KR20120024927A - Method for producing complex oxide powder, and complex oxide powder - Google Patents

Abstract

Fine, for example, when the specific surface area is 20 m 2 / g (50 nm at a specific surface equivalent diameter), the crystallinity (square) such that the ratio of the c axis to the a axis (c / a axis ratio) of the crystal axis is 1.007 or more. provides a composite oxide powder having a perovskite structure represented by ABO _3: stability) is high, the formula.
In preparing a composite oxide powder containing at least one of Ba and Ca as an A-site element and at least Ti as a B-site element, and having a perovskite-type structure represented by the general formula: ABO ₃ , after calcining, the general In the calcining step of calcining the combined raw materials combined to obtain a calcined powder of a composite oxide having a perovskite structure represented by the formula: ABO ₃ , the temperature raising rate is set to 1000 until the calcined maximum temperature is reached. It is set to at least C / min. More preferably, the temperature increase rate is 2400 ° C / minute or more.

Description

Manufacturing method of composite oxide powder and composite oxide powder {METHOD FOR PRODUCING COMPLEX OXIDE POWDER, AND COMPLEX OXIDE POWDER}

The present invention relates to a method for producing a composite oxide powder and a composite oxide powder, and more particularly, to a method for producing a composite oxide powder used in an electronic component material of a ceramic capacitor, and a composite oxide powder produced by the production method.

In recent years, as electronic devices have been miniaturized, miniaturization of electronic components used therein has been demanded. In addition, the miniaturization and the large capacity of the multilayer ceramic capacitor, which is one of the representative electronic components, are progressing. As a technique for enabling such a small size and large capacity, there are thinning and multilayering of a dielectric layer (ceramic layer).

At present, a multilayer capacitor having a thickness of about 1 μm and a laminated number of more than 800 layers has been put into practical use.

In order to further reduce the size of the multilayer capacitor, it is necessary to reduce the thickness of the dielectric layer to a submicrometer area of 1 µm or less. To realize a dielectric layer having a submicrometer thickness, the particle diameter of the ceramic sintered body constituting the dielectric layer is 100 nm or less. You need to make it as fine as possible.

However, it is known that the dielectric constant decreases when the ceramic sintered body (for example, BaTiO ₃ -based ceramic) constituting the dielectric layer becomes finer in particle size. This decrease in dielectric constant is attributable to the decrease in crystallinity of the ceramic sintered body (ratio of c-axis to a-axis (c / a-axis ratio) of the crystal axis).

In order to solve these problems, as a raw material powder before sintering (for example, a calcination powder of barium titanate-based material) for forming a dielectric layer, a raw material powder having a small particle diameter and high crystallinity can be used. There is a need.

Thus, in order to obtain fine barium titanate powder having high crystallinity, a method for producing a composite oxide powder having a temperature raising rate of 30 ° C./minute (0.5 ° C./second) or more at the time of calcination has been proposed (see Patent Document 1).

In addition, by using a composite oxide powder having a small crystal grain size and high crystallinity obtained by the method for producing a composite oxide powder, it is possible to obtain a dielectric having a fine grain size of a sintered body and a high? R.

However, the average particle diameter of the composite oxide powder obtained by the method of the said patent document 1 is about 0.3 micrometer, and it is reality that it cannot respond to thinning of the dielectric layer to submicrometer area | region.

Japanese Laid-Open Patent Publication 2005-8471

This invention solves the said subject, and is fine, for example, when the specific surface area is 20 m <2> / g (50 nm of specific surface equivalent diameter), the ratio of the c-axis to the a-axis of a crystal axis (c / a-axis ratio) And a method of producing a composite oxide capable of efficiently producing a composite oxide powder having a perovskite type structure represented by ABO ₃ , having a high crystallinity (quadraticity) such that) is 1.007 or more, and It is an object to provide a fine and highly crystalline composite oxide prepared by the above method.

Method for producing a composite oxide powder of the present invention,

A method for producing a composite oxide powder containing at least one of Ba and Ca as an A-site element, and at least Ti as a B-site element, and having a perovskite-type structure represented by General Formula: ABO ₃ ,

After calcining, in the calcining step of calcining a mixed raw material mixed to obtain a calcined powder of a complex oxide having a perovskite type structure represented by the above general formula: ABO ₃ , the calcining peak temperature is reached from the calcining start. It is characterized by making a temperature increase rate 1000 degree-C / min or more until it is set.

