JPS6311520A - Production of ceramics powder capable of easily sintering for producing dielectric porcelain - Google Patents

Abstract

PURPOSE:To produce a perovskite type oxide powder contg. Pb for producing the dielectric porcelain having a low temp. sintering property by mixing each solutions of Pb, Zr and Ti compds. and a calcined composite oxide to a solution capable of forming a precipitate, followed by calcining the obtd. precipitate. CONSTITUTION:The each solutions of the Pb, Zr and Ti compds. and the composite oxide which is shown by AO.B2O5 (wherein A is >=one kind of Mg, Ni, Zn and Mn, B is Nb and Ta) and is obtd. by previously calcining, are mixed to the solution capable of forming the precipitate such as an aqueous solution of ammonia, etc. The obtd. precipitate is optionally aged, and washed, followed by calcining it. By the method as mentioned above, the perovskite type piezoelectric ceramic particle composed of the oxide shown by the formula Pb(ZrtTi1-t)O3 (wherein t=0.1-0.9) and the oxide shown by the formula PbA1/3B2/3O3 is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing PZT-based piezoelectric ceramic raw material powder that is low-temperature sinterable and has high performance.

PZT ceramics are widely used as high frequency filters, ultrasonic vibrators, and resonator elements (pickup elements, ignition element mechanical filters, delay line conversion elements, bimorph elements, etc.).

[Prior art]

A dry method and a wet co-precipitation method are known as conventional methods for producing raw material powder for PZT-based ceramics.

The dry method is a method in which powders of constituent oxides or carbonates are mixed and calcined. In the wet coprecipitation method, PZT
In this method, a mixed solution of all the constituent components is prepared, a precipitate-forming liquid such as an alkali is added thereto to cause co-precipitation, followed by drying and calcining.

[Problem that the invention seeks to solve]

In the conventionally known dry method, it is difficult to obtain raw material powder with a uniform composition, and it is necessary to increase the calcination temperature to complete the PZT production reaction, so the particles become coarse and easily sintered. The drawback was that it was difficult to form a bond.

In addition, with the wet co-precipitation method, it is easy to obtain powder with excellent uniformity, but since the concentration of the precipitate forming liquid is constant when added, if the precipitate forming ability of each component is different, a certain component may be 100%
Although it produces a precipitate, other components may not produce 100% precipitate, which has the disadvantage that it is difficult to obtain a desired composition. Furthermore, since PZT contains lead and titanium, when producing it by coprecipitation method, if cheap titanium tetrachloride is used as the titanium raw material, the chlorine ions of titanium tetrachloride will react with the lead ions. Titanium tetrachloride cannot be used because it produces a white precipitate. In this case, the formation of this precipitate can be prevented by using titanium oxynitrate, but it is not practical because it is expensive.

In addition, as a wet method, there is also a method using an organometallic compound, and in this case, no harmful anions are generated, but the raw materials are expensive and it is not suitable for industrial production.

Furthermore, it is difficult for Mg + N r + Zn + Mn to form a precipitate within the same pH range using a common precipitate-forming solution, and Nb and Ta have few salts dissolved in an aqueous solvent. Therefore, PZ containing these metals
It has been difficult to obtain T-based ceramic powder as a perovskite-based oxide having a correct stoichiometric ratio by precipitation formation from an aqueous solution.

The object of the present invention is to use Mg, Ni, Zn, Mn, Nb, Ta
Eliminates the drawbacks of conventional methods for producing raw material powder for PZT-based piezoelectric ceramics containing metals such as metals, allows the use of inexpensive titanium tetrachloride as a titanium raw material, and produces PZT-based piezoelectric ceramics with high density and excellent electrical properties. The object of the present invention is to provide a method for producing a low-temperature sinterable powder suitable for

[Means for solving problems]

The present invention is based on the general formula Pb(Zrz Ti+-t)Os(
However, oxides represented by [・0.1 to 0.9) and -i
Formula PbA+zJz/5Oz (where A is Mg, Ni,
In the production of a PZT-based piezoelectric ceramic powder having a perovskite structure consisting of one or more selected from the group consisting of Zn and Mn and an oxide represented by (B represents Nb and or Ta), A lead-containing method consisting of mixing each solution of lead, zirconium, and titanium compounds and a composite oxide represented by 80.B2O5 obtained by pre-calcination with a precipitate forming solution and calcining the obtained precipitate. This is a method for producing perovskite-based oxides.

In the present invention, PZT-based piezoelectric ceramics include those in which the atomic ratio of pb in the above general formula is shifted higher or lower than 1.0, and systems in which trace amounts of other metal elements are added.

In the method of the present invention, precipitation of the PZT component is carried out by a coprecipitation method or a sequential precipitation method, but the following method is preferred.

