KR20080078101A - Synthesis of colloidal solution of ultrafine metal oxide for a thin film using a solvothermal method - Google Patents
Synthesis of colloidal solution of ultrafine metal oxide for a thin film using a solvothermal method Download PDFInfo
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- KR20080078101A KR20080078101A KR1020070017669A KR20070017669A KR20080078101A KR 20080078101 A KR20080078101 A KR 20080078101A KR 1020070017669 A KR1020070017669 A KR 1020070017669A KR 20070017669 A KR20070017669 A KR 20070017669A KR 20080078101 A KR20080078101 A KR 20080078101A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J13/00—Colloid chemistry, e.g. the production of colloidal materials or their solutions, not otherwise provided for; Making microcapsules or microballoons
- B01J13/0004—Preparation of sols
- B01J13/0008—Sols of inorganic materials in water
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- C—CHEMISTRY; METALLURGY
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- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G23/00—Compounds of titanium
Abstract
Description
1 shows a high temperature high pressure reactor for production used in the present invention.
2 shows a method for preparing ultrafine metal oxide, that is, a Solvothermal method.
Figure 3 shows the expected mechanism for the Solvothermal method of the present invention.
Figure 4 shows a photograph of the surface of the thin film prepared by heat treatment at 1000 degrees or more observed with an electron microscope.
In the preparation of ultra-fine metal oxides, metal oxide precursors are added to the organic alcohol solvent and distilled water mixture containing hydroxyl groups by composition, and a small amount of inorganic silicon-based additives are added and dispersed in an ultrasonic sonicator, followed by mixing sol. A method of preparing a colloidal solution containing ultrafine metal oxide particles of nanoparticles by subjecting the solution to heat treatment in a high temperature and high pressure reactor under mild conditions (nitrogen atmosphere, 200 ° C, 10-30 atmospheres), so-called Solvothermal method. To provide.
The conventional solution for thin metal oxide thin film was mainly prepared by two methods. First, the crystalline metal oxide powder, which was already prepared by sol-gel method or hydrothermal synthesis method, was dispersed in a suitable solvent, and then an organic or inorganic binder was appropriately added. After coating on the substrate was prepared by treating at a temperature of more than 250 degrees to remove the binder. However, these thin films have very low transparency, the thickness of the thin films are not constant, and the performance of the thin films is degraded due to damage of crystals by the remaining binder. Second, the sol-gel method dissolves the metal oxide precursors in an organic solvent or an aqueous solution and coats the mixed sol solution with a silica substrate (glass, pyrex, quartz, etc.) that can withstand temperatures of more than 400 degrees and then is higher than 400 degrees. It was prepared by crystallization by firing or sintering at temperature. However, such a thin film also has a limit of substrate selection in the step of firing at a high temperature, the metal oxide particle size of the prepared thin film was not able to exhibit the desired functionality.
The present invention is a technology for processing ultra-fine particles, that is, nano (nano, 1 billionth of a meter (one hundredth of hair thickness) ultra-fine material, which can overcome the limitation of miniaturization encountered in the existing micro-domain Nanoparticles vary in physical properties, ranging from particle size to particle size, such as an increased surface-to-mass ratio of the particles, resulting in a very large surface area per unit mass, improved particle performance, and reduced melting point. Therefore, due to the unique optical, magnetic, electrical, and catalytic properties that are different from bulk particles, catalysts, sensors, information recording media, abrasives, antibacterial / disinfectants, photoresists for photo films, paints, inks, textile dyes, cosmetics, ceramics, electromagnetic waves It is used in various industries such as shielding film, TV / computer monitor coating for electromagnetic wave shielding, and display field. Particle performance affects particle size and its distribution. Receive.
