JPS63225403A - Manufacture of dielectric ceramics - 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 Application Field) The present invention relates to a method for manufacturing dielectric ceramics, and particularly to a method for manufacturing dielectric ceramics, in particular P b (M g r7z N b a73) as a main component.
The present invention relates to a method for producing dielectric ceramic made of a solid solution containing Ox and other compounds having a composite perovskite structure containing lead.

(Prior Art) Recently, as dielectric ceramic compositions for high permittivity ceramic capacitors, ceramic compositions consisting of a composite perovskite structure mainly composed of lead niobate or lead tungstate, for example, have attracted attention. It can be sintered at a lower temperature than dielectric porcelain compositions mainly composed of barium titanate.

(Problems to be Solved by the Invention) These ceramic compositions that are supposed to have a composite perovskite structure mainly composed of lead have the following drawbacks.

(2) Although the sintering temperature is as low as 900°C to 1,100°C, the lead component volatilizes or evaporates during firing, resulting in variations in properties.

■ A pyrochlore structure phase with a low dielectric constant easily forms within the sintered porcelain, making it difficult to obtain the original high dielectric constant.

In order to solve these drawbacks, conventionally, when preparing a porcelain composition, an excess amount of lead oxide exceeding the stoichiometric ratio to form a perovskite structure was added to prepare for volatilization of the lead component. However, the influence of the atmosphere during calcination and firing is unavoidable, and the lead component remains in excess or is insufficient, and the variation in characteristics has not been resolved.

In addition, in order to suppress the formation of the pyrochlore structure phase in sintered porcelain, we have adopted a method of forming a perovskite structure via a columbite structure as a precursor of the perovskite structure, or adding magnesium oxide in a proportion higher than the stoichiometric ratio. The way to do this is S.

L, 5WARTZ et al., Mater, Res, B
ull, 17.1245-50 (19B2), J.
Am, Ceram, Soc, 67 (5) 311-
315 (1984). However, in these methods, the sintering temperature rises significantly due to reasons such as a decrease in the activity of the powder of the porcelain composition and a deviation from the stoichiometric ratio. It has the disadvantage that the lead component must be fired at high temperatures, resulting in increased volatilization of the lead component.

That is, in all conventional methods, the composition ratio of the dielectric ceramic produced varies greatly.

Therefore, the main object of the present invention is to provide a method for manufacturing dielectric ceramics in which fluctuations in composition ratio are small.

(Means for Solving the Problems) This invention provides P b (Mg+7s N
A method for manufacturing dielectric porcelain made of a solid solution containing bzy3)03 and other lead-containing compounds having a composite perovskite structure, the method comprising: preparing each component other than lead oxide in the composition of the dielectric porcelain; A process of mixing and calcining components other than lead to form a calcined product, a process of crushing the calcined product to form a pulverized product, a process of preparing lead oxide powder, and a process of mixing the pulverized product and lead acid. A step of mixing the compound powder in a predetermined ratio and calcining this mixture to form a calcined product, a step of molding the calcined mixture into a predetermined shape to form a molded product, and a step of forming a molded product. This is a method for manufacturing dielectric porcelain, including a step of firing.

(Function) Before calcining the lead oxide powder, that is, the lead component, each component other than lead oxide is calcined at a temperature of, for example, 900°C to 1,100°C, so the overall content of the components including the lead component is low. Calcining is performed at a temperature of, for example, 600°C to 900°C. Therefore, the amount of lead component volatilized during calcination can be suppressed. Moreover,
The entire calcined product containing the lead component becomes stable against heat.

Therefore, the amount of lead component volatilized during firing is also suppressed.

(Effects of the Invention) According to the present invention, compared to conventional methods, the amount of lead component volatilized during calcination and firing can be suppressed, thereby reducing fluctuations in the composition ratio of dielectric porcelain manufactured. Can be done.

Moreover, the dielectric ceramic produced by carrying out the present invention has a higher production ratio of the perovskite structure portion than that produced by the conventional method. That is, the generation of pyrochlore phase can be suppressed. Therefore, dielectric ceramics produced by carrying out the present invention have a higher dielectric constant than those produced by conventional methods.

