CN118005072A - Hydrothermal synthesis method of barium titanate - Google Patents
Hydrothermal synthesis method of barium titanate Download PDFInfo
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- 229910002113 barium titanate Inorganic materials 0.000 title claims abstract description 96
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 title claims abstract description 92
- 238000000034 method Methods 0.000 title claims abstract description 48
- 238000001027 hydrothermal synthesis Methods 0.000 title claims abstract description 26
- 239000000243 solution Substances 0.000 claims abstract description 59
- 239000000843 powder Substances 0.000 claims abstract description 48
- 238000005406 washing Methods 0.000 claims abstract description 34
- 239000002244 precipitate Substances 0.000 claims abstract description 31
- 238000001035 drying Methods 0.000 claims abstract description 30
- 239000002253 acid Substances 0.000 claims abstract description 26
- 238000002156 mixing Methods 0.000 claims abstract description 22
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 17
- 229910001507 metal halide Inorganic materials 0.000 claims abstract description 11
- 150000005309 metal halides Chemical class 0.000 claims abstract description 11
- 159000000009 barium salts Chemical class 0.000 claims abstract description 10
- 238000001816 cooling Methods 0.000 claims abstract description 10
- 239000003513 alkali Substances 0.000 claims abstract description 7
- 239000007864 aqueous solution Substances 0.000 claims abstract description 7
- 150000007529 inorganic bases Chemical class 0.000 claims abstract description 7
- 150000002978 peroxides Chemical class 0.000 claims abstract description 7
- 238000010992 reflux Methods 0.000 claims abstract description 5
- 238000001914 filtration Methods 0.000 claims abstract description 3
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 27
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical group [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 27
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 18
- RQPZNWPYLFFXCP-UHFFFAOYSA-L barium dihydroxide Chemical class [OH-].[OH-].[Ba+2] RQPZNWPYLFFXCP-UHFFFAOYSA-L 0.000 claims description 12
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 9
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 9
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical group Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 9
- 230000001105 regulatory effect Effects 0.000 claims description 2
- 239000013049 sediment Substances 0.000 claims description 2
- 239000002245 particle Substances 0.000 abstract description 47
- 239000013078 crystal Substances 0.000 abstract description 23
- 230000003197 catalytic effect Effects 0.000 abstract description 4
- 239000012535 impurity Substances 0.000 abstract description 4
- 229910010272 inorganic material Inorganic materials 0.000 abstract description 2
- 239000011147 inorganic material Substances 0.000 abstract description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 50
- 238000004146 energy storage Methods 0.000 description 15
- 238000012512 characterization method Methods 0.000 description 12
- 230000015556 catabolic process Effects 0.000 description 11
- 239000000047 product Substances 0.000 description 11
- 239000000463 material Substances 0.000 description 8
- 239000012071 phase Substances 0.000 description 8
- 238000005054 agglomeration Methods 0.000 description 7
- 230000002776 aggregation Effects 0.000 description 7
- 150000002500 ions Chemical class 0.000 description 7
- 238000013033 photocatalytic degradation reaction Methods 0.000 description 7
- 238000000967 suction filtration Methods 0.000 description 7
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 6
- 238000011056 performance test Methods 0.000 description 6
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 5
- -1 hydrogen ions Chemical class 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 230000001699 photocatalysis Effects 0.000 description 4
- 239000010936 titanium Substances 0.000 description 4
- 241001391944 Commicarpus scandens Species 0.000 description 3
- 229910003089 Ti–OH Inorganic materials 0.000 description 3
- 239000003985 ceramic capacitor Substances 0.000 description 3
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical group [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- 150000003608 titanium Chemical class 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 150000004703 alkoxides Chemical class 0.000 description 2
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000000975 co-precipitation Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 230000003301 hydrolyzing effect Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 230000002687 intercalation Effects 0.000 description 2
- CXKWCBBOMKCUKX-UHFFFAOYSA-M methylene blue Chemical compound [Cl-].C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 CXKWCBBOMKCUKX-UHFFFAOYSA-M 0.000 description 2
- 229960000907 methylthioninium chloride Drugs 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 229910001414 potassium ion Inorganic materials 0.000 description 2
- 239000000376 reactant Substances 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 238000010532 solid phase synthesis reaction Methods 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910003890 H2TiO3 Inorganic materials 0.000 description 1
- 229910003074 TiCl4 Inorganic materials 0.000 description 1
