阅读说明：本技术 一种稀土离子掺杂立方相钨酸锆上转换纳米晶体及其制备方法 (Rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal and preparation method thereof ) 是由 韩迎东 杨佳麒 程振洲 李凡 王杰 邓云杰 刘铁根 于 2019-09-12 设计创作，主要内容包括：本发明属于无机纳米材料领域,涉及一种稀土离子掺杂立方相钨酸锆上转换纳米晶体及其制备方法。该纳米晶体的化学式为ZrW<Sub>2</Sub>O<Sub>8</Sub>:Yb<Sup>3+</Sup>/A<Sup>3+</Sup>(A<Sup>3+</Sup>为Er<Sup>3+</Sup>,Tm<Sup>3+</Sup>,Ho<Sup>3+</Sup>中的一种或者任意组合),该纳米晶体为针状且尺寸均一。其制备方法为：向Na<Sub>2</Sub>WO<Sub>4</Sub>·2H<Sub>2</Sub>O水溶液中加入ZrOCl<Sub>2</Sub>·8H<Sub>2</Sub>O水溶液和稀土离子硝酸盐溶液,充分搅拌后加入盐酸和正丁醇,然后转移混合溶液转移至反应釜进行水热反应,结束后分离反应产物,洗涤、干燥、高温煅烧,冷却后即得稀土离子掺杂立方相钨酸锆上转换纳米晶体。该纳米晶体在950～1100nm近红外光的激发下可进行上转换发光,且具有负热膨胀性质,在高温下由于晶格收缩而产生荧光增强的现象,有助于克服上转换纳米材料高温猝灭的缺点,在荧光防伪、彩色显示等领域具有广阔的应用前景。(The invention belongs to the field of inorganic nano materials, and relates to a rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal and a preparation method thereof. The chemical formula of the nanocrystal is ZrW 2 O 8 :Yb 3+ /A 3+ (A 3+ Is Er 3+ ,Tm 3+ ,Ho 3+ One or any combination of them) that are needle-shaped and uniform in size. The preparation method comprises the following steps: to Na 2 WO 4 ·2H 2 ZrOCl is added into O aqueous solution 2 ·8H 2 And (3) fully stirring the O aqueous solution and the rare earth ion nitrate solution, adding hydrochloric acid and n-butanol, transferring the mixed solution to a reaction kettle for hydrothermal reaction, separating a reaction product after the hydrothermal reaction is finished, washing, drying, calcining at high temperature, and cooling to obtain the rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal. The nanocrystal can perform up-conversion luminescence under the excitation of 950-1100nm near infrared light, has negative thermal expansion property, and generates fluorescence enhancement due to lattice shrinkage at high temperatureThe method is favorable for overcoming the defect of high-temperature quenching of the up-conversion nano material, and has wide application prospect in the fields of fluorescence anti-counterfeiting, color display and the like.)

1. A rare earth ion doped cubic phase zirconium tungstate up-conversion nano-crystal is characterized in that: the chemical formula of the up-conversion nanocrystal is ZrW₂O₈:Yb³⁺/A³⁺；

Wherein A is³⁺Is Er³⁺,Tm³⁺,Ho³⁺One or any combination thereof.

2. The rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal as claimed in claim 1, wherein: prepared ZrW₂O₈:Yb³⁺/A³⁺The up-conversion nano crystal is needle-shaped, the average radial length of the up-conversion nano crystal is adjustable between 30nm and 70nm, and the average axial length of the up-conversion nano crystal is about 200nm to 800 nm.

3. The rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal as claimed in claim 1, wherein: prepared ZrW₂O₈:Yb³⁺/A³⁺The crystalline phase of the upconversion nanocrystals is cubic.

4. The rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal as claimed in claim 1, wherein: prepared ZrW₂O₈:Yb³⁺/A³⁺The upconversion nanocrystal can realize upconversion luminescence under the excitation of 950-1100nm waveband light.

