Upconversion luminescent material and preparation method and application thereof

Abstract

The present invention provides an up-conversion luminescent material and its preparation method and application, which belongs to the field of luminescent materials. The up-conversion luminescent material provided by the present invention is a core-shell structure, wherein the core is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doped ABO4, shell is Ho 3+ Ion doping AR2(BO4)4 or Ho 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+ 。 Yb 3+ Under the action of the excitation light source, ions can undergo energy level transitions and transfer energy to the shell material, thereby improving the utilization rate of the excitation light source; the reflection effect of the core layer reflects part of the excitation light source that has passed through the shell back into the shell, thereby further improving the utilization rate of the excitation light source.

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 Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doped ABO4, shell is Ho 3+ Ion doping AR2(BO4)4 or Ho 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 1.96-y (BO4)4:yYb3+ ,0.04Ho 3+ ;

[0011] The chemical formula of the shell is AR 1.96 (BO4)4:0.04Ho 3+ ;

[0012] The chemical formula of the nucleus is AR 2-y (BO4)4:yYb 3+ The 0.04≤y≤0.08.

[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 40 to 60 nm; and the thickness of the shell is 25 to 30 nm.

[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 Yb 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;

[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 Ho 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 165-175° C., and the time is independently 15-20 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 Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doped ABO4, shell is Ho 3+ Ion doping AR2(BO4)4 or Ho 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 Ho as the luminescent central ion 3+ ions are doped into the matrix material and in the form of a shell with rare earth Yb 3+ The ion-doped core layer is wrapped, which can effectively increase the utilization rate of the upconversion nanomaterial for the excitation light source, thereby improving its luminescence performance: the sensitizer Yb in the core layer material 3+ Under the action of the excitation light source, the ions can undergo energy level transitions and transfer energy to the shell material in the process, thereby improving the utilization rate and luminous efficiency of the excitation light source. In addition, the reflection effect of the core layer will reflect part of the excitation light that has passed through the shell back into the shell, thereby further improving the utilization rate of the excitation light source. 3+ The increase in the distance from the core-shell structure surface effectively increases the sensitizer Yb 3+ The distance from surface defects reduces the impact of surface defects and surface organic molecular vibrations on sensitization, thereby further improving luminescence performance. The results of the embodiment show that under 0.65W, 995nm excitation light, the green light emission peak intensity is 1217.351, the red light emission peak intensity is 431.596, the color purity is 99.5%, and the quantum yield is 1.7% in the range of 525-655nm.

[0029] Yb in the up-conversion luminescent material provided by the present invention3+ and Ho 3+ The unique 4f electron layer structure can achieve efficient emission of red and green light in the range of 525 to 655 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 excited by short wavelengths, the up-conversion luminescent material provided by the present invention can significantly improve the observation range of the observation equipment and have higher application value; it 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 This is a structural diagram of the upconversion luminescent material. DETAILED DESCRIPTION

[0032] The present invention provides an up-conversion luminescent material having a core-shell structure, wherein the core is Yb 3+ Ion doping AR2(BO4)4 or Yb 3+ Ion doped ABO4, shell is Ho 3+ Ion doping AR2(BO4)4 or Ho 3+ Ion doping ABO4;

[0033] A is a divalent transition metal ion or a divalent main group metal ion;

[0034] R is a positive trivalent rare earth metal ion;

[0035] The B is Mo 6+ or W 6+ .

[0036] In the present invention, the chemical formula of the up-conversion luminescent material is AR 1.96-y (BO4)4:yYb 3+ ,0.04Ho 3+ ; The chemical formula of the shell is preferably AR 1.96 (BO4)4:0.04Ho 3+ ; The chemical formula of the core is preferably AR 2-y (BO4)4:yYb 3+The 0.04≤y≤0.08; the particle size of the up-conversion luminescent material is preferably 40-60 nm, more preferably 48-50 nm; the thickness of the shell is preferably 0-20 nm, and not 0, more preferably 5-15 nm, and further preferably 8-12 nm.

