CN109796045B - Method for preparing compound tungstate by adopting self-sacrificial template - Google Patents
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Abstract
The invention relates to a method for preparing compound tungstate by using a self-sacrifice template, which comprises the following steps: preparing rare earth nitrate solution with corresponding concentration, dissolving ammonium sulfate particles in the rare earth nitrate solution according to a ratio to form mixed solution, adjusting the pH of the mixed solution, continuously stirring to obtain uniform turbid liquid, reacting to obtain a product, and immediately performing centrifugal separation on the product after the reaction is finished to obtain a layered compound nanosheet RE2(OH)4SO4·2H2O, addition of A2WO4Mixing the above solutions, performing hydrothermal reaction, cooling the reaction product to room temperature, centrifuging, and drying to obtain solid powder state tungstate ARE (WO)4)2. The invention uses the lamellar compound nano-sheet as the self-sacrifice template, which is more beneficial to REPO4·1.5H2And O is formed, a target product is directly obtained after hydrothermal, synthesis parameters are wide, the target product can be obtained without fine regulation, and the prepared compound tungstate can be widely applied to the preparation of fluorescent powder.
Description
The technical field is as follows:
the invention belongs to the technical field of material science, and particularly relates to a method for preparing compound tungstate by using a self-sacrifice template.
Background art:
complex tungstate ARE (WO)4)2(A＝Li+，Na+，K+RE is a rare earth element) and CaWO4Has the same structure type, belongs to a tetragonal scheelite structure, has stable physical and chemical properties and excellent thermal conductivity and mechanical property. The material is a very good laser crystal material substrate, and can be used as a good substrate material of display fluorescent powder and fluorescent lamp fluorescent powder. ARE (WO)4)2The performance is excellent when the fluorescent ion is doped as a matrix material. ARE (WO)4)2The absorption capacity in an ultraviolet light region is strong, and tungstate in the matrix has strong sensitization effect on doped rare earth ions, so that energy transfer is facilitated, and high-efficiency fluorescence is obtained. In the structure adjacent RE3+Are connected with each other through a structure of RE-O-W-O-RE, wherein A+And RE3+Alternately occupying the same lattice sites. In the structure RE3+Can be easily substituted by rare earth activator ions with similar radius without causing lattice distortion, and A in the structure+The activator can be well spaced, so that the concentration quenching phenomenon can be effectively inhibited, and the doping concentration can be effectively improved. In addition, in rare earth doped tungstate, since WO4 2-The W-O bond in the group has stronger covalent bond effect, and oxygen ions in the polyhedron are polarized by adjacent high-valence tungsten, so that the fluorescence concentration quenching effect of rare earth activated ions is weakened, the doping concentration of the rare earth ions can also be improved, and the fluorescent material with higher luminous intensity and luminous efficiency is obtained.
Currently, ARE (WO)4)2The synthesis method mainly comprises the traditional solid phase reaction method, a water/solvent thermal method, a microwave hydrothermal method, a precipitation method and the like. The solid phase method and the hydrothermal method are the two most commonly used methods. Pure phase materials are not easy to obtain by adopting a solid phase reaction method, and the pure phase can be obtained by often needing higher temperature (more than 1200 ℃). Moreover, the micro-morphology of the product obtained by the solid-phase reaction method often has a relatively serious agglomeration phenomenon, the powder cannot reach the required particle size, and the micro-morphology of the product cannot easily reach the required particle sizeHowever, the particle and morphology of the phosphor have a great influence on the light emitting performance of the light emitting device, and some applications may desire the phosphor to have a specific morphology. Preparation of ARE by hydrothermal method (WO)4)2The morphology of the target product can be adjusted to a certain extent, but the target product can be obtained only by calcining a precursor obtained through hydrothermal reaction. The hydrolysis behavior of tungstate radicals in a solution is complex and difficult to regulate, the obtained hydrothermal product is complex, and a proper precursor can be found only by multiple experimental regulation. Thus, a novel synthetic ARE was sought (WO)4)2The synthetic methods of (a) are therefore of great significance.
The invention content is as follows:
the object of the present invention is to overcome the above-mentioned disadvantages of the prior art, and to address the ARE (WO)4)2Problems in the Synthesis of double tungstates in combination with the ultrathin layered Compound RE2(OH)4SO4·2H2O, providing a layered compound RE2(OH)4SO4·2H2O is a preparation method of the self-sacrifice template. The aim is to enrich the existing NaRE (WO)4)2The preparation method of the retest tungstate enriches the microscopic morphology of the tungstate.