Further, according to the present invention, the firing temperature of the entire calcined material containing lead components can be lowered to, for example, 750° C., so that the energy consumption during firing can be reduced.

Furthermore, according to the present invention, since the firing temperature can be lowered, when the manufactured dielectric porcelain is used as a material for a multilayer capacitor, silver or silver, which is cheaper than palladium conventionally used, or It becomes possible to use an alloy mainly composed of silver.

The above objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

(Example) Example 1 First, the composition formula (P b (M g 1/3 N b x
ys ) 02) o, ao (P b (Zn+7s
Nbzzs ) 03]o, +s (PbTjO:+
). ,. , among the components other than lead oxide, industrial MgO and ZnO.

Nb2O2 and Ti0z were prepared. These industrial raw materials were blended at a predetermined molar ratio corresponding to the above-mentioned compositional formula.

Next, these raw materials were wet mixed using a ball mill, ground, and then evaporated to dryness to obtain a mixture. Then, this mixture was calcined at a temperature of 700 to 1.200° C. for 2 hours to form a calcined product, which was ground in a ball mill and then evaporated and dried to obtain a dry raw material.

After that, p as a lead oxide having a dry raw material and a lead component is mixed so as to have a predetermined molar ratio corresponding to the above-mentioned compositional formula.
b3 and o4 (dilead tetroxide) powder, the mixture was wet mixed in a ball mill, evaporated and dried, and calcined at a temperature of 500 to 1.000°C for 2 hours to obtain a calcined raw material. Ta.

After adding 5 parts by weight of a vinyl acetate binder as a binder to this calcined raw material, they were wet mixed in a ball mill, and then evaporated and dried.

A powder raw material was obtained through a sizing process. The obtained powder raw material was heated to a diameter of 10n and a thickness of 0.8z under a pressure of 2.5 ton/cn.
A molded product was obtained by molding it into a disk shape of m.

This molded product was placed in an alumina box lined with zirconia powder and heated at 400° C. for 2 hours to burn off the organic binder. Thereafter, samples 1 to 22 were obtained by firing at a firing temperature of 750°C to 1,150°C.

Then, the shrinkage rate and weight loss of each sample were determined.

In this case, the shrinkage rate and weight loss of the sample were measured based on the molded product in which the organic binder was burned.

Then, Ag paste was baked on both sides of the sample at a temperature of 800° C. to form electrodes, thereby preparing a sample for measuring electrical characteristics.

Then, for each sample, the dielectric constant ξ and dielectric loss tan
The electrical characteristics of δ were measured at 1 kHz, IVrmS, and a temperature of 25°C. We also measured variations in dielectric constant. The variation in dielectric constant was determined using the following formula.

Variation in permittivity = (Standard deviation of permittivity/average value of permittivity) x 100
The number of samples is 10.

The measurement results of the dielectric constant ε, dielectric loss tan δ, shrinkage rate, and variation in the dielectric constant are shown in Attached Table 1. In addition, in Attached Table 1, numerical values outside the scope of the present invention and numerical values with poor characteristics are underlined. In this case, the dielectric constant ε is 15,
000, and the dielectric loss tan δ is 1%
The above are shown as having poor characteristics.

In addition, the relationship between firing temperature and dielectric constant and the relationship between firing temperature and shrinkage rate for sample numbers 4, 12 to 19 shown in Attached Table 1 are shown in the graph in Figure 1. The graph in Figure 2 shows the relationship between the calcination temperature and dielectric constant of the components, and the relationship between the calcination temperature and dielectric constant after adding lead oxide in sample numbers 4.7 to 11, and the calcination temperature and weight. The relationship with the decrease is shown in the graph of Figure 3 by solid lines.

That is, as in sample numbers 1 and 2, if the calcination temperature of components other than lead oxide is less than 900°C, the dielectric constant becomes small. On the other hand, when the calcination temperature of components other than lead oxide exceeds 1,100°C, as in sample number 6, the dielectric constant becomes small.

In addition, if the calcination temperature after adding lead oxide is less than 600°C as in sample number 7, the dielectric constant becomes small, and if the calcination temperature exceeds 900°C as in sample number 11, the dielectric constant decreases. The dielectric loss decreases and the dielectric loss increases.

