JPS63190718A - Method for producing raw material powder for easily sinterable composite perovskite using multi-stage wet process - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing raw material powders of perovskites and solid solutions thereof.

Perovskites and their solid solutions are piezoelectric materials.

It is widely used as functional ceramics for dielectrics, semiconductors, sensors, optoelectronic materials, etc. Recently, it has been desired to further improve this functionality, and there are many raw material powders of perovskite and its solid solution that are easy to sinter, have uniformity, have high bulk density, and are low cost. There is a need for the development of technology that can efficiently manufacture these materials.

(Prior art and its problems) Conventionally, as a method for manufacturing perovskite raw material powder,
Dry methods, coprecipitation methods and multi-stage wet methods are known.

The dry method is a method in which compounds of constituent raw materials are mixed in a dry method and then calcined. However, with this method, it is difficult to obtain a raw material powder with a uniform composition, so it is difficult to obtain a perovskite with excellent functionality, and the sinterability is also not sufficient.

The coprecipitation method is a method in which a mixed solution containing all of the constituent components is prepared, a precipitate forming liquid such as an alkali is added to the mixed solution to cause coprecipitation, and the coprecipitate is dried and calcined.

According to this coprecipitation method, it is easy to obtain powder with excellent uniformity, but
Because of their uniformity, the particles tend to coagulate to form secondary particles during precipitate formation, drying, or calcination, making it difficult to sinter.

In addition, in the coprecipitation method, if the precipitate forming ability of each component with respect to the precipitate forming solution is not the same, for example, the acid component is substantially 10
Although 0% precipitate is produced, other components may only partially produce precipitate, making it difficult to obtain a desired composition.

The multi-stage wet method is disclosed in JP-A-61-53113 and JP-A-6
As described in Publication No. 1-53115, etc., the above-mentioned drawbacks of the coprecipitation method are solved by precipitating each component in stages. However, even in the multi-stage wet method, M (J component, Zn component, Ni component, C
It was difficult to precipitate substantially 100% of the G acid component.

(Objective of the Invention) An object of the present invention is to provide a method that improves the multi-stage wet method and can completely precipitate all the components to produce a raw material powder of perovskite and its solid solution having a desired composition. be.

Another object of the present invention is to provide a method for efficiently producing raw material powder of perovskite and its solid solution that satisfies the four requirements of easy sinterability, uniformity, low cost, and high bulk density. be.

(Technical Means for Solving the Problems) The present inventors have conducted intensive research to achieve the above object, and have arrived at the present invention.

The present invention is based on the general formula %) (where A represents at least one of MQ, Zn, Ni, and Co, B represents at least one of Nb and Ta, and x
, y and 2 indicate mol%, x + y + z =
It is 100. ) When producing the raw material powder of perovskite and its solid solution represented by (), the solution of each component of B, Pb, Ti, and Zr is brought into contact with a precipitate-forming liquid to form a precipitate of each component in a stepwise manner, and then The precipitate was washed so that the concentration of ions generated from the precipitate forming agent in the precipitate-containing solution was 12 mol/1 or less, and then the precipitate was precipitated with a precipitate forming solution.
After the pH of the i3 liquid is set to 11.5 or higher, a solution of the hydroxide of the A component is added to form a precipitate containing the A component, and the resulting precipitate is calcined. The present invention relates to a method for producing a raw material powder of an easily sinterable composite perovskite.

In the present invention, "solution 1" means a solution in which soluble matter is dissolved or a suspension in which insoluble matter is dispersed.

In the present invention, the A component of Belovsky 1~ and its solid solution represented by the general formula % formula % is at least one of MQ, Zn, Ni, and Co, the B component is at least one of Nb and Ta, and p
pb in b(A1/3B2/3)03 and (A1/3
B2/3) component atomic ratio [Pb / (A173B2
73)], pbTi O34: Pb and Ti
The g ratio (Pb/Ti) and the atomic ratio (Pb/Zr) of pb and ZrL:y in PbZrO3 are usually 1.
．． 0, but non-stoichiometric perovskites in which this atomic ratio is shifted to a value higher or lower than 1.0 are also included.

In addition, x, y and Z in the above general formula represent mol% and can take various values depending on the use, but usually X is 5 to 90.
, y is preferably selected from the range of 5 to 80.2 and 5 to 80 mol%. If it is outside this range, it is not preferable because it will cause problems in terms of characteristics.

Each component compound for preparing a solution of the metal element-containing compound of the B component, which is a component of perovskite and its solid solution, and the compound of the pb acid component, Ti component, and Zr component, is not particularly limited. Things, carbonates, oxysalts, sulfates, &! iM salt, chloride, etc.! !
It is appropriately selected from organic salts, organic acid salts such as acetate, oxalate, oxides, etc. Alkoxides can also be used as the titanium component. Further, as the compound containing a metal element as component A, hydroxides thereof are used.

These are generally used as aqueous solutions, but if they are not soluble in water, they may be made soluble by adding an acid.

