CN1172874C - Process for preparing tetragonal nanoparticles of barium titanate - Google Patents

Abstract

The present invention discloses a method for preparing barium titanate nanometer powder, which belongs to the field of the preparation of electronic raw materials. In the method, titanyl nitrate solution is prepared firstly, and the titanyl nitrate solution is uniformly mixed with the water solution of barium nitrate, citric acid and ammonium nitrate according to a certain proportion; the mixed solution is heated and evaporated into colloidal substances which are ignited to generate white loosened tetragonal-phase barium titanate powder, and the powder diameter is in a nanometer level. The method of the present invention has easy control of technological parameters, adjustable grain size of the product by controlling technological parameters, and high product purity; the spectrogram of the barium titanate nanometer powder does not contain spectral peaks of tetragonal-phase barium titanate and barium carbonate by X-ray frequency spectrum analysis. The method has the advantages of simple preparing technology, convenient operation and low device investment, and is suitable for industrial mass production.

Description

The method for preparing tetragonal nanoparticles of barium titanate

Technical field

The invention belongs to electronics raw material preparing field, particularly with a kind of method for preparing tetragonal nanoparticles of barium titanate of low-temperature combustion method preparing product.

Technical background

Barium titanate has three kinds of crystal formations to exist as a kind of electron ceramic material of important perovskite structure: cube phase, four directions mutually and six sides mutually.Wherein the four directions becomes most widely used a kind of crystal formation owing to having piezoelectricity, ferroelectricity and pyroelectricity mutually.Traditional solid sintering technology, because its product purity is low, particle diameter is big, and the component homogeneity is poor, and the needs that can not satisfy electronic ceramics production are eliminated; Preparation method commonly used obtains tetra phase barium titanate powder with synthetic barium titanium oxalate powder at first through 900 ℃ of thermolysiss.Owing to through high-temperature heat treatment, cause growing up of diameter of particle inevitably, the median size of the barium titanate powder that this method obtains is submicron or micron order, can not obtain nanometer grade powder; Low temperature wet is learned synthetic method, as hydrothermal method, sol-gel method and citric acid method etc., though can obtain nano level metatitanic acid barium, but mostly be a cube phase, even contain the dephasign of a small amount of barium carbonate, need further high-temperature heat treatment just can obtain cubic phase, and because raw material is expensive and to the reaction unit high requirement, cause cost too high, be unfavorable for producing in enormous quantities.

Summary of the invention

The purpose of this invention is to provide a kind of method for preparing tetragonal nanoparticles of barium titanate, it is characterized in that: the preparation process of this method is as follows:

1). titanyl nitrate TiO (NO ₃) ₂Preparation: with TiCl ₄Be Ti source, TiCl ₄Dropwise add in 0～5 ℃ of cold water TiCl ₄With the volume ratio of water be 1: 5, add and TiCl ₄The ammoniacal liquor of 1: 100 1.5 mol of volume ratio obtains white moisture TiO ₂Throw out TiO ₂NH ₂O; Add and TiCl ₄1: 1.22 concentrated nitric acid of volume ratio is stirred well to white depositions and all is dissolved as clear solution under the low temperature, or is placed on sub-zero zero and refrigerates, and to obtaining clear solution, is titanyl nitrate TiO (NO ₃) ₂Solution;

2). barium nitrate aqueous solution, aqueous citric acid solution, aqueous ammonium nitrate solution and self-control titanyl nitrate solution 1: 1 in molar ratio: (2～5): mix (6～30);

3). pH of mixed value: add in ammoniacal liquor adjust pH to 6～7 scopes;

4). heating evaporation: the mixed solution of front remained in 90～100 ℃ of temperature ranges evaporate,, obtain the thick material of brown until the moisture content evaporate to dryness;

5). ignition: about 300 ℃ of ignition temperature, in 10 minutes, just can react and finish, the barium carbonate powder that generate white, loosens;

6). pulverize: the powder of generation can be pulverized without grinding, and directly sieves, and its particle diameter is at nano level.

The beneficial effect that the present invention reaches: 1. preparation technology is simple, and processing parameter is easy to control.2. use the nano barium phthalate of present method preparation need not carry out the high-temperature heat treatment conversion of crystal formation, directly burning generates the powder of cubic phase, has overcome the deficiency that needs in the prior art through high-temperature processing method.3. the control preparation process condition can obtain the barium titanate that minimum grain size is about 50 nanometer scale, the decolorizing carbon of noresidue and carbonate.4. purity height does not contain the diffraction peak of cubic phase barium titanate and barium carbonate in the X-ray diffraction spectrogram.

Description of drawings

Fig. 1 is the process flow sheet of preparation tetragonal nanoparticles of barium titanate.

Fig. 2 is the X-ray diffraction analysis spectrogram of product.