As a method of synthesizing nanoparticles, techniques for preparing nanoparticles in the gas phase, such as aerosol method and evaporation / condensation method, and coprecipitation method for preparing metal nanoparticles by mixing a solution containing a reducing agent in a metal ion solution are known. However, in the case of the gas phase method (CVD, PVD, Plasma method, etc.), mass production is impossible, and the particle manufacturing cost is too high, and it is not yet industrially available. In addition, the co-precipitation method (Sol-gel, hydrothermal synthesis method, etc.) has a disadvantage in that the manufacturing process is simple and economical, but it is difficult to control the size of the obtained particles. As an alternative to these two methods, ultrasonic method, microemulsion method, high energy ball milling method, etc. are additionally introduced, and the known method for preparing microparticles is mechanical grinding method, coprecipitation method, spray method, sol-gel method and electric method. There are various kinds of decomposition methods, such as the use of reversed phase microemulsion, but such a manufacturing method has a disadvantage in that it is difficult to control the size of the formed particles or a lot of expense is required in preparing fine metal particles.
Nanotechnology is a technology that deals with small size ranges from 1 to 100 nanometers.Atoms or molecules are generally one tenth the size of one nanometer, so nanotechnology is actually a unit of atoms or molecules, the smallest unit of matter. It can be said to be a technology that combines them using (building block). Until now, the mainstream of functional material development has been to express various functions by exploring and synthesizing new compounds, but problems have arisen in terms of cost and time required to avoid environmental effects. In addition, it has been found that by miniaturizing the material (nanoparticles) to the nano-sized level, it is possible to express new functions not obtained in the bulk phenomenon. In development, problems related to the development of technology resulting from the stable production of nanoparticles with sufficient control over size distribution, chemical composition, material purity, material type, crystal structure, and the like, integration, arrangement, and It is pointed out that the development of a ONE system process that continuously performs thin film formation by tracking is extremely important in practical use. For this reason, as one of the most basic components for forming nanostructures, the development and establishment of functional thin-film technology by synthesizing and arranging single nanoparticles (particles with diameters ranging from 1 nm to 10 nm) is further required. In addition, the nano-coating technology introduced as such an original system is not limited to structural materials such as heat, environment, and abrasion, but is used as a foundation technology for function creation, material preservation, and low cost, reaching new industrial fields such as bio and information. There is also a need for further development of advanced coating techniques that are comparable to alternative energy and environmental savings. Until now, trial and error technology development has reached its limit in terms of material type and application field, and coating technology development by integrating and creating knowledge of their individually integrated coatings is in a new stage of need. .
The present invention is a one-system manufacturing method that enables nanostructure formation of various metal oxides at the same time in the preparation of a colloidal solution for thin films, and at the same time can be coated by itself, in the production of ultra-fine metal oxide, organic containing hydroxyl groups The metal oxide precursor was added to the alcohol solvent and the distilled water mixture by composition, and a small amount of inorganic silicon-based additive was added to disperse the mixture with an ultrasonic wave, and then the mixed sol solution was kept in a high temperature and high pressure reactor under mild conditions (under nitrogen atmosphere, 200 ° C). , 10-30 atmospheres)) to heat-treat to prepare a colloidal solution containing ultra-fine metal oxides of nanoparticles, and to establish a foundation technology for high-performance high-speed synthesis processing using the so-called Solvothermal method. Removed.
Hereinafter, the present invention will be described in detail.
In the preparation of ultra-fine metal oxides, metal oxide precursors are added to the organic alcohol solvent and distilled water mixture containing hydroxyl groups by composition, and a small amount of inorganic silicon-based additives are added and dispersed in an ultrasonic sonicator, followed by mixing sol. A method of preparing a colloidal solution containing ultrafine metal oxide particles of nanoparticles by subjecting the solution to heat treatment in a high temperature and high pressure reactor under mild conditions (nitrogen atmosphere, 200 ° C, 10-30 atmospheres), so-called Solvothermal method. To provide.
Nanoparticles have a wide range of application, but in the present invention, titania fine particles, which are applied in the field of semiconductors and catalysts, which are in the spotlight of the most attention, are manufactured using the preparation method of the present invention and analyzed for their physical properties. The purpose of the present invention is to formulate the Solvothermal method for preparing the functional metal oxide.
Figure 1 shows the high temperature high pressure reactor used for the present invention. The preparation was carried out under a nitrogen stream and its vapor pressure was determined by the chosen organic solvent and the preparation temperature. At this time, the pressure should be carefully controlled so as not to count.
