Ca 2+ Mg 2+ 、Sr 2+ Or Ba 2+ ;

[0041] The main group metal ions preferably include Pb 2+ ;

[0042] The rare earth metal ions include Gd 3+ .

[0043] The present invention also provides a method for preparing the upconversion luminescent material described in the above technical solution, comprising the following steps:

[0044] The first solution containing A, the first solution containing R, the first solution containing B, the solution containing Ho 3+ A solution containing A, a first complexing agent and a first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material; or a first solution containing A, a first solution containing B, a solution containing Ho 3+ The solution, the first complexing agent and the first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material

[0045] The core layer material is mixed with a second solution containing A, a second solution containing R, a second solution containing B, a solution containing Yb 3+ The solution, the second complexing agent, and the second pH adjusting agent are mixed for a second time and then subjected to a second crystallization reaction to obtain the up-conversion luminescent material; or the core layer material is mixed with a second solution containing A, a second solution containing B, a solution containing Yb 3+The up-conversion luminescent material is obtained by mixing a second solution, a second complexing agent, and a second pH regulator and then performing a second crystallization reaction.

[0046] In the present invention, unless otherwise specified, all raw materials used are commercially available products well known in the art.

[0047] The present invention comprises a first solution containing A, a first solution containing R, a first solution containing B, a solution containing Ho 3+ The solution, the first complexing agent and the first pH adjuster are mixed and then subjected to a first crystallization reaction to obtain a core layer material.

[0048] In the present invention, the pH value of the mixed solution is preferably 2 to 3. In the present invention, the first pH adjuster preferably comprises a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is preferably 40 to 60%.

[0049] In the present invention, the mixing preferably comprises the following steps:

[0050] performing a first mixing of the first solution containing A and the first solution containing B to obtain a first solution;

[0051] performing a second mixing of the first solution and the first R-containing solution to obtain a second solution;

[0052] The second solution and the Ho 3+ The solution is mixed for the third time to obtain a third solution;

[0053] performing a fourth mixing of the third solution and the first complexing agent to obtain a fourth solution;

[0054] The fourth solution and the first pH adjuster are mixed for the fifth time.

[0055] In the present invention, the first mixing, second mixing, third mixing, fourth mixing and fifth mixing are preferably carried out at room temperature. The present invention has no special requirements on the time of the first mixing, second mixing, third mixing, fourth mixing and fifth mixing, as long as the materials are mixed evenly. In the present invention, the first mixing, second mixing, third mixing, fourth mixing and fifth mixing are preferably carried out under stirring conditions. The present invention has no special requirements on the specific implementation process of the stirring.

[0056] In the present invention, the A in the first A-containing solution, the R in the first R solution, the B in the first B-containing solution and the Ho-containing solution 3+ Ho in the solution 3+ The molar ratio of the target Ho 3+ A, R, B and Ho in ion-doped AR2(BO4)4 3+ The ratio of the amount of substance.

[0057] In the present invention, the concentration of A in the first A-containing solution is preferably 0.05-0.07 mol / L, more preferably 0.051-0.069 mol / L. The mass ratio of the amount of A in the first A-containing solution to the complexing agent is preferably (0.01-0.02) mol:0.5 g. The first A-containing solution is preferably a water-soluble salt solution of A, more preferably a nitrate solution of A. The first complexing agent preferably includes polyethylene glycol and / or EDTA. The polyethylene glycol preferably includes one or more of PEG1000, PEG1500, and PEG4000.

[0058] The molar concentration of R in the first R solution is preferably 0.06 to 0.09 mol / L, more preferably 0.068 to 0.089 mol / L; the first R-containing solution is preferably a water-soluble salt solution of R, more preferably a nitrate solution of R.

[0059] In the present invention, the molar concentration of B in the first B-containing solution is preferably 0.06 to 0.09 mol / L, more preferably 0.061 to 0.089 mol / L; the first B-containing solution is preferably a water-soluble alkali metal salt aqueous solution, more preferably a sodium molybdate aqueous solution.

[0060] In the present invention, the Ho-containing 3+ Ho in solution 3+ The molar concentration of the substance is preferably 0.002 to 0.01 mol / L, more preferably 0.003 to 0.009 mol / L; the Ho-containing 3+ The solution is preferably a holmium salt aqueous solution, more preferably a holmium nitrate aqueous solution. In the present invention, there is no special requirement for the source of holmium nitrate in the holmium nitrate aqueous solution, and commercially available holmium nitrate or homemade holmium nitrate can be used.

[0061] In the present invention, the temperature of the first crystallization reaction is preferably 170-175° C., more preferably 171-175° C.; the time is preferably 18-20 h, more preferably 19-20 h.

[0062] In the present invention, the first crystallization reaction preferably further comprises washing and drying the obtained first crystallization reaction product to obtain the core layer material.