- 229910003077 Ti−O Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 229910001863 barium hydroxide Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 239000002064 nanoplatelet Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000000870 ultraviolet spectroscopy Methods 0.000 description 1
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
Abstract
The invention belongs to the technical field of inorganic materials, and particularly relates to a hydrothermal synthesis method of barium titanate. The method comprises the following steps: 1) Dropwise adding metal halide into cold acid liquor, adding alkali liquor to adjust the pH value to obtain precipitate, washing the precipitate, uniformly mixing the precipitate with an inorganic peroxide solution, refluxing, and cooling to obtain a solution 1; 2) Adding mineralizer and inorganic base into the solution 1, and performing hydrothermal treatment, washing and drying to obtain powder A; 3) Adding acid liquor into the powder A, uniformly mixing, filtering, washing and drying to obtain powder B, adding barium salt aqueous solution for hydrothermal treatment, washing and drying to obtain barium titanate. The barium titanate prepared by the method is uniform and compact, has complete crystal form, good crystal development, presents a cubic phase crystal structure, has no other impurity phases, and has small particle size, high dispersibility, electrical property and catalytic property.
Description
Technical Field
The invention belongs to the technical field of inorganic materials, and particularly relates to a hydrothermal synthesis method of barium titanate.
Background
Barium titanate is a typical perovskite structure crystal, and is a typical perovskite ABO3 type below 1460 ℃, and is a hexagonal type above 1460 ℃. Barium titanate has the characteristics of higher dielectric constant, lower dielectric loss, larger resistivity, excellent compressive strength and the like, and is an important raw material for multilayer chip ceramic capacitors. While the multilayered chip ceramic capacitor requires high purity barium titanate, and also requires its particle size and morphology.
The barium titanate synthesis method comprises a solid phase synthesis method, an oxalate coprecipitation method, an alkoxide hydrolysis method and a hydrothermal synthesis method. The method of heat treatment by mixing only equal amounts of barium carbonate and titanium dioxide is a solid phase synthesis method, which is simple to operate, but due to the characteristics of ceramic powder, the particle size of BaTiO3 powder obtained by solid phase inter-diffusion at high temperature is large, reaches the micron level, and requires further operation. And the high-temperature treatment energy consumption is higher, the powder components are uneven and are easy to agglomerate, the purity of the obtained product is insufficient, and the product is difficult to be applied to the multilayer chip ceramic capacitor. The oxalate coprecipitation method is to dissolve titanium salt and barium salt in oxalic acid and obtain BaTiO3 powder through a series of treatments, but impurities are easy to introduce in the process, the product is doped due to low calcination temperature, the Ba/Ti atomic ratio is difficult to control, and particle agglomeration is also caused. The BaTiO3 is prepared by hydrolysis and heat treatment of titanium and barium-containing alkoxide, and has high product purity, good dispersibility and small particle size, but the cost of raw materials is high, and the raw materials are easy to deliquesce and difficult to store. The hydrothermal synthesis method is to mix titanium salt and barium salt in a sealed autoclave by taking water as a solvent, and the method can obtain high-activity BaTiO3 powder at a low temperature, and has the advantages of uniform powder components, good dispersibility, small and uniform particle size, but the method needs high pressure and also needs to avoid the problems of Ti-OH condensation, ba defect and the like.
Disclosure of Invention
Based on the above, the invention provides a hydrothermal synthesis method of barium titanate, which aims to solve the problems of high price of barium titanate raw materials, low product purity, large particle size, uneven size, more impurities, low activity, easy agglomeration and the like.
The primary objects of the present invention include, but are not limited to:
1. The uniformity and compactness of the material are improved;
2. reducing the particle size of the product;
3. the purity of the product is improved;
4. So that the barium titanate has good electrical property and catalytic capability.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
A hydro-thermal synthesis method of barium titanate,
The method comprises the following steps:
1) Dropwise adding metal halide into cold acid liquor, adding alkali liquor to adjust the pH value to obtain precipitate, washing the precipitate, uniformly mixing the precipitate with an inorganic peroxide solution, refluxing, and cooling to obtain a solution 1;
2) Adding mineralizer and inorganic base into the solution 1, and performing hydrothermal treatment, washing and drying to obtain powder A;
3) Adding acid liquor into the powder A, uniformly mixing, filtering, washing and drying to obtain powder B, adding barium salt aqueous solution for hydrothermal treatment, washing and drying to obtain barium titanate.
