JPH0450121A - Compound oxide powder composition, sintered material thereof and production thereof - Google Patents

Abstract

PURPOSE:To improve a dielectric constant, by excessively adding a Mg component and a Ni component to specific compound oxide powder. CONSTITUTION:A powder composition containing Pb(Mg1/3Nb2/3)O3Pb(Ni1/3Nb2/3) O3 (PMN-PNN for short)-based compound oxide powder, a Mg component and an Ni component is obtained by sintering. The powder composition contains more excessively the Mg component and the Ni component than a stoichiometric amount constituting PMN-PNN-based compound oxide.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides Pb(Mg1/3Nb2/3)03-Pb(
Ni+/1Nb2zi)03 (hereinafter referred to as PMN-PN
The present invention relates to a complex oxide powder composition (abbreviated as N), a sintered body thereof, and a method for producing the same. PMN-PNN
The complex oxide exhibits ferroelectricity and is used for dielectric materials, piezoelectric materials, pyroelectric materials, and the like.

[Prior art] Pb(Mg+/i Nbz/3)03 (hereinafter referred to as PMN
) or Pb(Ni1/g Nb2/3)03
Lead-based perovskite-type composite oxides, represented by PNN (hereinafter abbreviated as PNN), tend to have a pyrochlore phase as a by-product during their production, and the ferroelectric properties of materials using this material tend to increase. This causes a decrease in For this reason, various attempts have been made to obtain composite oxides having a single perovskite phase. For example, Mg and Nb
A method of reacting in advance, adding PB to it, mixing it, and then performing a solid-phase reaction to obtain single-phase PMN (
Materials Research Bullet
In vol. 17, 1245, Mitsugu 1982), etc. The present inventors have succeeded in producing a lead-based perovskite-type composite oxide by finely pulverizing and mixing raw material components in the presence of a dispersant, and then performing multi-stage calcination, without producing a pyrochlore phase as a by-product. A patent application was filed for a single-phase synthesis method (Japanese Patent Application No. 196553/1999).

BACKGROUND ART Currently, as electrical appliances become smaller, it is desired that the elements used in these products be smaller and more functional, and elements using ferroelectric materials, such as capacitors, are no exception. In order to miniaturize capacitors, it is important to stack thin layers of elements and improve the dielectric constant of the materials used, and PMN-PNN composite oxides with improved dielectric constants are also desired. .

[Problems to be Solved by the Invention] An object of the present invention is to provide a PMN-PNN-based composite oxide composition with improved dielectric constant, a sintered body thereof, and a manufacturing method thereof.

[Means for Solving the Problems] As a result of intensive studies to solve the above problems, the present inventors have developed a PMN-PNN composite oxide powder containing an excessive amount of Ig acid component and Ni component. - A PMN-PNN-based composite oxide sintered body obtained by sintering a PNN-based composite oxide powder composition, that is, containing Mg and Ni components in excess of the stoichiometric amounts, is composed of stoichiometric amounts. The present invention has been completed by discovering that the present invention is a sintered body having a higher dielectric constant than that of a PMN-PNN composite oxide sintered body. The present invention will be explained in more detail below.

The PMN-PNN complex oxide in the present invention refers to P)I
N.

A complex oxide containing PNN, for example, PMN
- PNN itself, PMN-PNN with PbTiOs,
Pb(Zn1/3 Nb2/s)03, PbZr0g
It refers to a solid solution of components such as.

The PMN-PNN composite oxide powder used in the present invention may be obtained by any method, including solid phase reaction method, coprecipitation method,
Products produced by methods such as alkoxide hydrolysis can also be used, but the method previously proposed by the present inventors (
(Japanese Patent Application No. 1-196553), that is, a method of multi-stage firing of a mixture of finely pulverized raw materials in the presence of a dispersant.
This is a preferred method because it yields a fine and uniform powder free of the by-product pyrochlore phase, and it is relatively inexpensive to mill.

The sintered body of the present invention is obtained by sintering a powder composition containing a PMN-PNN composite oxide powder, an Mg component, and a NI acid component. As mentioned above, the powder composition used here is composed of Mg
This composition contains the Ni component in excess of the stoichiometric amount constituting the PMN-PNN composite oxide powder.
It can be obtained by containing g component and Ni component. The dielectric constant of the obtained sintered body is improved regardless of whether one of the Mg component and the Ni component is contained in the PMN-PNN composite oxide powder, but in order to obtain the effects of the present invention, M
The purpose is to use a material containing both g5Ni components.

The Mg component used here is not particularly limited as long as it becomes MgO through thermal decomposition, and organic magnesium components such as magnesium oxide, magnesium carbonate, magnesium hydroxide, magnesium alkoxide, magnesium nitrate, magnesium chloride, acetate, etc. Examples include acid salts. Among these, magnesium nitrate, magnesium acetate, etc. are particularly preferred. In addition, the Ni component refers to N that is produced by thermal decomposition.
It is not particularly limited as long as it is iO, and examples include organic acid salts of nickel such as nickel oxide, nickel carbonate, nickel hydroxide, nickel alkoxide, nickel nitrate, nickel chloride, and acetate.