[0037] In the present invention, the transition metal ions preferably include Zn 2+ 、Mn 2+ 、Ni 2+ 、Fe 2+ or Co 2+ ;

[0038] The alkaline earth metal ions preferably include Ca 2+ Mg 2+ 、Sr 2+ Or Ba 2+ ;

[0039] The main group metal ions preferably include Pb 2+ ;

[0040] The rare earth metal ions include Gd 3+ .

[0041] In the present invention, the structure of the up-conversion luminescent material preferably includes a tetragonal lattice structure.

[0042] The present invention also provides a method for preparing the upconversion luminescent material described in the above technical solution, comprising the following steps:

[0043] The first solution containing A, the first solution containing R, the first solution containing B, the solution containing Yb 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;

[0044] 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 Ho 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;

[0045] Or the first solution containing A, the first solution containing B, the solution containing Yb 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;

[0046] The core layer material is mixed with a second solution containing A, a second solution containing B, a solution containing Ho 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.

[0047] In the present invention, unless otherwise specified, all raw materials used are commercially available products well known in the art.

[0048] The present invention comprises a first solution containing A, a first solution containing R, a first solution containing B, a solution containing Yb 3+ The solution, the first complexing agent and the first pH regulator are mixed and then subjected to a first crystallization reaction to obtain a core layer material.

[0049] 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%.

[0050] In the present invention, the mixing preferably comprises the following steps:

[0051] performing a first mixing of the first solution containing A and the first solution containing B to obtain a first solution;

[0052] performing a second mixing of the first solution and the first R-containing solution to obtain a second solution;

[0053] The second solution and the Yb 3+ The solution is mixed for the third time to obtain a third solution;

[0054] performing a fourth mixing of the third solution and the first complexing agent to obtain a fourth solution;

[0055] The fourth solution and the first pH adjuster are mixed for the fifth time.

[0056] 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.

[0057] 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 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.

[0058] 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 PEG 1000, PEG 1500, and PEG 4000.

[0059] 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.

[0060] 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.

[0061] 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 ytterbium salt, more preferably an aqueous solution of ytterbium nitrate. In the present invention, there is no special requirement for the source of ytterbium nitrate in the aqueous solution of ytterbium nitrate, and commercially available ytterbium nitrate or homemade ytterbium nitrate can be used.

[0062] In the present invention, the temperature of the first crystallization reaction is preferably 165-175° C., more preferably 171-175° C.; the time is preferably 15-20 h, more preferably 19-20 h.

[0063] 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.

[0064] 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.

[0065] In the present invention, the drying temperature is preferably 50-75° C., more preferably 60-70° C.; the drying time is preferably 6-8 h, more preferably 7-8 h.

[0066] 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 Ho 3+ The second crystallization reaction is carried out after mixing the solution, the second complexing agent and the second pH adjuster.

[0067] 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%.

[0068] In the present invention, the mixing preferably comprises the following steps:

[0069] mixing the second solution containing A and the second solution containing B for a sixth time to obtain a sixth solution;

[0070] Mixing the sixth solution and the second R-containing solution for a seventh time to obtain a seventh solution;

[0071] The seventh solution and the Ho 3+ The solution is mixed eighthly to obtain an eighth solution;

[0072] Mixing the eighth solution and the second complexing agent for a ninth time to obtain a ninth solution;

[0073] The ninth solution and the second pH adjuster are mixed for a tenth time.

[0074] 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.

[0075] 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 Ho-containing solution 3+ Ho in 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.

[0076] 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.

[0077] The molar concentration of R in the second R solution is preferably 0.06 to 0.09 mol / L, more preferably 0.068 to 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.

[0078] 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.

[0079] In the present invention, the Ho-containing 3+ Ho in solution 3+ The molar concentration of the substance is preferably 0.006 to 0.02 mol / L, more preferably 0.001 to 0.0018 mol / L; the Ho-containing 3+ The solution is preferably a water-soluble holmium salt aqueous solution, more preferably a holmium nitrate aqueous solution.