In the manufacturing method of the composite oxide powder of this invention, it is preferable to make the said temperature increase rate into 2400 degreeC / min or more.

In addition, the composite oxide powder produced by the method of the present invention is preferably represented by the general formula: (Ba _{1- x} Ca _x ) TiO ₃ (where x = 0 to 0.15).

Moreover, in the manufacturing method of the composite oxide powder of this invention, after reaching maximum temperature, it is preferable to cool, without maintaining temperature.

Further, in the method for producing a composite oxide powder of the present invention, before the calcination step, the mixture of the A-site element compound containing the A-site element and the ceramic small raw material containing the B-site element compound containing the B-site element is mixed and ground. It is preferable to have a process.

In addition, the composite oxide powder of the present invention is characterized in that the composite oxide powder having a perovskite type structure produced by the above-described production method of the present invention.

The method for producing a composite oxide powder of the present invention is a calcination process for calcining a combined raw material which is combined so that a calcined powder of a composite oxide having a perovskite structure represented by the general formula: ABO ₃ after calcining is obtained from the start of calcining. Since the temperature increase rate until reaching the maximum plastic temperature is set to 1000 ° C / min or more, the plasticizing time can be shortened and abnormal formation can be suppressed, resulting in fine and crystalline ( Composite oxide powder (plasticized powder) with high tetragonality can be manufactured efficiently.

That is, according to the present invention, the ratio of the c-axis to the a-axis (c / a) of the crystal axis when the crystal grain size is minute and the particle diameter is 20 m 2 / g (50 nm with a specific surface area equivalent diameter) as a specific surface area, for example. It is possible to efficiently and reliably produce a composite oxide powder having a high perovskite structure with high crystallinity (square crystal) such as an axial ratio) of 1.007 or more.

In the method for producing a composite oxide powder of the present invention, by raising the temperature increase rate from the start of plasticization to the maximum plastic temperature of 2400 ° C./min or more, it is fine and crystallized while suppressing abnormal formation more efficiently and more reliably. It is possible to produce a composite oxide powder having high stiffness (quadraticity), which makes the present invention more effective.

In addition, the composite oxide powder of the present invention is preferably represented by the general formula: (Ba _{1 - x} Ca _x ) TiO ₃ (where x = 0 to 0.15), which means that when x exceeds 0.15 (substitution amount of Ca is 15 mol%). It is because defects, such as segregation of Ca and crystallinity fall, arise.

In addition, in the method for producing a composite oxide powder of the present invention, the composite having a perovskite-type structure represented by general formula: ABO ₃ , which is more efficiently fine and crystalline by cooling without reaching the temperature after reaching the maximum temperature. An oxide powder (plasticized powder) can be obtained.

Moreover, in the manufacturing method of the composite oxide powder of this invention, the process of mixing and grinding the A-site element compound containing A site element and the ceramic small raw material containing B site element compound containing B site element is provided before a calcination process. By this, a finer composite oxide powder (plasticized powder) can be obtained.

In addition, since the composite oxide powder of the present invention prepared by the method according to any one of claims 1 to 5 has a perovskite-type structure having high crystallinity in the fine grain region and high dielectric constant, the dielectric layer of the multilayer ceramic capacitor It can use suitably for a constituent material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structure of the firing furnace used for carrying out a calcination process with the manufacturing method of the composite oxide powder of this invention.
It is a figure qualitatively showing the heat processing profile in the calcination process of an Example and a comparative example.
FIG. 3 shows the specific surface area of the plasticized product (BaTiO ₃ powder) obtained by calcining the composition of “Composition 1” of Table 1, that is, the raw material powder to be BaTiO ₃ under the conditions of Examples? 1, 2 and Comparative Example, and c / a. It is a figure which shows the relationship of an axial ratio.
4 is shown in Table 1 "Composition 2" of the composition, that is, (Ba Ca _{0 .95 0 .05)} TiO embodiment the raw material powder be ₃ for example,? Is obtained by calcining under the conditions 1, 2 and Comparative Examples condition gasomul ((Ba the specific surface area of _{0 .95} Ca _{0 .05)} TiO ₃ powder) and a diagram showing the relationship between the c / a axial ratio.
5 is shown in Table 1 "Composition 3" of the composition, that is, (Ba Ca _{0 .85 0 .15)} TiO embodiment the raw material powder be ₃ for example,? Is obtained by calcining under the conditions 1, 2 and Comparative Examples condition gasomul ((Ba _{0 .85} Ca _{0 .15)} is a view showing the relationship between surface area and ratio, c / a axial ratio of TiO ₃ powder).
Fig. 6 is a diagram showing a multilayer ceramic capacitor produced by using the composite oxide powder produced by the production method of the present invention as a dielectric material.