On the other hand, when the crushed particle size after calcining of components other than lead oxide is made to exceed 1 μm as in sample numbers 21 and 22, the dielectric constant decreases, and especially when the particle size is increased as in sample number 22, the dielectric Losses will also increase.

Furthermore, as a method outside the scope of the present invention, the compositional formula [P b
(Mg+/+Nbt/3) 03) o, so (
P b (ZnI/z Nbz/l ) Ox ) o
, +s (P bTi O3) o.

. Dielectric porcelain was manufactured by calcining all of the components at once, and its electrical properties were measured.

In this case, first, as each component in the above compositional formula, MgO
, ZnO, NbzOs, TiOz and Pb3O4
prepared.

Then, these raw materials were blended in a molar ratio corresponding to the above-mentioned compositional formula, and these blended raw materials were wet mixed using a ball mill, pulverized, and then evaporated and dried to obtain a dried product. Then, this dried material was calcined at 750° C. for 2 hours to produce a calcined raw material.

A vinyl acetate binder is added to this calcined raw material as a binder.
After adding parts by weight, wet mixing was carried out using a ball mill, followed by evaporation drying and sizing to obtain a powder raw material.

The obtained powder raw material was molded into a disk shape with a diameter of IQms and a thickness of 0.8 fl under a pressure of 2.5 ton/cal to obtain a molded product.

Then, this molded product was placed in an alumina box lined with zirconia powder, heated at 400°C for 2 hours to burn off the organic binder, and then fired at a firing temperature of 900°C to 1050°C. I got it.

As for this sample, its dielectric constant ε and dielectric loss tan δ are as same as the sample of the above-mentioned example.

The variation in shrinkage rate and dielectric constant was measured, and the measurement results are shown in Attached Table 1. In addition, the relationship between firing temperature and dielectric constant and the relationship between firing temperature and shrinkage rate are shown in the graph of Figure 1.
Each is indicated by a dotted line.

As is clear from this result, if all the components of dielectric porcelain are mixed and calcined at the same time, the calcined product cannot be sintered at a low temperature, for example, 900°C, and the dielectric porcelain produced has large variations in dielectric constant and large dielectric loss.

Further, as a method outside the scope of the present invention, components other than lead oxide are calcined at 1,050°C, and the calcined product is not crushed, but lead oxide is mixed with the calcined product, and after calcining, , molding,
Samples were prepared using a method that involved a firing process. Then, its dielectric constant and shrinkage rate were measured. The results are shown in the graph of FIG. 1 by a dashed line.

From this result, it can be seen that unless components other than lead oxide are calcined at a temperature exceeding 900° C. and the calcined product is not crushed, the dielectric constant of the dielectric ceramic to be manufactured becomes small.

In addition, as a method outside the scope of the present invention, a calcined material containing components other than lead oxide is pulverized to a particle size of 2 μm.
A sample was prepared by mixing lead oxide with the calcined product, calcining it, and then going through the steps of molding and firing. and,
The dielectric constant was measured in the same manner as described above. The results are shown in the graph of FIG. 1 by a two-dot chain line.

From this result, it can be seen that even if the calcined product containing components other than lead oxide is ground to 2 μm, the dielectric constant of the dielectric ceramic produced is small.

Example 2 In this example, first, the composition formula (Pb (Mgl/5N
bzzz)○z) 0.1+6 [P b (Z n
+7s N bzz3 ) 03) o, +s (P
b T i 03 ] o, ost Table Salel M g (NOz )z ' 6Hz so that the elements of each component other than lead and titanium have a predetermined molar ratio.
O, Zn CNOx )z ・6Hz O and Nb
Weighed (OH)5 accurately and mixed them into pure water. This liquid mixture was designated as liquid A.

Next, Ti (QC, + H?i)4 was accurately weighed to a predetermined molar ratio, and it was added to
Mixed with H. A small amount of HtO□ was added to this mixed solution, and then HNO, was added to completely dissolve the titanium precipitate. This solution was designated as Solution B.

