Ultrasonic-assisted method for preparing spherical BaFeO3-X nano powder

Abstract

The invention belongs to the technical field of ferroelectric material synthesis, and particularly relates to an ultrasonic-assisted method for preparing spherical BaFeO3-X nano powder. Under the condition of ultrasonic oscillation, ferric chloride and ferrous chloride tetrahydrate generate a ferric hydroxide and ferrous hydroxide blended precipitate on the surface of barium titanate powder in situ. Afterwards, in the high-temperature roasting process, the iron element gradually replaces titanium sites in barium titanate crystal lattices, meanwhile, oxygen vacancies are introduced, and therefore the nanometer spherical BaFeO3-X nanometer powder with the perovskite structure is formed. The method has the advantages of mild reaction conditions, effective reduction of the energy consumption and reduction of the production cost; no toxic or harmful solvent is used in the reaction process, and the method has good environmental protection performance and economic feasibility. The preparation process promotes effective substitution of Fe element to Ti site and introduction of oxygen vacancy, endows the product with good thermochemical stability and potential multiferroic property, and expands the application prospect in the high-tech fields of fuel cells, environmental catalysis and the like.

Description

Technical Field

[0001] This invention belongs to the field of ferroelectric material synthesis technology, specifically relating to a method for preparing nanoscale ferroelectric material powder using ultrasound-assisted co-precipitation, particularly an ultrasound-assisted preparation method for spherical BaFeO. 3-X Methods for producing nanopowders. Background Technology

[0002] Ferroelectric materials are a class of functional materials possessing ferroelectric, piezoelectric, pyroelectric, and nonlinear optical properties, and are widely used in high-tech fields such as fuel cells, non-volatile memories, piezoelectric transducers, catalysts, and infrared detectors. Among them, BaFeO... 3-X Ferroelectric materials are typical multiferroic materials, exhibiting both ferroelectric and antiferromagnetic properties. They are primarily used as cathode materials in solid oxide fuel cells and in environmental catalysis and gas treatment. Currently, common synthesis methods for ferroelectric materials include sol-gel methods, hydrothermal reactions, solid-state reactions, and chemical vapor deposition.

[0003] Chinese Patent (Publication No. CN101773832A) discloses a method for preparing a BaFeO3 perovskite catalyst with good sulfur resistance to nitrogen oxides. The main preparation process is as follows: First, barium salt solution and iron salt solution are mixed in a certain molar ratio and subjected to ultrasonic treatment. Then, under constant temperature and stirring conditions at 70-90℃, citric acid solution is added dropwise according to the molar amount of barium salt, while simultaneously adjusting the pH of the solution to 8.0-10.0 with ammonia water. The reaction is continuously stirred for 4-6 hours to generate a viscous precursor. This precursor is dried at 110-130℃ for 10-14 hours. Subsequently, the precursor is first calcined at 400-450℃ for 2 hours, and then calcined a second time at a rate of 4-6℃ / min to 750-950℃ for 6 hours. Finally, the obtained solid is ground and sieved to obtain the BaFeO3 perovskite catalyst. The advantage of this method is its low preparation cost, but its disadvantage is that the resulting BaFeO3 does not introduce oxygen vacancy defects, and the reaction process requires a high temperature and a long time.

[0004] Chinese patent (publication number CN201210536215.6) discloses a BaFeO 3-X Preparation method: First, 5.41 g Ba(NO3)2, 8.36 g Fe(NO3)3·9H2O, 13.05 g citric acid, and 12.09 g ethylenediaminetetraacetic acid were dissolved in 300 mL of deionized water. The resulting solution was ultrasonically vibrated for 30 min, and then the pH value of the solution was adjusted to 6 using ammonia water. The solution was stirred in an 80 °C water bath until a stable sol was formed. Subsequently, it was dried at 120 °C to form a gel, and then the obtained gel was calcined at 750 °C for 6 h. Finally, the calcined sample was pressed into tablets and sieved to obtain BaFeO.3-X Catalyst particles. However, the above preparation process is cumbersome, energy-intensive, and the prepared BaFeO... 3-X The particle size is difficult to control.