EMBODIMENT OF THE INVENTION Embodiment of this invention is shown to the following, and the characteristic point of this invention is demonstrated in detail.

&Lt; Example 1 >

As starting material

(a) BaCO ₃ powder having a specific surface area of 50 m 2 / g,

(b) CaCO ₃ powder having a specific surface area of 30 m 2 / g,

(c) TiO ₂ powder having a specific surface area of 100 m 2 / g,

Three types of raw material powders were prepared, and weighed and blended so that the compositions were composed of "composition 1", "composition 2" and "composition 3" in Table 1.

Composition Composition 1 BaTiO ₃ Composition 2 (Ba Ca _{0 .95 0 .05)} TiO ₃ Composition 3 (Ba Ca _{0 .85 0 .15)} TiO ₃

Water was added to this blended raw material (ceramic small raw material), mixed and pulverized with a ball mill (using PSZ media having a diameter of 2 mm).

The mixed and pulverized slurry was discharged and dried to obtain dry powder in which BaCO ₃ powder, CaCO ₃ powder, and TiO ₂ powder were uniformly mixed and pulverized.

The dried powder was placed in a zirconium oxide box and preheat treated by holding at a temperature of 400 to 600 ° C. for 5 to 10 hours in a batch type kiln. The CO ₂ gas was sufficiently released by this preliminary heat treatment.

Next, the raw material powder subjected to the preliminary heat treatment was heat-treated using the baking furnace 1 shown in FIG.

On the other hand, the kiln 1 is composed of a kiln body 2, a kiln core tube 3, an electric heater (heating means) 4 for heating the kiln core tube 3 on its outer periphery side, and firing ( A setter 5 for placing the raw material powder 10 after preliminary heat treatment, which is to be calcined), is provided. The setter 5 is also equipped with a supporting rod 6 for putting the setter 5 into and out of the kiln core pipe 3.

In the kiln 1 shown in FIG. 1, the kiln core pipe 3 is comprised so that it may rotate by the drive of the kiln core pipe rotation means (not shown).

The electric heater 4 is formed of SiC or the like, and a plurality of electric heaters 4 are arranged inside the kiln main body 2 and around the kiln core tube 3, so that the kiln core tube 3 can be heated to a predetermined temperature. It is.

In addition, the setter 5 is made of zirconium oxide and has a size of 50 mm x 50 mm, and the plane shape is substantially square. As the support rod 6, a rod-shaped ceramic material is used.

In this firing furnace 1, a predetermined amount (5 to 10 g) of the raw material powder 10 is placed on a zirconium oxide setter 5 supported by the support rod 6 on the inlet side of the firing furnace core tube 3, which is then fired. The raw material was heat-treated by inserting it into the core tube 3.

The supporting rod 6 is connected to a driving device (not shown), and is configured to be inserted into the kiln core tube 3 at a predetermined speed. The temperature increase rate can be arbitrarily changed by changing the insertion speed of the setter 5 in accordance with the setting of the facility.

And using the baking furnace 1 of FIG. 1 comprised as mentioned above, about the raw material powder used as the composite oxide of "composition 1", "composition 2", and "composition 3" of Table 1, the Example shown in Table 2 Heat treatment (calcination) was performed under the conditions of Condition 1, Example 2, and Comparative Example.

That is, in Example 1 and Condition 1, the raw material powder to be the composite oxide of "Composition 1", "Composition 2" and "Composition 3" in Table 1 was heated up so that the plasticized maximum temperature might be 1000-1200 degreeC, and a temperature increase rate At the insertion rate of 1000 ° C./min (16.7 ° C./sec), the setter 5 on which the raw material powder 10 is placed is inserted into the kiln core tube 3, and the temperature is maintained after reaching the maximum calcining temperature. It calcined by cooling without cooling.

