CN1472169A - Technology for preparing high-purity nanometer strontium titanate powder - Google Patents
Technology for preparing high-purity nanometer strontium titanate powder Download PDFInfo
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- CN1472169A CN1472169A CNA031387411A CN03138741A CN1472169A CN 1472169 A CN1472169 A CN 1472169A CN A031387411 A CNA031387411 A CN A031387411A CN 03138741 A CN03138741 A CN 03138741A CN 1472169 A CN1472169 A CN 1472169A
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Abstract
A process for preparing high-purity strontium titanate nanoparticles as dielectric material includes such steps as preparing high-purity water, preparing the gel of n-titanic acid, adding strontium source to the gel to synthesize the suspension of strontium titanate, washing, regulating the mole ratio of Sr to Ti, and drying. Its advantages are low cost, easy control and high activity of product.
Description
One. technical field: the present invention relates to a kind of preparation method of dielectric material titanate, specifically relate to a kind of preparation technology who is applied to the dielectric substance hydro-thermal strontium titanate of high voltage capacitor, grain-boundary layer capacitor, voltage dependent resistor, thermistor and other electronic devices and components etc.
Two. background technology: strontium titanate has higher dielectric constant, is the important source material of electronic ceramics powder, and its goods have advantages such as the dielectric consume is low, Heat stability is good, thereby are widely used on electronic industry.Chinese patent, 1267653, " preparation method of barium strontium titanate film material " announced on September 27th, 2000, the technological method of this patent is to use barium acetate, strontium acetate, metatitanic acid fourth fat, acetic acid and methyl ethyl diketone with certain mol proportion mixed preparing precursor solution mutually, because adopting metal alkoxide is raw material, this method cost is higher, gelation process is slower simultaneously, therefore general synthesis cycle is longer, in addition, some be not easy by hydrolytic polymerization metal difficulty be firmly bonded in the gel network and go; The preparation method of Chinese patent---nano strontium titanate, the patent No.: 1239076, announce that on December 22nd, 1999 method of this patent also is to use organism as presoma, not only cost is high but also will carry out high temperature sintering.The natural science magazine is a lot of to the report of strontium titanate preparation recently, most typical method is the laboratory method that 2002 " inorganic chemicals industry " " research of Sr titanate powder new synthetic method " is provided, this method is a raw material with titanium tetrachloride and strontium chloride, volatile salt and ammoniacal liquor are as precipitation agent, use the synthetic Sr titanate powder of chemical coprecipitation, studied the influence of processing condition to product purity and strontium titanium ratio, optimum reaction condition is: titanium tetrachloride and strontium chloride mol ratio are 1.02, volatile salt and strontium chloride mol ratio are 1.40, temperature of reaction is a room temperature, need be 900 ℃ of calcinings 4 hours; The shortcoming of this kind method is to need calcining for a long time, may make size-grade distribution inhomogeneous because of the grain growth of part strontium titanate; In addition, crystallization mechanism to strontium titanate in " crystallisation process of strontium titanate crystal grain in the hydrothermal solution (author: Zhang Shicheng etc.) " literary composition in " silicate journal " in September calendar year 2001 has carried out more detailed elaboration, but the solution of its compound method and synthetic strontium titanate feasibility in industrial production is relatively poor.
The method for preparing strontium titanate in the world has technologies such as solid phase method, coprecipitation method, sol-gel method, organic coordination compound precursor process.Solid phase method technology is that titanium oxide and Strontium carbonate powder are carried out high temperature sintering, because the strontium titanate size-grade distribution after the calcination is wayward, purity is low, thereby greatly influences the performance of product.Coprecipitation method is the method that liquid-phase chemical reaction synthesizing superfine high pure metal oxide particle adopts the earliest, and precipitator method cost is lower, but following problem is arranged: throw out is generally jelly, and washing, filtration be difficulty; Precipitation agent is easily sneaked into as impurity, and segregation may take place various compositions in the precipitation process, and the partly precipitated thing dissolves during washing; Because a large amount of metal ion is not easy to take place precipitin reaction, therefore this method applicable surface is also narrower in addition.It is raw material that sol-gel method generally adopts the organo-metallic alkoxide, obtains the solid precursor by processes such as hydrolysis, polymerization, dryings, obtains nano material through appropriate heat treatment more at last; Because adopting metal alkoxide is raw material, make this method cost higher, gelation process is slower simultaneously, therefore general synthesis cycle is longer, in addition, some be not easy by hydrolytic polymerization metal ion difficulty be firmly bonded in the gel network, thereby the ultra-fine high-purity combined oxidation species that makes this method make is limited.The organic coordination compound precursor process is the preparation method of another important ultra-fine high pure oxide, its principle is to adopt the multiple tooth title complex of removing by thermolysis easily, as citric acid is dispersion agent, obtain the composite precursor of high dispersing by title complex and the mating reaction of different metal ionic, remove organic ligand by the pyrolysated method more at last and obtain ultra-fine high-purity composite oxides, the part that this method adopts is citric acid mostly, small molecules such as ethylenediamine tetraacetic acid (EDTA), because the different coordination abilities of different metal ionic, segregation phenomena takes place in small molecules part a part of metal ion in the process that forms composite precursor easily, makes that the mixed effect of metal ion is desirable not to the utmost.Therefore, if use the strontium titanate of prepared such as present solid phase method, coprecipitation method, sol-gel method, organic coordination compound precursor process all to exist deficiency and defective.Hydrothermal technique is state-of-the-art in the world at present powder production technology, compare with other technology, the strontium titanate electronic ceramics powder of hydrothermal method prepared have crystal grain grow complete, granularity is little and be evenly distributed, stoichiometry thing and crystal grain that particle agglomeration is light, can use comparatively cheap material, be easy to get suitable can be by changing the advantages such as particle properties of technological process control product; Especially the strontium titanate electronic ceramics powder of Hydrothermal Preparation does not need high-temperature calcination to handle, and grain growth, the defective having avoided causing in the calcination process form and the impurity introducing, so the powder of gained has higher activity.