As a preferred alternative to this,
Step 1) the metal halide is titanium tetrachloride;
the acid liquor in the step 1) is an HCl solution, the concentration of the acid liquor is 0.5-1 mol/L, the temperature of the acid liquor is 0-5 ℃, and the dosage of the acid liquor is 2-2.5 mL/mL of metal halide.
As a preferred alternative to this,
The alkali liquor in the step 1) is ammonia water, the concentration of the alkali liquor is 1-2 mol/L, and the pH value is regulated to 7-7.5.
As a preferred alternative to this,
The inorganic peroxide solution in the step 1) is hydrogen peroxide solution, and the dosage of the inorganic peroxide solution is 2-2.5 mL/g sediment;
The reflux in the step 1) is carried out at the constant temperature of between 80 and 90 ℃ of between 10 and 12h.
As a preferred alternative to this,
Step 2) the mineralizer is potassium hydroxide, and the dosage of the mineralizer is 2.8-3.5 g/mL of metal halide;
the inorganic base in the step 2) is lithium hydroxide, and the dosage of the inorganic base is 6.7-8.3 g/mL of metal halide.
As a preferred alternative to this,
The hydrothermal treatment in the step 2) is carried out at a constant temperature of 5-7 h at 240-260 ℃.
As a preferred alternative to this,
The acid liquor in the step 3) is an HCl solution, the concentration of the acid liquor is 0.5-1 mol/L, and the dosage of the acid liquor is 50-60 mL/g of powder A.
As a preferred alternative to this,
The barium salt aqueous solution in the step 3) is a saturated barium hydroxide solution, and the dosage of the saturated barium hydroxide solution is 3.5-3.8 mL/g of powder B.
As a preferred alternative to this,
The hydrothermal treatment in the step 3) is carried out at a constant temperature of between 160 and 180 ℃ and between 12 and 24 h.
In the field, barium titanate is directly prepared by TiO2 particles and barium salt aqueous solution, and because the surface of TiO2 has a plurality of polar hydroxyl groups, the direct input of the TiO2 particles can cause the surface of the particles to adsorb a plurality of polar groups, so that the particles are agglomerated. In the technical scheme of the invention, tiO2 is prepared by taking TiCl4 as a titanium source. In an acidic environment, tiCl4 is hydrolyzed stably at a low temperature, ammonia water is added to obtain a precipitate, and NH4 < + >, cl < = > are removed through washing. According to the invention, hydrogen peroxide is added into the precipitate, besides O22-, a large amount of OOH-, OH-and H2O are contained in the solution, and enough hydrogen peroxide can ensure that reactants are completely converted into peroxytitanic acid, the peroxytitanic acid and polymer molecules thereof can be decomposed in a hydrothermal environment, and the small-volume OH-attacks the complex ion center Ti4+, so that a molecular chain is broken, and the concentration of Ti4+ ions is further increased. Further, the hydrolytic ions interact when the ti4+ ions reach supersaturation to form hydrated ti4+ ion growth motifs, thereby forming TiO2. Meanwhile, tiO2 can be obtained by further adding acid liquor, and the hydrogen ions are attractive to hydroxyl groups, so that the bond energy of Ti-OH bonds is weakened, and the hydroxyl groups are easy to remove, thereby forming TiO2. However, compared with acid liquor, the effect of promoting the amorphous TiO2 to be converted into anatase crystals by hydrogen peroxide is better, and TiO2 with higher crystallinity and more complete crystal forms is obtained.