Temperature rise rate Plasticizer maximum temperature To the maximum temperature
Tipping time Comparative example 60 ° C / min (1.0 ° C / sec) 800 ~ 1050 ℃ 2 hours Example Condition 1 1000 ° C / min (16.7 ° C / sec) 1000 ~ 1200 ℃ 0 (no skipping) Example Condition 2 2400 ° C./min (40 ° C./sec) 1100 ~ 1300 ℃ 0 (no skipping)

In Example and Condition 2, the raw material powder to be the composite oxides of "Composition 1", "Composition 2" and "Composition 3" in Table 1 was heated up so that the plasticized maximum temperature became 1100-1300 degreeC, and a temperature increase rate The setter 5 on which the raw material powder 10 is placed is inserted into the kiln core tube 3 at an insertion rate of about 2400 deg. C / min (40 deg. C / sec), and the temperature is maintained after reaching the maximum plastic temperature. It calcined by cooling without cooling.

On the other hand, changing the maximum plastic temperature to 1000 to 1200 ° C. (Example? Condition 1) and 1100 to 1300 ° C. (Example? Condition 2) changes the specific surface area (particle size) of the obtained plastic product (BaTiO ₃ powder). For that.

In the comparative example, similarly, the raw material powders 10 to be the composite oxides of "Composition 1", "Composition 2" and "Composition 3" in Table 1 were placed on the setter 5, and the temperature increase rate was 60 in a batch type kiln. It heated up on the conditions of ° C / min (1.0 ° C / second), maintained at the maximum temperature of calcining for 2 hours, and calcined by natural cooling in a batch furnace.

The comparative example by changing the calcining temperature up to the range of 800 ~ 1050 ℃, changed the surface area of the obtained gasomul (BaTiO ₃ powder).

Example-Qualitative heat treatment profile in the calcination process of conditions 1, 2, and a comparative example is shown in FIG.

The specific surface area of the calcined product (BaTiO ₃ powder and Ca-modified BaTiO ₃ powder in which Ba was partially substituted by Ca) obtained by calcining under the conditions of Examples? 1, 2 and Comparative Example obtained as described above was obtained by the BET method. Measured.

Furthermore, by measuring the X-ray diffraction and performing Rietveld analysis, the ratio of the c-axis to the a-axis of the crystal axis of the plastic product (BaTiO ₃ powder and Ca-modified BaTiO ₃ powder in which Ba was partially substituted by Ca) (c / a axis ratio) (hereinafter also referred to simply as "c / a axis ratio"). The results are shown in Tables 3, 4 and 5 and FIGS. 3, 4 and 5.

On the other hand, Table 3 shows the specific surface area of plasticized material (BaTiO ₃ powder) and c when the composition of "Composition 1" of Table 1, that is, the raw material powder to be BaTiO ₃ was calcined under the conditions of Examples? The relationship between the / a axis ratio is shown.

Table 4 shows a case where a plasticizer in the composition, that is, (Ba Ca _{0 .95 0 .05)} For the raw material powder to be subjected to a TiO _3? Conditions 1, 2 and Comparative Examples, the conditions of the "Composition 2" in Table 1, gasomul ( It indicates the ratio between the surface area and c / a axial ratio of (Ba Ca _{0 .95 0 .05)} TiO ₃ powder).

Table 5 in the case where a plasticizer in the composition, that is, (Ba Ca _{0 .85 0 .15)} For the raw material powder to be subjected to a TiO _3? Conditions 1, 2 and Comparative Examples, conditions of "Composition 3" in Table 1, gasomul ( It indicates the ratio between the surface area and c / a axial ratio of (Ba Ca _{0 .85 0 .15)} TiO ₃ powder).

3 shows the specific surface area and c / a of the calcined product (BaTiO ₃ powder) obtained by calcining the composition of "Composition 1" in Table 1, that is, the raw material powder to be BaTiO ₃ under the conditions of Examples 1, 2, and Comparative Example. The relationship of the axial ratio is shown.