[0063] In the present invention, the washing is preferably carried out in sequence of water washing and alcohol washing, the number of water washings is preferably 1 to 3 times, and the present invention has no special requirements on the amount of water used in the water washing; in the present invention, the solvent for the alcohol washing is preferably ethanol, the number of alcohol washings is preferably 1 to 3 times, and the present invention has no special requirements on the amount of alcohol used in the alcohol washing.

[0064] In the present invention, the drying temperature is preferably 55 to 75° C., more preferably 60 to 70° C.; the drying time is preferably 6 to 9 hours, more preferably 7 to 8 hours.

[0065] After obtaining the core layer material, the present invention mixes the core layer material with a second solution containing A, a second solution containing R, a second solution containing B, a solution containing Yb 3+ The second crystallization reaction is carried out after mixing the solution, the second complexing agent and the second pH adjuster.

[0066] In the present invention, the pH value of the mixed solution is preferably 2 to 3. In the present invention, the second pH adjuster is preferably a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is preferably 40 to 60%.

[0067] In the present invention, the mixing preferably comprises the following steps:

[0068] mixing the second solution containing A and the second solution containing B for a sixth time to obtain a sixth solution;

[0069] Mixing the sixth solution and the second R-containing solution for a seventh time to obtain a seventh solution;

[0070] The seventh solution and the Yb-containing 3+ The solution is mixed eighthly to obtain an eighth solution;

[0071] Mixing the eighth solution and the second complexing agent for a ninth time to obtain a ninth solution;

[0072] The ninth solution and the second pH adjuster are mixed for a tenth time.

[0073] In the present invention, the sixth mixing, seventh mixing, eighth mixing, ninth mixing and tenth mixing are preferably carried out at room temperature. The present invention has no special requirements on the time of the sixth mixing, seventh mixing, eighth mixing, ninth mixing and tenth mixing, as long as the materials are mixed evenly. In the present invention, the sixth mixing, seventh mixing, eighth mixing, ninth mixing and tenth mixing are preferably carried out under stirring conditions. The present invention has no special requirements on the specific implementation process of the stirring.

[0074] In the present invention, the A in the second A-containing solution, the R in the second R solution, the B in the second B-containing solution and the Yb-containing solution 3+ Yb in solution 3+ The amount ratio of the target Yb 3+ Ion doping of A, R, B and Yb in AR2(BO4)4 3+ The ratio of the amount of substance.

[0075] In the present invention, the concentration of A in the second A-containing solution is preferably 0.05-0.07 mol / L, more preferably 0.051-0.069 mol / L. The mass ratio of the amount of A in the second A-containing solution to the complexing agent is preferably (0.01-0.02) mol:0.5 g. The second A-containing solution is preferably a water-soluble salt solution of A, more preferably a nitrate solution of A. The second complexing agent preferably includes polyethylene glycol and / or EDTA. The polyethylene glycol preferably includes one or more of PEG 1000, PEG 1500, and PEG 4000.

[0076] The molar concentration of R in the second R solution is preferably 0.06-0.09 mol / L, more preferably 0.068-0.089 mol / L; the second R-containing solution is preferably a water-soluble salt solution of R, more preferably a nitrate solution of R.

[0077] In the present invention, the molar concentration of B in the second B-containing solution is preferably 0.06 to 0.09 mol / L, more preferably 0.061 to 0.089 mol / L; the second B-containing solution is preferably a water-soluble alkali metal salt aqueous solution, more preferably a sodium molybdate aqueous solution.

[0078] In the present invention, the Yb-containing 3+ Yb in solution 3+ The molar concentration of the Yb-containing 3+ The solution is preferably an aqueous solution of an ytterbium salt, more preferably an aqueous solution of ytterbium nitrate.

[0079] The present invention has no special requirements on the source of ytterbium nitrate in the ytterbium nitrate aqueous solution, and commercially available ytterbium nitrate or homemade ytterbium nitrate can be used.

[0080] In the present invention, the temperature of the second crystallization reaction is preferably 170-175° C., more preferably 171-175° C.; the time is preferably 18-20 h, more preferably 19-20 h.

[0081] In the present invention, the second crystallization reaction is preferably carried out in a reactor.

[0082] In the present invention, the second crystallization reaction preferably further comprises washing and drying the obtained second crystallization reaction product to obtain the up-conversion luminescent material.

[0083] In the present invention, the washing is preferably carried out in sequence of water washing and alcohol washing, the number of water washings is preferably 1 to 3 times, and the present invention has no special requirements on the amount of water used in the water washing; in the present invention, the solvent for the alcohol washing is preferably ethanol, the number of alcohol washings is preferably 1 to 3 times, and the present invention has no special requirements on the amount of alcohol used in the alcohol washing.

