JPS61186219A - Production of lead-containing fine powder - Google Patents

Abstract

PURPOSE:To produce lead-containing fine powder having high purity and uniform composition and particle size, by reacting an acidic solution or suspension containing various kinds of metals with a precipitant, calcining the resultant precipitate, mixing with a lead compound powder, and calcining the mixture. CONSTITUTION:An acidic solution and/or suspension containing various kinds of metals constituting the objective lead-containing oxide is added with <=60vol% precipitation assistant such as methanol, acetone, etc., and then with a precipitant such as ammonium carbonate, methylamine, etc. The pH of the mixture is adjusted to 5.5-10.5 to effect the reaction of the components, and the resultant precipitate is washed with ethanol, acetone, etc. to remove impurities, and calcined at 450-1,200 deg.C to obtain powder. The powder is mixed with a lead compound powder such as PbO, Pb3O4, etc., and calcined at 600-1,000 deg.C.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing easily sinterable lead-containing fine powder.

In general, many lead-containing oxides are useful as ferroelectric materials, piezoelectric materials, pyroelectric materials (A materials, etc.), and are useful as ref.1-roceramics.

As electroceramic components become smaller and more sophisticated, there is an increasing demand for highly reactive fine powder raw materials with high purity and narrow particle size distribution. For example, when forming a thin film using the doctor blade method, it is necessary to improve the surface roughness, etc.
This is also because excellent fine powder is required to improve the quality of the film.

(Prior art) Conventionally, a method for producing lead-containing oxide powder involves weighing and mixing compound powders such as oxides and carbonates containing various metals that should constitute the lead-containing oxide so as to have the desired composition. There is a so-called in-phase method in which a solid phase reaction involving calcination, pulverization, and calcination is repeated many times.

With this method, it was difficult to produce highly pure powder due to impurities mixed in during pulverization. Furthermore, the particle size of the powder that can be efficiently produced by pulverization is limited to a few micrometers, and the particle size tends to be non-uniform, resulting in poor reactivity.

Co-precipitation is a known method for improving the disadvantages of these in-phase methods, in which powder is produced using a solution as a starting material.This method generally has the advantage of producing fine powder with a narrow particle size distribution. There is.

(Problems to be solved by the invention) Regarding the application of coprecipitation method useful for preparing lead-containing fine powder,
Among the metals that should constitute the lead-containing oxide, for example, MO has a high solubility in the precipitate formed in the starting material solution, so the desired composition can be obtained by elution, and the pH of the moving precipitate can be reduced to 1.
It is necessary to increase the concentration to about 2, and in this case, if hydroxide is used, a high p l-1 can be maintained. To prevent impurities from entering, it is possible to use ammonia water, but ammonia water can hold it11.
+-1 had a limit of about rl1110.5, which was insufficient to prevent elution.

It is an object of the present invention to provide an effective solution for such moving points.

(Means for solving and overcoming the problems) The inventors conducted research on a method for producing a lead-containing oxide fine powder containing components that are easily eluted during coprecipitation, and arrived at the present invention.

In producing lead-containing fine powder, an acidic solution and/or suspension containing various metals to constitute the lead-containing oxide is reacted with a precipitant in the presence of a precipitation aid, and the resulting precipitate is A step of calcining the product at 450 to 1200°C to obtain 1 q of powder, a step of adding and mixing lead compound powder to the powder obtained in the above step, and a step of heating the powder mixture obtained through each of the above steps to a temperature of 600 to 1 q.
This is a method for producing lead-containing fine powder, which is characterized by combining the steps of firing at 000°C.

Specific examples of various metals constituting the lead-containing oxide in the present invention include Pb, Zr, Ti, and tVlo.

Nb, Mn, Sn, Zn, Sb, AA, Fe.

Ta, Co, Ni, Bi, W, li, sr, Ba.

Ca, Se, La, Cu, Y, Yll, le, R8°C
Examples include d and In.

Acidic solutions containing various metal components that should constitute lead-containing oxides are not particularly limited, but examples include inorganic acid solutions such as nitric acid solutions, hydrochloric acid solutions, and sulfuric acid solutions, oxalic acid solutions, and formic acid solutions. Examples include organic acid solutions such as and mixed solutions thereof.

As a method for preparing the solution, a general method of dissolving various salts in water is used.