(1) After mixing an aqueous mixed solution of zirconium and titanium compounds with an excess precipitate-forming liquid to form a precipitate, the obtained mixed hydroxide is thoroughly washed with water, and dispersed again in the excess precipitate-forming liquid. A method of mixing an aqueous compound solution to form a precipitate of a PZT component, (2) mixing an aqueous zirconium compound solution to an excess precipitate forming solution to form a precipitate, and then mixing an aqueous titanium compound solution to form a mixed hydroxide. ,
A method of thoroughly washing the obtained mixed hydroxide, dispersing it again in an excess precipitate forming liquid, and mixing it with an aqueous lead compound solution to form a precipitate of the PZT component. (3) Precipitating the mixed aqueous solution of zirconium and lead compound A method in which a titanium compound aqueous solution is mixed with a liquid to form a precipitate, and then a titanium compound aqueous solution is mixed to form a precipitate of the PZT component.

P b + Z r + T used as raw material compound
Examples of the i-compound include hydroxides, oxychlorides, carbonates, oxynitrates, sulfates, nitrates, acetates, formates, oxalates, chlorides, oxides, and the like. If these are not soluble in water, mineral acids etc. can be added to make them soluble, but the cheapest and most suitable for the method of the present invention are zirconium oxychloride or silconinium oxynitrate, titanium tetrachloride and It is lead nitrate.

In addition, components 8 and B are prepared at 400-1000°C, preferably at 700-100°C, after mixing the raw material compounds of both components in advance.
Insoluble composite oxide AO-B obtained by calcining at 00°C
The gos is ground and usually added as a suspension. The addition time may be before or after the formation of a precipitate of the PZT component, or in the middle. The raw material compounds for components A and B include hydroxides, oxychlorides, carbonates, oxynitrates, nitrates, acetates, formates, nitrates, oxides, and the like. A
O・B20. The powder needs to have a uniform particle size distribution and a small particle size by controlling the raw materials, calcination temperature, pulverization process, etc. The particle size is usually preferably 1.0 μm or less.

Examples of the precipitate-forming solution include solutions of ammonia, caustic alkali, soda carbonate, ammonium oxalate, amines, etc., but they do not contain sodium or potassium, which can affect electrical properties if mixed in trace amounts, and are easily formed during the calcination stage. Aqueous ammonia, which decomposes and is inexpensive, is preferred.

In addition to cleaning the final precipitate, intermediate cleaning is performed to clean the precipitate. In particular, when titanium tetrachloride is used as a titanium raw material, sufficient cleaning is performed as an intermediate cleaning before adding lead compounds to remove anions, especially It is necessary to remove chloride ions. For washing, it is preferable to use water or aqueous ammonia and repeat repulp washing with water. If the intermediate cleaning is not sufficient, lead chloride, etc., which are difficult to remove in the final cleaning, will be produced, resulting in weight loss during sintering, and sinterability and electrical properties will deteriorate.

Further, in order to obtain a powder with better performance, it is preferable to perform aging after precipitation. Aging is carried out for a long time at low temperatures and for a short time at high temperatures, and is usually aged between 10 and 80
℃ for 30 minutes or more, preferably 1 to 24 hours.

Precipitation formation in the present invention is carried out in an aqueous solvent, such as water or water-alcohol.

In the present invention, in order to control the sinterability and properties of PZT ceramics, trace components such as Ba, Ca,
Sr, Sn, Mn+ AI, La+ Nb, C
s, Ge, V, Y, Bit Fe, CrtN
i, Ir, Rh, Na, Sc, In+ K+
Compounds of elements such as Ga, TI, W, and Th may be added.

The mixed precipitate obtained by the above method was
The perovskite oxide of the present invention can be obtained by calcining at 0°C, preferably 7QQ to 1000°C.

The PZT-based piezoelectric ceramic raw material powder obtained by the present invention has low-temperature sintering properties, allowing a PZT-based piezoelectric ceramic sintered body with high density and excellent electrical properties to be obtained by sintering at 800 to 1220'C. powder.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1゜0.0135 mol of zirconium oxychloride in 50 ol of water
After gradually dropping this solution into 3N ammonia water 11 which was maintained at 60°C and stirred, 60°C
The reaction was aged by stirring for 1 hour at °C.

While continuing to stir, add 0.0% titanium tetrachloride to this dispersion.
An aqueous solution of 365 mol dissolved in 500 ml of water was added dropwise to form a mixed hydroxide of Zr and Ti, and at room temperature -
Stirring was continued day and night to ripen the precipitate.

After filtration, the filter cake was again dispersed in dilute ammonia water and filtered (repulp washing) several times to sufficiently remove chlorine ions. In addition, in order to prevent the stoichiometric ratio of each component from changing due to adhesion to the filter paper during repulp washing, filtration was always performed on the same filter paper.

The filter cake was redispersed in aqueous ammonia IA, and while stirring, a solution of 0.1 mol of lead nitrate dissolved in 300 ml of water was added dropwise to form a mixed precipitate of Zr, Ti, and PB hydroxides.