In order to achieve the purpose, the invention adopts the following technical scheme:
preparation of double tungstate ARE (WO) by adopting self-sacrificial template4)2The method comprises the following steps:
(1) lanthanum nitrate hexahydrate (RE (NO)3)3·6H2O) is evenly mixed in deionized water to prepare RE3+Rare earth nitrate (RE (NO) with a concentration of 0.03-0.20 mol/L3)3) A solution; the RE is one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (RE (NO)3)3) In the solution to form a mixed solution, wherein the mixed solution isAmmonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (RE (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-：RE3+＝0.5～10；
(3) Adding ammonia water into the mixed solution, adjusting the pH of the mixed solution to 7-10, and continuously stirring for 10-30 min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 4-120 ℃, and the reaction time is 12-72 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, the product is immediately centrifuged to obtain the layered compound nanosheet RE2(OH)4SO4·2H2O；
Step 3, using the layered compound nano-sheet as a self-sacrifice template to prepare NaRE (WO)4)2
(1) Get A2WO4Solution of RE2(OH)4SO4·2H2O nanosheet and A2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶RE3+The reaction temperature is 150-220 ℃, the reaction time is 4-72 h, and A is one of Li, Na and K;
(2) cooling the reaction product to room temperature, centrifugally cleaning, and drying to obtain the double tungstate ARE (WO)4)2(ii) a Wherein the double tungstate ARE (WO)4)2In the form of solid powder.
In the step 1(3), when RE is Ce, the ammonia is added dropwise under protection of an argon atmosphere to prevent Ce3+Oxidation to Ce4+。
In the step 1(3), the pH of the mixed solution is adjusted to 8.5 to 10 when RE is La, Ce, Pr, Nd, Sm, and to 7 to 8 when RE is Eu, Gd, Tb, Dy.
In the step 1(3), the reaction temperature is 4 to 120 ℃ when RE is La, Ce, Pr, Nd or Sm, and is 50 to 120 ℃ when RE is Eu, Gd, Tb or Dy.
In the step 2(1), the centrifugal separation process is as follows: after the product is centrifugally separated, the supernatant is poured off, and the residual solid is washed with deionized water for three times to obtain the layered compound nanosheet RE2(OH)4SO4·2H2O。
In the step 3(1), RE2(OH)4SO4·2H2The O nano-sheet is used as a self-sacrifice template.
In the step 3(1), A2WO4The concentration of the solution is 0.3-3.0 mol/L; the source of tungstate radical is sodium tungstate Na2WO4Other tungsten acid sources such as ammonium tungstate cannot be used.
In the step 3(1), the hydrothermal reaction is carried out in a reaction kettle.
In the step 4(2), the centrifugal cleaning process of the cooling product comprises the following steps: the method comprises the steps of firstly carrying out centrifugal cleaning by using distilled water and then carrying out centrifugal cleaning by using absolute ethyl alcohol, wherein the centrifugal cleaning times of the distilled water are 3 times, and the centrifugal cleaning times of the absolute ethyl alcohol are 1 time.
In the step 3(2), the drying temperature is 40-60 ℃, and the drying time is 12-24 hours.
In the step 3(2), the double tungstate ARE (WO)4)2The micro-morphology is a disk-shaped micro-morphology with a diameter of about 4.5 to 5.5 μm and a thickness of about 500 to 600 nm.
The invention has the beneficial effects that:
(1) the invention uses a self-sacrifice template method to prepare the compound tungstate NaRE (WO)4)2. The template is a self-sacrifice template and participates in chemical reaction, and during the reaction process, reactants are gradually generated on the surface of the template, so that the template is removed without subsequent treatment after a target product is obtained.
(2) The invention uses a novel layered compound gel as a self-sacrifice template, and the compound has a chemical formula of RE2(OH)4SO4·2H2O, RE in the template3+∶OH-1: 2, in the course of the solution reaction, OH-With WO4 2-To compete for coordinationIs a higher RE3+∶OH-In a ratio of WO4 2-Is easier to react with RE3+Coordination thereby facilitating the formation of the desired product and thus facilitating the ARE (WO)4)2Is performed.
