CN109913218B

CN109913218B - Micron-sized hexagonal phase NaYF4Up-conversion material and rapid preparation process thereof

Info

Publication number: CN109913218B
Application number: CN201910199622.4A
Authority: CN
Inventors: 王松; 刘雨薇; 胡雍诗玲; 钟志成; 梁桂杰
Original assignee: Hubei University of Arts and Science
Current assignee: Hubei University of Arts and Science
Priority date: 2019-03-15
Filing date: 2019-03-15
Publication date: 2020-10-20
Anticipated expiration: 2039-03-15
Also published as: CN109913218A

Abstract

The invention relates to the technical field of up-conversion materials, and provides a micron-sized hexagonal phase NaYF₄An up-conversion material and a rapid preparation process thereof. Wherein, the micron-sized hexagonal phase NaYF₄The up-conversion material has uniform appearance and high luminous intensity. In addition, the invention also relates to the micron-sized hexagonal NaYF₄The rapid preparation process of the up-conversion material has the advantages of simple synthesis process, rapid preparation process and low cost; no toxic and harmful organic raw materials are added in the preparation process, so that the method has great industrial application value.

Description

Micron-sized hexagonal phase NaYF4Up-conversion material and rapid preparation process thereof

Technical Field

The invention relates to the technical field of up-conversion materials, in particular to a micron-sized hexagonal phase NaYF₄An up-conversion material and a rapid preparation process thereof.

Background

In photoluminescence, a phenomenon in which long-wavelength radiation is converted into short-wavelength radiation by a multiphoton mechanism to thereby realize conversion of low-energy light waves into high-energy light waves is called up-conversion luminescence. The upconversion material is a fluorescent material capable of emitting light with a wavelength shorter than an excitation wavelength when excited by light. NaYF₄The material is an ideal up-conversion crystal material discovered in recent years, has lower phonon energy, can reduce the multiphoton relaxation rate, and improves the up-conversion luminous efficiency. In the normal state, NaYF₄There are two crystal structures, one cubic and the other hexagonal, where the hexagonal phase NaYF₄Is a matrix material with low vibrational energy, low non-radiative decay rate, and high radiative emission frequency. Reported as hexagonal phase NaYF₄As a host, an upconversion luminescent material codoped with ytterbium (Yb) and erbium (Er) is one of the upconversion luminescent materials having the highest upconversion efficiency so far.

In the prior art, NaYF₄The up-conversion material is mostly in nanometer level, and the preparation processMost of the materials are hydrothermal solvothermal methods, and the size of the materials has a large influence on the fluorescence characteristics of the materials, so that the increase of the grain size causes the increase of the propagation path in the photonic materials, which can cause the increase of the light intensity, and the luminous intensity of the micron-scale up-conversion materials is superior to that of the nanometer-scale up-conversion materials. Preparing hexagonal phase NaYF simultaneously₄The up-conversion material has long period, the preparation time is about 48 hours, and organic auxiliary reagents are needed to participate, and the organic reagents have volatility, complex toxic components and different toxicity precautionary measures, so the environment is polluted to a certain extent, and the pollution is difficult to control.

In view of this, the present application is specifically made.

Disclosure of Invention

The invention aims to provide a micron-sized hexagonal NaYF₄The up-conversion material has uniform appearance and high luminous intensity.

Another purpose of the invention is to provide a micron-sized hexagonal phase NaYF₄The rapid preparation process of the up-conversion material has the advantages of simple process, low production cost, controllable crystal phase, strong repeatability, short preparation time, no introduction of organic auxiliary reagent in the preparation process and no pollution to the environment in the reaction process.

The technical problem to be solved by the invention is realized by adopting the following technical scheme:

the invention provides a micron-sized hexagonal NaYF₄Upconverting material in the micro-scale hexagonal phase NaYF₄Is used as a substrate and is codoped with Yb and Er elements.

The invention provides a micron-sized hexagonal NaYF₄The rapid preparation process of the up-conversion material comprises the following steps:

adding sodium hydroxide into the solution containing Y³⁺、Yb³⁺And Er³⁺Forming a uniform precursor solution in the initial solution;

adding fluoride into the precursor solution, and adjusting the pH value to 4-6 to prepare a colloidal solution;

and carrying out hydrothermal reaction on the colloidal solution at 160-180 ℃ for 40-60 min.

