JPH0331647B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a solid ternary lead perovskite solid solution powder made of lead zirconate-lead titanate-composite perovskite, which has excellent uniformity and particle size characteristics. The present invention relates to a method for manufacturing high-density ceramics using the solid solution powder as a raw material with high productivity and at low cost. It is useful as a functional ceramic used in dielectrics, semiconductors, various sensors, optoelectronic materials, etc.

[Prior Art] It is already known that the solid ternary lead perovskite ceramics described above have excellent properties as functional ceramics. However, recently, as the field of application of functional ceramics has expanded rapidly and technology has become more sophisticated, the characteristics required for functional ceramics have become even more stringent, and conventional materials have not been able to sufficiently meet market demands. I've become unable to do that.

In order to deal with this situation, various improvement studies are being carried out with a focus on the properties (particularly particle size characteristics) of solid solution powder (meaning calcined powder; the same applies hereinafter), which has the greatest impact on the performance of ceramics. .

By the way, the solid ternary lead perovskite solid solution powder with the above-mentioned composition is usually produced by a dry method in which raw material powders (metal oxides, carbonates, etc.) containing calculated amounts of constituent elements are uniformly mixed and then calcined. However, if the particle size characteristics of the raw material powders are poor, the particle size characteristics of the solid solution powder obtained by mixing and calcining these powders will also be poor, which in turn will affect the performance of the ceramics obtained by molding and sintering this powder. cannot be made sufficiently good either. Especially the above
Among the components of lead perovskite, zirconia raw powder is extremely prone to agglomeration, and it is impossible to obtain monodispersed submicron-level fine powder using either the wet method or the dry method. Even if lead perovskite solid solution powder is produced by a dry method by mixing coarse raw material powder with other fine metal oxide powders (titanium oxide, lead oxide, etc.), the average particle size will be coarse, with an average particle size of about 2 μm or more. Put it away. In order to obtain high-density functional ceramics from such coarse-grained solid solution powder, sintering must be carried out under ultra-high pressure, and even if such a sintering method were adopted, it would not be as expected. High-density products cannot be obtained. Furthermore, when attempting to use functional ceramics as dielectrics, semiconductors, etc., one of the important points in improving performance is how thin the walls can be made. The particle size of the calcined solid solution powder is almost determined by the particle size of the calcined solid solution powder, so as long as coarse solid solution powder is used, it is not possible to obtain functional ceramics with performance that satisfies the demands of consumers.

On the other hand, if a method is adopted in which a precipitate is formed from a soluble salt containing zirconium, lead, titanium, etc. by a wet method such as an alkoxide method or a coprecipitation method, and then calcined after washing and drying, it is possible to It is possible to obtain a fine and dense coagulated ternary lead perovskite solid solution powder, and by using such a solid solution powder, not only can high-density ceramics be easily obtained even when using the pressureless sintering method, but also This is a promising functional ceramic that can fully meet the demands for thinner walls. However, the wet method is much more complicated and time-consuming to operate than the dry method, and it also has the disadvantage that it is very expensive due to the increased expense required for the use of chemicals and waste liquid treatment.

[Problems to be Solved by the Invention] The present invention has been made by paying attention to the above-mentioned circumstances, and its purpose is to produce a homogeneous and submicron material made of lead zirconate, lead titanate, and composite perovskite. The ultra-fine coagulated ternary lead perovskite solid solution powder can be produced using relatively simple operations.
The aim is to establish a method that can be manufactured at low cost with good productivity, and to provide a method that can produce high-density functional ceramics that exhibit excellent performance.

[Means for Solving the Problems] A method for producing a solid solution powder according to the present invention that achieves the above object is a solid solution powder of a solid ternary lead perovskite composed of lead zirconate, lead titanate, and a composite perovskite. []: A zirconium salt solution (A) containing the necessary total amount of zirconium, which accounts for the entire calculated amount, and 0.01 to 10 mol% of lead, which corresponds to a part of the calculated amount and based on the above zirconium salt. A lead salt solution (B) containing
A process of adding ammonia and/or amines solution in any order, washing and drying the resulting homogeneous precipitate, and then calcining at 800 to 1400℃, []: Calcination obtained in the above process [] The gist of this method is to uniformly mix the powder with a compound powder corresponding to the remaining amount of the calculated amount and calcinate the mixture at 500 to 1200°C. Furthermore, the method for producing ceramics according to the present invention uses a solid solution powder produced in the same manner as described above;
The gist lies in the fact that it is sintered under normal pressure at 700-1300°C.