Figure 2 shows the Solvothermal method of the manufacturing method of the present invention. The organic solvents used were alcohols having a low viscosity and a boiling point of less than 100 having hydroxyl groups of 4 carbons or less, because of eliminating limitations in the use of coating substrates after crystallization. That is, for the manufacture of a thin film possible only by the step of drying after coating. The added metal oxide precursor preferably contains mainly alkoxide groups, but precursors having other ligands are also possible. In particular, the amount of water added was compared by selectively adding 1-4 mol with respect to 1 mol of the metal oxide precursor, and especially an acid was added to prevent rapid reaction with the precursor, which resulted in an improvement in the metal oxide crystallization rate. In addition, the silicon-based inorganic material is added to supplement the coating property of the solution after crystallization, and the amount is fixed to about 1-5% of the total solution. These final sol solutions are intermolecular condensation between metal oxide precursors substituted by heat treatment after substitution of one or two alkoxide group end groups in the ligand of the metal oxide precursor by hydroxyl groups in water in a high temperature and high pressure reactor. The reaction forms to form small oligomeric molecules (FIG. 3: expected mechanism). After coating them on the substrate and applying a temperature of 150 ° C. or lower, the unsubstituted terminal alkoxide groups in the oligomer molecules are removed due to intramolecular condensation to form metal oxides. At this time, the crystallization is already improved through the condensation reaction, so that it is possible to induce complete and stable crystallization only by drying temperature alone. Figure 4 shows a photograph of the surface of the thin film prepared by heat treatment at 1000 degrees or more observed with an electron microscope.
Table 1 compares the physical properties of the sol-gel method and the titania fine particles thin film prepared by the production method of the present invention.
Table 1
* Solvent: isopropanol, * Amount of solvent: 100 ml per 10 ml of precursor, * Metal oxide precursor: TTIP, * Reaction time: 1 h (invention), * Amount of water: 2 mol per mol of precursor
Example
Hereinafter, an Example is given and this invention is demonstrated concretely.
Example 1 Comparison of Metal Oxide Thin Films with Various Organic Solvents
Alcohol-based organic solvents having 4 or more carbons have high viscosity, low volatility, and high boiling point, so that the coating state is not uniform, it is difficult to control the thickness of the thin film, and cannot be removed by heat treatment drying after coating. Therefore, the low molecular weight, low viscosity and low boiling point below 150 ℃, Methanol (CH 3 OH), Ethanol (C 2
Table 2 compares the states of metal oxide thin films according to various organic solvent selections.
TABLE 2
* Amount of solvent: 100 ml per 10 ml of precursor, * Metal oxide precursor: TTIP, * Reaction time: 1 h, * Amount of water: 2 mol per mol of precursor
* 1 content of metal oxide powder in colloidal solution after crystallization,
* 2 When 3 coatings are carried out,
* 3 Coating surface observed by electron microscope after 3 coatings
* 4 Thickness equivalent to one coating
* 5 crystal structure observed by X-ray diffraction after three coatings,
* 6 Particle size observed by electron microscope on the surface of the substrate after coating,
* 7 Hydrophilicity to water after 2 hours of exposure to ultraviolet light (254 nm) after 3 coatings
; The numbers above indicate that the smaller the size, the better (from 0 to 10).
; The substrate used is a pyrex substrate.
It can be seen that the state and physical properties of the colloidal solution prepared according to the type of organic solvent, in particular, the amount of powdered metal oxide formed by mixing in the colloidal solution when methanol and ethanol having a low boiling point and high volatility are used. This increased and also the thickness of the coating film is not proportional, it varies irregularly by the number of coatings and the stability of the formed thin film surface can be seen that slightly deteriorated. On the other hand, when isopropanol is used, the colloidal solution prepared has almost no powder, the coating thickness is about 200 nm, and when the number of coatings is increased up to 10 times, the increase rate of the thickness is regular, and the flaw is smooth and stable on the surface of the thin film. A thin film was obtained. However, when using a high viscosity butanol, the formed thin film is too thick and tends to be difficult to completely remove butanol during the drying process.
Example 2 Effect of Ratio of Distilled Water and Precursor of Metal Oxide
The amount of water added was compared by selectively adding 1-4 mol to 1 mol of the metal oxide precursor, and was added with an appropriate amount of acid to prevent rapid reaction with the precursor. Table 3 compares the physical properties of the prepared thin film according to the change of ratio of distilled water and metal oxide precursor.
