JPS6335449A - Manufacture of ceramic composition - Google Patents

Abstract

(57) [Abstract] 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 producing a porcelain composition, which is particularly useful for telephone materials, translucent ceramic materials, electro-optic functional materials, etc. Formula (I) Pb La (Zr
The present invention relates to a method for manufacturing a ceramic raw material powder represented by the following formula: Ti1-, ) l-x/4031-x x y (wherein O<x<1.0<y<1).

[Conventional technology] In recent years, functional ceramics such as ceramic capacitors and ceramic optical materials have become smaller and smaller.
High precision is desired, and high reliability is also required.

In addition, when these ceramics are put into practical use, the high sintering temperature results in high firing costs.Especially when using these ceramics in multilayer capacitors, it is difficult to use them as internal electrodes.
This requires the use of expensive high-melting point noble metals such as Pd and Pt, which is a major obstacle to reducing capacitor manufacturing costs.

Therefore, in order to reduce the manufacturing cost of multilayer capacitors by using inexpensive silver-based electrodes as the internal electrodes of multilayer capacitors, low-temperature sinterability is also strongly desired for these functional ceramics. There is.

As such functional ceramics, the above-mentioned formula (1
) (hereinafter sometimes abbreviated as rPLZTJ) has been attracting more attention than ever before as a multifunctional material with dielectric properties, translucency, electro-optical properties, etc.

Conventionally, PLZT porcelain compositions have generally been produced by using oxides and carbonates of respective metal components as starting materials, mixing them in a mortar, ball mill, etc., pulverizing them, and then firing them.

[Problems to be solved by the invention] However, with such conventional PLZT manufacturing methods, it is difficult to perform sufficient mixing, impurities are easily mixed during mixing, and there is a limit to the degree of pulverization. Therefore, it is extremely difficult to achieve uniform composition, high purity, and refinement of the raw material powder.

For this reason, the obtained PLZT cannot be said to be fully satisfactory in terms of its properties and low-temperature sinterability, and in the past, efforts have been made to improve the precision and low cost of functional ceramics, and to achieve high reliability. I was unable to secure sex.

[Means for Solving the Problems] The present invention solves the drawbacks of the above-mentioned conventional method, and solves the above-mentioned formula (I).
The purpose is to provide a method that can obtain the PLZT ceramic raw material powder shown in the form of extremely fine powder with high purity and good compositional uniformity. The aim is to improve sexual performance.

The present invention provides a method for producing a porcelain composition having a chemical composition represented by the following formula: % (where O<X<i, O<y<1). ? At night, a mixture of lead alkoxide and zirconium alkoxide is mixed to cause hydrolysis of the alkoxide and coprecipitation of the lanthanum component, and the resulting precipitate is heated to obtain a porcelain composition having the above composition. A method for manufacturing a porcelain composition characterized by the following.

Hereinafter, the present invention will be explained in detail.

In the present invention, first, an aqueous solution containing lanthanum nitrate and/or lanthanum acetate is mixed with a mixed solution of lead alkoxide, zirconium alkoxide, and titanium alkoxide, and the water in the aqueous solution containing lanthanum nitrate and/or lanthanum acetate is used. Then, lead alkoxide, zirconium alkoxide and titanium alkoxide are hydrolyzed, and at the same time, the lanthanum component is co-precipitated.

That is, in the present invention, lanthanum nitrate and/or lanthanum acetate are used as raw materials for the lanthanum component of PLZT. These raw materials can be easily purified to a high degree by recrystallizing commercially available products.

To prepare an aqueous solution containing lanthanum nitrate and/or lanthanum acetate, these raw materials may be dissolved in a predetermined amount of water to obtain a desired PLZT composition ratio. On this occasion,
It is desirable that the amount of water be as small as possible for convenience of handling.

On the other hand, as raw materials for lead, titanium, and zirconium components,
Lead alkoxide, titanium alkoxide, and zirconium alkoxide each represented by the following chemical formulas (a), (b), and (C) are used.

Pb(OR)2 − (a) Ti(OR)4 ... (b) Zr(OR)+ ・= (c) (In formulas (a), (b), and (c), R represents an alkyl group The type of alkyl group R in these alkoxides is not important in terms of wood quality, but from the viewpoint of removability etc., alkoxides of lower alkyl groups such as methyl, ethyl, isopropyl and butyl groups are generally used. It is preferable to use

Titanium alkoxide and zirconium alkoxide can be obtained by conventional methods, for example, by reacting metal Ti or Zr with alcohol, but commercially available products with sufficiently high purity are also available.