Next, the suspension as used in the present invention refers to a liquid in which solid particles are uniformly dispersed, and includes, for example, a sol-like liquid in which fine precipitated particles are uniformly dispersed.

Next, examples of precipitation aids include alcohols such as methanol and ethanol, alcohols such as acetone, benzene toluene, xylene, trichlene, chlorocene, hydrogen peroxide, etc., but the solubility of the precipitate It is applicable to any substance that reduces the The precipitation aid is used in an amount of 1 q of the above-mentioned ones or a mixture of two or more.

The amount of precipitation aid added varies depending on the metal components contained in the acidic solution and/or suspension containing various metals that are to constitute the lead-containing oxide, but it should be an amount that precipitates 95 mol% or more of the metal components. is appropriate, and is generally 60% by volume or less, preferably 10 to 50% by volume of the content (volume) in the precipitation tank. The amount added varies depending on the pH of the reaction with the precipitant, but in general, the lower the pH, the more the elution is prevented! The amount of addition required for rice increases.

Examples of the precipitant include inorganic bases such as aqueous ammonia, various salts such as ammonium carbonate and ammonium oxalate, and organic bases such as methylamine and ethylamine.

The reaction pH is preferably 5.5 or higher, more preferably 7 or higher.

Regarding the upper limit of pl-1, for example, the upper limit of pH that can be efficiently maintained with aqueous ammonia is about 10.5.

As for the coprecipitation method, an acidic solution containing various metals to constitute the lead-containing oxide and/or is placed in a coprecipitation tank in which p +-+ is maintained with a precipitation aid and a precipitant, with sufficient stirring.
Alternatively, it is preferable to introduce the suspension by a method such as lIN atomization.

The solution portion of the precipitate thus obtained is removed by a method such as filtration. ” Cleaning of the precipitate should be carried out under the same conditions as the precipitate formation, or even better.
It is preferable to use an aqueous solution containing a precipitant and/or precipitation aid with high H content in order to prevent elution during the washing step.

It is desirable that the washing be sufficient to remove impurities such as 0°C and NOs in the precipitate, and after removing the impurities, the precipitated particles can be removed by washing with ethanol or atmospheric water. It is also effective to prevent comrades from clumping together.

Drying methods include conventional heating drying, vacuum drying, spray drying, vibration fluidized drying, drum drying A7-drying, film evaporator drying, and the like.

Preventing agglomeration of powders is important when obtaining fine powder, and in this respect it is effective to perform crushing using a ball mill, vibrating ball mill, jet mill, etc. before and/or after calcination.

When the calcination temperature is lower than 450°C, removal of moisture in the precipitate is insufficient, and rotation is required to achieve the desired composition when weighing and charging in the next step. Further, if the temperature is higher than 1200° C., agglomeration occurs due to sintering of powders, resulting in decreased reactivity, and calcining at high temperatures is not practical in terms of energy.

Therefore, the calcination temperature is preferably 450 to 1200°C.
-1000 degreeC is more preferable.

The lead compound used in the next step is lead oxide (PI).
0. PI] 304), lead carbonate, basic lead carbonate, lead hydroxide, lead oxalate, lead formate, and the like.

Regarding the powder characteristics of the lead compound powder, a fine powder with good mixability is preferable.

The mixing method may be a commonly used method, for example, using a mixer such as a mortar or a ball mill. Note that wet mixing using limo alcohol, acetin, etc. is more efficient and preferable.

The amount of lead compound powder to be mixed is 8 mol% or less in excess of the chemical stoichiometric amount to form the desired phase, which is effective for forming the desired group and increasing the reactivity of the powder. be.

Next, if the treatment temperature in the firing step is lower than 600°C, the efficiency of the reaction will be low, while if the temperature is higher than 1000°C, the lead compound will easily melt and form hard agglomerates of powders, making it difficult to form fine powders. Therefore, the firing temperature is 600~
1000'C, more preferably 700-900°C, and most preferably 750-850°C.

(Example) Example 1 A zirconyl chloride aqueous solution with a metal concentration of 1.02 mol/β and a titanium tetrachloride aqueous solution with a metal concentration of 1.63 mol/β were mixed with Zr.
:Mn is mixed in an atomic ratio of 0,125:0,4375, and the metal MO powder and metal Mn powder are mixed in the solution so that the atomic ratio of :MO:Mn is 30:10:1. was added to the solution with stirring to obtain a purple solution.