[0005] In summary, the current understanding of BaFeO 3-X There are few synthetic methods for ferroelectric materials, and existing methods for preparing ferroelectric materials suffer from drawbacks such as complex processes, high costs, and high energy consumption. Meanwhile, BaFeO... 3-X The introduction of oxygen vacancies further increases the complexity of its preparation. Therefore, developing a simple, green, and economical method for preparing BaFeO is crucial. 3-X The synthesis methods of nanopowders are crucial for their application in batteries and environmental catalysis. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing spherical BaFeO with ultrasound assistance. 3-X A nanoparticle method was employed. Ferric chloride and ferrous chloride tetrahydrate were precipitated in situ on the surface of barium titanate powder under ultrasonic oscillation to form a co-precipitate of ferric hydroxide and ferrous hydroxide. Subsequently, during high-temperature calcination, iron gradually replaced titanium sites in the barium titanate lattice, while simultaneously introducing oxygen vacancies, thereby forming nanospheres of BaFeO with a perovskite structure. 3-X Nanopowder. The technical solution adopted is as follows:

[0007] An ultrasound-assisted preparation method for spherical BaFeO 3-X The method for processing nanopowders includes the following steps:

[0008] (1) Titanium dioxide and barium hydroxide octahydrate were dissolved in deionized water to obtain solution A. Solution A was magnetically stirred at room temperature and then transferred to a reaction vessel. The reaction vessel was sealed and then placed in a vacuum drying oven for reaction. After the reaction was completed, the reaction vessel was allowed to cool naturally to room temperature. Solution A obtained after the reaction was transferred to a beaker, then filtered and the obtained powder was dried to obtain precursor BaTiO3 (barium titanate) powder.

[0009] (2) Weigh the barium titanate powder obtained in step (1), add it to deionized water, then add alkaline solution to adjust the pH of the solution to alkaline, and obtain mixed solution B; stir the obtained mixed solution B magnetically at room temperature until the solution is milky white to ensure that barium titanate is uniformly dispersed in the solution;

[0010] (3) Add FeCl3 and FeCl2·4H2O to the acidic solution and dissolve them completely to obtain a mixed solution C; stir the solution magnetically at room temperature until the solids are completely dissolved.

[0011] (4) Place the mixed solution B in an ultrasonic cleaner, shake it, and slowly add solution C. After mixing thoroughly, solution D is formed. Continue to ultrasonically treat under the same conditions.

[0012] (5) Subsequently, the ultrasonically vibrated mixed solution D was filtered to recover the obtained solid sample and dry it; the dried block sample was ground and then calcined in a muffle furnace at a constant temperature. After heating, it was naturally cooled to room temperature with the furnace to obtain BaFeO with a nano-spherical structure. 3-X Nanopowder.

[0013] Preferably, in step (1), the molar ratio of titanium dioxide and barium hydroxide octahydrate in solution A is 1:0.9-1.1;

[0014] Preferably, in step (1), the reaction temperature in the reactor is 140-180℃, and the reaction time is set to 4-8h.

[0015] Preferably, in step (2), the alkaline solution is sodium hydroxide or ammonia, and the pH value of the solution is adjusted to 10-13.

[0016] Preferably, in step (3), the acidic solution is a mixture of dilute hydrochloric acid with a pH of 1-2 and deionized water.

[0017] Preferably, in step (3), Fe 3+ with Fe 2+ The molar ratio is 1:1.7-2.3.

[0018] Preferably, in step (4), the oscillation frequency is 30-50kHz, the oscillation time is 5-10 minutes, and the ultrasonic treatment time is 60-100 minutes.

[0019] Preferably, in step (4), the molar ratio of barium to iron in solution D is 1:0.8-1.2.

[0020] Preferably, in step (5), the temperature is raised to 500-600°C in a muffle furnace at a rate of 10°C / min, and calcined at a constant temperature for 3-4 hours.

[0021] This invention relates to an ultrasound-assisted preparation method for spherical BaFeO. 3-X Spherical BaFeO prepared by nanopowder method 3-X Nanopowder.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention adopts an ultrasonic-assisted co-precipitation combined with heat treatment method, which has a simple process flow, few operation steps, easy process control, simple equipment requirements, and is suitable for industrial continuous production, significantly reducing the complexity of preparation.

[0024] (2) The reaction conditions are mild and the preparation temperature is significantly lower than that of traditional solid-phase and gas-phase methods, which effectively reduces energy consumption. No toxic or harmful solvents are used in the reaction process, which has good environmental performance and economic feasibility.