5. A method of making rare earth ion doped cubic zirconium tungstate upconversion nanocrystals according to any one of claims 1 to 4, comprising the steps of:

step one, sodium tungstate (Na)₂WO₄·2H₂O) dissolving the crystal in water, then adding the rare earth ion nitrate solution into the sodium tungstate solution, and uniformly stirring;

step two, adding a proper amount of zirconium oxychloride (ZrOCl)₂·8H₂O) dissolving the crystal in water, slowly dropwise adding the crystal into a mixed solution of sodium tungstate and rare earth ions until white flocculent precipitate is generated, and then stirring for a period of time to obtain a reaction solution;

adding a proper amount of n-butanol and adjusting the pH value of the solution to be 0-3.0 by using concentrated hydrochloric acid;

transferring the solution to a stainless steel reaction kettle lined with polytetrafluoroethylene for hydrothermal reaction, after the reaction is finished, naturally cooling the reaction kettle to room temperature, and washing and drying the product to obtain white solid powder;

and fifthly, placing the prepared powder in a quartz crucible, annealing, and calcining at 550-650 ℃ for 0.5-1 h to obtain the rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystal.

6. The method for preparing rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystals according to claim 5, wherein the method comprises the following steps: different rare earth ions are respectively used as a sensitizing agent and an activating agent to be simultaneously doped into the zirconium tungstate matrix material, wherein the sensitizing agent can be Yb³⁺The activator may be Er³⁺、Tm³⁺、Ho³⁺Any one, two or three of the three ions.

7. The method for preparing rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystals according to claim 5, wherein the method comprises the following steps: the tungsten source is Na₂WO₄·2H₂O, rare earth nitrate as rare earth source and ZrOCl as zirconium source₂·8H₂O, and Na used in the synthesis process₂WO₄·2H₂O, rare earth nitrate, ZrOCl₂·8H₂The purity of O and n-butanol is not lower than that of analytical purity.

8. The method of claim 5, wherein hydrochloric acid and n-butanol are used as reagents.

9. The method for preparing rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystals according to claim 5, wherein the temperature of the hydrothermal reaction is 120-140 ℃ and the reaction time is longer than 12 hours.

Technical Field

The invention belongs to the field of inorganic nano materials, and particularly relates to a rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal and a preparation method thereof.

Background

Zirconium tungstate is a good luminescent matrix material, and different rare earth ions can be doped into the zirconium tungstate to generate up-conversion luminescence with different colors. On the other hand, zirconium tungstate is a negative thermal expansion material, and has a negative thermal expansion property in a temperature range of 0.3-1050K, and the lattice spacing of the zirconium tungstate is reduced along with the temperature increase. It is known that the upconversion luminescence intensity is closely related to the distance between ions: as the ion spacing increases, the energy transfer efficiency decreases and the up-conversion luminescence intensity decreases. In upconversion luminescence, the problem of temperature increase of the host material is often inevitably encountered, while the lattice spacing of common host materials increases with temperature increase, while phonon-assisted non-radiative transitions enhance, and therefore, in most cases, luminescence of upconversion materials faces temperature quenching problems. Zirconium tungstate has special negative thermal expansion property, and is expected to overcome the problem of upconversion temperature quenching. Therefore, the rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal provided by the invention has wide application prospects in the fields of display and imaging, fluorescence anti-counterfeiting and the like.

In the thesis, in 2007, X.Cheng et al prepared ZrO with a controlled coefficient of thermal expansion by a combustion process₂/ZrW₂O₈Composite material, and by adding small amount of Al₂O₃The density of the composite material is greatly increased (Composites Science and Technology,67, 1167-. In 2010, J.Yang et al prepared negative thermal expansion ZrW by adopting solid phase reaction method₂O₈Adding ZrW into BTDA-ODA polyamic acid₂O₈Powder to form polyimide/ZrW₂O₈The thermal stability of the composite material is remarkably improved while the thermal expansion rate is reduced (Journal of materials science)&Technology,26, 665-. In 2015, Eu was synthesized by J.Liao et al by hydrothermal method³⁺Doped ZrW₂O₈The nanometer material generates strong red light emission at 616nm under the excitation of 466nm laser, and the ZrW is caused by the characteristic of high quantum yield₂O₈:Eu³⁺The nano material has wide application prospect in the field of fluorescence and luminescence (Materials Research Bulletin,70,7-12,2015). However, to date, no research on rare earth ion doped zirconium tungstate up-conversion nanocrystals and methods for preparing the same has been reported.