Insoluble raw materials may be used as a suspension solution, or an alcoholic solution may be used instead of an aqueous solution.

As a precipitation forming liquid, ammonia, aqueous ammonia carbonate 1
, caustic alkali, amine, oxalic acid, alkylamine, and other solutions. Examples of the alkylamine include primary amines having a lower alkyl group such as methylamine, ethylamine, propylamine, and butylamine; primary amines such as cyclohexylamine; tertiary amines having a lower alkyl group such as dimethylamine and diethylamine;
Mention may be made of tertiary amines having lower alkyl groups such as triethylamine.

When bringing the component solutions of B, Pb, "i", and Zr into contact with the precipitate-forming solution to generate precipitates of each component in a stepwise manner, care must be taken to prevent the Pb component and Ti component from forming precipitates at the same time. , and it is preferable to prevent the formation of lead chloride precipitates.The specific method for this is (
1) From a solution of a compound containing a metal element of component B and a solution of a compound of pb and Zr, a precipitation forming liquid is used to generate a precipitate of component B, Pb component and Zr component, and then a Ti compound is formed. or (2) using a precipitate forming solution from a solution of a compound containing a metal element as component B, a solution of a Zr compound, and a solution of a Ti compound. Preferred methods include a method in which a B component, a Zr component, and a Ti component are precipitated, and then a solution of a pb compound is added to produce a precipitate with F>bQ.

In the method (1) or (2) above, the B component, Pb
In producing the precipitation of the component and the Zr component, or the precipitation of the B component, the Zr component, and the T1 component, 1. Each component solution may be added to the precipitate forming liquid while stirring the precipitate forming liquid, or vice versa, or each component solution may be added to the precipitate forming liquid in multiple stages or alternately as necessary. They may be brought into contact with each other, but it is preferable that the addition is carried out while sufficiently stirring the liquid.

The precipitate obtained by the above method is washed with water or the like by a normal washing method such as a decantation method, so that the concentration of ions generated from the precipitate forming agent in the precipitate-containing liquid is 0.2 mol/fJ or less. Adjust as follows. By controlling the concentration of ions generated from the precipitant to 0.2 mol/j or less, Cj-1NO, ions in the solution, which are undesirable impurities, can be removed.

Next, the pH of the precipitate-containing solution is adjusted to 11.5 or higher using a precipitate-forming solution.
Preferably it is 120 to 125, and a solution of the hydroxide of component A is added to form a precipitate containing component A.

The precipitate obtained by the above method can be filtered, dried, and then calcined without any washing. According to this method, A
Elution of precipitates of components can be prevented, and raw material powders for perovskites and solid baths thereof having desired compositions can be obtained. Drying of the precipitate may be performed under atmospheric pressure or under reduced pressure.

If the calcination temperature is too low, the dehydration and thermal decomposition of the precipitate will be insufficient, and if it is too high, the powder will become coarse. be.

(Example) The present invention will be explained in more detail by showing Examples and Comparative Examples below.

Example 1 37.5[Pb(Mg1/3Nb2/3)03co-3
7.5 (Pb Ti 03) = 25.0 (Pb
Zr O3) Dissolve 13.509 g of niobium pentachloride (Nb Cl 5 ) in 300 mJ of ethanol, and further add 100,100 O of a 6N ammonia aqueous solution. This is combined with lead nitrate [Pb
(No. 3) 2] f) 6.242 g to 500 mJ)
of water was added. Furthermore, zirconyl chloride (Zr 0Cjl 2 ・81420> 16.11
0-order titanium tetrachloride (Ti CJI 4) 14 which was prepared by adding a solution of 500 mJ of titanium tetrachloride (Ti CJI 4) in 500 mJ of water to form a precipitate.
A solution of 23 g of 23 g dissolved in 500 mN of water was added to form a precipitate. After washing the precipitate by repeating decantation with water four times and adjusting the ammonium ion concentration to 0.11 mol/j, 50 mL of an aqueous solution containing 10 mg of 15N ammonia water was added.
N was added to set the pit to 121. Add 5.141 g of magnesium hydroxide [M9(OH)2] to this solution and 350 ml of water.
A solution in N was gradually added to form a precipitate.

This precipitate was separated without washing, dried, and then analyzed for composition, and found to be the same as the original elemental composition. Further, this precipitate was calcined at 750°C for 2 hours. Ethanol was added to this powder and it was ball-milled, and when a part of it was observed using a transmission electron microscope, the particle size was 0.2.
The thickness was uniform on the order of μm.

0.8 wt% of polyvinyl alcohol was added to this calcined powder, it was molded at 1/- and sintered at 1150°C for 2 hours in a lead atmosphere, and the density of the obtained sintered body was 7.99 g/-. Met.