[0025] (3) The preparation process promotes the effective substitution of Ti sites by Fe elements and introduces oxygen vacancies, endowing the product with good thermochemical stability and potential multiferroic properties, and expanding its application prospects in high-tech fields such as fuel cells and environmental catalysis.

[0026] (4) By adjusting the particle size of the precursor BaTiO3, the product BaFeO can be optimized. 3-X The control of nanoparticle size makes it easier to adjust performance in different application scenarios, thereby improving the versatility and adaptability of materials.

[0027] (5) This method has no strict requirements on the initial morphology and size of the sample, and can use commercially available or self-made BaTiO3 as raw material. It has strong process compatibility, lowers the preparation threshold, and further enhances its potential for promotion and widespread adoption. Furthermore, the product particle size can be precisely controlled by the particle size of the precursor barium titanate, demonstrating strong adaptability. The prepared nanospheres of BaFeO3... 3-X Nanopowders possess excellent thermochemical stability and structural integrity, significantly reducing production costs while ensuring performance, and have high potential for industrial application and promotion value. Attached Figure Description

[0028] Figure 1 This is a scanning electron microscope (SEM) image of BaTiO3 prepared according to the present invention.

[0029] Figure 2 BaFeO prepared according to this invention 3-X The X-ray diffraction (XRD) pattern.

[0030] Figure 3 BaFeO prepared according to this invention 3- Image of X using a scanning electron microscope (SEM).

[0031] Figure 4 BaFeO prepared according to this invention 3-X The X-ray photoelectron spectroscopy (XPS) image.

[0032] Figure 5 BaFeO prepared according to this invention 3-X X-ray photoelectron spectroscopy (XPS) of the 3d orbital of Ba element.

[0033] Figure 6 BaFeO prepared according to this invention 3-XX-ray photoelectron spectroscopy (XPS) of the 2p orbital of Ba element. Detailed Implementation

[0034] The figures are for illustrative purposes only; certain well-known structures and their descriptions in the figures may be omitted by those skilled in the art, and therefore should not be construed as limiting the invention.

[0035] Unless otherwise specified, the chemical reagents used in this invention can be obtained through conventional commercial channels; and the test methods used can be implemented by existing technology or conventional methods unless otherwise specified.

[0036] Example 1

[0037] The purpose of this invention is to develop a simple, green, and economical nanospherical structure BaFeO 3-X A method for synthesizing nanopowders. It includes the following steps:

[0038] (1) First, 0.8 g of titanium dioxide and 3.8 g of barium hydroxide octahydrate were dissolved in 50 mL of deionized water to obtain solution A. Solution A was magnetically stirred at 25 °C for 30 min and then transferred to a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was sealed and then placed in a vacuum drying oven at 140 °C for 8 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. Solution A was then transferred to a beaker and filtered using a vacuum filter. The resulting powder was dried in a vacuum drying oven at 60 °C to obtain barium titanate powder.

[0039] (2) Weigh 0.8 g of barium titanate powder obtained in step (1) and add it to 50 mL of deionized water. Then add sodium hydroxide to adjust the pH of the solution to 10. Stir the resulting mixed solution B magnetically for 20 min at room temperature until the solution turns milky white, ensuring that the barium titanate is uniformly dispersed in the solution. The barium titanate powder used in this step can also be replaced by commercially available barium titanate powder.

[0040] (3) Add 0.1 mol / L dilute hydrochloric acid dropwise to 40 mL of deionized water to adjust the pH of the solution to 1. Then, proceed according to Fe... 3+ :Fe 2+ A mixed solution C was prepared by adding FeCl3 and FeCl2·4H2O at a molar ratio of 1.7 and dissolving them completely. The solution was then magnetically stirred at room temperature for 20 minutes until the solids were completely dissolved. The resulting solution C was a reddish-brown transparent state.

[0041] (4) Place solution B in an ultrasonic cleaner and vibrate at a frequency of 50 kHz for 10 min. Then slowly add solution C and mix thoroughly to form solution D. Continue ultrasonic treatment under the same conditions for 60 min. Throughout the process, ensure that the molar ratio of barium to iron is maintained at 0.8.

[0042] (5) Subsequently, the ultrasonically vibrated mixed solution D was filtered, and the resulting solid sample was recovered and dried in an oven at 60°C for 3 hours. After drying, the block sample was ground and then heated to 500°C in a muffle furnace at a rate of 10°C / min, and calcined at this temperature for 4 hours. After heating, the sample was allowed to cool naturally to room temperature to obtain BaFeO with a nanospherical structure. 3-X powder.