Embodiment

The present invention is a kind of method for preparing tetragonal nanoparticles of barium titanate that adopts low-temperature burning technology.The preparation process of this method is as follows:

1). titanyl nitrate TiO (NO ₃) ₂Preparation: with TiCl ₄Be Ti source, TiCl ₄Dropwise add (0～5 ℃) in the cold water TiCl ₄With the volume ratio of water be 1: 5, add and TiCl ₄The ammoniacal liquor of 1: 100 1.5 mol of volume ratio obtains white moisture TiO ₂Throw out TiO ₂NH ₂O; Add and TiCl ₄Be 1: 1.22 concentrated nitric acid of volume ratio, at low temperatures, be stirred well to white depositions and all be dissolved as transparent solution, or be placed on sub-zero zero refrigeration,, be titanyl nitrate TiO (NO to obtaining clear solution ₃) ₂Solution;

2). barium nitrate aqueous solution, aqueous citric acid solution, aqueous ammonium nitrate solution and self-control titanyl nitrate solution are 1: 1 in molar ratio: (2～5): mix (6～30);

3). the pH of mixed value: add in ammoniacal liquor adjust pH to 6～7 scopes, can guarantee the clarification that all keeps solution in the whole process of heating evaporation mixing solutions, thus guarantee component evenly;

4). heating evaporation temperature: remain on 90～100 ℃ until the moisture content evaporate to dryness, obtain brown thickness gelatinoid, in this temperature range, both kept the stable of effects of ion state, accelerated velocity of evaporation again;

5). ignition: ignition temperature just can be reacted in 10 minutes and finishes for about 300 ℃, generated the loose barium carbonate powder of white.

6). pulverize: the powder of generation can be pulverized without grinding, and directly sieves, and through X-ray diffraction analysis, is tetragonal-phase barium titanate, does not contain cubic phase barium titanate, and its particle diameter is at nano level.

For example the inventive method is illustrated again below:

Embodiment 1: the 10ml titanium tetrachloride dropwise adds in the 50ml frozen water, forms titanium tetrachloride aqueous solution, adds the ammoniacal liquor of 1 liter of 1.5 mol again, forms white moisture TiO ₂Precipitation is under the ice bath environment, with the dissolving of 12.2ml concentrated nitric acid.If temporarily can not dissolve, its low temperature in refrigerator-freezer can be placed, can realize dissolving.What obtain like this is transparent titanyl nitrate solution.Nitrate of baryta, titanyl nitrate, citric acid and ammonium nitrate were with 1: 1: 3: 17 mixed in molar ratio, its mixed aqueous solution is regulated pH value to 6～7 with ammoniacal liquor, then at 95 ℃ of heating evaporations, until the moisture content evaporate to dryness, be the thick material of brown, and be attended by bubble and emerge, ignition temperature is lighted for about 300 ℃, rapidly burning, the several minutes internal reaction finishes, generate fluffy white titanium barium powder, need not grind, directly sieve.As (S in Fig. 2 X-ray diffractogram ₂) shown in, X-ray diffraction analysis is the result show, powder is a tetragonal-phase barium titanate, does not contain the diffraction peak of cubic phase barium titanate and barium carbonate.Reunion is to a certain degree arranged, about grain size 50nm.

Embodiment 2: nitrate of baryta, titanyl nitrate, citric acid and ammonium nitrate were with 1: 1: 2: 8 mixed in molar ratio, other is with embodiment 1.As (S in Fig. 2 X-ray diffractogram ₁) shown in, X-ray diffraction analysis is the result show, powder is a tetragonal-phase barium titanate, does not contain the diffraction peak of cubic phase barium titanate and barium carbonate.About grain size 50～80nm.

Embodiment 3: nitrate of baryta, titanyl nitrate, citric acid and ammonium nitrate were with 1: 1: 4: 26 mixed in molar ratio, other is with embodiment 1.As (S in Fig. 2 X-ray diffractogram ₃) shown in, X-ray diffraction analysis is the result show, powder is a tetragonal-phase barium titanate, does not contain the diffraction peak of cubic phase barium titanate and barium carbonate.About grain size 100～150nm.

Fig. 2 is that diffraction such as (001) that occurs among the figure, (100), (200), (102), (112), (211) are bimodal, are the characteristic diffraction peaks of tetragonal-phase barium titanate with the X-ray diffractogram of the barium titanate nano crystalline substance of method preparation provided by the invention.

Claims (1)

1. method for preparing tetragonal nanoparticles of barium titanate, it is characterized in that: the preparation process of this method is as follows:

1). titanyl nitrate TiO (NO ₃) ₂Preparation: with TiCl ₄Be Ti source, TiCl ₄Dropwise add in 0～5 ℃ of cold water TiCl ₄With the volume ratio of water be 1: 5, add and TiCl ₄The ammoniacal liquor of 1: 100 1.5 mol of volume ratio obtains white moisture TiO ₂Throw out TiO ₂NH ₂O; Add and TiCl ₄1: 1.22 concentrated nitric acid of volume ratio is stirred well to white depositions and all is dissolved as clear solution under the low temperature, or is placed on sub-zero zero and refrigerates, and to obtaining clear solution, is titanyl nitrate TiO (NO ₃) ₂Solution;

2). barium nitrate aqueous solution, aqueous citric acid solution, aqueous ammonium nitrate solution and self-control titanyl nitrate solution 1: 1 in molar ratio: (2～5): mix (6～30);

3). pH of mixed value: add in ammoniacal liquor adjust pH to 6～7 scopes;

4). heating evaporation: the mixed solution of front remained in 90～100 ℃ of temperature ranges evaporate,, obtain the thick material of brown until the moisture content evaporate to dryness;

5). ignition: about 300 ℃ of ignition temperature, finish the barium carbonate powder that generate white, loosens at 10 minutes internal reactions;

6). pulverize: the powder of generation can be pulverized without grinding, and directly sieves, and its particle diameter is 50～150nm.