Then, liquid A and liquid B were mixed, and while stirring the mixed liquid with a stirrer, a predetermined amount of H2O2 was added to the mixed liquid, and further, NH and OH were added to adjust the pH to 9 to 1O. . Then, the mixture was stirred for 30 minutes, and the resulting precipitate was aged. The aged precipitate was then evaporated and dried to obtain a dried product containing components other than lead oxide.

Thereafter, a sample 23 was created using the dried material containing components other than lead oxide and Pb504 through the same steps as those for creating the sample No. 4 of Example 1. That is, after calcining a dried product containing components other than lead oxide at 1,000°C, the calcined product is crushed to a particle size of 0.9 μm to form a pulverized product, and Pb5Oa is added to the pulverized product. After adding and mixing the powder and calcining the mixture at 700℃,
Sample 23 was prepared by firing at ℃.

The dielectric constant ε and dielectric loss tan δ of the prepared sample were measured under the same conditions as in Example 1.

Variations in shrinkage rate and dielectric constant were measured. The measurement results are shown in Attached Table 2 together with the results of sample number 4 of Example 1.

As is clear from these results, it can be seen that the method of this example can also produce dielectric porcelain having almost the same characteristics as the dielectric porcelain manufactured by the method of Example 1.

Example 3 In Example 1, after calcining each component other than lead oxide,
Dielectric porcelain was produced by blending Pb30a, but in this example, dielectric porcelain was produced by blending Pbo (lead oxide) or P b (NOx) t (lead nitrate) instead of Pb3O4. In this case, in this example, components other than lead oxide are calcined at L 000°C, the calcined product is pulverized to a particle size of 0.9 μm, and PbO or Pb (NO3)z is added to the pulverized product. Samples 24 and 25 were prepared by adding and mixing lead oxide and calcining at 700°C, followed by firing at 900°C. That is, in this example, in the method of preparing the sample No. 4 of Example 1, the lead oxide to be added and mixed was pbo or P b (
NO3) Replaced with z.

Then, for each sample, its dielectric constant ε, dielectric loss ta
Variations in nδ, shrinkage rate, and dielectric constant were measured. The measurement results and the results of sample number 4 of Example 1 are shown in Attached Table 3.

As is clear from this result, as a lead component, Pb30
．． It can be seen that even if pbo or Pb(NO+)t is used instead of PBO or Pb(NO+)t, the dielectric ceramic produced has almost the same characteristics.

Example 4 In Example 1, (p b (M g l/3 N b z
zz ) Os) +1.110 (P b (Zn+
z+ Nbzy3) 0+ ) 0.15 (PbTi
O:+). ,. In this example, dielectric ceramics were manufactured with a composition in which MgO was further added as a subcomponent to the above composition. That is, in this example, when blending each component other than lead oxide, MgO as a subcomponent was added at a ratio of 0.5.1.0 to the main component.
Alternatively, samples 26 to 28 were prepared by adding 3.0% by weight.

In this case, components other than lead oxide, that is, components containing MgO, are calcined at 1,000°C, and the calcined product has a particle size of 0.9 μm.
PI) z04 was added to the pulverized product, calcined at 700°C, and then fired at 900°C to prepare a sample. That is, in this example, when components other than lead oxide were mixed in the method for preparing sample No. 4 of Example 1, MgO was further mixed.

Then, for each sample, its dielectric constant ε, dielectric loss ta
Variations in nδ, shrinkage rate, and dielectric constant were measured. The measurement results and the results of Sample No. 4 of Example I are shown in Attached Table 4.

As is clear from this result, even when mixing components other than lead oxide, even if MgO is added as a subcomponent in an amount of 1% by weight or less to the main component, the dielectric ceramic produced will have a dielectric constant of It can be seen that ε, dielectric loss tan δ, and shrinkage rate are good.

Example 5 In Example 1, (Pb (Mg+zs Nbtys)
03) 11.116 (P b (Zn+zs Nb
z73) 03) o, +s (P bT i Os
). ,. Dielectric porcelain was manufactured with a composition of , but in this example, in particular, when each component other than lead oxide was mixed, Mn as a reduction inhibitor was added to each of the components at the same time to produce dielectric porcelain. was manufactured. That is, in this example, after adding and mixing 0.1% by weight of MnO□ as a subcomponent to the main component, the mixture was
Sample 29 was prepared by calcining at 0.000°C, pulverizing the calcined product to a particle size of 0.9 μm, adding Pb3O4, calcining at 700°C, and firing at 900°C. In other words, in this example, when mixing components other than lead oxide in the method for creating sample number 4 of Example 1, M
nO was added.