[0084] In the present invention, the drying temperature is preferably 55 to 75° C., more preferably 60 to 70° C.; the drying time is preferably 6 to 9 hours, more preferably 7 to 8 hours.

[0085] The present invention also provides applications of the up-conversion luminescent material described in the above technical solution or the up-conversion luminescent material prepared by the preparation method described in the above technical solution in the fields of astronomical observation instruments, solid-state lasers, lighting products or flat-panel displays.

[0086] The up-conversion luminescent material, preparation method and application thereof provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0087] The structure of the up-conversion luminescent material of the present invention is as follows Figure 1 shown.

[0088] Example 1

[0089] Take 1.392g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 90℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0090] Take 0.0394g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0091] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 90℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0092] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0093] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0094] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0095] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0096] The crystallized product was washed with water three times and ethanol three times, and then dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm to 30nm and a shell thickness of 25nm to 30nm. The chemical formula is CaGd 1.92 (MoO4)4:0.05Yb 3+ ,0.03Ho 3+ .

[0097] The chemical formula of the shell is CaGd 1.95 (MoO4)4:0.05Yb 3+ ;

[0098] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0099] Example 2

[0100] Take 1.414g Gd2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Gd(NO3)3 solution.

[0101] Take 0.0158g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0102] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0103] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0104] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0105] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0106] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0107] The crystallized product was washed with water three times and ethanol three times, and then dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm to 30nm and a shell thickness of 25nm to 30nm. The chemical formula is CaGd 1.95 (MoO4)4:0.02Yb 3+ ,0.03Ho 3+ .

[0108] The chemical formula of the shell is CaGd 1.98 (MoO4)4:0.02Yb 3+ ;

[0109] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0110] Example 3

[0111] Take 1.407g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0112] Take 0.0236g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0113] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, it is acid-exhausted at 80℃ and dried at 90℃. Then 25mL of deionized water is added to obtain Ho(NO3)3

[0114] solution;

[0115] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0116] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0117] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0118] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0119] The crystallized product was washed with water three times and ethanol three times, and then dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm to 30nm and a shell thickness of 25nm to 30nm. The chemical formula is CaGd 1.94 (MoO4)4:0.03Yb3+ ,0.03Ho 3+ .

[0120] The chemical formula of the shell is CaGd 1.97 (MoO4)4:0.03Yb 3+ ;

[0121] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0122] Example 4

[0123] Take 1.399g Gd2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Gd(NO3)3 solution.

[0124] Take 0.0315g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0125] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0126] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0127] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0128] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0129] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0130] The crystallized product was washed with water three times and ethanol three times, and then dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm to 30nm and a shell thickness of 25nm to 30nm. The chemical formula is CaGd 1.93 (MoO4)4:0.04Yb 3+ ,0.03Ho 3+ .

[0131] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Yb 3+ ;

[0132] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0133] Example 5

[0134] Take 1.385g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0135] Take 0.0473g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0136] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0137] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0138] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0139] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0140] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0141] The crystallized product was washed with water three times and ethanol three times, and then dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm to 30nm and a shell thickness of 25nm to 30nm. The chemical formula is CaGd 1.91 (MoO4)4:0.06Yb 3+ ,0.03Ho 3+ .

[0142] The chemical formula of the shell is CaGd 1.94 (MoO4)4:0.06Yb 3+ ;

[0143] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0144] Example 6

[0145] Take 1.378g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0146] Take 0.0552g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0147] Take 0.0227g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 68%). After it is completely dissolved at 80℃, remove the acid at 80℃ and dry it at 90℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0148] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0149] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0150] 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution were stirred and mixed for 10 minutes, and then 10 mL of gadolinium nitrate solution was added and stirred and mixed for 10 minutes. Then, 10 mL of holmium nitrate solution was added and stirred and mixed for 10 minutes. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to pH 2 with 45% sodium hydroxide solution. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core layer crystallization product.

[0151] After stirring 20 mL of sodium molybdate solution and 10 mL of calcium nitrate solution for 10 minutes, 10 mL of gadolinium nitrate solution was added and stirred for 10 minutes, and then 10 mL of ytterbium nitrate solution was added and stirred for 10 minutes, and then the core layer crystallized product was added. Finally, 0.5 g of PEG 1000 was added and stirred and mixed evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution with a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0152] The crystallized product was washed with water three times, washed with ethanol three times, and dried at 60°C for 6 hours to obtain an upconversion luminescent material with a core diameter of 25nm-30nm and a shell thickness of 25nm-30nm. The chemical formula is CaGd 1.9 (MoO4)4:0.07Yb 3+ ,0.03Ho 3+ .

[0153] The chemical formula of the shell is CaGd 1.93 (MoO4)4:0.07Yb 3+ ;

[0154] The chemical formula of the core layer is CaGd 1.97 (MoO4)4:0.03Ho 3+ .