4 is shown in Table 1 "Composition 2" of the composition, that is, (Ba Ca _{0 .95 0 .05)} TiO embodiment the raw material powder be ₃ for example,? Is obtained by calcining under the conditions 1, 2 and Comparative Examples condition gasomul ((Ba the specific surface area of _{0 .95} Ca _{0 .05)} TiO ₃ powder) and shows the relationship between the c / a axial ratio.

5 is shown in Table 1 "Composition 3" of the composition, that is, (Ba Ca _{0 .85 0 .15)} TiO embodiment the raw material powder be ₃ for example,? Is obtained by calcining under the conditions 1, 2 and Comparative Examples condition gasomul ((Ba the specific surface area of _{0 .85} Ca _{0 .15)} TiO ₃ powder) and shows the relationship between the c / a axial ratio.

As shown in Fig. 3 and Table 3, in Table 1 "Composition 1" of the composition, i.e., the raw material powder to be a gasomul calcining the BaTiO ₃ (BaTiO ₃ composite powder) in the case of the comparative example, a specific surface area of 3.4 to In the range of 8.2 m2 / g (120 to 290 nm in specific surface equivalent diameter), the crystallinity shows high crystallinity with a c / a axis ratio of 1.009 or more. It was confirmed that c / a-axis ratio becomes small and crystallinity falls.

For example, when the specific surface area is 20 m 2 / g (50 nm at a specific surface equivalent diameter), the c / a axis ratio (crystalline) is lowered to about 1.0065, and the specific surface area is 25 m 2 / g (40 nm at a specific surface equivalent diameter). ), The c / a-axis ratio (crystallinity) was lowered to about 1.0057 (see FIG. 3).

On the other hand, in Example 1 in which the temperature increase rate was 1000 ° C./min, in the condition 1, when a crystalline plastic material (BaTiO ₃ powder) was obtained, and the specific surface area was 20 m 2 / g (50 nm at a specific surface equivalent diameter), It was confirmed that c / a-axis ratio (crystallinity) became about 1.0075 and crystallinity became high compared with the comparative example (refer FIG. 3).

Also, in Example 2 where the temperature increase rate was 2400 ° C./min, a more crystalline plastic product (BaTiO ₃ powder) was obtained, and when the specific surface area was 20 m 2 / g (50 nm at a specific surface equivalent diameter), c When the / a axis ratio (crystallinity) is about 1.0085 and the specific surface area is about 35 m 2 / g (28 nm with a specific surface area equivalent diameter), the c / a axis ratio (crystallinity) becomes 1.0078, which is more crystalline than the comparative example. It was confirmed to be very high (see FIG. 3).

Further, in Table 1 "Composition 2" of the composition, that is, (Ba _0.95 Ca _0.05) a gasomul (Preparative plasticizing the raw material powder be ₃ TiO (Ba Ca _{0 .95 0 .05} As shown in Figure 4 and Table 4 TiO ₃ powder), in the comparative example, the c / a-axis ratio is 1.009 or higher in the range where the specific surface area is 3.0 to 6.9 m 2 / g (150 to 330 nm at a specific surface equivalent diameter), but the crystallinity is high. When the surface area was increased (in the comparative example, the specific surface area was increased by lowering the calcining temperature), it was confirmed that the c / a-axis ratio was small and the crystallinity was lowered.

For example, at a specific surface area of 20 m 2 / g (50 nm at a specific surface area equivalent diameter), the c / a axis ratio (crystal) was lowered to about 1.006 (see FIG. 4).

On the other hand, for one embodiment the rate of temperature increase to 1000 ℃ / min? 1, the condition is the crystallinity obtained high gasomul ((Ba Ca _{0 .95 0 .05)} TiO ₃ powder), the specific surface area 20㎡ / g (non- When the c / a axis ratio (crystallinity) is about 1.0084 at a surface area equivalent diameter of 50 nm) and the specific surface area is about 35 m 2 / g (28 nm at a specific surface area equivalent diameter), the c / a axis ratio (crystallinity) becomes 1.0082. It was confirmed that the crystallinity was higher than that of the comparative example (see FIG. 4).