Separately, an acid-resistant solution of niobium of 0.422 m01/β was prepared using niobium hydroxide precipitate.

Adding 390 g of oxalic acid trihydrate (H2C204.2H20) to the acid-resistant solution of niobium per mole of niobium metal in the acid-resistant solution of niobium,
Further, the purple solution containing Zr 2 , Ti 2 , M(] and Mn was added at an atomic ratio of Nb:MU of 2:1 to obtain a brownish brown solution.

This solution was mixed with ethanol (precipitation aid) and aqueous ammonia (
The mixture was sprayed with stirring into a co-precipitation tank maintained at PL-19.0 using a precipitant (precipitant) to form a precipitate. The amount of ethanol (precipitation aid) added at this time was 50% by volume based on the content in the coprecipitation tank.

The generated precipitate was filtered and then washed with aqueous ammonia of pH 1i containing 50% by volume of ethanol, and the resulting precipitate was dried at a temperature of 80°C.

The metal components eluted into the filtrate were analyzed, but no elution was observed. After crushing the dried material, it was calcined at a temperature of 900° C. for 1 hour to obtain a powder. When this powder was observed with a scanning electron microscope, it was found to be a fine powder with a uniform particle size of about 0.3 μm.

Lead oxide (Pb 0
)223.2000() was wet mixed using ace]・n and then calcined at a temperature of 780°C for 1 hour to obtain a lead-containing oxide powder.As a result of scanning electron microscopy observation, this powder had a lead-containing oxide powder.
It is a fine powder with a very uniform particle size of about 3 μm. 1.
:.

Further, an impurity analysis revealed that carbon, chlorine, and impurity metals were 10 ppm or less, indicating high purity.

3.0g of this fine powder to evaluate the reactivity of this powder.
Molding pressure 1000K (] / ci and diameter 20mm
It was formed into a disk shape of φ and sintered at a temperature of 1150° C. for 1 hour.

As a result, the sintered body had a sintered density of 7.94 (]/cIll, which was approximately the theoretical density).

Comparative Example 1 A precipitate was produced in the same manner as in Example 1 except that ethanol (precipitation aid) was not added. Analysis of the filtrate revealed that 26 mol% of M(+ was eluted.

As described above, if a precipitation aid is not added, a large amount of elution occurs and the desired composition cannot be obtained.

Example 2 Used in Example 1! : Zr, Ti, M (1, strontium chloride aqueous solution with a metal concentration of 1.01 mol/β is added to a brown solution containing Mn and Nb at a Zr:Sr atomic ratio of 0.125: 0.05); A solution was prepared by mixing the sea urchins.

As a result, Zr and Ti were obtained by the same operation as in Example 1.

Obtain calcined powder containing Mfl, Mn, Nll and Sr! child .

In this case as well, no elution of metal components from the liquid during precipitation formation was observed.

The obtained powder is a fine powder with a uniform particle size of about 0.3 μm, and has an IC6 value of lead monoxide (Pb) per 101.441 g of this fine powder.
O) 212.0400() was wet-mixed using acetone and then fired at a temperature of 180° C. for 1 hour to obtain a lead-containing oxide fine powder.

The properties of this powder were almost the same as in Example 1.

(Effects of the Invention) By using a precipitation aid during precipitation generation, the present invention can efficiently produce a precipitate from a stock solution containing alkaline earth metals, etc., which was previously difficult to produce using only a precipitant such as aqueous ammonia. Is possible. Therefore, easily sinterable lead-containing oxide fine powder with high purity, highly uniform composition, and uniform particle size can be obtained.

Claims (1)

[Claims] 1. In the production of lead-containing fine powder, an acidic solution and/or suspension containing various metals to constitute a lead-containing oxide is added to a precipitating agent in the presence of a precipitating agent. The precipitate obtained was reacted with 450-12
A step of calcining at 00°C to obtain a powder, a step of adding and mixing lead compound powder to the powder obtained in the above step, and a step of firing the powder mixture obtained through each of the above steps at a temperature of 600 to 1000°C. A method for producing lead-containing fine powder, which is characterized by combining each process.