Under the action of mineralizer, tiO2 is combined with OH-to obtain the K, li-containing titanic acid compound powder A through hydrothermal treatment, ti < 4+ > starts to form perovskite octahedral crystal structure, and the obtained particles have smoother surface and are orderly. If the TiO2 and barium hydroxide aqueous solution are simply added and subjected to hydrothermal treatment, on one hand, the excessive solution quantity can cause uneven heating of reactants, and on the other hand, the concentration of titanium salt and barium salt aqueous dispersion liquid needs to be controlled, and the excessive concentration of Ba2+ ions can be reduced more quickly in the initial stage of hydrothermal treatment, so that the particle size of the prepared barium titanate is rapidly increased, and serious agglomeration phenomenon occurs, thereby influencing the product performance. According to the invention, H2TiO3 with good crystal development is prepared, further, the H+ and H3O+ ion exchange is used for replacing K+ and Li+ to further regulate and control the morphology, composition and uniformity of the material through hydrothermal treatment.
As the hydrothermal temperature increases, the crystallinity of barium titanate increases, the particle size increases, the characterization can find that the particles are single grains, clear lattice stripes are formed, and no obvious element segregation phenomenon exists, so that the barium titanate has good uniformity. If the reaction temperature is too low, barium titanate particles are not uniform in size and have an uncrystallized portion, and the particle surfaces have extremely high activity due to the small number of crystal grains and insufficient crystallization, so that an agglomeration phenomenon is caused. At lower temperatures, the unit cell lengthens to one side, taking on a tetragonal form, and structural changes may lead to a decrease in electrical properties. And the Ti-O bond is easy to break due to the too high hydrothermal treatment temperature, and atoms are rearranged into rutile phase, so that the proportion of the titanium dioxide crystal structure is difficult to control, and the intercalation of K+ ions and Li+ ions is uneven. Finally, the barium titanate particles are gradually enlarged to generate holes, so that the barium titanate particles are easy to break, the crystal structure is unstable, and the material performance is influenced.
The beneficial effects of the invention are as follows:
(1) The barium titanate prepared by the method is uniform and compact, has complete crystal form, good crystal development, and has a cubic phase crystal structure and no other impurity phase;
(2) The barium titanate prepared by the invention has small particle size and high dispersibility;
(3) The barium titanate prepared by the invention has high purity and electrical property and catalytic property.
Drawings
FIG. 1 is a SEM characterization of barium titanate product prepared in example 1 of the present invention.
Detailed Description
The invention is described in further detail below with reference to specific examples and figures of the specification. Those of ordinary skill in the art will be able to implement the invention based on these descriptions. In addition, the embodiments of the present invention referred to in the following description are typically only some, but not all, embodiments of the present invention. Therefore, all other embodiments, which can be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
The raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art unless specifically stated otherwise; the methods used in the examples of the present invention are those known to those skilled in the art unless specifically stated otherwise.
Example 1
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with hydrogen peroxide solution in a proportion of 2 mL, keeping the temperature at 80 ℃ for 12: 12 h, and cooling to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 160 ℃ for 24h, washing and drying to obtain the barium titanate.
The obtained barium titanate was subjected to SEM characterization, and the characterization result is shown in fig. 1. As can be seen from fig. 1, the barium titanate prepared by the method basically presents a relatively regular particle shape, and has a flat surface, a stable and compact structure and smaller particles. From the results, the prepared product particles are relatively uniform and stable, and the appearance is complete and clear.
The barium titanate obtained in this example was characterized and tested for performance by the following method.
1. Particle size:
the average particle size of barium titanate was characterized by TEM electron microscopy.
2. Dielectric loss:
According to 10:1 mass ratio, mixing the barium titanate and silver paste prepared by the invention, and keeping the constant temperature of 4h at 600 ℃ to obtain the barium titanate and silver paste with the size of 20 Mm×1 mm barium titanate sample capacitance and dielectric loss (tan/>) of the barium titanate sample was tested by HP4294A LCR analyzer at 30℃）。
Wherein: c is the capacitance of the barium titanate sample; a dielectric constant of a barium titanate sample; /(I) Is vacuum dielectric constant; s is the surface area of the barium titanate sample; d is the thickness of the barium titanate sample.
3. Breakdown field strength:
taking the barium titanate prepared by the invention, keeping the constant temperature of 4h at 600 ℃ to obtain the barium titanate with the size of 20 Mm×1mm barium titanate samples were subjected to the 50-point electrode method according to GB/T13542.2-2009, the thickness of each point was tested, and the breakdown voltage of each barium titanate sample was divided by the thickness to obtain the breakdown field strength.