Lead alkoxide can be easily obtained in high purity by the method disclosed in Japanese Patent Application No. 52332/1988, which was previously filed by the applicant.

A mixture of these metal alkoxides can be prepared by dissolving the necessary metal alkoxides in an organic solvent to obtain the desired PLZT composition ratio, and then thoroughly mixing the mixture by mechanical stirring, etc., to obtain a uniform composition. This is preferable from the viewpoint of preserving the properties.

In this case, the organic solvent may be one that dissolves the metal alkoxide, but from the viewpoint of solubility, benzene,
Aromatic hydrocarbons such as toluene and xylene, alcohols such as ethanol and propatool, or mixtures thereof are suitable.

The metal alkoxide mixture prepared in this manner and the aqueous solution containing lanthanum ions may be mixed by dropping the aqueous solution containing lanthanum ions into the metal alkoxide mixture under stirring, or conversely, by adding lanthanum ions to the metal alkoxide mixture. The metal alkoxide mixture may be added dropwise to the aqueous solution with stirring.

Mixing of both solutions causes hydrolysis of the alkoxide and coprecipitation of the lanthanum component. In this case, the reaction temperature is preferably within the range of G to 100°C for convenience of handling.

The filtrate of the thus obtained precipitate is separated and removed by filtration or the like, dried, and then heated to obtain PLZT crystals. In this case, the heating temperature is 20
Preferably, the temperature is 0° C. or higher and lower than the decomposition temperature of PLZT.

As is clear from the analysis of the filtrate obtained by separating the precipitate, in the present invention, almost no lead, lanthanum, titanium, or zirconium components leak or remain in the filtrate, and the desired content is almost completely eliminated. It is possible to co-precipitate the composition.

According to electron microscope observation, the particle size of the PLZT powder obtained by the method of the present invention is 0.008 to 0.01 μm when the precipitate is calcined at 400°C for 2 hours, which is extremely fine. It is a powder with uniform particle size.

[Function] Since the method of the present invention is basically a liquid phase reaction, it is possible to obtain PLZT with a higher purity and a more uniform composition than with conventional methods. Moreover, the PLZT obtained by heating becomes an extremely uniform fine powder.

Therefore, PLZT produced according to the present invention has excellent various functional properties and is also extremely excellent in low-temperature sinterability.

[Example] Examples and comparative examples will be given below to explain the low-temperature sinterability of the PLZT powder produced according to the present invention and the dielectric properties as one of the functions of PLZT.

It should be noted that the present invention is not limited to the following examples unless it exceeds the gist thereof.

In the following Examples and Comparative Examples, the dielectric properties of PLZT powder are determined by 3000 k
After pressure molding into a disk shape with a diameter of 16 mm and a thickness of 1 mm at a pressure of 1050 g f/c rn'' in air.
1 at each temperature of ℃, 1100℃, 1150℃, 1200℃
After firing for a period of time, silver electrodes were baked on both sides of the disc of the obtained sintered body, and the dielectric constant, dielectric loss, and electrical resistance were measured at 25°C. Furthermore, the rate of change (TC) in capacitance at -55°C and 125°C was measured based on the capacitance at 25°C. Note that the dielectric constant and dielectric loss were measured using a digital LCR meter at 1 kHz. Further, the electrical resistance was measured using an insulation resistance meter after applying a voltage of 100 cm for 5 seconds.

Pb La (Zr Ti
) 00.88 0.12 0
．． 70 0.30 0.97 Synthesis Example 1 of 3 Lanthanum nitrate aqueous solution (0,694 mol/λ) 173 m
iL in a benzene solution of lead butoxide (0,672 mo
1/u) 131 QrrIL, 82.7 g of titanium isopropoxide, and 261 g of zirconium butoxide were slowly added dropwise to a mixed solution with stirring.

Note that the temperature during the reaction was maintained at 30°C.

After the precipitate thus obtained was filtered, it was dried at 80°C for 10 hours, and then heated at 700°C for 5 hours to obtain PLZT powder with the desired composition.

Table 1 shows the measurement results of the dielectric properties of the obtained ceramic composition.