(3) The technical scheme of the invention is simple and easy to implement. By adopting the technical scheme of the invention, the target product ARE (WO) can be directly obtained after hydrothermal reaction4)2The target product can be obtained without calcining the intermediate product after hydrothermal reaction as in the conventional method. The morphology of the target product after hydrothermal treatment can be better maintained. Many conventional hydrothermal methods obtain intermediates after hydrothermal reaction, and the intermediates need to be further calcined to obtain the target product NaRE (WO)4)2. The specific calcination temperature can be determined by multiple experiments, and the high-temperature calcination process has the possibility of destroying the original micro-morphology of the product, in the prior art, the hydrothermal product NaGd (WO) is obtained under different hydrothermal temperature conditions4)2SEM image is shown in FIG. 7, the target product is directly obtained by hydrothermal reaction, the dispersibility is poor, the agglomeration phenomenon exists, the target product is obtained by calcining the hydrothermal intermediate, and NaGd obtained by calcining the hydrothermal product at different temperatures0.9Eu0.1(WO4)2The SEM image is shown in FIG. 8, and the agglomeration phenomenon exists, the particle size distribution is not uniform, and the morphology of the hydrothermal product is damaged by high-temperature calcination.
(4) The application of the fluorescent powder can be influenced from multiple directions by different microscopic shapes, if the fluorescent powder needs to be coated, the fluorescent powder is expected to have better coating performance, and the monodisperse spherical fluorescent powder can be easily self-assembled and arranged into a film or a plane, so that the fluorescent powder has wider application due to the diversification and homogenization of the shapes. NaRE with novel micro-morphology can be obtained by the technical means in the application (WO)4)2。
Description of the drawings:
FIG. 1 shows NaLa (WO) prepared in example 1 of the present invention4)2An XRD pattern of (a);
FIG. 2 shows NaLa (WO) prepared in example 1 of the present invention4)2FE-SEM picture of (b);
FIG. 3 shows NaCe (WO) prepared in example 2 of the present invention4)2An XRD pattern of (a);
FIG. 4 shows NaCe (WO) prepared in example 2 of the present invention4)2FE-SEM picture of (b);
FIG. 5 shows NaGd prepared in example 3 of the present invention (WO)4)2An XRD pattern of (a);
FIG. 6 is NaTb (WO) prepared according to example 6 of the present invention4)2An XRD pattern of (a);
FIG. 7 shows the hydrothermal reaction product NaGd (WO) obtained under different hydrothermal temperature conditions in the prior art4)2SEM picture;
FIG. 8 shows NaGd obtained after calcination of hydrothermal products at different temperatures in the prior art0.9Eu0.1(WO4)2SEM image.
The specific implementation mode is as follows:
the present invention will be described in further detail with reference to examples.
The chemical reagents adopted in the embodiment of the invention are all analytical pure-grade products;
in the embodiment of the invention, XRD analysis is carried out by adopting a RINT2200V/PC type X-ray diffractometer of Rigaku corporation in Japan; observing the appearance of the sample by using an S-5000 field emission scanning electron microscope (FE-SEM) of Hitachi corporation of Japan;
the inner container of the hydrothermal reaction kettle is made of polytetrafluoroethylene with the specification of 100ml, the steel sleeve is made of stainless steel, the oven is an electronic temperature control oven, and the temperature difference is less than 1 ℃;
the following are preferred embodiments of the present invention.
Example 1
Compound tungstate NaLa (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) lanthanum nitrate hexahydrate (La (NO)3)3·6H2O) is evenly mixed in deionized water to prepare La3+Rare earth nitrate (La (NO) with concentration of 0.03mol/L3)3) And (3) solution.
(2) Ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (La (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (La (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶La3+＝0.5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 10, and continuously stirring for 30min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 4 ℃, and the reaction time is 72 hours;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain layered compound nanosheet La2(OH)4SO4·2H2O；
Step 3, preparing NaLa (WO) by taking layered compound nanosheets as self-sacrifice templates4)2
(1) Taking Na with the concentration of 0.3mol/L2WO4Solution of La2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶La3+The reaction temperature is 150 ℃, and the reaction time is 72 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning times of distilled water is 3 times, the centrifugal cleaning times of absolute ethyl alcohol is 1 time, and drying to obtain the tungstate NaLa (WO)4)2(ii) a Wherein the drying temperature is 40 ℃, the drying time is 12h, and the tungstate NaLa (WO)4)2The powder is in solid powder state, and has XRD pattern as shown in figure 1, and FE-SEM pattern as shown in figure 2A disk-like micro-morphology with a diameter of about 4.5 to 5.5 μm and a thickness of about 500-600 nm.
Example 2
Compound tungstate NaCe (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) cerous nitrate hexahydrate (Ce (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Ce3+Rare earth nitrate (Ce (NO) with concentration of 0.20mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolved in rare-earth nitric acid (Ce (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Ce (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Ce3+＝10；
(3) Under the protection of argon atmosphere, adding ammonia water into the mixed solution, adjusting the pH of the solution to 8.5, and continuously stirring for 30min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 120 ℃, and the reaction time is 12 h; when ammonia water is dripped into the reaction kettle, the ammonia water is dripped into the reaction kettle under the protection of argon atmosphere to prevent Ce3+Oxidation to Ce4+；
And 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain the layered compound nanosheet Ce2(OH)4SO4·2H2O；
Step 3, preparing NaCe (WO) by taking layered compound nanosheets as self-sacrifice templates4)2
(1) Taking Na with the concentration of 3.0mol/L2WO4Solution of Ce2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-：Ce3+The reaction temperature is 220 ℃, and the reaction time is 4 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning frequency of distilled water is 3 times, the centrifugal cleaning frequency of absolute ethyl alcohol is 1 time, and drying to obtain tungstate NaCe (WO)4)2(ii) a Wherein the drying temperature is 60 ℃, the drying time is 24h, and the tungstate NaCe (WO)4)2The powder is in a solid powder state, the XRD spectrum is shown in figure 3, the FE-SEM image is shown in figure 4, the microstructure is a disc-shaped microstructure with the diameter of about 4.5-5.5 μm, and the thickness of the disc is about 500-600 nm.
Example 3
Compound tungstate NaGd (WO) prepared by adopting self-sacrifice template4)2The method comprises the following steps:
(1) gadolinium nitrate hexahydrate (Gd (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Gd3+Rare earth nitrate (Gd (NO) with a concentration of 0.10mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (Gd (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Gd (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Gd3+＝5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 8, and continuously stirring for 15min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 50 ℃, and the reaction time is 36 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain the layered compound nanosheet Gd2(OH)4SO4·2H2O；
Step 3, preparing NaGd (WO) by taking the layered compound nanosheet as a self-sacrifice template4)2
(1) Taking Na with the concentration of 2.0mol/L2WO4Solution of Gd2(OH)4SO4·2H2O nanosheet template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Gd3+The reaction temperature is 180 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning times of distilled water is 3 times, the centrifugal cleaning times of absolute ethyl alcohol is 1 time, and drying to obtain tungstate NaGd (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate NaGd (WO)4)2The XRD pattern of the powder is shown in figure 5.
Example 4
Compound tungstate KPr (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) praseodymium nitrate hexahydrate (Pr (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Pr3+Rare earth nitrate (Pr (NO) with concentration of 0.15mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (Pr (NO)3)3) SolutionIn the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Pr (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Pr3+＝4；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 9, and continuously stirring for 15min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 80 ℃, and the reaction time is 36 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain the layered compound nanosheet Pr2(OH)4SO4·2H2O；
Step 3, preparing KPr (WO) by taking the layered compound nano-sheet as a self-sacrifice template4)2
(1) Taking K with the concentration of 2.0mol/L2WO4Solution of Pr2(OH)4SO4·2H2O template and K2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Pr3+The reaction temperature is 180 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature, centrifuging and cleaning the cooled product with distilled water for 3 times, centrifuging and cleaning with anhydrous ethanol for 1 time, wherein the centrifuging and cleaning times of distilled water is 3 times and the centrifuging and cleaning times of anhydrous ethanol is 1 time, and drying to obtain tungstate KPr (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate KPr (WO)4)2Is in a solid powder state, has a disc-shaped microscopic morphology with a diameter of about 4.5-5.5 μm, and has a disc thickness of about 500-600 nm.
Example 5
Compound tungstate NaNd (WO) prepared by adopting self-sacrificial template4)2Method of, and packageThe method comprises the following steps:
(1) adding neodymium nitrate hexahydrate (Nd (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Nd3+Rare earth nitrate (Nd (NO) with concentration of 0.10mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)25O4) Dissolving in rare-earth nitric acid (Nd (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Nd (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Nd3+＝5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 9.5, and continuously stirring for 15min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 110 ℃, and the reaction time is 32 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain layered compound nanosheet Nd2(OH)4SO4·2H2O；
Step 3, preparing NaNd (WO) by taking layered compound nanosheets as self-sacrifice templates4)2
(1) Taking Na with the concentration of 2.0mol/L2WO4Solution of Nd2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Nd3+The reaction temperature is 180 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, and then carrying out centrifugal cleaningCentrifuging and cleaning with anhydrous ethanol for 1 time, wherein the centrifugal cleaning times of distilled water is 3 times and the centrifugal cleaning times of anhydrous ethanol is 1 time, and drying to obtain tungstate NaNd (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate NaNd (WO)4)2Is in a solid powder state, has a disc-shaped microscopic morphology with a diameter of about 4.5-5.5 μm, and has a disc thickness of about 500-600 nm.
Example 6
Compound tungstate NaDy (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) dysprosium nitrate hexahydrate (Dy (NO)3)3·6H2O) is evenly mixed in deionized water to prepare RE3+Rare earth nitrate (Dy (NO) with concentration of 0.20mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (Dy (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Dy (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Dy3+＝3；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 7, and continuously stirring for 30min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 120 ℃, and the reaction time is 36 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain the layered compound nanosheet Dy2(OH)4SO4·2H2O；
Step 3, preparing NaDy (WO) by taking the layered compound nanosheet as a self-sacrifice template4)2
(1) Taking Na with the concentration of 2.0mol/L2WO4Solution of Dy2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Dy3+The reaction temperature is 180 ℃, and the reaction time is 48 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning times of distilled water is 3 times, the centrifugal cleaning times of absolute ethyl alcohol is 1 time, and drying to obtain the tungstate NaDy (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate NaDy (WO)4)2The XRD pattern of the powder is shown in figure 6.
Example 7
Compound tungstate LiSm (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) samarium nitrate hexahydrate (Sm (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Sm3+Rare earth nitrate (Sm (NO) with concentration of 0.10mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (Sm (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Sm (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Sm3+＝5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 8.5, and continuously stirring for 15min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 130 ℃, and the reaction time is 18 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain the layered compound nanosheet Sm2(OH)4SO4·2H2O；
Step 3, preparing LiSm (WO) by taking layered compound nanosheets as self-sacrifice templates4)2
(1) Taking Li with the concentration of 2.0mol/L2WO4Solution of Sm2(OH)4SO4·2H2O template and Li2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Sm 3+20 ℃, the reaction temperature is 220 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning times of distilled water is 3 times, the centrifugal cleaning times of absolute ethyl alcohol is 1 time, and drying to obtain the tungstate LiSm (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate LiSm (WO)4)2Is in a solid powder state, has a disc-shaped microscopic morphology with a diameter of about 4.5-5.5 μm, and has a disc thickness of about 500-600 nm.
Example 8
Compound tungstate NaEu (WO) prepared by adopting self-sacrificial template4)2The method comprises the following steps:
(1) europium nitrate hexahydrate (Eu (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Eu3+Rare earth nitrate (Eu (NO) with concentration of 0.10mol/L3)3) A solution;
(2) Ammonium sulfate particles ((NH)4)2SO4) Dissolved in rare earth nitric acid (Eu (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Eu (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Eu3+＝5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 8, and continuously stirring for 15min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 50 ℃, and the reaction time is 36 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain a layered compound nanosheet Eu2(OH)4SO4·2H2O；
Step 3, preparing NaEu (WO) by taking layered compound nanosheets as self-sacrifice templates4)2
(1) Taking Na with the concentration of 2.0mol/L2WO4Solution of Eu, Eu2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Eu3+The reaction temperature is 180 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature, centrifugally cleaning the cooled product with distilled water for 3 times, centrifugally cleaning with absolute ethyl alcohol for 1 time, wherein the centrifugal cleaning frequency of distilled water is 3 times, the centrifugal cleaning frequency of absolute ethyl alcohol is 1 time, and drying to obtain tungstate NaEu (WO)4)2(ii) a Wherein the drying temperature is 50 ℃, the drying time is 18h, and the tungstate NaEu (WO)4)2In the form of solid powder.