[Function] As is clear from the above structure, the present invention skillfully combines a wet method and a dry method, takes advantage of the advantages of both methods, and mutually compensates for their drawbacks, resulting in improved operability, productivity, and economy. The purpose of the present invention is to provide a method for producing a solid solution powder with excellent particle size characteristics while satisfying the above requirements, and furthermore, using this solid solution powder to produce high-density and excellent functional ceramics with good productivity.

That is, in the present invention, a wet method is adopted for producing zirconia powder, which tends to agglomerate and makes it difficult to obtain fine powder.
In addition, as a means to prevent agglomeration during the period from precipitation generation to the calcination process and to ensure a submicron-level particle size structure, first, as specified in the above process [], calculations for the solidified ternary perovskite solid solution were carried out. A zirconium salt solution (A) containing the necessary total amount of zirconium that occupies the entire amount, and a solution that corresponds to a part of the calculated amount and is 0.01 to 10
A lead salt solution (B) containing mol% of lead is added in any order to an alkaline solution containing ammonia and/or amine, and a metal containing 0.01 to 10 mol% of lead is added together with zirconium to the alkaline solution containing ammonia and/or amine. After forming a hydroxide precipitate and washing and drying it
A fine mixed oxide powder mainly composed of zirconium oxide is produced by calcining at 800-1400°C.

The reason for adding a portion of lead salt (B) in the process of wet precipitation of zirconium hydroxide is to make the resulting zirconium hydroxide precipitate submicron-level fine, and also to prevent the precipitation of zirconium hydroxide from occurring in the subsequent drying or calcination process. This is to prevent agglomeration and coarse grain formation, and the amount of lead salt (B) required to achieve this purpose may be extremely small, and is 0.01 mol% or more based on the zirconium salt (A). More preferably, it is 0.1 mol% or more. 0.01
When the amount is less than mol%, the modification effect is lost and the number of aggregated particles increases. However, if the amount of lead salt (B) is too large,
The composition of the calcined powder synthesized in the next step [] cannot be made rich in zirconia, and the calcined powder obtained in the step [] not only loses its versatility, but also contains coarse lead zirconate in the calcined powder. Since particles are generated and fine monodisperse modified zirconia cannot be obtained, the amount of lead salt (B) added should be smaller than that of zirconium salt (A).
It should be kept to 10 mol% or less, more preferably 2 mol% or less.

Any type of zirconium salt used in the above wet precipitation process can be used as long as it is soluble in water (in some cases, organic solvents such as alcohol); Considering the ease of forming a hydroxide precipitate and the economic efficiency, the most common ones are oxyzirconium salts such as zirconium oxynitrate and zirconium oxychloride. Also, any lead salt can be used as long as it is soluble in water (or alcohol, etc.) and can form a hydroxide precipitate in the presence of ammonia or amines, but the most practical one is nitric acid. Lead salts such as lead and lead acetate.

Although it has been described that ammonia and/or amines can be used as the precipitant, economic efficiency and
Considering toxicity, ease of handling, etc., the most common one is ammonia water.

There are no particular restrictions on the order of addition of the zirconium salt solution (A) and the lead salt solution (B), but the lead hydroxide precipitate, which is produced in a relatively small amount, can be more uniformly dispersed into the zirconium hydroxide precipitate. For this purpose, it is recommended to first add the lead salt solution (B) to the precipitant solution to generate lead hydroxide, and then add the zirconium salt solution (A) under stirring.

The composite hydroxide precipitate obtained in this way was collected by filtration,
When calcined after washing and drying, a composite oxide powder mainly composed of zirconia is obtained. However, due to the coexistence of a small amount of lead oxide, zirconia particles do not agglomerate with each other, and are extremely fine at the submicron level. A calcined powder is obtained. Furthermore, the calcination temperature at this time is
The temperature range of 800 to 1,400°C was set because if the temperature is lower than 800°C, calcination will be insufficient and agglomeration will tend to occur if left after calcination.If calcination is performed at a high temperature exceeding 1,400°C, some of the oxides will This is because the particles melt and the particles are fused together, resulting in coarsening of the calcined powder.