Example 2 12.5 [Pb(Zn1/3Nb2/3) 03]
-50,0 (Pb Ti 03) -37,5 (PI)
ZrO3) 4.503g of niobium pentachloride (NbCl5) was dissolved in 100mJ of ethanol, and 10100O of a 6N ammonia aqueous solution was added. To this, nitric acid 89 [P b
A solution of 6.242 g of (N 2 O3) 2 dissolved in 500 mN water was added. Furthermore, zirconyl chloride (Zr
A solution of 24.17g of 0Cj2-8H20) dissolved in 500mJ of water was added to form a precipitate. 1897g of titanium tetrachloride (T i Cj 4) was dissolved in 500mJ of water.
A solution dissolved in was added to form a precipitate. The precipitate was decanted four times with water, washed and brought to an ammonium ion concentration of 0.11 mol/j, and then 50 mJ of an aqueous solution containing 10 mJ of 15N ammonia water was added to adjust the pH to 12.
It was set to 1. Add 80% nitrogen hydroxide to this solution [l n(OH)2
] Z 92g and 350mj of water! was gradually added to form a precipitate iii. This precipitate was separated without washing, dried, and then analyzed for composition, which revealed that the elemental composition was the same as that of the precipitate. Further, this precipitate was calcined at 750°C for 2 hours. Ethanol was added to this powder, ball milled, and a portion of it was added to the transmission electron S! fiW
When the particles were observed using an L mirror, the diameter of one particle was 0°3 no Af.
It was uniform at about f1.

Polyvinyl alcohol was added to this calcined powder in an amount of 0, swt%, molded at It/l-j, and sintered at 1150° C. for 2 hours in a lead atmosphere. The density of the obtained sintered body was 7.85 g/
It was aJ.

Comparative Example 1 37.5 [Pb(Mg1,3Nb2/3) 031-
37. ri (r-'b-r”x 03)-25,0(
Pb Zr O3) Niobium oxide (N b20 !,) 33-3 g -i
! ! 223.2 g of bicarbonate forceps (1-' bO), titanium oxide (T' 102 ) 30. 30.8 g of Og-zirconyl oxide (Zr 02) and 5.1 g of magnesium oxide (MgO) were weighed, a small amount of water was added thereto, and the mixture was thoroughly mixed, followed by drying for 92 hours. This is 75
Calcination was performed for 2 hours at 0°C. The composition ratio of the (-) crumbled calcined powder was the same as in Example 1, but a TEM photograph of the particles showed nonuniform particle diameters of 1 to 2 μm. When this calcined powder was fired in the same manner as in Example 1, the density of the sintered body was 7.30 g/aJ.

Comparative Example 2 In Example 1, particle size 1 was used instead of magnesium hydroxide.
A calcined powder was obtained in the same manner as in Example 1, except that 3.55 g of magnesium oxide (M(10) of ~3 μm was used.

The particle size was several μm and nonuniform. When this calcined powder was fired in the same manner as in Example 1, the density of the sintered body was 7.50 g/J.

(Effect of the invention) X [Pb(A1.B2/3)031-3/ (r'
b Ti 03) -Z (Pb Zr 03) (where -A represents at least one of Mg, Zn'', Ni, and CO; B represents at least one of Nb and Ta; x, y, and 2 represent mol% and x+y-1z=100.

) When producing the raw material powder of perovskite and its solid solution represented by
In the coprecipitation method, 100% precipitation is achieved in the co-precipitation method because the precipitation of the r component is generated stepwise and then the concentration and pH of ions generated from the precipitate forming agent in the precipitate-containing liquid are regulated, and then the A component is precipitated. It is possible to completely precipitate components that were difficult to precipitate, and as a result of obtaining a precipitate in which two or more phases are highly interdispersed, there is no agglomeration during precipitate formation, or during drying or calcination. By causing aggregation, it is possible to produce powder with high bulk density and easy sinterability with good reproducibility.

In addition, in this process, each phase is highly mutually dispersed, so that the calcined material achieves sufficient uniformity. Furthermore, since it is easy to process 10 times, it has excellent effects such as being able to obtain easily sinterable powder with good reproducibility and at low cost.

Claims (1)

[Claims] General formula x[Pb(A_1_/_3B_2_/_3)O_3]-
y(PbTiO_3)-z(PbZrO_3(However,
A represents at least one of Mg, Zn, Ni, and Co;
B represents at least one of Nb and Ta, x, y and z represent mol%, and x+y+z=100. ) When producing raw material powders for composite perovskite structure compounds (hereinafter referred to as perovskites) and their solid solutions, solutions of each component of B, Pb, Ti, and Zr are brought into contact with a precipitation forming solution to precipitate each component. After stepwise generation, the precipitate is washed so that the concentration of ions generated from the precipitate-forming agent in the precipitate-containing liquid is 0.2 mol/l or less,
Next, after adjusting the pH of the precipitate-containing solution to 11.5 or higher with a precipitate-forming solution, a solution of the hydroxide of component A is added to form a precipitate containing component A, and the resulting precipitate is calcined. A method for producing an easily sinterable composite perovskite raw material powder, characterized by: