CN1098826C

CN1098826C - Process for preparing nm-class barium titanate material

Info

Publication number: CN1098826C
Application number: CN98113027A
Authority: CN
Inventors: 郭水虎
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-11-26
Filing date: 1998-11-26
Publication date: 2003-01-15
Anticipated expiration: 2018-11-26
Also published as: CN1255465A

Abstract

The present invention provides a method for preparing barium titanate nanometer materials, which has the purpose that the problems of high material cost, low reaction speed, long production period, difficult control for generated products, and more impurities are solved. The present invention has the technical scheme that a quick-precipitation method is adopted, and the method comprises the following steps: firstly, 0.2M of the salt solution of soluble barium ions is prepared for use, and metatitanic acid having equal molar weight with barium ion salts, and strong oxidizer are mixed according to the molar ratio that the metatitanic acid to the strong oxidizer is 1: 15 to 30; then the pH value of solution is regulated to 10 to 14, the salt solution of barium ions is added to react, and the finished products are obtained by post processing after the reaction is finished. The method is suitable for industrialized mass production, the production cost can be greatly reduced, the production efficiency is improved, and the requirements of the barium titanate nanometer materials for markets are satisfied.

Description

Preparation method of barium titanate nano material

The invention relates to a preparation method of a barium titanate nano material.

The barium titanate material is an important ferroelectric, has very high dielectric constant and changes along with the change of an external electric field, and the barium titanate ceramic prepared by taking the barium titanate material as a main raw material has wide application in industry and can be used for manufacturing ferroelectric dielectric ceramics, ceramic capacitors on a surface layer or a boundary layer and the like. The particle size of the barium titanate material has a significant influence on the properties of the sintered barium titanate ceramic and the barium titanate ceramic itself, such as: when the particle size of the barium titanate material is 20 micrometers (mum) to 50 micrometers (mum), the sintering temperature is about 1350 ℃, and when the particle size is 20 nanometers (nm), the sintering temperature of the barium titanate ceramic can be reduced by about 100 ℃; the sintering density of the barium titanate ceramic prepared from the barium titanate material containing 1 percent of ultrafine powder (nano material) is greatly improved; when the particle size of the barium titanate material is 1nm, the room temperature dielectric constant of the barium titanate ceramic is increased to 6000 from 1500-2000 with the particle size of 20-50 mu m; but also has great influence on characteristics such as Curie temperature, crystal structure, wet titanium and the like. In conclusion, the sodium barium titanate nano material plays a crucial role in the properties of barium titanate ceramics. The conventional barium titanate nano material is prepared by four common preparation methods, wherein one of the common main raw materials of a sol-gel method, a sol-precipitation method and a stearate method is butyl titanate which reacts with a substance containing barium ions to prepare barium titanate, and the fourth method is a coprecipitation method which takes titanium tetrachloride and barium chloride as raw materials and then dissolves in oxalic acid solution to react to prepare barium titanate. And after the reaction is finished, calcining the generated sol or precipitate to obtain the barium titanate material. The four preparation methods have the common defects of high raw material cost, slow reaction speed, long production period, uncontrollable products and more impurities.

The invention aims to provide a preparation method of a barium titanate nano material with low cost, short production period, high product yield and less impurities by changing raw materials and an original process method.

In order to achieve the purpose of the invention, the technical scheme is as follows, which is characterized in that the production is carried out in a reaction kettle by adopting a rapid precipitation method, and the method sequentially comprises the following steps: adding deionized water into a container, adding soluble barium ion salt into the container, and stirring to prepare a solution with the concentration of 0.2M for later use; secondly, adding metatitanic acid with the same mole as barium ion salt into the reaction kettle; thirdly, slowly adding a strong oxidant into the reaction kettle while stirring, wherein the adding amount of the strong oxidant is that the molar ratio of the metatitanic acid to the strong oxidant is 1: 5-30; fourthly, adding an alkaline solution, and adjusting the pH value to be 10-14; fifthly, adding the barium salt solution for later use into the reaction kettle; and sixthly, performing post-treatment, after the precipitate is generated, filtering to obtain a precipitate barium titanate, washing with deionized water until the pH value of a washing solution is 7-9, soaking with a surfactant until the washing solution is completely wet, drying with a dryer, and calcining at 300-900 ℃ for 1 hour (h) to obtain a finished product.

In the above method, the molar ratio of the added metatitanic acid to the added strong oxidant is 1: 16-24, preferably in this range.

In the above method, the calcination temperature is preferably 380 to 650 ℃.

In the above method, Ba is added when preparing the barium salt solution²⁺The amount may be in excess, which is not more than 5% of the equimolar amount of the barium salt, to suppress Ba₂Ti₄O₄、BaTi₅O₁₁、Ba₂Ti₉O₂₀And the like.

In the above method, when preparing the barium salt solution, an equimolar or excessive amount of Ba may be added²⁺Adding soluble salt such as Pb in an amount not more than 2% by mole of the barium salt²⁺、La³⁺、Sr²⁺、Li⁺Isosoluble salts to inhibit Ba₂Ti₄O₄、BaTi₅O₁₁、Ba₂Ti₉O₂₀And the like.

In the above process, Ba²⁺The salt can be Ba (NO)₃)₂Or BaCl₂。

In the above method, the strong oxidant is selected from H₂O₂、KMnO₄、KCrO₄Etc. to select H₂O₂Preferably, the purity of the product is high.