The calcined fine powder mainly composed of zirconia thus obtained is processed in the next step [] by adding the above-mentioned [] among the components constituting the solid ternary lead perovskite solid solution powder.
Lead compound powder and titanium compound powder corresponding to the total amount remaining after subtracting the lead used in the process, as well as the component elements constituting the composite perovskite (specifically, Mg, Mn, Cr, Mn, Fe, Co, Ni,
Examples include compounds of elements selected from Cd, In, Sb, and rare earth elements, and compounds of elements selected from Nb, Ta, Te, Sb, W, etc., and these usually have an effective charge of +4. A coagulated ternary lead perovskite solid solution powder is obtained by mixing with the compounds (used in combination so as to achieve the desired results) and calcining at 500 to 1200°C. This mixing and calcination process is carried out using substantially the same equipment and method as the conventional dry method, but the raw materials used at this point are calcined fine powder mainly composed of zirconia, which is finely divided as described above. In addition, titanium compounds, lead compounds, and the metal compounds mentioned above that constitute composite lead perovskites (including oxides or carbonates and oxalates that undergo thermal decomposition during the calcination process and turn into oxides) Since both of these can be obtained as extremely fine particles on the submicron level, the coagulated ternary lead-based perovskite solid solution powder obtained by mixing and calcining them can also be obtained as extremely fine particles on the submicron level. can.

The temperature during the above mixing and calcination should be set in the range of 500 to 1200°C; if it is less than 500°C, the solid phase reaction between each oxide will be insufficient and a homogeneous perovskite structure will not be obtained. On the other hand, the calcination temperature
When the temperature exceeds 1200°C, part of the oxide melts and fuses, and the particles tend to become coarse.

However, when mixed and calcined at 500 to 1200℃, an extremely homogeneous and fine solidified ternary lead perovskite solid solution powder can be obtained.If this is formed into an arbitrary shape and then sintered, it becomes extremely homogeneous and has a packing density. Ceramics with high quality can be obtained. In particular, since the solid solution powder of the present invention is extremely fine and homogeneous as described above, it is possible to obtain high-density ceramics by sintering under normal pressure without using the conventional high-pressure sintering method. This greatly simplifies the sintering operation.
In addition, since the calcined powder is extremely fine at the submicron level, the wall thickness of the molded product can be made extremely thin, several times the particle size, resulting in highly functional products with extremely high performance. Becomes ceramics. The sintering temperature must be set within the range of 700 to 1300℃; if it is less than 700℃, sintering will be insufficient and sufficient strength will not be obtained, while if it exceeds 1300℃, the sintered particles will partially break down. As a result, the grain size increases and some of the component elements volatilize, resulting in a decline in performance as functional ceramics.

[Example] Example 1 1.3248 g of lead nitrate in 1 part of 4N ammonia water
Pb ²⁺
After forming a hydroxide precipitate, the concentration
A 0.75076 mol/aqueous zirconium oxychloride solution was gradually added to form a homogeneous precipitate of a mixed hydroxide of Pb ²⁺ and Zr ⁴⁺ . After washing and drying this, 1000
It was calcined at ℃ for 1 hour to obtain a calcined fine powder having a composition of (Zr _0.99 Pb _0.02 )O ₂ . The primary particles of the calcined fine powder had an average diameter of 0.1 μm and were almost monodispersed.

3.8320 g of calcined fine powder obtained above and commercially available TiO ₂
Powder 3.1952g, PbO powder 22.18g, ZnO powder 0.8139
g, Nb ₂ O ₅ powder 2.6581 g (average particle size of each is 1 μm)
After mixing the following) in a ball mill for 20 hours, 730℃
The composition formula is 0.3Pb (Zn _1/3 Nb _2/3 )O ₃
A solid ternary lead perovskite solid solution powder of −0.3PbZrO ₃ −0.4PbTiO ₃ was obtained. The average particle size of the solid solution powder was about 0.2 μm, and the particles were spherical and almost monodispersed.

This solid solution powder was formed into a disk shape at 2 tons/cm ² and then sintered at 1200℃ for 2 hours under normal pressure, resulting in a density of 8.14.
(99.6% of theoretical density) ceramics were obtained.

Comparative Example 1 Commercially available powders of PbO, ZrO ₂ , TiO ₂ , ZnO, and Nb ₂ O ₅ were blended to give the same solidified ternary lead perovskite composition as in Example 1, and mixed in a ball mill for 20 hours. , and calcined at 800℃ for 1 hour. The average particle size of the calcined powder was 1.4 μm.