Further, in Example 2 in which the temperature increase rate was 2400 deg. C / min, the c / a-axis ratio (crystalline) was 1.0096 and the specific surface area was 35 m2 / g at a specific surface area of 20 m2 / g (50 nm with a specific surface equivalent diameter). high (with a specific surface area equivalent diameter of 28nm) on the c / a axial ratio (crystalline) is so determined as 1.0090 sex gasomul that was identified is obtained ((Ba Ca _{0 .95 0 .05)} TiO ₃ powder) (see FIG. 4 ).

Further, in Table 1 "Composition 3" of the composition, that is, (Ba _0.85 Ca _0.15) TiO ₃ gasomul a calcining a raw material powder become a (Preparative (Ba Ca _{0 .85 0} as shown in Fig. 5 and Table 5 _.15 In the TiO ₃ powder), in the comparative example, the specific surface area is 4.5-8.4 m 2 / g (120-220 nm in the equivalent diameter of the specific surface area), but the c / a axis ratio is 1.0089 or more, which shows high crystallinity, but the specific surface area When the ratio was increased (in the comparative example, the specific surface area was increased by lowering the calcining temperature), it was confirmed that the c / a-axis ratio was small and the crystallinity was lowered.

For example, when the specific surface area is 20 m 2 / g (50 nm with a specific surface area equivalent diameter), the c / a axis ratio (crystalline) is lowered to about 1.006 (see FIG. 5).

On the other hand, for one embodiment the rate of temperature increase to 1000 ℃ / min? 1, the condition is the crystallinity obtained high gasomul ((Ba _{0 .85 0 .15} Ca) TiO ₃₎ TiO ₃ powder), the specific surface area 20㎡ c / a axis ratio (crystalline) is about 1.0086 at / g (50 nm at a specific surface equivalent diameter) and c / a axis ratio (crystalline) at 1.0082 at 35 m2 / g (28 nm at a specific surface equivalent diameter) It turned out that it is a plastic crystal with high crystallinity and it is confirmed that crystallinity is higher than a comparative example (refer FIG. 5).

Moreover, in Example 2 which raised temperature rate to 2400 degree-C / min, when the specific surface area is 20 m <2> / g (50 nm of specific surface area equivalent diameter), c / a axis ratio (crystallinity) is about 1.0096 and specific surface area is 35 m <2> / in g (as a specific surface area equivalent diameter of 28nm) c / a axial ratio (crystalline) have been confirmed to be extremely high crystallinity is obtained gasomul ((Ba Ca _{0 .85 0 .15)} TiO ₃ powder) to 1.0091 (5 Reference).

On the other hand, from FIGS. 3 to 5 and Tables 3 to 5, in all cases of BaTiO ₃ and Ca modified barium titanate in which Ba is partially substituted with Ca, the temperature increase rate, the specific surface area of the plastic product, and c / a The same tendency was recognized about the relationship of axial ratio (crystallinity), and it was confirmed that crystallinity (c / a axial ratio) improves compared with the case of a comparative example by increasing the temperature increase rate.

In addition, the comparison between the case of BaTiO _{3 and} the case of Ca-modified barium titanate in which Ba was partially substituted with Ca confirmed that the Ca-modified barium titanate was more improved in crystallinity than the barium titanate without Ca modification.

On the other hand, the Ca-modified barium titanate improves crystallinity over the barium titanate without Ca-modification because Ca-modified barium titanate is a solid solution of barium titanate and calcium titanate, and calcium titanate tends to have a higher c / a ratio than barium titanate. I think.

In the case of Ca-modified barium titanate, when the substitution amount of Ca exceeds 15 mol%, problems of segregation and crystallinity of Ca occur, and when used as a dielectric of a multilayer capacitor, desired characteristics are not obtained. Therefore, the substitution amount of Ca is 15 mol% or less. It is preferable to set it as.

[Production of Multilayer Ceramic Capacitor]

Produced in the above Example? Condition 2, and a specific surface area (50nm with surface area-equivalent diameter) 20㎡ / g, c / a axial ratio of Ca-modified barium titanate 1.0096 ((Ba Ca _{0 .85 0 .15)} Using TiO ₃ ) (see FIG. 5) as the dielectric material, a multilayer ceramic capacitor having the structure shown in FIG. 6 was produced.