Among these, nickel nitrate, nickel acetate, etc. are particularly preferred.

M contained in PMN-PNN composite oxide powder composition
The amount of component g is the amount of PMN in the PMN-PNN composite oxide.
Although it varies depending on the amount of O, the amount is preferably 0.1 to 20 νt% (as Mg) based on the amount of Mg contained in the composite oxide powder, and more preferably 0.5 to LOwt.
%. Here, the amount of MgO is 2oνt%
If it is more than 0.1 wt%, excess MgO will segregate, which is undesirable, and if it is less than 0.1 wt%, the effect of the presence of MgO will be insufficient.

On the other hand, the amount of Ni component contained in the PMN-PNN-based composite oxide powder composition varies depending on the amount of PNNO in the PMN-PNN-based composite oxide, but is 0% for Niff1 contained in the composite oxide powder. .1 to 20vt% i (N
i), more preferably 0.
The amount is 5 to 10 νt%. Here, if the amount of Ni is more than 20wt%, excessive NiO will segregate, which is undesirable, and if it is less than 0.1vt%, NiO
The effect of its presence is insufficient.

As a method for incorporating the Mg component and the Ni component into the PMN-PNN composite oxide powder, if the Mg component and the Ni component are powders such as oxides or carbonates, they can be mixed using a dry method or a wet method using a ball mill, etc. Although they can be mixed, in this case, it is preferable that the Mg component and Ni component used are fine, and it is particularly preferable to use particles of 0.6 μm or less. Further, since wet mixing enables more uniform mixing than dry mixing, it is preferable to add water or the like to the mixing system and mix wet.

Moreover, in order to contain the Mg component and Ni component used in a more uniform state, it is more preferable to use the Mg component and Ni component in the form of a solution. This mixing method is, for example, M
PMN-PNN composite oxide powder with aqueous solutions of nitrates, acetates, etc. of g and Ni, solutions of oxides, carbonates, hydroxides, etc. dissolved in dilute acids, alcohol solutions of alkoxides of Mg and Ni, etc. It is about mixing.

The mixed slurry etc. when mixed by the above wet method are, for example,
Drying may be performed by spray drying, hot air drying, etc.

In the present invention, PMN- containing Mg component and Ni component
The PNN complex oxide powder composition may be subjected to heat treatment. In this heat treatment, the Mg component and Ni component used are thermally decomposed, and these are adhered to the surface of the PMN-PNN composite oxide powder in the form of oxides. It is suitable for preventing falling off and segregation.

The heat treatment temperature in this case is 200°C to 800°C, preferably 300°C to 600°C.

If the heat treatment temperature is lower than this temperature, the heat treatment will be insufficient and there is no point in carrying out the heat treatment, and if it is too high than necessary, grain growth of the powder will occur, which is undesirable.

P containing Mg component and Ni component by the above method
A MN-PNN composite oxide powder composition is obtained.

In the present invention, the method of making the PMN-PNN-based composite oxide powder composition contain an excessive amount of Mg component is as follows:
It is essential to add and mix the Mg component to the N-based composite oxide powder, but in order to contain an excessive amount of Ni component, in addition to the above method, it is necessary to add this in advance when preparing the PMN-PNN-based composite oxide powder. The oxide powder may be prepared by adding Ni component in excess of the stoichiometric amount. That is, the composite oxide powder composition containing Mg component and Ni component in excess of the stoichiometric amount of the present invention refers to the composite oxide powder composition containing Mg component and Ni component as described above. It also includes a composite oxide powder composition obtained by adding an Mg component as described above to a composite oxide prepared by using an excessive amount of Ni component in the raw material components.

When adding excess Ni component during powder preparation, for example, in the case of a solid phase reaction method when obtaining composite oxide powder, the time when raw materials such as oxides, hydroxides, and carbonates of each element are weighed and mixed. PMN-PNN composite oxide powder can be obtained by weighing and mixing the Ni raw material in advance so that the amount is in excess of the stoichiometric ratio, and then preparing the powder in a usual manner, but preferably is the method previously proposed by the present inventors (Japanese Patent Application No. 1-198553), that is,
In the presence of a dispersant, the raw ingredients are pulverized and mixed, and
In the method of performing multi-stage firing, it is preferable to use a raw material nickel component in excess of the stoichiometric ratio to prepare a PMN-PNN-based composite oxide powder containing an excessive amount of Ni component. In this way, a PMN-PNN-based composite oxide powder composition containing Mg component and Ni component in excess of the stoichiometric amount is obtained.