This calcined powder was formed into a disk shape at 2 tons/cm ² ,
After normal pressure sintering at 1200℃ for 2 hours, the density was 7.32.
(89.6% of the theoretical density) ceramics could only be obtained.

Comparative Example 2 Commercially available PbO, ZrO ₂ , TiO ₂ , Zb ₂ O ₅ , Example 3
Co ₃ O ₄ powders obtained in the same manner as in Example 3 were blended to give the coagulated ternary lead perovskite composition, and after mixing in a ball mill for 20 hours,
It was calcined at 800°C for 1 hour. The average particle size of the obtained calcined powder was 1.9 μm. This calcined powder was molded into a disk shape at 2 tons/cm ² and sintered at 1200° C. for 2 hours under normal pressure. The density of the ceramic obtained was as low as 7.29 (88.9% of the theoretical density).

Example 2 Created in the same manner as Example 1 (Zr _0.99 Pb _0.02 )
6.0034 g of calcined fine powder with O ₂ composition, 3.2750 g of commercially available TiO ₂ powder, 22.11 g of PbO powder, and 0.7974 g of Nb ₂ O ₅ powder.
g, Fe ₂ O ₃ powder 0.4791 g (average particle size of each is 1 μm)
(below) was mixed in a ball mill for 20 hours at 720°C.
The composition formula is 0.12Pb (Fe _1/2 Nb _1/2 )−
A solid ternary lead perovskite solid solution fine powder of 0.47PbZrO ₃ -0.41PbTiO ₃ was obtained. The solid solution fine powder had an average particle size of 0.25 μm, and each particle was spherical and almost monodispersed.

The obtained solid solution fine powder was molded into a disk shape at 2 tons/cm ² and then sintered at 1100℃ for 2 hours under normal pressure.
Ceramics with a density of 8.02 (99.3% of theoretical density) were obtained.

Example 3 Created in the same manner as Example 1 (Zr _0.99 Pb _0.02 )
6.3866 g of calcined fine powder with O ₂ composition, 3.6744 g of commercially available TiO ₂ powder, 22.09 g of PbO powder, and 0.2658 g of Nb ₂ O ₅ powder.
g, Y ₂ O ₃ powder 0.2258 g (average particle size of each is 1 μm)
(below) was mixed in a ball mill for 20 hours at 750°C.
Calcined for 1 hour, the composition formula is 0.04Pb (Y _1/2 Nb _1/2 )
A solid ternary lead perovskite solid solution powder of O ₃ −0.5PbZrO ₃ −0.46PbTiO ₃ was obtained. The solid solution fine powder had an average particle size of 0.3 μm, and each particle was spherical and almost monodispersed.

The obtained solid solution fine powder was formed into a disk shape at 2 tons/cm ² and then sintered at 1200℃ for 2 hours under normal pressure.
Ceramics with a density of 8.01 (99.1% of the theoretical density) were obtained.

Comparative Example 3 An aqueous solution of 0.0033 g of lead nitrate (0.005 mol % based on zirconium salt) dissolved in 50 c.c. of water in 4N ammonia 1 was gradually added to form a hydroxide precipitate of Pb ²⁺ After that, the concentration is 0.75076mol/
133.19 cc of zirconium oxychloride aqueous solution was gradually added to form a homogeneous precipitate of mixed hydroxide of Pb ²⁺ and Zr ⁴⁺ . After washing and drying, this was calcined at 1000° C. for 1 hour to obtain a calcined powder having a composition of (Zr _0.99995 Pb _0.0001 ) O ₂ . Although the average diameter of the primary particles of the calcined powder was 0.1 μm, aggregated particles were observed.

3.6974g of calcined powder obtained above, 3.1952g of commercially available TiO ₂ powder, 22.30g of PbO powder, 0.8139g of ZnO powder
g, Nb ₂ O ₅ powder 2.6581 g (average particle size of each is 1 μm)
After mixing the following) in a ball mill for 20 hours, 730℃
Calcinate for 1 hour and do the same as in Example 1.
The composition formula is 0.3Pb(Zn _1/3 Nb _2/3 )O ₃ −0.3PbZrO ₃ −
A solid ternary lead perovskite powder of 0.4PbTiO ₃ was obtained.

Although the particle size of the solid solution powder was approximately 0.2 μm, considerable agglomeration was observed.

This solid solution powder was formed into a disk shape at 2 tons/cm ² and then sintered at 1200℃ for 2 hours under normal pressure.
Only ceramics with a density of 7.52 (92% of theoretical density) were obtained.

Comparative Example 4 An aqueous solution of 7.945 g of lead nitrate (12 mol % based on zirconium salt) dissolved in 100 c.c. of water in 4N ammonia 1 was gradually added to form a Pb ²⁺ hydroxide precipitate. Then, 117.21 cc of an aqueous solution of zirconium oxychloride having a concentration of 0.75076 mol/ml was gradually added to form a homogeneous precipitate of a mixed hydroxide of Pb ²⁺ and Zr ⁴⁺ . After washing and drying, this was calcined at 1100° C. for 1 hour to obtain a calcined powder having a composition of (Zr _0.88 Pb _0.24 )O ₂ . The average particle size of the primary particles of the calcined powder is 0.2 μm
Coarse particles with particle diameters of 2 to 3 μm were also included.

Calcined powder 5.5229g obtained above, commercially available TiO ₂ powder 3.1952g, PbO powder 20.49g, ZnO powder 0.8139g
g, Nb ₂ O ₅ powder 2.6581 g (average particle size of each is 1 μm)
After mixing the following) in a ball mill for 20 hours, 730℃
Calcinate for 1 hour and do the same as in Example 1.
The composition formula is 0.3Pb(Zn _1/3 Nb _2/3 )O ₃ −0.3PbZrO ₃ −
A solid ternary lead perovskite powder of 0.4PbTiO ₃ was obtained.

The solid solution powder had a particle size of approximately 0.2 μm and contained many coarse particles.

This solid solution powder was formed into a disk shape at 2 tons/cm ² and then sintered at 1200℃ for 2 hours under normal pressure.
Only ceramics with a density of 7.68 (94% of the theoretical density) were obtained.

[Effects of the Invention] The present invention is configured as described above, and zirconium oxide powder, which tends to agglomerate during the manufacturing process and is difficult to obtain as a fine powder, can be obtained by using a multi-stage wet method in combination with an appropriate amount of lead compound. Therefore, the submicron-level fine particles are mixed with titanium compounds, lead compounds, etc., which can originally be obtained as fine particles, by a dry method and calcined to produce lead zirconate-lead titanate-composite perovskite. It has now become possible to provide a coagulated ternary lead perovskite solid solution powder with excellent particle size characteristics at a low cost and with good productivity through relatively simple operations. Since this solid solution powder is homogeneous and extremely fine, it is possible to obtain high-density ceramics even when sintered at normal pressure after forming it into any shape, and it also meets the demand for thinner walls. This will greatly contribute to improving the performance of functional ceramics.

Claims (1)

[Scope of Claims] 1. In producing a coagulated ternary lead perovskite solid solution powder consisting of lead zirconate, lead titanate, and composite perovskite, []: A zirconium salt solution containing the necessary total amount of zirconium that accounts for the entire calculated amount. (A) and a lead salt solution (B) which corresponds to a part of the calculated amount and contains 0.01 to 10 mol% of lead based on the above zirconium salt,
A process of adding ammonia and/or amines solution in any order, washing and drying the resulting homogeneous precipitate, and then calcining at 800 to 1400℃, []: Calcination obtained in the above process [] A method for producing a coagulated three-component perovskite solid solution powder, comprising the steps of uniformly mixing the powder with a compound powder corresponding to the remainder of the calculated amount and calcining at 500 to 1200°C. 2. In producing a solid ternary lead perovskite solid solution powder consisting of lead zirconate, lead titanate, and composite perovskite, []: A zirconium salt solution (A) containing the required total amount of zirconium that accounts for the total amount of the calculated amount, and A lead salt solution (B) containing 0.01 to 10 mol% of lead based on the zirconium salt,
A process of adding ammonia and/or amines solution in any order, washing and drying the resulting homogeneous precipitate, and then calcining at 800 to 1400℃, []: Calcination obtained in the above process [] The step of uniformly mixing the powder with the compound powder corresponding to the remaining amount of the calculated amount and calcining at 500 to 1200°C, []: Shaping the calcined powder obtained in the above [],
1. A method for producing solid three-component perovskite ceramics, comprising: a step of sintering under normal pressure at ~1300°C.