4. Energy storage performance:
the hysteresis loop of the sample was tested with PREMIER II/Radiant tester at room temperature with a test frequency of 10 Hz.
5. Photocatalytic performance:
0.1 g barium titanate was weighed and uniformly dispersed in 80 mL methylene blue solution with a concentration of 20 ppm, magnetic stirring was started and 0.5 h was adsorbed in a dark state, and the mixture was thoroughly mixed, and 3mL supernatant was taken. The ultraviolet lamp was turned on, and the supernatant was taken every 0.5 h and absorbance test was performed on the obtained supernatant. The absorbance a of the methylene blue characteristic wavelength at 665 nm (A0) was measured by an ultraviolet-visible spectrophotometer, and the corresponding degradation rate D was calculated by the formula d= (1-a/A0) ×100%.
The results are as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 124 | <0.05 | >395 | 3.9 | 99.7 |
According to the results in the above table, the barium titanate prepared by the present invention has small particle size, excellent electrical properties and photocatalytic activity. The dielectric loss of barium titanate is low, and the barium titanate shows good frequency stability. Because the grain size is small, the hysteresis loop of the barium titanate sample is similar under 10 Hz, and the charging curve and the discharging curve can not completely coincide due to hysteresis. The energy storage density (W) is the area integral enclosed by the charging current curve and the polarization axis, while the releasable energy storage density represents the area integral enclosed by the discharging current curve and the polarization axis (W1), both of which are important criteria for evaluating the energy storage performance of the material. Compared with the releasable energy storage density (2-3J/cm < 3 >) of the barium titanate disclosed in the art, the barium titanate prepared by the invention has higher releasable energy storage density and better applicability. Meanwhile, the energy storage efficiency (W1/W) is high, otherwise, a large amount of electric energy is converted into heat energy during charge and discharge. And after twice hydro-thermal treatment, the forbidden bandwidth of barium titanate becomes small, and electron transition is promoted, so that electron-hole pairs are generated, and extremely high photocatalytic activity is shown.
In addition, through characterization, the barium titanate crystal is of a cubic phase structure, and the catalytic activity of the cubic phase structure is better than that of a tetragonal phase structure for the barium titanate crystal.
Example 2
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with hydrogen peroxide solution in a proportion of 2 mL, keeping the temperature at 80 ℃ for 12: 12 h, and cooling to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 175 ℃ for 16 h, washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 186 | <0.03 | >407 | 4.1 | 99.6 |
From the results in the above table, it can be seen that the barium titanate particle size increases with an increase in hydrothermal temperature. The barium titanate particles of the embodiment have good component uniformity and dispersibility, and the electrical property is improved because the side reaction on the surface of the material is reduced. To improve the purity of barium titanate, the hydrothermal reaction condition should be reasonably controlled.
Example 3
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with hydrogen peroxide solution in a proportion of 2 mL, keeping the temperature at 80 ℃ for 12: 12 h, and cooling to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 180 ℃ for 12 h ℃ and washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 240 | <0.06 | >386 | 3.5 | 99.3 |
According to the results in the above table, the particle size of barium titanate further increases, resulting in a somewhat deteriorated photocatalytic effect of the material. As the particle size of the barium titanate of the embodiment is increased, the surface damping effect is enhanced, the energy storage efficiency is reduced, the electric energy is converted into heat energy, and the material performance is further reduced.
Comparative example 1
A hydrothermal synthesis method of barium titanate, which is the same as in example 2, uses only commercial TiO2 instead of the precipitate prepared in step 1), comprises the following steps:
1) According to 1 g: mixing commercial TiO2 and hydrogen peroxide solution in a proportion of 2mL, keeping the temperature at 80 ℃ and cooling to obtain solution 1at a constant temperature of 12 h;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 175 ℃ for 16 h, washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 684 | <0.12 | >322 | 2.4 | 91.3 |
According to the results in the table, the TiO2 surface has a plurality of polar hydroxyl groups, and the direct input of the TiO2 particles with large particle size into hydrogen peroxide can cause the adsorption of a large number of polar groups on the particle surface, so that the agglomeration of the particles is caused. In addition, the concentration of barium salt aqueous dispersion in the example is obviously too high, and the Ba2+ ions with high concentration can be reduced more rapidly in the initial stage of hydrothermal reaction, so that the particle size of the prepared barium titanate is rapidly increased, and serious agglomeration phenomenon occurs, thereby influencing the product performance.