[0155] The products obtained in Examples 1 to 4 were measured at room temperature using a Fluoromax-4 fluorescence spectrophotometer under 0.6W, 990nm excitation light, and the normalized excitation spectra at 650nm and 540nm were as follows: Figure 2 As shown in Table 1, the color purity and quantum yield of the products of Examples 1 to 4 were calculated, and the results are shown in Tables 2 and 3.

[0156] Table 1 Peak intensity of green light and red light when the excitation light source power of the products of Examples 1 to 4 is 0.6W

[0157] Serial number Green light peak intensity (540nm) Red light peak intensity (650nm) Example 2 867.307 281.351 Example 3 1132.284 432.494 Example 1 1377.397 483.291 Example 4 479.394 136.273

[0158] Table 2 Color purity of products in Examples 1 to 4 when the excitation light source power is 0.6W

[0159] Serial number Color purity Example 2 96.5％ Example 3 98.6％ Example 1 99.6％ Example 4 94.1％

[0160] Table 3 Quantum yield of products in Examples 1 to 4 when the excitation light source power is 0.6W

[0161] Serial number Quantum yield Example 2 1.6％ Example 3 1.7％ Example 1 1.8％ Example 4 1.4％

[0162] Table 4 Green light peak intensity and red light peak intensity of the products of Examples 5 to 6 when the excitation light source power is 0.6W

[0163]

[0164] From Tables 1 to 3, we can see that the formula CaGd 2-x-y (MoO4)2:yYb 3+ ,xHo 3+ The x=0.03, 0.02≤y≤0.07. In the present invention, when the x is 0.03 and the y is 0.05, the luminous intensity, color purity and quantum yield are the highest.

[0165] It can be seen from Table 4 that when x is 0.03 and y is 0.06, the peak intensity of green light (540 nm) of the sample is 317.264, and the peak intensity of red light (650 nm) is 110.319.

[0166] When x is 0.03 and y is 0.07, the peak intensity of green light (540 nm) of the sample is 126.391, and the peak intensity of red light (650 nm) is 41.037.

[0167] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An upconversion luminescent material, characterized in that: It is a core-shell structure, the core is Ho 3+ Ion doped AR2(BO4)4, shell is Yb 3+ Ion doping AR2(BO4)4; A is Ca 2+ ; R is Gd 3+ ; Stated as B by Mo 6+ ; The chemical formula of the up-conversion luminescent material is AR 1.97-y (BO4)4:yYb 3+ ,0.03Ho 3+ ; The chemical formula of the nuclear layer is AR 1.97 (BO4)4:0.03Ho 3+ ; The chemical formula of the shell is AR 2-y (BO4)4:yYb 3+ ; y＝0.05； The particle size of the up-conversion luminescent material is 45 to 60 nm; the thickness of the shell is 0 to 30 nm and is not 0; The method for preparing the upconversion luminescent material comprises the following steps: The first solution containing A, the first solution containing R, the first solution containing B, the solution containing Ho 3+ A solution, a first complexing agent and a first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material; The core layer material is mixed with a second solution containing A, a second solution containing R, a second solution containing B, a solution containing Yb 3+ A solution of the invention, a second complexing agent, and a second pH regulator are mixed for a second time and then subjected to a second crystallization reaction to obtain the up-conversion luminescent material; The temperature of the first crystallization reaction and the second crystallization reaction is 175° C. and the time is 20 h; The first complexing agent and the second complexing agent independently include polyethylene glycol and / or EDTA.

2. The method for preparing the upconversion luminescent material according to claim 1, characterized in that: The following steps are involved: The first solution containing A, the first solution containing R, the first solution containing B, the solution containing Ho 3+ A solution, a first complexing agent and a first pH regulator are first mixed and then subjected to a first crystallization reaction to obtain a core layer material; The core layer material is mixed with a second solution containing A, a second solution containing R, a second solution containing B, a solution containing Yb 3+ A solution of the invention, a second complexing agent, and a second pH regulator are mixed for a second time and then subjected to a second crystallization reaction to obtain the up-conversion luminescent material; The temperature of the first crystallization reaction and the second crystallization reaction is 175° C. and the time is 20 h; The first complexing agent and the second complexing agent independently include polyethylene glycol and / or EDTA.

3. The preparation method according to claim 2, characterized in that The ratio of the amount of A in the first A-containing solution to the mass of the first complexing agent and the ratio of the amount of A in the second A-containing solution to the mass of the second complexing agent are independently 0.01-0.02 mol:0.5 g.

4. Use of the up-conversion luminescent material according to claim 1 or the up-conversion luminescent material prepared by the preparation method according to any one of claims 2 to 3 in the fields of astronomical observation instruments, solid-state lasers, lighting products or flat-panel displays.

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