TABLE 3
* * Solvent: isopropanol, * Amount of solvent: 100ml per 10ml of precursor, * Metal oxide precursor: TTIP, * Reaction time: 1 h
The amount of water is very small as shown in Table 3, but the effect on the state of the colloidal solution prepared is very large. As the amount of added water increases, the amount of metal oxide powder present in the prepared colloidal solution increases or becomes extremely high, so that a solid solid oxide is obtained and sinks without floating in the colloidal state. Conversely, if the amount of water is too small, the resulting colloidal solution is very sensitive to air or water, making it difficult to store and can form unstable thin films. The most suitable amount of water can be substituted for the two end groups of the metal oxide precursor to the hydroxyl group, and the most stable colloidal solution can be obtained when the amount corresponding to 2 moles per mole of the metal oxide precursor.
Example 3 Effect of Ratio of Metal Oxide Precursor and Organic Solvent
In order to control the thickness of the thin film, the selection of the organic solvent is also important, but the amount of the solvent is also very important. In order for the metal oxide particles to be made fine, the farther the distance between the particles is, the better. This requires a large amount of organic solvent. However, if the amount of solvent is too great and the particles are too far apart, the particles present on the thin film may be so small that their performance may be degraded due to quantitative effects.
Table 4 shows the physical properties according to the ratio between the metal oxide precursor and the organic solvent.
Table 4
* Solvent Used: Isopropanol, * Metal Oxide Precursor: TTIP, * Reaction Time: 1 h, * Water Amount: 2 Moles per Mole of Precursor
Usually, the amount of solvent may be compared in molar ratio, but it is useful to compare in weight ratio. When 50, 100, 150, or 200 ml of organic solvent is used per 10 ml of the metal oxide precursor, a stable and transparent colloidal solution for the metal oxide thin film is obtained. In case of organic solvent in the amount of 50 ml or less, the concentration of the metal oxide contained is too high, and it is troublesome to re-dilute when coating. The steps need to be performed several times and the activity due to quantitative effects tends to be low. The most suitable amount of organic solvent is ideal when the metal oxide precursor is used in a 5% weight ratio of the total solution.
Example 4 Effect of types of metal oxide precursors
The kind of precursor of the metal oxide has a great influence on the crystallinity. The particle size varies depending on the rate and degree of solubility dissolved in these organic solvents. The higher the solubility, the more uniform and finely obtained the particle size.
Table 5 compares the physical properties of the thin film according to the type of metal oxide precursor.
Table 5
* Solvent: Isopropanol, * Amount of solvent: 100ml per 10ml of precursor * Reaction temperature: 200 ° C, Reaction time: 1h * Amount of water: 2mol per mol of precursor
Metals with ligands of nitro or sulfuric acid groups dissolve in organic solvents relatively slower than alkoxide groups, resulting in inconsistent colloidal phases. It may cause defects in the metal oxide crystals in the middle, and also its applicability due to the high removal temperature. The metal precursor having a hydroxyl group is hardly dissolved in the organic solvent and exists in an amorphous solid phase. In addition, the precursor having a chloride ligand is very sensitive to air or water, and thus has a high possibility of rapid occurrence of amorphous, dangerous to handle, high hydrochloric acid during the manufacturing reaction has a disadvantage of corroding the reactor. However, in the case of a precursor having an alkoxide group, the affinity of the organic solvent is excellent and stable, and there is an advantage that can be easily removed through the drying process without generating a dangerous gas to corrode the reactor during the reaction.
Example 5 Effect of Reaction Temperature
The crystallization rate varies depending on the reaction temperature. Usually, the higher the reaction temperature, the faster the crystallization rate, and the lower, the lower the crystallinity and the longer the rate. However, if the temperature is too high, there is a high possibility that the crystal phase is converted into an unwanted phase. Therefore, the desired crystal phase can be obtained by adjusting the appropriate reaction temperature.
Table 6 compares the properties of the thin film according to the change in reaction rate.