[0080] The present invention has no special requirements on the source of holmium nitrate in the holmium nitrate aqueous solution, and commercially available holmium nitrate or homemade holmium nitrate can be used.

[0081] In the present invention, the temperature of the second crystallization reaction is preferably 165-175° C., more preferably 171-175° C.; the time is preferably 15-20 h, more preferably 19-20 h.

[0082] In the present invention, the second crystallization reaction is preferably carried out in a reactor.

[0083] 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.

[0084] 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.

[0085] In the present invention, the drying temperature is preferably 50-75° C., more preferably 60-70° C.; the drying time is preferably 6-8 h, more preferably 7-8 h.

[0086] 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.

[0087] 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.

[0088] The structure of the up-conversion luminescent material of the present invention is as follows Figure 1 shown.

[0089] Example 1

[0090] All amounts in the formula are calculated based on 0.004.

[0091] Take 1.385g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0092] Take 0.0394g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0093] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0094] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0095] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0096] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0097] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0098] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.91 (MoO4)4:0.05Yb 3+ ,0.04Ho 3+ ;

[0099] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0100] The chemical formula of the core layer is CaGd 1.95 (MoO4)4:0.05Yb 3+ .

[0101] Example 2

[0102] All amounts in the formula are calculated based on 0.004.

[0103] Take 1.392g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0104] Take 0.0315g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0105] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0106] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0107] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0108] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0109] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0110] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.92 (MoO4)4:0.04Yb 3+ ,0.04Ho 3+ .

[0111] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0112] The chemical formula of the core layer is CaGd 1.96 (MoO4)4:0.04Yb 3+ .

[0113] Example 3

[0114] All amounts in the formula are calculated based on 0.004.

[0115] Take 1.378g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0116] Take 0.0473g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0117] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0118] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0119] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0120] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0121] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0122] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.9(MoO4)4:0.06Yb 3+ ,0.04Ho 3+ .

[0123] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0124] The chemical formula of the core layer is CaGd 1.94 (MoO4)4:0.06Yb 3+ .

[0125] Example 4

[0126] All amounts in the formula are calculated based on 0.004.

[0127] Take 1.37g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0128] Take 0.0552g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0129] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0130] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0131] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0132] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0133] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0134] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.89 (MoO4)4:0.07Yb 3+ ,0.04Ho 3+ .

[0135] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0136] The chemical formula of the core layer is CaGd 1.93 (MoO4)4:0.07Yb 3+ .

[0137] Example 5

[0138] All amounts in the formula are calculated based on 0.004.

[0139] Take 1.363g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0140] Take 0.063g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0141] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0142] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0143] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0144] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0145] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0146] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.88 (MoO4)4:0.08Yb 3+ ,0.04Ho 3+ .

[0147] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0148] The chemical formula of the core layer is CaGd 1.92 (MoO4)4:0.08Yb 3+ .

[0149] Example 6

[0150] All amounts in the formula are calculated based on 0.004.

[0151] Take 1.356g of Gd2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain Gd(NO3)3 solution.

[0152] Take 0.0709g Yb2O3 and stir and dissolve it in 20mL concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL deionized water to obtain Yb(NO3)3 solution.

[0153] Take 0.03g of Ho2O3 and stir and dissolve it in 20mL of concentrated nitric acid (mass percentage concentration is 65%). After it is completely dissolved at 80℃, remove the acid at 80℃ and then dry it at 75℃. Add 25mL of deionized water to obtain a Ho(NO3)3 solution.

[0154] Take 0.656gCa(NO3)2 and stir and dissolve it in 25mL deionized water to obtain calcium nitrate solution;

[0155] Take 3.3g Na2MoO4 and stir and dissolve it in 25mL deionized water to obtain sodium molybdate solution;

[0156] 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. Finally, 0.5 g of PEG 1000 was added and stirred evenly. The pH value of the reaction solution was adjusted to 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing evenly, the solution was transferred to a reactor and crystallized at 170° C. for 18 hours to obtain a core layer crystallization product.