Compared with the prior art, the embodiment of the invention has the beneficial effects that: the invention provides a micron-sized hexagonal NaYF₄The up-conversion material has uniform appearance, high luminous intensity and micron-sized hexagonal NaYF₄The preparation process is simpler than the prior art, the preparation process is rapid, the reaction is easy to control, and green, general, environment-friendly and nontoxic reagents are selected in the reaction process without adding any organic auxiliary materials, so that the method has less environmental pollution and is easy for industrial production.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and therefore should not be considered as limiting the scope of protection, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

FIG. 1 shows a micron-sized NaYF prepared in example 1 of the present invention₄Scanning electron microscopy of the upconverting material;

FIG. 2 shows a micron-sized NaYF prepared in example 1 of the present invention₄A luminescent picture of the up-conversion material under the excitation of a 980 laser;

FIG. 3 shows a micron-sized NaYF prepared in example 1 of the present invention₄An XRD pattern of the upconverting material;

FIG. 4 shows a micron-sized NaYF prepared in example 2 of the present invention₄Scanning electron microscopy of the upconverting material;

FIG. 5 shows a micron-sized NaYF prepared in example 2 of the present invention₄A luminescent picture of the up-conversion material under the excitation of a 980 laser;

FIG. 6 shows NaYF prepared in example 3 of the present invention₄Scanning electron microscopy of the upconverting material;

FIG. 7 shows NaYF prepared in example 3 of the present invention₄An XRD pattern of the upconverting material;

FIG. 8 shows a micron-sized NaYF prepared in example 3 of the present invention₄Luminescence pictures of upconverting materials under excitation by a 980 laser.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Following is a description of the micron-sized hexagonal NaYF of embodiments of the present invention₄The up-conversion material and the rapid preparation process thereof are specifically described.

The invention provides a micron-sized hexagonal NaYF₄The up-conversion material has the advantages of uniform appearance, high luminous intensity and the like.

The invention also provides a micron-sized hexagonal NaYF₄The rapid preparation process of the up-conversion material comprises the following steps:

s1, preparing a precursor solution:

dissolving the ytterbium source, the yttrium source and the erbium source in water to obtain a mixed initial solution, adding sodium hydroxide in the magnetic stirring process, and being more beneficial to uniformly mixing the ytterbium source, the yttrium source, the erbium source and the sodium hydroxide, thereby ensuring that a uniform precursor solution is obtained.

Adding sodium hydroxide into the initial solution under magnetic stirring, and stirring until the sodium hydroxide is completely dissolved in Y³⁺、Yb³ ⁺And Er³⁺Wherein the sodium hydroxide is both hexagonal phase NaYF₄The synthesis of the up-converting material provides a source of sodium, and is reacted with Y³ ⁺、Yb³⁺And Er³⁺Coordination; sodium hydroxide is also hexagonal phase NaYF₄The synthesis of the upconverting material provides basicity which further facilitates the reaction to be completed in a short time, preferably with reduced time. Compared with the reaction of sodium citrate as a sodium source and ethanolamine as alkalinity in the prior art, the hexagonal-phase NaYF with sodium hydroxide as an inorganic raw material as the sodium source and the alkalinity₄Preparation of upconverting materialsIn the process, the whole reaction is an inorganic reaction system, no organic reagent is added, and meanwhile, the reaction steps are reduced, so that the whole preparation process is quicker.

Further, the ytterbium source, yttrium source and erbium source are all salts, and in some embodiments of the invention, the ytterbium source, yttrium source and erbium source can be nitrate, chloride or acetate, preferably acetate, and specifically, Y is³⁺Yb provided by ytterbium nitrate³⁺Er supplied from yttrium nitrate³⁺Provided by erbium nitrate. When the initial solution is prepared, a certain amount of yttrium nitrate, ytterbium nitrate and erbium nitrate are dissolved in water.

Further, Y³⁺、Yb³⁺And Er³⁺In a molar ratio of 75-85: 13-23: 2, such as 75:23:2, 78:20:2, 80:18:2, 85:13:2, etc., preferably Y³⁺、Yb³⁺And Er³⁺In a molar ratio of 78:20:2, in such a ratio that NaYF is present₄The upconverting material has good optical properties.

Further, Y³⁺、Yb³⁺And Er³⁺In the initial solution formed, Y³⁺、Yb³⁺And Er³⁺The total molar concentration of (b) is 0.1-0.2 mol/L, preferably 0.1 mol/L.