In patent, in 2006, a ceramic body with a cubic phase zirconium tungstate as a basic structure was prepared by combining a sol-gel method and a high-temperature solid phase method, and the ceramic body was applied to a ceramic substrate for manufacturing a bragg optical grating with an adjustable negative thermal expansion coefficient, and a chinese invention patent was applied (200610087416.7). In 2007, from the chenchenchenchen of the university of beijing, the inventor invented a method for preparing a cerium-doped zirconium tungstate conductive ceramic material by a hydrothermal method, the obtained zirconium tungstate material not only has negative thermal expansion characteristics, but also has conductivity within a certain temperature range, and applied for the Chinese invention patent (200710179205.0). In 2015, Yangtze et al of Harbin university invented a method for preparing zirconium tungstate by a solid phase reaction sintering method, which can achieve the purpose of quickly and effectively preparing zirconium tungstate with high yield, and applied for Chinese invention patent (201510474815.8). In the above patents relating to zirconium tungstate or rare earth doped zirconium tungstate, no report is made on rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystals and the preparation method thereof.

In summary, in recent years, although the synthesis methods of zirconium tungstate and part of rare earth doped zirconium tungstate materials have been rapidly developed, the application range is expanding, and the methods are spread in a series of fields such as optical element manufacturing, building material manufacturing, aerospace engine manufacturing and sensor manufacturing. However, no research on rare earth ion doped cubic phase zirconium tungstate nanocrystals with up-conversion luminescence characteristics and a preparation method thereof has been reported, and no patent related thereto has been published. The rare earth ion doped zirconium tungstate upconversion nanocrystal provided by the invention can reduce the upconversion temperature quenching effect to a certain extent by utilizing the negative thermal expansion characteristic of a zirconium tungstate matrix, and has important significance for researching novel temperature quenching resistant upconversion luminescent materials and developing applications of upconversion nanomaterial such as fluorescence anti-counterfeiting, color display and the like.

Disclosure of Invention

The invention aims to provide a rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal and a preparation method thereof.

The rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystal has the chemical formula as follows: ZrW₂O₈:Yb³⁺/A³⁺(A³⁺Is Er³⁺,Tm³⁺,Ho³⁺One or any combination thereof).

The rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal is needle-shaped, the radial average length of the rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal is adjustable between 30nm and 70nm, and the axial average length of the rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal is about 200nm to 800 nm.

The crystalline phase of the rare earth ion doped cubic phase zirconium tungstate up-conversion nano-crystal is a cubic phase.

The rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystal can perform upconversion luminescence, and a characteristic emission peak of an activator ion can be clearly seen in a luminescence spectrum under the excitation of 950-1100nm near infrared light.

The preparation method of the rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal comprises the following steps:

step one, sodium tungstate (Na)₂WO₄·2H₂O) dissolving the crystal in water, then adding the rare earth ion nitrate solution into the sodium tungstate solution, and uniformly stirring;

step two, adding a proper amount of zirconium oxychloride (ZrOCl)₂·8H₂O) crystals are dissolved in water and slowly added dropwise to tungstic acidIn the mixed solution of sodium and rare earth ions, white flocculent precipitate is generated, and then the mixed solution is stirred for a period of time to obtain reaction solution;

adding a proper amount of n-butanol and adjusting the pH value of the solution to be 0-3.0 by using concentrated hydrochloric acid;

transferring the solution to a stainless steel reaction kettle lined with polytetrafluoroethylene for hydrothermal reaction, after the reaction is finished, naturally cooling the reaction kettle to room temperature, and washing and drying the product to obtain white solid powder;

and fifthly, placing the prepared powder in a quartz crucible, annealing, and calcining at 550-650 ℃ for 0.5-1 h to obtain the rare earth ion doped cubic phase zirconium tungstate upconversion nanocrystal.

Furthermore, in the prepared rare earth ion doped cubic phase zirconium tungstate up-conversion nano crystal, different rare earth ions are respectively used as a sensitizer and an activator to be simultaneously doped into a zirconium tungstate matrix material, wherein the sensitizer can be Yb³⁺The activator may be Er³⁺、Tm³⁺、Ho³⁺Any one, two or three of the three ions.

Further, the tungsten source is Na₂WO₄·2H₂O, rare earth nitrate as rare earth source and ZrOCl as zirconium source₂·8H₂O, and Na used in the synthesis process₂WO₄·2H₂O, rare earth nitrate, ZrOCl₂·8H₂The purity of O and n-butanol is not lower than that of analytical purity.

Further, in step three, hydrochloric acid and n-butanol were used as the reaction reagents.