[0157] 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 holmium 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 uniformly. The pH value of the reaction solution was adjusted to pH 2 with a sodium hydroxide solution having a mass concentration of 45%. After stirring and mixing uniformly, the solution was transferred to a reactor and crystallized at 175° C. for 20 hours to obtain a core-shell combined crystallized product.

[0158] The crystallized product was washed with water three times and ethanol three times, and then dried at 70°C for 7 hours to obtain an upconversion luminescent material with a core diameter of 25-30 nm and a shell thickness of 25-30 nm. The chemical formula is CaGd 1.87 (MoO4)4:0.09Yb 3+ ,0.04Ho 3+ .

[0159] The chemical formula of the shell is CaGd 1.96 (MoO4)4:0.04Ho 3+ ;

[0160] The chemical formula of the core layer is CaGd1.91 (MoO4)4:0.09Yb 3+ .

[0161] Test Case

[0162] The products of Examples 1 to 5 were measured at room temperature using a Fluoromax-4 fluorescence spectrophotometer under 0.65 W, 995 nm excitation light. The normalized excitation results at 650 nm and 540 nm are shown in Table 1. The color purity of the products of Examples 1 to 4 is calculated as shown in Table 2, and the quantum yield is shown in Table 3.

[0163] Table 1 Peak intensity of green light and red light when the excitation light source power of Examples 1 to 4 is 0.65W

[0164] Serial number Green light peak intensity (540nm) Red light peak intensity (650nm) Example 2 904.651 304.458 Example 3 1147.554 405.561 Example 1 1217.351 431.596 Example 4 489.61 144.846

[0165] Table 2 Color purity of products in Examples 1 to 4 when the excitation light source power is 0.65W

[0166]

[0167]

[0168] Table 3 Quantum yield of products in Examples 1 to 4 when the excitation light source power is 0.65W

[0169] Serial number Quantum yield Example 2 1.6％ Example 3 1.7％ Example 1 1.7％ Example 4 1.5％

[0170] Table 4 Peak intensity of green light and red light when the excitation light source power of Examples 5 to 6 is 0.65W

[0171] Serial number Green light peak intensity (540nm) Red light peak intensity (650nm) Example 5 328.466 118.486 Example 6 115.416 53.58

[0172] From Tables 1 to 3, we can see that the formula CaGd 2-x-y (MoO4)4:yYb 3+ ,xHo 3+ The x=0.04, 0.04≤y≤0.08. In the present invention, when the x is 0.04 and the y is 0.05, the luminous intensity, color purity and quantum yield are the highest.

[0173] As shown in Table 4, when x is 0.04 and y is 0.08, the sample's green peak intensity (540nm) is 328.466, and the red peak intensity (650nm) is 118.486. When x is 0.04 and y is 0.09, the sample's green peak intensity (540nm) is 115.416, and the red peak intensity (650nm) is 53.58.

[0174] 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 Yb 3+ Ion doped AR2(BO4)4, shell is Ho 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 1.96-y (BO4)4:yYb 3+ , 0.04Ho 3+ ; The chemical formula of the shell is AR 1.96 (BO4)4:0.04Ho 3+ ; The chemical formula of the nucleus is AR 2-y (BO4)4:yYb 3+ Said y=0.05; The particle size of the up-conversion luminescent material is 40-60 nm; the thickness of the shell is 25-30 nm.

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 Yb 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 Ho 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 first complexing agent and the second complexing agent independently include polyethylene glycol and / or EDTA; The temperature of the first crystallization reaction is 170°C and the time is 18 hours; The temperature of the second crystallization reaction is 175° C. and the time is 20 h.

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 upconversion luminescent material according to claim 1 or the upconversion 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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