Further, sodium hydroxide was added to dissolve Y³⁺、Yb³⁺And Er³⁺In the initial solution of (3), the initial concentration of sodium hydroxide is 0.1 to 0.3mol/L, for example, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.25mol/L, 0.3mol/L, etc., preferably 0.225mol/L, and therefore, the molar amount of sodium hydroxide and the Y are the same³⁺Yb of³⁺And said Er³⁺The ratio of the total molar amount of (a) to (b) is 1 to 3:1 to 2, preferably 2.25: 1.

S2, preparing a colloidal solution:

and (3) adding fluoride into the precursor solution prepared in the step S1, and adjusting the pH to 4-6 to prepare a colloidal solution.

In particular, the fluoride is F-containing^-The salt, varying its amount, can adjust the crystalline phase, morphology and size of the product due to F^-The increase in the amount of (a) affects the growth rate of the primary and secondary crystallographic axes of the nanoparticleDue to F^-And Y³⁺F in strong coordination between^-Inevitably adsorbed on NaYF₄Surface, and its adsorption strength and NaYF₄The density of Y atoms on each crystal face is directly proportional, and the density of Y atoms on different crystal faces is different, according to Gibbs-Thompson theory, due to F^-The adsorption on the {1010} crystal plane is larger than that of the Y atom on the {0001} crystal plane, so that the chemical potential of the Y atom is changed. The difference in growth rate between crystal axes facilitates anisotropic growth of the nanoparticles, thus causing a change in morphology. F^-The increase in the amount of (A) makes the reaction process easier to control, while the excess of F^-Can significantly reduce the crystallization temperature of the crystals.

Further, in the preferred embodiment of the present invention, the fluorine source may be ammonium fluoride or sodium fluoride, etc., preferably ammonium fluoride in which F is present^-Molar amount and Y³⁺、Yb³⁺And said Er³⁺The ratio of the total molar amount of (a) is 24-48: 1. Specifically, F is added according to the proportion under the magnetic stirring of 600-1500r/min^-Salt of (a) to contain F^-The salt and the precursor solution can be mixed thoroughly.

Further, F will be contained^-After the salt is added into the precursor solution, hydrochloric acid is adopted to adjust the pH value to 4-6 to prepare a colloidal solution which is easier to control NaYF₄A crystalline phase of the upconverting material.

S3, hydrothermal reaction:

and (3) placing the colloidal solution prepared in the step S2 into a high-pressure reaction kettle, and carrying out hydrothermal reaction at 180 ℃ for 40-60 min. The hydrothermal temperature has great influence on the shape, size and lattice structure of the sample, low hydrothermal temperature is favorable for forming particles with smaller size, and high hydrothermal temperature can provide enough high energy to satisfy NaYF₄The energy required for the transition from cubic to hexagonal phase, and the NaYF for hexagonal phase₄Certain crystal planes of the seed crystal provide energy to grow it anisotropically along the corresponding crystal planes.

Further, washing the obtained product after the hydrothermal reaction is completed, specifically, subjecting the high-pressure reaction toCooling the kettle to room temperature, performing centrifugal separation on the product, alternately cleaning the centrifuged product with deionized water and ethanol for multiple times, performing ultrasonic treatment in the cleaning process to fully disperse the product in the solvent, preferably cleaning the deionized water and the ethanol for three times respectively, after cleaning, drying the product at the temperature of 60-80 ℃ to obtain the hexagonal phase NaYF₄An upconverting material.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The present embodiment provides a micron-sized hexagonal NaYF₄The up-conversion material is columnar hexagonal NaYF as shown in the SEM image of FIG. 1₄:20％Yb³⁺/2％Er³⁺And (4) up-conversion of the micron crystals.

The embodiment also provides a rapid preparation process of the micron-sized hexagonal-phase NaYF4 upconversion material, which comprises the following steps:

s1, preparing a precursor solution:

dissolving yttrium nitrate, ytterbium nitrate and erbium nitrate in water to obtain mixed initial solution, specifically according to Y³⁺:Yb³⁺:Er³⁺Weighing 1mmol of yttrium nitrate, ytterbium nitrate and erbium nitrate according to the molar ratio of 78:20:2, dissolving the yttrium nitrate, ytterbium nitrate and erbium nitrate in 10mL of water, adding 2.25mmol of sodium hydroxide into the initial solution under the magnetic stirring of 600r/min, and stirring for 5min to obtain a precursor solution.