Comparative example 2
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with nitric acid solution with concentration of 1 mol/L at a ratio of 2 mL, keeping the temperature at 80 ℃ and cooling to 12 h to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 175 ℃ for 16 h, washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 281 | <0.08 | >346 | 3.1 | 95.2 |
According to the results in the above table, nitric acid was continuously added in this example, and since hydrogen ions are attractive to hydroxyl groups, the Ti-OH bond energy was weakened and the hydroxyl groups were easily removed, thereby forming TiO2. Although the TiO2 nanoplatelets grow preferentially along the c-axis of the anatase lattice, the TiO2 crystallinity is lower.
According to the invention, hydrogen peroxide is added into the precipitate to generate peroxytitanic acid, the peroxytitanic acid and polymer molecules thereof are decomposed in a hydrothermal environment, and a small volume of OH-attacks the ion center Ti & lt4+ & gt of the complex, so that a molecular chain is broken, and the molecular chain is further increased. The hydrolytic ions interact when the ti4+ ions reach supersaturation to form hydrated ti4+ ion growth motifs, forming TiO2. The TiO2 prepared in this way has higher crystallinity and more complete crystal form, the characterization shows that TiO2 presents lamellar, clear lattice stripes are observed, the inter-plane distance d is 0.48 nm, and the inter-plane distance d is consistent with an anatase phase (002) crystal face, so that the TiO2 nano lamellar crystal preferentially grows along the c axis of the anatase crystal lattice.
Comparative example 3
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with hydrogen peroxide solution in a proportion of 2 mL, keeping the temperature at 80 ℃ for 12: 12 h, and cooling to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 150 ℃ for 16 h ℃ and washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 117 | <0.14 | >301 | 2.2 | 99.1 |
According to the results in the above table, if the reaction temperature is too low, barium titanate particles are not uniform in size and have an uncrystallized portion, and the number of crystal grains is small and crystallization is insufficient, so that the particle surface has extremely high activity, thereby causing agglomeration phenomenon. At lower temperatures, the unit cell extends to one side, taking on the tetragonal form. With the structural change, larger dielectric anomalies are generated, which affect the electrical properties of barium titanate.
Comparative example 4
A method for hydrothermal synthesis of barium titanate, the method comprising:
1) 2 mL titanium tetrachloride was added dropwise to 4 mL of 0℃HCl solution, pH 7 was adjusted to give a precipitate by adding 2 mol/L aqueous ammonia, and the precipitate was washed according to 1 g: mixing the precipitate with hydrogen peroxide solution in a proportion of 2 mL, keeping the temperature at 80 ℃ for 12: 12 h, and cooling to obtain solution 1;
2) Adding 5.6 g potassium hydroxide and 13.4 g lithium hydroxide into the solution 1, keeping the temperature at 240 ℃ and 7 h, washing and drying to obtain powder A;
3) According to 1 g:50 Powder A and HCl solution are mixed according to the proportion of mL, and powder B is obtained through suction filtration, washing and drying according to the proportion of 1 g:3.5 mixing powder B and saturated barium hydroxide solution in the ratio of mL, keeping the temperature at 190 ℃ for 16 h ℃ and washing and drying to obtain the barium titanate.
The barium titanate obtained in this example was subjected to the same characterization and performance test as in example 1, and the results were as follows.
| Particle size (nm) | Dielectric loss | Breakdown field strength (MV/m) | Releasable energy storage Density (J/cm 3) | Photocatalytic degradation Rate (%) |
| 24 | <0.05 | >395 | 11.9 | 99.7 |
According to the results in the above table, the ti—o bond is easily broken due to the excessively high hydrothermal treatment temperature, and atoms are rearranged into the rutile phase, thereby causing the difficulty in controlling the ratio of the titanium dioxide crystal structure, and causing non-uniformity of intercalation of k+ ions and li+ ions. Finally, the holes of the barium titanate particles are gradually larger, the barium titanate particles are easy to break, the crystal structure is unstable, and the material performance is influenced.