Table 6
* Solvent: Isopropanol, * Amount of solvent: 100ml per 10ml of precursor, * Metal oxide precursor: TTIP, * Reaction time: 1h, * Water: 2mol per mole of precursor
When the metal oxide colloidal solution is prepared by a low heat treatment of less than 100 degrees, the crystals are still insufficient to grow, and the state of the thin film is uneven, and cracks are likely to occur on the surface of the thin film after high heat treatment. In addition, the use of an organic solvent having a low boiling point is not appropriate at a high temperature of 250 degrees or more, there is a possibility that the powder is mixed in the resulting solution phase, the reaction pressure is too high can be a problem of cost increase in the commercialization. When using an alcoholic organic solvent of about 3 carbon atoms, a temperature of about 150-200 degrees is appropriate.
Example 6 Effect of reaction time
Along with the reaction temperature, the reaction time also greatly affects the crystallinity and yield of the crystals obtained. Usually, the longer the reaction time, the higher the crystallinity and the higher the yield (solid phase) produced. However, in the present invention, unlike the method of obtaining a metal oxide in a solid phase, the method requires a long time for crystallization because it is obtained in a solution phase. On the contrary, in too long time, the decomposition of the organic solvent may be so great that the solid phase may be obtained by mixing with the colloidal phase. Therefore, an appropriate reaction time is required.
Table 7 compares the properties of the thin films obtained according to the reaction time.
TABLE 7
* Solvent: Isopropanol, * Amount of solvent: 100ml per 10ml of precursor, Metal oxide precursor: TTIP, * Reaction temperature: 200 °, * Water: 2mol per mol of precursor
The colloidal solution for thin films was able to obtain a stable and uniform thin film in about 1 hour. When the reaction is terminated within a short time of about 30 minutes, the crystallization process is not finished yet, it is unstable when exposed to air. For a long time of about 4 hours, good results are obtained at a low reaction temperature (about 150 degrees), but 200 degrees. At the reaction temperature, the organic solvent was decomposed and the volatilization loss was increased, resulting in the mixing of many solid oxides. The most appropriate reaction time at the reaction temperature of 200 ° C was about 1-2 hours.
Compared to the titania thin film manufactured by the conventional Sol-gel method, the titania thin film prepared by the present invention already contains crystallized fine particles in the form of anatase in the solution, and thus does not require firing or sintering, and has excellent transparency. In addition, the coating strength is very high, and the particle size has a distribution of 20-50 nm, and excellent functionality is expected.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102631873A (en) * | 2012-04-10 | 2012-08-15 | 同济大学 | Low-cost preparation method of micro/nano structural copper chloride hydroxide aerogel materials |
| CN103041754A (en) * | 2013-01-30 | 2013-04-17 | 同济大学 | Polymer micelle modified by nano copper oxide and preparation method of polymer micelle |
| CN103933902A (en) * | 2014-05-12 | 2014-07-23 | 武汉大学 | Binary ordered colloidal crystal, metal nano array and preparation method thereof |
| CN114560485A (en) * | 2022-03-19 | 2022-05-31 | 长沙宁曦新材料有限公司 | Preparation method of superfine alumina |
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2007
- 2007-02-22 KR KR1020070017669A patent/KR20080078101A/en not_active Application Discontinuation
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102631873A (en) * | 2012-04-10 | 2012-08-15 | 同济大学 | Low-cost preparation method of micro/nano structural copper chloride hydroxide aerogel materials |
| CN103041754A (en) * | 2013-01-30 | 2013-04-17 | 同济大学 | Polymer micelle modified by nano copper oxide and preparation method of polymer micelle |
| CN103041754B (en) * | 2013-01-30 | 2015-06-03 | 同济大学 | Polymer micelle modified by nano copper oxide and preparation method of polymer micelle |
| CN103933902A (en) * | 2014-05-12 | 2014-07-23 | 武汉大学 | Binary ordered colloidal crystal, metal nano array and preparation method thereof |
| CN103933902B (en) * | 2014-05-12 | 2016-03-02 | 武汉大学 | A kind of binary ordered colloidal crystal, metal nano array and preparation method thereof |
| CN114560485A (en) * | 2022-03-19 | 2022-05-31 | 长沙宁曦新材料有限公司 | Preparation method of superfine alumina |
| CN114560485B (en) * | 2022-03-19 | 2024-03-22 | 长沙宁曦新材料有限公司 | Preparation method of superfine alumina |
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