S2, preparing a colloidal solution:

and adding 24mmol of ammonium fluoride into the precursor solution prepared in the step S1 for reaction for 1min, and adjusting the pH of the reaction solution to 6 by using concentrated hydrochloric acid to prepare a colloidal solution.

S3, hydrothermal reaction:

and (3) placing the colloidal solution prepared in the step S2 into a high-pressure reaction kettle, and carrying out hydrothermal reaction in an oven at 180 ℃ for 40 min. After the hydrothermal reaction is finished, cooling the high-pressure reaction kettle to room temperature, alternately ultrasonically cleaning the obtained product by using deionized water and absolute ethyl alcohol for three times, and drying at 80 ℃ to finally obtain the columnar hexagonal phase NaYF₄An upconverting material.

Examples 2 to 4

Examples 2-4 provide a micro-scale hexagonal NaYF₄Fast preparation process of up-conversion material and micron-sized hexagonal phase NaYF provided in embodiment 1₄The rapid preparation process of the up-conversion material is basically consistent in operation, except that specific operating conditions are changed.

Example 2

As shown in the SEM image of FIG. 4, the upconversion material is cylindrical hexagonal NaYF₄:20％Yb³⁺/2％Er³⁺And (4) up-conversion of the micron crystals.

S2, preparing a colloidal solution: and adding 24mmol of ammonium fluoride into the precursor solution prepared in the step S1 for reaction for 1min, and adjusting the pH of the reaction solution to 4 by using concentrated hydrochloric acid to prepare a colloidal solution.

Example 3

As shown in the SEM image of FIG. 6, the upconversion material is cylindrical hexagonal NaYF₄:20％Yb³⁺/2％Er³⁺And (4) up-conversion of the micron crystals.

S2, preparing a colloidal solution: adding 48mmol of ammonium fluoride into the precursor solution prepared in the step S1 for reaction for 1min, and adjusting the pH of the reaction solution to 4 by using concentrated hydrochloric acid to prepare a colloidal solution.

Example 4

S3, hydrothermal reaction: and (3) placing the colloidal solution prepared in the step S2 into a high-pressure reaction kettle, and carrying out hydrothermal reaction in an oven at 160 ℃ for 40 min.

FIG. 1 is a scanning electron microscope image of example 1, FIG. 4 is a scanning electron microscope image of example 2, and FIG. 6 is a scanning electron microscope image of example, comparing the upconverting material in FIGS. 1 and 4, it can be seen that it has hexagonal prism-like structure and is micron-sized, the side length of the hexagonal prism cross-section is 2-3 μm, and the length is 6-8 μm, so that the pH of 6 or 4 can be used to prepare high-purity micron-sized hexagonal phase NaYF with uniform appearance₄Up-conversion materialFeeding; as can be seen from FIGS. 4 and 6, 24mmol or 48mmol of ammonium fluoride, F, was added in step S2 under otherwise unchanged conditions^-Molar amount and Y³⁺、Yb³⁺And Er³⁺When the molar ratio of the total amount of the nano-particles is 24:1 and 48:1, the process can prepare the high-purity micron-sized hexagonal phase NaYF with uniform appearance₄An upconverting material.

Since the size of the material has a large influence on the fluorescence properties of the material, the increase in the size of the crystal grains, which mainly contributes to the increase in the propagation path in the photonic material, can cause an increase in the light intensity, and thus the luminescence intensity of the micro-scale upconversion material is better than that of the nano-scale upconversion material.

FIG. 2 is a photograph showing the luminescence of example 1 under the excitation of 980 laser, FIG. 5 is a photograph showing the luminescence of example 2 under the excitation of 980 laser, and FIG. 8 is a photograph showing the micron-sized NaYF prepared in example 3₄The upconversion material emits a light picture under the excitation of a 980 laser, and as can be seen from the picture, under the condition that other reaction conditions are consistent, the yellow luminescent NaYF can be prepared in the three embodiments₄:20％Yb³⁺/2％Er³⁺Up-conversion of the crystallites was consistent with the results obtained from analysis of SEM pictures.

FIGS. 3 and 7 are NaYF prepared in example 1 and example 3, respectively₄XRD pattern of upconverting material. NaYF prepared in example 1 and example 3₄XRD diffraction peaks of the up-conversion material all accord with hexagonal phase NaYF₄Standard cards of upconverting material. Thus, examples 1 and 3 produced high purity, micron-sized hexagonal phase NaYF with uniform morphology₄Upconverting material, consistent with the results obtained from analysis of SEM images.