Example 2 A PLZT powder having the desired composition was obtained in the same manner as in Example 1, except that the lanthanum nitrate aqueous solution was replaced with a lanthanum acetate aqueous solution having the same concentration.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 3 In the same manner as in Example 1, except that titanium isopropoxide was changed to titanium butoxide,
A PLZT powder having the desired composition was obtained.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 4 A PLZT powder having the desired composition was obtained in the same manner as in Example 1, except that zirconium butoxide was replaced with zirconium isopropoxide.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 5 PLZT having the desired composition was obtained in the same manner as in Example 1 except that lead butoxide was replaced with lead isopropoxide.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 6 P of the desired composition was prepared in the same manner as in Example 1, except that the temperature during the reaction was changed from 30°C to 85°C.
LZT powder was obtained.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 7 PLZT powder having the desired composition was obtained in the same manner as in Example 1, except that the benzene solution of lead butoxide was replaced with an n-xylene solution of lead impropoxide.

The measurement results of the dielectric properties of the obtained ceramic composition were equivalent to those of Example 1 within the measurement error.

Example 8 A PLZT powder having the desired composition was obtained in the same manner as in Example 1, except that the benzene solution of lead butoxide was replaced with a toluene solution of lead impropoxide.

The measurement results of the dielectric properties of the obtained porcelain composition are as follows.
It was equivalent to Example 1 within a certain error.

Comparative Example 1 Metal oxides of pbo, TiO2, La203, and ZrO2 were mixed and ground in a ball mill to have the same composition ratio as in Example 1, then calcined at 700°C for 5 hours, and then ground again in a ball mill. PL with the same composition as Example 1
ZT powder was prepared.

Table 1 shows the measurement results of the dielectric properties of the obtained ceramic composition.

Koiōki Example 9 PLZT powder having the desired composition was obtained in the same manner as in Example 1 except that the blending ratio of each raw material was changed.

Table 2 shows the measurement results of the dielectric properties of the obtained ceramic composition.

Comparative Example 2 A PLZT powder having the same composition as in Example 9 was prepared in the same manner as Comparative Example 1 except that the blending ratio of the raw materials was changed.

Table 2 shows the measurement results of the dielectric properties of the obtained ceramic composition.

Tables 1 and 2 show that the PLZT powder according to the present invention has an extremely low sintering temperature and excellent electrical properties.
It is clear that LZT porcelain compositions can be obtained.

[Effects of the Invention] As detailed above, according to the method for producing a porcelain composition of the present invention, it is possible to easily and easily produce PLZT powder having a high purity, extremely uniform composition, and a uniform fine powder with a desired composition. It is possible to manufacture it reliably.

Therefore, the resulting porcelain composition has extremely excellent properties,
The dielectric constant, insulation resistance, and capacitance-resistance product are large, and the dielectric loss is small. Therefore, by using the ceramic composition obtained by the present invention, a highly reliable small-sized, large-capacity capacitor can be obtained.

In addition, the ceramic composition obtained by the present invention has excellent low-temperature sintering properties and has a low firing temperature, so the firing cost is monovalent, and when used in a multilayer capacitor, it can be used for internal electrodes made of relatively inexpensive silver-based materials. Can be used. Therefore, the manufacturing cost of the multilayer capacitor can be reduced, and its price can be significantly reduced.

Agent: Patent Attorney: Shigeno Tsuyoshi Procedural Amendment September 10th, 1986

Claims (3)

[Claims] (1) The chemical composition has the following general formula Pb_1_-_xLa_x(Zr_yTi_1_-_y
)_1_-_x_/_4O_3 (in the formula, 0<x<1, 0
<y<1) In the method of manufacturing a ceramic composition represented by <y<1), an aqueous solution containing lanthanum nitrate and/or lanthanum acetate is mixed with a mixed solution obtained by mixing lead alkoxide, zirconium alkoxide, and titanium alkoxide. A method for producing a porcelain composition, which comprises: hydrolyzing the alkoxide and co-precipitating the lanthanum component, and heating the resulting precipitate to obtain a porcelain composition having the above composition. (2) The method for producing a ceramic composition according to claim 1, wherein the lead alkoxide, zirconium alkoxide, and titanium alkoxide are mixed in a state dissolved in an organic solvent. (3) The method for producing a porcelain composition according to claim 1 or 2, characterized in that the precipitate is heated in a temperature range of 200° C. or higher and lower than the decomposition temperature of the porcelain composition. .