Then, the prepared samples were measured for their dielectric constant ε2 dielectric loss tan δ, shrinkage rate, and variation in dielectric constant. The results and the results of sample number 4 of Example 1 are shown in Appendix 5.
It was shown to.

As is clear from this result, when each component other than lead oxide is mixed, MnO is added to these components as a reduction inhibitor.
, is added in an amount of 0.1% by weight, the dielectric ceramic produced has good dielectric constant ε, dielectric loss tan δ, and shrinkage rate.

In the examples, the composition formula (P b (M g +/3 N
bx/s ) 03 ) o, so (P b (Z
n+zs Nbt/3 ) 0* ) 0.1S (P
b T i O3) The composition represented by o, os is the main component, and 2.0, 5.
0 and 7.0 parts by weight of Pb(cu+z2'byt
) A dielectric ceramic having a composition to which O was added was manufactured. In this case, as in Example 1, each component other than lead oxide is mixed, calcined at 1.000°C, and the calcined product is crushed to a particle size of 0.9 μm. Pbf in the crushed material
Samples 30 to 32 were prepared by adding f04, calcining at 700°C, and then firing at a temperature of 900°C or lower. That is, in this example, when each component other than lead oxide is mixed in the method for preparing sample number 4 of Example 1, P b (cul/l W17t ) O*
Of these, each component other than lead oxide was blended.

Then, for each sample, its dielectric constant ε, dielectric loss ta
Variations in nδ, shrinkage rate, and dielectric constant were measured. The results and the results of sample number 4 of Example 1 are shown in Attached Table 6.

As is clear from this result, when combining components other than lead oxide, Pb(cu, 7□Wait) is added to those components.
) It can be seen that if Os is added in an amount of 5% by weight or less based on the main components, the sintering temperature for producing dielectric ceramics can be lowered.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between firing temperature and dielectric constant and the relationship between firing temperature and shrinkage rate in dielectric porcelain manufactured by a method within the scope of the present invention and a method outside the scope of the present invention. FIG. 2 is a graph showing the relationship between the calcination temperature and dielectric constant of components other than lead oxide in dielectric ceramics manufactured by a method within the scope of the present invention and a method outside the scope of the present invention. Figure 3 shows the relationship between the calcination temperature and dielectric constant after adding lead oxide in dielectric porcelain produced by a method within the scope of this invention and a method outside the scope of this invention, and the relationship between calcination temperature and weight. It is a graph showing the relationship with decrease.

Claims (1)

[Claims] 1 Pb (Mg_1_/_3N_2_/
_3) A method for producing dielectric porcelain made of a solid solution containing O_3 and other compounds with a composite perovskite structure containing lead, the method comprising: (a) preparing each component other than lead oxide in the composition of the dielectric porcelain; (b) a step of mixing and calcining each component other than the lead oxide to form a calcined product; (c) a step of crushing the calcined product to form a pulverized product; (d) a step of forming a crushed product of lead oxide. a step of preparing a powder; (e) a step of mixing the pulverized material and the lead oxide powder in a predetermined ratio and calcining the mixture to form a calcined product; (f) a calcined product of the mixture; A method for manufacturing dielectric porcelain, comprising: forming a molded product into a predetermined shape; and (g) firing the molded product. 2 The calcination temperature in the step (b) is 900°C to 1,
The method for manufacturing dielectric ceramic according to claim 1, wherein the temperature is in the range of 100°C. 3. The method for manufacturing dielectric porcelain according to claim 1 or 2, wherein the step (c) includes a step of pulverizing the calcined material of each component other than lead oxide to an average particle size of 1 μm or less. . 4 The calcination temperature in the step (e) is 600°C to 90°C.
The method for manufacturing dielectric ceramic according to any one of claims 1 to 3, wherein the temperature is in the range of 0°C.