Three. summary of the invention: the objective of the invention is to avoid the shortcoming of technologies such as solid phase method, coprecipitation method, sol-gel method, organic coordination compound precursor process and other method and a kind of technology for preparing the high-purity Sr titanate powder of nano level of providing.
Industrialized producing technology route provided by the invention is: preparation pure water (deionized water), obtain solution, resulting solution, the strontium titanate of washing preparation, the element mol ratio of adjustment strontium, titanium, the strontium titanate of dry preparation, classification, packing.
Concrete scheme is:
1. obtain solution: with the desired titanic acid gel of pure water configurable chemical dosing formula of preparation, the preparation technology of titanic acid gel joins 20-30% ammoniacal liquor to prepare in the qualified titanium tetrachloride solution to go, mix, make it complete reaction and generate the titanic acid gel; Preparation to titanium tetrachloride solution: the percentage concentration of dichloro oxygen titanium, hydrochloric acid need be controlled at about 20%-30% and 10%; Join the ammoniacal liquor for preparing in the titanium tetrachloride solution for preparing with certain speed, but need prevent that the titanic acid gel for preparing from making component hydrolysis variation because of long ageing, be unfavorable for forming quality titanic acid colloids network structure preferably, the pH value that reaction generates titanic acid gel afterreaction liquid should remain on 7-8, after at last the residual chlorine ion in the titanic acid gel being washed till standard-required, must fast the titanic acid gel be placed reaction vessel.
2. resulting solution: in reactor, will join in the titanic acid gel through the strontium source of metering and go (, therefore need not add water and dilute), and form the mixture of reaction because the water of titanic acid gel can provide enough reaction mediums.The element mol ratio of Sr/Ti in the mixture can not be lower than 1.2, pH value in this reaction solution should remain on more than 13, to guarantee that presoma reacts under enough basicity, a rule aborning is that particle diameter and basicity have confidential relation, the high more particle diameter of basicity is more little, therefore, selects suitable basicity, the particle diameter of strontium titanate can be controlled between the 50-300 nanometer, the particle size range that is easy to get most is the 100-200 nanometer.In the process of synthetic strontium titanate, nucleation rate and quality in order to ensure strontium titanate crystals, must be with the temperature rise rate of 2 ℃-3 ℃ of per minutes, temperature of reaction is risen to 220 ℃-270 ℃ of best synthesis temperatures, and pressure risen to 4-8MPa, the measure that rises to best pressure can use the method that charges into nitrogen or rare gas element to pressurize, and the hold-time of thermostat temperature is 10-15 hour.Described strontium source comprises eight water strontium hydroxides, six water strontium chlorides, is preferably eight water strontium hydroxides.
3. wash the strontium titanate of preparation: will synthesize and wash after the strontium titanate suspension liquid that finishes is put into special container cooling; if the strontium hydroxide of abundant residues is arranged in the suspension liquid; prevent to touch carbon dioxide in air; in order to avoid reaction generates Strontium carbonate powder; must carry out the sfgd. of certain anti-Carbon Dioxide in Air contact solution to the washing of strontium titanate, as take measures such as container sealing, gas shield.