Further, in the hydrothermal reaction in the fourth step, the temperature of the hydrothermal reaction is 120-140 ℃, and the reaction time is more than 12 hours.

The invention has the following beneficial effects:

the rare earth ion doped zirconium tungstate upconversion nanocrystal provided by the invention can perform upconversion luminescence, and convert near-infrared pump light into visible light emission with shorter wavelength. Meanwhile, the enhancement of up-conversion luminescence at high temperature is expected to be realized by combining the negative thermal expansion property of zirconium tungstate, so that the modulation of the up-conversion luminescence is obvious. The rare earth ion doped zirconium tungstate up-conversion nanocrystal is expected to be used as a novel fluorescent anti-counterfeiting material and a display material. The preparation method of the rare earth ion doped zirconium tungstate upconversion nanocrystal provided by the invention has the advantages of low experimental cost, low reaction energy consumption, simple and controllable preparation process, high reaction yield, high product purity, uniform product phase and the like.

Drawings

FIG. 1 shows ZrW of rare earth ion doped cubic phase zirconium tungstate of example 1 of the present invention₂O₈:Yb³⁺/Er³⁺(8/1 mol%) X-ray diffraction pattern of upconverted nanocrystals;

FIG. 2 shows ZrW of rare earth ion doped cubic phase zirconium tungstate of example 1 of the present invention₂O₈:Yb³⁺/Er³⁺(8/1 mol%) imaging from a low-power scanning electron microscope of the upconverted nanocrystals;

FIG. 3 shows ZrW of the rare earth ion doped cubic phase zirconium tungstate of example 1 of the present invention₂O₈:Yb³⁺/Er³⁺(8/1 mol%) high power scanning electron microscope image of the upconverted nanocrystal;

Detailed Description

The invention will be further described with reference to the accompanying drawings and examples. These examples are to be construed as merely illustrative and not limitative of the remainder of the disclosure in any way whatsoever. After reading the disclosure of the present invention, various changes or modifications made based on the principle of the present invention also fall within the scope of the present invention as defined in the appended claims. Meanwhile, the technical scheme of the invention is not limited to the specific embodiments listed below, and also comprises any combination of the reaction conditions of the specific embodiments; and is not limited to the specific reactants listed below, but also includes any combination of the same types of reagents of the same family.

Example 1: the method for synthesizing rare earth ion doped cubic phase zirconium tungstate up-conversion nano-crystal according to the embodiment is realized by the following steps:

step one, weighing 0.660g and 0.4095g of Na respectively₂WO₄·2H₂O and ZrOCl₂·8H₂O solid powder, and ultrasonic dissolving in 2mL and 1.37mL deionized water respectively to obtain a solution a and a solution b.

Step two, adding Er of 0.2mmol/mL prepared by deionized water into the solution b obtained in the step one³⁺And Yb of 0.2mmol/mL³⁺And (5) solution to obtain a solution c.

And step three, dripping the solution a obtained in the step one into the solution c obtained in the step two to generate white flocculent precipitates, and stirring for 30min at the rotating speed of 1200rpm to obtain a solution d.

Step four, adding 4mL of concentrated hydrochloric acid and 2mL of n-butanol into the solution d obtained in the step three to obtain a solution e.

And step five, pouring the solution e prepared in the step four into a stainless steel high-pressure reaction kettle with a polytetrafluoroethylene lining, carrying out hydrothermal reaction for 24 hours at 130 ℃, and naturally cooling the reaction kettle to room temperature after the hydrothermal reaction is finished.

And step six, centrifuging the solution with the precipitate obtained in the step five after the hydrothermal reaction is finished for 5min at the rotating speed of 10000rpm to obtain a precipitate, washing the obtained precipitate by using deionized water, and re-dissolving the washed precipitate in the deionized water to form a solution. Then drying the precursor at the temperature of 60 ℃ to obtain a precursor f;

and seventhly, placing the precursor f in a quartz crucible for full grinding, placing the quartz crucible in a muffle furnace for high-temperature calcination under the conditions of 600 ℃ and 30min, and naturally cooling to room temperature after the reaction is finished to obtain the rare earth ion doped cubic phase zirconium tungstate up-conversion nanocrystal with the chemical formula of ZrW₂O₈:Yb³⁺/Er³⁺(8/1mol％)。

The raw materials used in the present embodiment are all commercially available analytical pure raw materials.