The action strength of the rare earth element and different complexing agents is different, and the difference also necessarily causes different mechanisms for fusing small grains into large grains. Therefore, as can be seen from an SEM image, an XRD image and a luminescence image excited by a 980 laser, the sodium citrate and the ethanolamine are replaced by appropriate general and environment-friendly sodium hydroxide, so that the particle size of the prepared material is basically kept at the micron level, and the material has the obvious preferred characteristic of a hexagonal prism shape and has good luminescence performance.

In summary, the present invention provides a micron-sized hexagonal NaYF₄The up-conversion material has uniform appearance and good luminescence, and meanwhile, the preparation process does not need atmosphere protection, the process is simple, and the preparation process is rapid, green and environment-friendly; sodium hydroxide is added to replace other organic complexes in the preparation process to reduce environmental pollution, and the waste liquid after reaction is inorganic waste liquid containing excessive F^-And also Y which does not participate in the reaction³⁺、Yb³⁺And said Er³⁺After purification, the waste liquid can be reused to prepare hexagonal phase NaYF₄The up-conversion material saves cost, recycles waste liquid and has little pollution to the environment. The reaction can be completed within 40-60min, the production period is short, and the method is suitable for large-scale production.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. Micron-sized hexagonal phase NaYF₄The rapid preparation process of the up-conversion material is characterized in that the micron-sized hexagonal phase NaYF₄The up-conversion material is micron-sized hexagonal NaYF₄Co-doping Yb and Er elements as a substrate, and replacing sodium citrate and ethanolamine with sodium hydroxide;

the preparation method comprises the following steps:

adding sodium hydroxide into the solution containing Y³⁺、Yb³⁺And Er³⁺Forming a uniform precursor solution in the initial aqueous solution;

carrying out hydrothermal reaction on the colloidal solution at 160-180 ℃ for 40-60 min;

said Y is³⁺Yb of³⁺And said Er³⁺Are respectively formed by respective pairsProviding nitrate, chloride and acetate; the fluoride is ammonium fluoride or sodium fluoride;

in the initial aqueous solution, the Y³⁺Yb of³⁺And said Er³⁺The molar ratio of (A) to (B) is 75-85: 13-23: 2; molar amount of said sodium hydroxide and said Y³⁺Yb of³⁺And said Er³⁺The molar total amount of the fluorine compound is 1-3: 1-2, and F in the fluoride compound^-Molar amount with said Y³⁺Yb of³⁺And said Er³⁺The ratio of the total molar amount of (a) is 24-48: 1.

2. The micro-scale hexagonal-phase NaYF of claim 1₄A rapid preparation process of an up-conversion material, characterized in that Y is³⁺Yb of³⁺And said Er³⁺Respectively provided by the respective nitrate.

3. The micro-scale hexagonal-phase NaYF of claim 1₄A rapid preparation process of an up-conversion material, characterized in that Y is³⁺Yb of³⁺And said Er³⁺In a molar ratio of 78:20: 2.

4. The micro-scale hexagonal-phase NaYF of claim 1₄A rapid preparation process of an up-conversion material, characterized in that Y is³⁺Yb of³⁺And said Er³⁺The total molar concentration of (a) is 0.1-0.2 mol/L.

5. The micro-scale hexagonal NaYF of claim 3₄Process for the rapid preparation of an upconverting material, characterized in that the molar amount of sodium hydroxide and Y are³⁺Yb of³⁺And said Er³⁺The ratio of the total molar amount of (a) to (b) is 2.25: 1.

6. The micro-scale hexagonal NaYF alloy as claimed in claim 4₄A rapid preparation process of an up-conversion material is characterized in that,the fluoride is ammonium fluoride.

7. The micro-scale hexagonal NaYF alloy as claimed in claim 4₄The rapid preparation process of the up-conversion material is characterized in that after the fluoride is added, hydrochloric acid is adopted to adjust the pH value to 4-6.

8. The micro-scale hexagonal-phase NaYF of claim 1₄The rapid preparation process of the up-conversion material is characterized in that a product prepared after the hydrothermal reaction is washed and centrifuged alternately by ethanol and water and is dried at the temperature of 60-80 ℃.