4. adjustment strontium, the element mol ratio of titanium: take a morsel with the strontium titanate of the qualified no trash matter of washing, use x-ray fluorescence analyzer that the element ratio is analyzed, the requirement whether the element mol ratio that purpose is to detect Sr/Ti meets stoichiometric equation (generally, the element mol ratio of Sr/Ti is between 0.998-1.002), if the element mol ratio of Sr/Ti is lower than the requirement that the desired numerical value of stoichiometric equation maybe can not reach dielectric material, need the element mol ratio is regulated, measure is various, can add and contain strontium, the compound of titanium, to add compound be standard with dielectric material character and the application performance that does not influence electronic devices and components, be preferably SrO and TiO
2Ultrafine powder, but the adjusting of this element ratio is only applicable to the little situation of element mol ratio deviation of Sr/Ti, if deviation is excessive, has only as unacceptable product and handles.
5. the dry strontium titanate for preparing: qualified strontium titanate suspension liquid is carried out drying with drying plant, the high pure and ultra-fine metatitanic acid strontium powder body material that can obtain.
Technology of the present invention is compared with other technology, and the final stoichiometry thing and the crystal grain that can use the initial material of comparatively cheap reactant, are easy to get suitable can be by changing the advantages such as particle properties of technological process control product; Prepared strontium titanate electronic ceramics powder have crystal grain grow complete, granularity is little and be evenly distributed, particle agglomeration is lighter, especially the strontium titanate electronic ceramics powder of this prepared does not need high-temperature calcination to handle, crystal grain-growth, the defective having avoided causing in the calcination process form and the impurity introducing, therefore, prepared powder has higher activity.
Four. description of drawings:
Figure 1A: strontium titanate crystals diffractogram;
Figure 1B: strontium titanate transmission electron microscope (TEM) figure.
Five. embodiment:
Preparation method embodiment of the present invention is respectively described below:
The strontium titanate sample that is used for X-ray diffraction (XRD) analyte preparation, need to be positioned on the clean unformed silicon oxide slide with preparing the exsiccant strontium titanate powder, then strontium titanate is positioned over temperature and is set in 100 ℃ the vacuum drying oven 1 hour, oven dry moisture content can make the powder of strontium titanate.This powder is positioned over temperature is set in vacuum groom's stove of 1100 ℃, heat up rapidly and 1100 ℃ of insulation coolings after 1 hour down.Adopt Holland to fly sharp Pu x ' pert-MPD powder diffractometer and automatic diffraction software the phase purity XRD analysis of this calcining back powder, under 20 ~ 60 degree, 2 θ, carry out.
Use transmission electron microscope (TEM) that sample is analyzed, can be undertaken analyzing after the sonication by will about 0.04 strontium titanate powder that restrains vacuum-drying being dispersed in 20 milliliters the acetone.
The mensuration of specific surface area can be measured by the absorption instrument BET technology of routine, and the model of absorption instrument is ASAP2010, and the specific surface area of affirmation is based on the linear regression analysis of 5 point analysiss.
Shown in Figure 1A, demonstration be strontium titanate crystals diffractogram situation.
Figure 1B electromicroscopic photograph shows different spherical polycrystalline particles and approximate single size distributes, and the particle diameter of this powder is about the 80-120 nanometer, and the range estimation particle diameter on average is approximately about 90 nanometers.
The specific surface area of embodiment 1 powder is 12.5 meters squared per gram, and corresponding particle size (supposition is desirable spherical) is 89 nanometers, so it is consistent with range estimation target by TEM.
Therefore this embodiment 1 shows in the hydro-thermal technology of the present invention, thereby titanic acid gel, the mixing of strontium source are formed a kind of hydro-thermal reaction mixture and can prepare strontium titanate under certain environment.
Claims (5)
1. technology for preparing the high-purity Sr titanate powder of nano level, it comprises: the preparation pure water, obtain solution, resulting solution, the strontium titanate of washing preparation is adjusted the element mol ratio of strontium, titanium, the strontium titanate of dry preparation, classification, packing is characterized in that:
(1) obtain solution: with the desired titanic acid gel of pure water preparation stoichiometric equation of preparation, the preparation technology of titanic acid gel is to be that the ammoniacal liquor of 20-30% joins to prepare in the qualified titanium tetrachloride solution and goes with concentration range, mix, make it to be generated as fully the titanic acid gel, to the preparation of titanium tetrachloride solution, the percentage concentration of dichloro oxygen titanium, hydrochloric acid need be controlled at about 20%-30% and 10%;
(2) resulting solution: in reactor, to join in the titanic acid gel through the strontium source of metering and go, preferred strontium source is a strontium hydroxide, the mixture of preparation reaction, the element mol ratio of Sr/Ti in the mixture can not be lower than 1.2, guarantee that the basicity pH value of reaction solution can not be lower than 13; In the process of synthetic strontium titanate, temperature rise rate with 2 ℃-3 ℃ of per minutes, rise to 220 ℃-270 ℃ of constant temperature synthesis temperatures, and when constant temperature, pressure is controlled to 4-8MPa, control the measure of best pressure and can use the method that charges into nitrogen or rare gas element to pressurize, the hold-time of thermostat temperature is 10-15 hour;
(3) strontium titanate of washing preparation: after will synthesizing the strontium titanate suspension liquid that finishes and putting into special container and be cooled to room temperature, wash, will take to prevent the sfgd. of carbonic acid gas in the ingress of air in the water washing process with pure water;
(4) the element mol ratio of adjustment strontium, titanium: taking a morsel washes the strontium titanate of qualified no trash matter with water, use the xrf analysis instrument to strontium, titanium the element mol ratio analyze, utilize related process with strontium, titanium the element mol ratio be adjusted between the 0.998-1.002.