On the other hand, Mg00.0167 mol and Nb, o, 0.016
After mixing with 7 mol in a ball mill, about 2
Mg-
A slurry-like dispersion of Nb calcined powder was added to the PZT mixed hydroxide slurry, and after filtration, washing, and drying, it was calcined at 800°C for about 2 hours, and the resulting calcined powder was Grind with a ball mill to give Pb (Mg+7Jbzzx). ,
,.

Ceramic powders having the following compositions were obtained: o Zro, +3sTio, xb, ox.

Example 2゜0.1 mol of lead nitrate and 0.013 mol of zirconium oxynitrate
An aqueous solution prepared by dissolving 5 mol in 300 ts 1 of water was dropped into 1 liter of 5N ammonia to form a coprecipitate. While stirring the coprecipitate dispersion, 0.0365 mol of titanium tetrachloride was added to 30011 mol of water! ! Gradually drop it into an aqueous solution dissolved in
A mixed precipitate of Zr, Ti and PB hydroxides was prepared.

Hereinafter, the same process as in Example 1 was carried out, and Pb(Mg+7Jbz
zx) 0.500 Zro, +3sTio, 5b5
A ceramic powder having a 0z composition was obtained.

Comparative examples Commercially available PbO, Ti0z, ZrO□, MgO, Nb2O
Pb(Mg+7Jbzzx)o, 5G. Z
ro, IzsTio, 3bsOy, mixed in a ball mill, tentatively heated at 800°C for about 2 hours, ground again in a ball mill, dried, and Pb(
Mg+7Jbzzx) O, So. Zrol: +5Ti
o.

A ceramic powder having a composition of 3 bsos'a was obtained.

(Evaluation test) (A) The characteristic particle size distribution of the raw material powder was measured using a centrifugal sedimentation type particle size distribution measuring machine (Kaho Seisakusho 5).
A-CP type).

(A-1) Average particle size. : Particle size (A-2) particle size distribution exhibiting a cumulative weight percentage of 5oχ. / pasted. : Cumulative weight percentage is 9
The particle size is 0x. (A-3) Specific surface area: Measured using an automatic specific surface area measuring device (Koho Micromeritics Model 2200).

(B) Characteristics of dielectric porcelain Piezoelectric porcelain was manufactured using the powders obtained in the Examples and Comparative Examples.

Put 1g of raw material powder into a mold with a diameter of 2011111+,
A molded article was obtained by pressure molding at a pressure of ton/cmz. This molded body was placed in a magnesia crucible, covered with a lid, and sintered in a firing furnace to obtain piezoelectric porcelain.

(B-1) Sintered density: Measured by an underwater displacement method.

(B-2) Dielectric properties ε and tan δ: Using an LCZ meter (4276^ manufactured by Yokogawa Hewlett-Packard), the relative dielectric constant ε and the dielectric loss tangent tan δ were measured at 20° C. and 1KH2.

The results are listed in Table 1.

〔Effect of the invention〕

The raw material powder produced by the method of the present invention has a uniform composition,
PZT is sinterable at low temperatures and is obtained by sintering the powder.
The piezoelectric ceramic sintered body has high density and excellent electrical properties. Furthermore, the method of the present invention is excellent as an industrial method, since a mixed precipitate can be formed in the same precipitate forming liquid by selecting the raw material form and the order of precipitate formation.

Patent applicant Science and Technology Agency Inorganic Materials Research Institute (430) Nippon Soda Co., Ltd. Agent (6286) Haruyuki Ito (7125)
Yoshimi Yokotoba

Claims (4)

[Claims] (1) General formula Pb(Zr_tTi_1_-_t)O_3
(However, t = 0.1 to 0.9) and the general formula PbA_1_/_3B_2_/_3O_3 (However, A is one selected from the group consisting of Mg, Ni, Zn, and Mn or In the production of perovskite piezoelectric ceramic powder consisting of two or more oxides (B represents Nb and/or Ta), each solution of lead, zirconium, and titanium compounds and the oxide obtained by pre-calcination. AO・B
A method for producing a lead-containing perovskite composite oxide, which comprises mixing a composite oxide represented by _2O_5 with a precipitate forming liquid and calcining the obtained precipitate. (2) After mixing an aqueous mixed solution of zirconium and titanium compounds with an excess precipitate forming liquid to form a precipitate, the obtained mixed hydroxide is sufficiently washed with water, dispersed again in the excess precipitate forming liquid, and The method according to claim 1, wherein the aqueous compound solution is mixed to form a precipitate of the PZT component. (3) After mixing the zirconium compound aqueous solution with the excess precipitate-forming liquid to form a precipitate, the titanium compound aqueous solution is mixed to form a mixed hydroxide, the obtained mixed hydroxide is thoroughly washed, and the excess precipitate is again mixed. The method according to claim 1, wherein the PZT component is dispersed in a precipitate forming liquid and mixed with an aqueous lead compound solution to form a precipitate of the PZT component. (4) The method according to claim (1), in which a zirconium and lead compound mixed aqueous solution is mixed with a precipitate forming liquid to form a precipitate, and then a titanium compound aqueous solution is mixed to form a PZT component precipitate. .