[0043] Example 2

[0044] First, 1.3 g of titanium dioxide and 4.3 g of barium hydroxide octahydrate were dissolved in 50 mL of deionized water to obtain solution A. Solution A was magnetically stirred at 25 °C for 30 min and then transferred to a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was sealed, and then placed in a vacuum drying oven at 180 °C for 4 h. After the reaction, the reactor was allowed to cool naturally to room temperature. Solution A was then transferred to a beaker and filtered using a vacuum filter. The resulting powder was dried in a vacuum drying oven at 60 °C to obtain barium titanate powder.

[0045] (2) Weigh 0.8-1.4 g of barium titanate powder obtained in step (1) and add it to 50 mL of deionized water. Then add sodium hydroxide to adjust the pH of the solution to 13. Stir the resulting mixed solution B magnetically for 20 min at room temperature until the solution turns milky white, ensuring that the barium titanate is uniformly dispersed in the solution. The barium titanate powder used in this step can also be replaced by commercially available barium titanate powder.

[0046] (3) Add 0.1 mol / L dilute hydrochloric acid dropwise to 40 mL of deionized water to adjust the pH of the solution to 2. Then, proceed according to Fe... 3+ :Fe 2+ A mixed solution C was prepared by adding FeCl3 and FeCl2·4H2O at a molar ratio of 2.3 and dissolving them completely. The solution was then magnetically stirred at room temperature for 20-30 minutes until the solids were completely dissolved. The resulting solution C was a reddish-brown, transparent liquid.

[0047] (4) Place solution B in an ultrasonic cleaner and vibrate at a frequency of 30 kHz for 10 min. Then slowly add solution C and mix thoroughly to form solution D. Continue ultrasonic treatment under the same conditions for 60-100 min. Throughout the process, ensure that the molar ratio of barium to iron is maintained at 1.2.

[0048] (5) Subsequently, the ultrasonically vibrated mixed solution D was filtered, and the resulting solid sample was recovered and dried in an oven at 60°C for 3 hours. After drying, the block sample was ground and then heated to 500°C in a muffle furnace at a rate of 10°C / min, and calcined at this temperature for 4 hours. After heating, the sample was allowed to cool naturally to room temperature to obtain BaFeO with a nanospherical structure. 3-X powder.

[0049] Example 3

[0050] A method for preparing spherical BaFeO3-X nanopowder with ultrasound assistance includes the following steps:

[0051] (1) First, 1.03 g of titanium dioxide and 4.06 g of barium hydroxide octahydrate were dissolved in 50 mL of ultrapure water to obtain solution A. Solution A was magnetically stirred at 25 °C for 30 min and then transferred to a stainless steel reactor with a polytetrafluoroethylene liner. The reactor was sealed and then placed in a vacuum drying oven at 150 °C for 6 h. After the reaction was completed, the reactor was allowed to cool naturally to room temperature. Solution A was then transferred to a beaker and the mixture was filtered. The obtained powder was dried in a vacuum drying oven at 60 °C to obtain barium titanate powder.

[0052] (2) Weigh 1.16 g of barium titanate powder and add it to 50 mL of deionized water. Then add 1.00 g of sodium hydroxide and adjust the pH of the solution to 13. Stir the resulting mixed solution A magnetically for 20 min at room temperature until the solution turns milky white.

[0053] (3) Add 4 mL of 0.1 mol / L dilute hydrochloric acid to 40 mL of deionized water to adjust the pH of the solution to 2. Then, proceed according to Fe... 3+ :Fe 2+ A mixed solution B was prepared by adding 0.54 g of FeCl3 and 0.33 g of FeCl2·4H2O at a molar ratio of 2 and dissolving them completely. The solution was then magnetically stirred at room temperature for 30 minutes until the solids were completely dissolved.

[0054] (4) Place solution A in an ultrasonic cleaner and vibrate at a frequency of 40 kHz for 10 min. Then slowly add solution B and mix thoroughly to form solution C. Continue to sonicate under the same conditions for 60 min.

[0055] (5) Subsequently, the ultrasonically vibrated solution C was filtered, and the resulting solid sample was recovered and dried in an oven at 60°C for 3 hours. The dried block sample was then ground and heated to 500°C in a muffle furnace at a rate of 10°C / min, and calcined at this temperature for 4 hours. After heating, the sample was allowed to cool naturally to room temperature to obtain nano-spherical BaFeO. 3-X powder.

[0056] like Figure 1 The morphology of barium titanate nanoparticles;

[0057] like Figure 2 In the XRD pattern shown, the diffraction peaks at 31.6°, 38.9°, and 45.3° correspond to BaFeO, respectively. 3-X The (110), (100) and (200) crystal planes;

[0058] like Figure 3 As shown, the synthesized BaFeO 3-X The powder is in the form of nanospheres with a relatively uniform size distribution.

[0059] like Figure 4 BaFeO shown 3-X XPS total spectra confirmed that the obtained BaFeO 3-X The powder does indeed contain four elements: Ba, Fe, O, and Ti.

[0060] like Figure 5 BaFeO 3-X The fine spectrum of the 3d orbitals of Ba element, with diffraction peaks at binding energies of 779 V and 794 eV, confirms the synthesis of BaFeO. 3-X The oxidation state of Ba in the powder is +2;

[0061] like Figure 6 BaFeO 3-X The fine spectrum of the 2p orbitals of Fe element, with diffraction peaks at binding energies of 711 eV and 724 eV, confirms the synthesis of BaFeO. 3-X The Fe element in the powder has oxidation states of +3 and +4, which indirectly proves the existence of oxygen vacancies.

[0062] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. An ultrasound-assisted method for preparing spherical BaFeO 3-X The method for using nanopowders is characterized by, Includes the following steps: (1) Dissolve titanium dioxide and barium hydroxide octahydrate in deionized water to obtain solution A. Stir the obtained solution A magnetically at room temperature, then transfer it to a reaction vessel, seal it, and then place the reaction vessel in a vacuum drying oven for reaction. After the reaction is completed, wait for the reaction vessel to cool naturally to room temperature, transfer the solution A obtained after the reaction to a beaker, filter it, and dry the obtained powder to obtain barium titanate powder. (2) Weigh the barium titanate powder obtained in step (1), add it to deionized water, then add alkaline solution to adjust the pH of the solution to alkaline, and obtain mixed solution B; stir the obtained mixed solution B magnetically at room temperature until the solution is milky white to ensure that barium titanate is uniformly dispersed in the solution; (3) Add FeCl3 and FeCl2·4H2O to the acidic solution and dissolve them completely to obtain a mixed solution C; stir the solution magnetically at room temperature until the solids are completely dissolved. (4) Place the mixed solution B in an ultrasonic cleaner, shake it, and slowly add solution C. After mixing thoroughly, solution D is formed. Continue to ultrasonically treat under the same conditions. (5) Subsequently, the ultrasonically vibrated mixed solution D was filtered to recover the obtained solid sample and dry it; the dried block sample was ground and then calcined in a muffle furnace at a constant temperature. After heating, it was naturally cooled to room temperature with the furnace to obtain BaFeO with a nano-spherical structure. 3-X Nanopowder.

2. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (1), the molar ratio of titanium dioxide and barium hydroxide octahydrate in solution A is 1:0.9-1.

1.

3. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (1), the reaction temperature in the reactor is 140-180℃, and the reaction time is set to 4-8h.

4. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (2), the alkaline solution is sodium hydroxide or ammonia, and the pH value of the solution is adjusted to 10-13.

5. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (3), the acidic solution is a mixture of dilute hydrochloric acid with a pH of 1-2 and deionized water.

6. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (3), Fe 3+ with Fe 2+ The molar ratio is 1:1.7-2.

3.

7. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (4), the oscillation frequency is 30-50kHz, the oscillation time is 5-10 minutes, and the ultrasonic treatment time is 60-100 minutes.

8. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (4), the molar ratio of barium to iron in solution D is 1:0.8-1.

2.

9. The method for preparing spherical BaFeO with ultrasound assistance according to claim 1 3-X The method for using nanopowders is characterized by, In step (5), the temperature is raised to 500-600℃ in a muffle furnace at a rate of 10℃ / min, and calcined at a constant temperature for 3-4 hours.

10. The method for ultrasonic-assisted preparation of spherical BaFeO as described in any one of claims 1-9 3-X Spherical BaFeO prepared by nanopowder method 3-X Nanopowder.

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