On the other hand, in the multilayer ceramic capacitor 20, a plurality of internal electrodes 13a and 13b are laminated in the multilayer ceramic element 11 via the ceramic dielectric layer 12 and face each other via the ceramic dielectric layer 12. The internal electrodes 13a and 13b alternately lead to the other end faces 14a and 14b of the multilayer ceramic element 11, and the internal electrodes 13a and 13b are formed on the end faces 14a and 14b. It is electrically connected to the external electrodes 15a and 15b.

When manufacturing the multilayer ceramic capacitor 20, first, a ceramic green sheet containing Ca-modified barium titanate ((Ba _0.85 Ca _0.15 ) TiO ₃ ) as a main component is produced.

Then, an internal electrode layer is formed by screen printing the conductive paste for internal electrodes containing Ni as a main component on the ceramic green sheet.

Next, a ceramic green sheet having an internal electrode layer and a ceramic green sheet having no internal electrode layer are stacked, and inner electrode layers facing each other are drawn out on opposite sides, and internal electrode layers are formed on both upper and lower main surfaces. An unbaked laminated ceramic element having a structure in which a ceramic green sheet (exterior sheet) which is not provided is prepared.

Then, the unbaked laminate is heat-treated under predetermined conditions to remove the binder, and then fired under predetermined conditions to obtain a ceramic sintered body (laminated ceramic element 11, see FIG. 6).

Next, the conductive paste for external electrodes is apply | coated to both end surfaces 14a and 14b of the laminated ceramic element 11, and it bakes to form external electrodes 15a and 15b.

For this reason, the multilayer ceramic capacitor 20 which has a structure shown in FIG. 6 is obtained.

The use of the above-described specific surface area 20㎡ / g in (50nm with surface area-equivalent diameter), c / a axial ratio of 1.0096 Ca-modified barium titanate _{((Ba 0 .85 Ca 0 .15} ) TiO 3) as a dielectric material As a result, a small, high performance (high capacity) multilayer ceramic capacitor is obtained, for example, where the thickness of the ceramic dielectric layer 12 is less than 1 µm (0.5 µm in this example), and the number of laminated dielectric ceramic layers contributing to the capacitance is 1000. It is confirmed.

On the other hand, the composite oxide powder produced by the method of the present invention can be applied not only to a multilayer ceramic capacitor but also to an LC composite component, a PTC thermistor and the like.

The present invention is not limited to the above examples in other respects as well, and the invention relates to the type of raw materials, the temperature increase rate in the calcination step, the substitution rate by Ca of Ca, and the like when the composite oxide powder of the present invention is produced. Various applications and modifications can be made within the scope of.

1 kiln
2 kiln body
3 kiln core tube
4 electric heaters (heating means)
5 setters
6 support rod
10 raw powder
11 multilayer ceramic elements
12 ceramic dielectric layers
13a, 13b internal electrode
Cross section of 14a, 14b multilayer ceramic element
15a, 15b external electrode
20 multilayer ceramic capacitors

Claims (6)

A method for producing a composite oxide powder containing at least one of Ba and Ca as an A-site element, and at least Ti as a B-site element, and having a perovskite-type structure represented by General Formula: ABO ₃ ,
After calcining, in the calcining process of calcining the combined raw materials combined to obtain a calcined powder of a complex oxide having a perovskite-type structure represented by the above general formula: ABO ₃ , the calcining peak temperature is reached from the calcining start. The temperature rising rate is 1000 degreeC / min or more, until it is a manufacturing method of the composite oxide powder. The method of claim 1,
The temperature raising rate is 2400 ℃ / min or more method for producing a composite oxide powder. The method according to claim 1 or 2,
General formula: (Ba _{1 - x} Ca _x ) TiO ₃ (However, x = 0 ~ 0.15) A method for producing a composite oxide powder, characterized in that. 4. The method according to any one of claims 1 to 3,
After reaching a maximum temperature, it cools, without maintaining temperature, The manufacturing method of the composite oxide powder characterized by the above-mentioned. 5. The method according to any one of claims 1 to 4,
And a step of mixing and grinding the A-site element compound containing the A-site element and the ceramic small raw material containing the B-site element compound containing the B-site element before the calcining step. Method for preparing the powder. A composite oxide powder having a perovskite structure, which is produced by the method according to any one of claims 1 to 5.

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