In the above method, the alkaline solution can be NaOH or NH₄OH, etc. to select NH₄Better OH, high product purity and the like.

In the above method, the surfactant can be selected from anhydrous alcohol, alkyl sodium sulfonate, etc.

Compared with the prior art, the invention has the following advantages:

1. the cost is low.The metatitanic acid is a chemical raw material with lower price, and the price of the raw material selected by the method is reduced by 5-10 times compared with that of the raw material used in the prior art, so that the method is suitable for the requirement of industrial mass production.

2. The reaction speed is high and the production period is short. For general reactions, the reaction speed of the reactions in which organic matters participate is relatively slow, and in the prior art, organic matters participate, for example, a coprecipitation method in the prior art, a reaction period of which takes about three days. Meanwhile, in the post-treatment step, the dispersibility of the barium titanate is improved by washing with a surfactant, so that the calcined barium titanate precipitate is not easy to agglomerate and can directly generate a nano material, obviously, the production efficiency is greatly improved.

3. The yield is high. In the prior art, three methods taking butyl titanate as a main raw material are taken as examples, ester can be hydrolyzed when meeting water, and the reaction is reversible reaction, so that the ester is difficult to completely react in one direction, and is difficult to fully utilize when reacting with other substances, so that the yield is low.

4. The impurities are less. In the above preparation method, an excess of soluble Ba is added³⁺Salt, or adding sufficiently soluble Ba²⁺Adding a proper amount of Pb on the basis of the salt²⁺、La³⁺、Sr³⁺、Li⁺And soluble salts of the same kind, one or two kinds being added according to circumstances, the additive being effective in suppressing Ba₂Ti₄O₄、BaTi₅O₁₁、Ba₂Ti₃O₂₀And the like.

5. And the material performance is improved. When adding Pb²⁺、Sr²⁺When the soluble salt is of equivalent value, PbTiO will be present in the resultant product₃、SrTiO_aEtc. ofIn which PbTiO is present₃Can improve the high-temperature sintering performance of barium titanate ceramics, and the existence of Li⁺、La³⁺The barium titanate material of the precipitate of isovalent ions can realize semiconducting.

Example 1:

weighing 4.72kg of 20mol Ba (NO)₃)₂Putting into a container, adding deionized water into the container, and uniformly preparing into 0.2M Ba with a magnetic stirrer²⁺Salt solution is reserved;

secondly, adding 1.56kg of 20mol H into the reaction kettle₂TiO₂；

Thirdly, adding 30H into the reaction kettle₂O₂Solution 57L with stirring, H₂TiO₂And H₂O₂The molar ratio of the added amount is equal to 1: 25, ；

fourthly, adding NH with the concentration of 25 percent into the reaction kettle₄OH, adjusting the pH value to be about 12;

fifthly, mixing Ba²⁺Adding the salt solution into the reaction kettle, stirring uniformly, standing for 1h to allow BaTiO to react₃Completely precipitating;

sixthly, post-treatment: filtering to obtain precipitate, washing the precipitate with deionized water until the pH value of the washing solution is about 8, soaking twice with anhydrous ethanol until the precipitate is completely wet, drying in a dryer, and calcining at 600 deg.C for 55min to obtain barium titanate nano material with particle size of about 30 nm.

Examples 2 to 5: in contrast to example 1, as shown in the following table,(unit: mol)

Claims

1. The preparation method of the barium titanate nano material is characterized by comprising the following steps: the method adopts a rapid precipitation method to produce in a reaction kettle, and sequentially comprises the following steps: firstly, adding deionized water into a containerWater, soluble barium ion salt Ba (NO) is added into the water₃)₂Stirring to prepare a solution with the concentration of 0.2M for later use; secondly, adding metatitanic acid with the same mole as barium ion salt into the reaction kettle; thirdly, slowly adding a strong oxidant H into the reaction kettle at normal temperature and normal pressure₂O₂Stirring while adding metatitanic acid and a strong oxidant in a molar ratio of 1: 5-30; fourthly, adding alkaline solution NH₄OH, adjusting the pH value to be 10-14; fifthly, adding the barium salt solution for later use into the reaction kettle; and sixthly, performing post-treatment, after the precipitate is generated, filtering to obtain a precipitate barium titanate, washing with deionized water until the pH value of the solution is 7-9, soaking with a surfactant, namely absolute ethyl alcohol, until the solution is completely wet, drying by a dryer, and calcining for 1 hour at 300-900 ℃ to obtain a finished product.

2. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: the molar ratio of the added metatitanic acid to the strong oxidant is 1: 16-24.

3. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: the calcining temperature is 380-650 ℃.

4. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: ba in the barium salt solution²⁺The amount of addition is equal to or in excess of metatitanic acid, and the excess is not more than 5% of the equimolar amount of barium salt.

5. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: preparing barium salt solution, adding equimolar or excessive Ba²⁺When the salt is prepared, soluble salt with the molar weight not more than 2% of the barium salt is added. Such as Pb²⁺、La³⁺、Sr²⁺、Li⁺A soluble salt of (a).

6. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: the strong oxidant is H₂O₂、KMnO₄Or KrCO₄。

7. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: the alkaline solution is NH₄OH、NaOH。

8. The method for preparing a barium titanate nanomaterial according to claim 1, characterized in that: the surfactant is selected from anhydrous alcohol and sodium alkylsulfonate.