Example 9
Compound tungstate N prepared by adopting self-sacrificial templateaTb(WO4)2The method comprises the following steps:
(1) terbium nitrate hexahydrate (Tb (NO)3)3·6H2O) is evenly mixed in deionized water to prepare Tb3+Rare earth nitrate (Tb (NO) with concentration of 0.20mol/L3)3) A solution;
(2) ammonium sulfate particles ((NH)4)2SO4) Dissolving in rare-earth nitric acid (Tb (NO)3)3) In the solution, a mixed solution is formed, wherein the ammonium sulfate particles ((NH)4)2SO4) With rare earth nitrates (Tb (NO)3)3) The amount of the solution added is in terms of molar ratio, SO4 2-∶Tb3+＝5；
(3) Adding ammonia water into the mixed solution, adjusting the pH value of the solution to 7, and continuously stirring for 30min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 80 ℃, and the reaction time is 36 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, immediately performing centrifugal separation on the product, pouring out supernatant, washing the residual solid for three times by using deionized water to obtain layered compound nanosheet Tb2(OH)4SO4·2H2O；
Step 3, preparing NaTb (WO) by taking the layered compound nanosheet as a self-sacrifice template4)2
(1) Taking Na with the concentration of 2.0mol/L2WO4Solution of Tb2(OH)4SO4·2H2O template and Na2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction in a reaction kettle under a sealed condition to obtain a reaction product; wherein the amount is in molar ratio, WO4 2-∶Tb3+The reaction temperature is 180 ℃, and the reaction time is 34 h;
(2) cooling the reaction product to room temperature to obtain the productCentrifuging and cleaning with distilled water for 3 times, centrifuging and cleaning with anhydrous ethanol for 1 time, wherein the centrifuging and cleaning times are 3 times and 1 time, and drying to obtain tungstate NaTb (WO)4)2(ii) a Wherein the drying temperature is 60 ℃, the drying time is 24h, and the tungstate NaTb (WO)4)2In the form of solid powder.
Claims (7)
1. A method for preparing compound tungstate by using a self-sacrifice template is characterized by comprising the following steps:
step 1, layered Compound RE2(OH)4SO4·2H2Preparation of O:
(1) mixing rare earth nitrate hexahydrate in deionized water uniformly to prepare RE3+A rare earth nitrate solution with the concentration of 0.03-0.20 mol/L; the RE is one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy;
(2) dissolving ammonium sulfate particles in a rare earth nitrate solution to form a mixed solution, wherein the adding amount of the ammonium sulfate particles and the rare earth nitrate solution is in molar ratio, SO4 2-：RE3+=0.5~10；
(3) Adding ammonia water into the mixed solution, adjusting the pH of the mixed solution to 7-10, and continuously stirring for 10-30 min to obtain a uniform suspension; reacting the uniform suspension to obtain a product; wherein the reaction temperature is 4-120 ℃, and the reaction time is 12-72 h;
and 2, cleaning and purifying a product:
(1) after the reaction is finished, the product is immediately centrifuged to obtain the layered compound nanosheet RE2(OH)4SO4·2H2O；
Step 3, using the layered compound nano-sheet as a self-sacrifice template to prepare ARE (WO)4)2
(1) Get A2WO4Solution of RE2(OH)4SO4·2H2O nanosheet and A2WO4After the solution is uniformly mixed, carrying out hydrothermal reaction to obtain a reaction product; wherein the content of the first and second substances,the addition amounts are in molar ratios, WO4 2-：RE3+= 10-100, reaction temperature 150~The reaction time is 4-72 h at 220 ℃, A is one of Li, Na and K;
(2) cooling the reaction product to room temperature, centrifugally cleaning, and drying to obtain the double tungstate ARE (WO)4)2(ii) a Wherein the double tungstate ARE (WO)4)2In the form of solid powder.
2. The method for preparing double tungstate using self-sacrifice template as in claim 1, wherein in step 1(3), when RE = Ce, ammonia is added in an argon atmosphere to prevent Ce3+Oxidation to Ce4 +。
3. The method for preparing double tungstate using self-sacrifice template as claimed in claim 1, wherein in step 1(3), when RE = La, Ce, Pr, Nd, Sm, the pH of the mixture is adjusted to 8.5-10, and when RE = Eu, Gd, Tb, Dy, the pH of the mixture is adjusted to 7-8.
4. The method for preparing a double tungstate using a self-sacrifice template as claimed in claim 1, wherein in step 1(3), the reaction temperature is 4-120 ℃ when RE = La, Ce, Pr, Nd, Sm, and 50-120 ℃ when RE = Eu, Gd, Tb, Dy.
5. The method for preparing double tungstate using self-sacrifice template as claimed in claim 1, wherein in step 3(1), A2WO4The concentration of the solution is 0.3-3.0 mol/L.
6. The method for preparing the double tungstate using the self-sacrifice template as claimed in claim 1, wherein the drying temperature in step 3(2) is 40-60 ℃ and the drying time is 12-24 hours.
7. A method of preparing double tungstate using self-sacrifice template as in claim 1, wherein in the step 3(2), the double tungstate ARE (WO)4)2The micro-morphology is a disk-shaped micro-morphology with the diameter of 4.5-5.5 mu m, and the thickness of the disk is 500-600 nm.
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