Claims (9)
1. A hydro-thermal synthesis method of barium titanate is characterized in that,
The method comprises the following steps:
1) Dropwise adding metal halide into cold acid liquor, adding alkali liquor to adjust the pH value to obtain precipitate, washing the precipitate, uniformly mixing the precipitate with an inorganic peroxide solution, refluxing, and cooling to obtain a solution 1;
2) Adding mineralizer and inorganic base into the solution 1, and performing hydrothermal treatment, washing and drying to obtain powder A;
3) Adding acid liquor into the powder A, uniformly mixing, filtering, washing and drying to obtain powder B, adding barium salt aqueous solution for hydrothermal treatment, washing and drying to obtain barium titanate.
2. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
Step 1) the metal halide is titanium tetrachloride;
the acid liquor in the step 1) is an HCl solution, the concentration of the acid liquor is 0.5-1 mol/L, the temperature of the acid liquor is 0-5 ℃, and the dosage of the acid liquor is 2-2.5 mL/mL of metal halide.
3. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
The alkali liquor in the step 1) is ammonia water, the concentration of the alkali liquor is 1-2 mol/L, and the pH value is regulated to 7-7.5.
4. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
The inorganic peroxide solution in the step 1) is hydrogen peroxide solution, and the dosage of the inorganic peroxide solution is 2-2.5 mL/g sediment;
The reflux in the step 1) is carried out at the constant temperature of between 80 and 90 ℃ of between 10 and 12h.
5. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
Step 2) the mineralizer is potassium hydroxide, and the dosage of the mineralizer is 2.8-3.5 g/mL of metal halide;
the inorganic base in the step 2) is lithium hydroxide, and the dosage of the inorganic base is 6.7-8.3 g/mL of metal halide.
6. A hydrothermal synthesis method of barium titanate according to claim 1 or 5, wherein,
The hydrothermal treatment in the step 2) is carried out at a constant temperature of 5-7 h at 240-260 ℃.
7. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
The acid liquor in the step 3) is an HCl solution, the concentration of the acid liquor is 0.5-1 mol/L, and the dosage of the acid liquor is 50-60 mL/g of powder A.
8. The method for hydrothermal synthesis of barium titanate according to claim 1, wherein,
The barium salt aqueous solution in the step 3) is a saturated barium hydroxide solution, and the dosage of the saturated barium hydroxide solution is 3.5-3.8 mL/g of powder B.
9. A hydrothermal synthesis method of barium titanate according to claim 1, 7 or 8,
The hydrothermal treatment in the step 3) is carried out at a constant temperature of between 160 and 180 ℃ and between 12 and 24 h.
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| JPH05330824A (en) * | 1991-04-19 | 1993-12-14 | Teika Corp | Barium titanate and its production |
| KR20030092646A (en) * | 2002-05-30 | 2003-12-06 | 주식회사 나노 | METHOD OF PREPARING BaTiO3 POWDER |
| CN101850251A (en) * | 2010-06-10 | 2010-10-06 | 大连大学 | Preparation method of magnetic separation titanium dioxide visible light catalyst |
| CN105329939A (en) * | 2015-12-03 | 2016-02-17 | 安徽中创电子信息材料有限公司 | Preparation method of size-controllable nanoscale cubic-phase super-fine barium titanate powder |
| CN107555987A (en) * | 2017-09-07 | 2018-01-09 | 安徽中创电子信息材料有限公司 | A kind of submicron order barium carbonate powder Nanoparticle preparation method |
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|---|---|---|---|---|
| JPH05330824A (en) * | 1991-04-19 | 1993-12-14 | Teika Corp | Barium titanate and its production |
| KR20030092646A (en) * | 2002-05-30 | 2003-12-06 | 주식회사 나노 | METHOD OF PREPARING BaTiO3 POWDER |
| CN101850251A (en) * | 2010-06-10 | 2010-10-06 | 大连大学 | Preparation method of magnetic separation titanium dioxide visible light catalyst |
| CN105329939A (en) * | 2015-12-03 | 2016-02-17 | 安徽中创电子信息材料有限公司 | Preparation method of size-controllable nanoscale cubic-phase super-fine barium titanate powder |
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