2. the Hydrothermal Preparation technology of the high-purity Sr titanate powder of nano level according to claim 1 is characterized in that: in the process of obtain solution, the preferred concentration of ammoniacal liquor is 23%; In the process of resulting solution, optimum temperature rise speed is 2.5 ℃ of per minutes, 250 ℃ of best constant temperature temperature of reaction, and best pressure is 7Mpa during constant temperature, the optimum temps hold-time is 12 hours.
3. the Hydrothermal Preparation technology of the high-purity Sr titanate powder of nano level according to claim 1 is characterized in that: the strontium source comprises high-purity strontium salt such as eight water strontium hydroxides, six water strontium chlorides.
4. the Hydrothermal Preparation technology of the high-purity Sr titanate powder of nano level according to claim 1 is characterized in that: the element mol ratio to strontium, titanium is adjusted, and preferably uses high-purity compound that contains strontium, titanium.
5. the Hydrothermal Preparation technology of the high-purity Sr titanate powder of nano level according to claim 1 is characterized in that: the strontium titanate particle grain size is less than 300 nanometers.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100391893C (en) * | 2004-11-29 | 2008-06-04 | 中国科学院成都有机化学有限公司 | Synthesis of solvent heat method nano strontium titanate powder |
| CN100462332C (en) * | 2007-08-08 | 2009-02-18 | 西安交通大学 | Method for preparing nano strontium titanate by lactic acid adjuvant process |
| CN102139916A (en) * | 2011-04-20 | 2011-08-03 | 浙江大学 | Method for preparing strontium titanate nanoparticles |
| CN101863456B (en) * | 2009-03-05 | 2013-06-12 | 微宏动力系统（湖州）有限公司 | Method for preparing composite metal oxide |
| CN101525151B (en) * | 2009-03-20 | 2013-09-04 | 仙桃市中星电子材料有限公司 | Manufacturing technique for high-purity electronic grade strontium titanate |
| CN107216592A (en) * | 2017-07-20 | 2017-09-29 | 安徽盛华管业有限公司 | A kind of preparation method of the CPVC tubing with photocatalytic self-cleaning function |
| CN113620340A (en) * | 2021-08-27 | 2021-11-09 | 西安理工大学 | Flower-shaped SrTiO prepared by rotary evaporation method3Method for preparing nano material |
| CN114477998A (en) * | 2022-01-12 | 2022-05-13 | 陕西科技大学 | Preparation method of strontium titanate ceramic with high dielectric constant and frequency stability |
-
2003
- 2003-06-30 CN CNA031387411A patent/CN1472169A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100391893C (en) * | 2004-11-29 | 2008-06-04 | 中国科学院成都有机化学有限公司 | Synthesis of solvent heat method nano strontium titanate powder |
| CN100462332C (en) * | 2007-08-08 | 2009-02-18 | 西安交通大学 | Method for preparing nano strontium titanate by lactic acid adjuvant process |
| CN101863456B (en) * | 2009-03-05 | 2013-06-12 | 微宏动力系统（湖州）有限公司 | Method for preparing composite metal oxide |
| CN101525151B (en) * | 2009-03-20 | 2013-09-04 | 仙桃市中星电子材料有限公司 | Manufacturing technique for high-purity electronic grade strontium titanate |
| CN102139916A (en) * | 2011-04-20 | 2011-08-03 | 浙江大学 | Method for preparing strontium titanate nanoparticles |
| CN107216592A (en) * | 2017-07-20 | 2017-09-29 | 安徽盛华管业有限公司 | A kind of preparation method of the CPVC tubing with photocatalytic self-cleaning function |
| CN113620340A (en) * | 2021-08-27 | 2021-11-09 | 西安理工大学 | Flower-shaped SrTiO prepared by rotary evaporation method3Method for preparing nano material |
| CN114477998A (en) * | 2022-01-12 | 2022-05-13 | 陕西科技大学 | Preparation method of strontium titanate ceramic with high dielectric constant and frequency stability |
| CN114477998B (en) * | 2022-01-12 | 2023-02-21 | 陕西科技大学 | Preparation method of strontium titanate ceramic with high dielectric constant and frequency stability |
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