In the present invention, the excessive Mg component and Ni component are present in the powder composition in the form of oxides, etc. between grain boundaries of the PMN-PNN composite oxide powder forming a perovskite lattice. It is presumed that the

In the present invention, the composite oxide powder composition obtained by the method described above is molded. This molding method may be any molding method suitable for the desired final shape, and examples thereof include a mold pressing method, a slip casting method, a doctor blade method, and the like.

Next, the molded powder is sintered, and the sintering temperature of the present invention is
Although it varies depending on the composition of the powder used and the method of obtaining the powder,8
00°C to 1300°C is preferred. If the sintering temperature is lower than 800℃, sintering is insufficient, and if it is higher than 1300℃, p
b This is not preferred because the acid component evaporates.

The sintering time is 1 to several tens of hours, preferably 2 to 10 hours. If this temperature is shorter than 1 hour, the sintering will be insufficient, and if it is longer than necessary, the loss of the pb acid component in the components will be large, which is not preferable. The temperature increase rate during sintering varies depending on the size and shape of the sintered body, but is 1°C/hour to 300°C/hour, for example, if the sintered body is a single plate, it is 50°C/hour to 200°C.
°C/hour.

If this temperature increase rate is faster than necessary, the resulting sintered body will not be sufficiently densified, making it difficult to obtain a high-density sintered body, and unfavorably, cracks will occur during sintering.

The sintering atmosphere in the present invention is not particularly limited, and the sintering may be performed in the air or in oxygen. Further, it is preferable to perform sintering in a PbO atmosphere as necessary in order to compensate for losses caused by heating the Pb acid component.

A PMN-PNN composite oxide sintered body is obtained by the method described above.

The sintered body thus obtained exhibits high dielectric properties and can be used for capacitors and the like.

[Effects of the Invention] The sintered body of the present invention exhibits a higher dielectric constant than a conventional sintered body that does not contain excessive amounts of Mg and Ni components.

[Example code] Next, the present invention will be explained in more detail with reference to Examples.

Example 1 MgO1,235g, Nb2O532,237g5
6,794 g of NiO and 27,298 g of TiO were placed in a polyethylene pot along with 120 ml of zirconia balls of 2 sq. lφ and 701 g of distilled water, and a dispersant (product name: rDispex A-4D J manufactured by Hoechst) was added.
．． 76 g of the slurry was added and wet-pulverized for 10 hours using a vibration mill, and the resulting slurry was evaporated to dryness using an evaporator to obtain a mixed powder. Next, the mixed powder was fired at 900°C for 2 hours.

Obtained powder 15.945g, PbO34,055g
2mm+φ zirconia ball 12hl and distilled water 7
The slurry was placed in a polyethylene pot along with 0 ml of the slurry and subjected to wet pulverization for 10 hours using a vibration mill, and the resulting slurry was evaporated to dryness using an evaporator to obtain a mixed powder. Next, the mixed powder was calcined at 800°C for 2 hours to PbTi0i (hereinafter referred to as P
(abbreviated as T) -PMN-PNN powder (powder-1
) was obtained.

To 120 g of the obtained powder, add 0 polyvinyl alcohol.
．． 1 g of nickel acetate tetrahydrate, 1.519 g of magnesium acetate tetrahydrate, 0.0438 g of magnesium acetate tetrahydrate, and 10 g of distilled water were mixed wet for 5 minutes using a pestle, dried with hot air, and heat treated at 500°C. A PT-PMN-PNN powder composition (powder-2) was obtained.

Approximately 1.6 g of this powder-2 was placed in a mold with a diameter of 13 mm + φ, pressure molded at a pressure of 1 ton/cm 2 , and sintered at 1000° C. for 2 hours. The sintered body density of this sintered body is 8.21
g/c+a3 (according to Archimedes method), relative dielectric constant is 1
8,200 (measurement temperature 25°C).

Example 2 Mg01.235g 5Nb20s 32.237g
-Ni07.134g (5νt% excess over stoichiometric amount)
, 7,298 g of TiO was crushed in the same manner as in Example 1,
After mixing, it was calcined.

Obtained powder 15.931g, PbO34,069g
was pulverized in the same manner as in Example 1, mixed, and then calcined to 5νt%.
PT-PMN-PNN powder with excessive Ni content (powder-3)
I got it.

Powder - 320g, polyvinyl alcohol 0.1g.

Magnesium acetate tetrahydrate 0.0438g, distilled water 10
g was added, wet-mixed for 5 minutes using a pestle, and then dried with hot air to form a powder composition (powder-4) in which 5vt% Ni component excess PT-PMN-PNN powder and 3vt% Hg component excess (powder-4). I got it.

Powder-4 was molded in the same manner as in Example 1 and sintered at 1000°C for 2 hours. The sintered body density of this sintered body is 8.18g
/cm3 (according to Archimedes method), relative permittivity is 18.
800 (measurement temperature: 25°C).

Comparative Example 1 After adding 0.5 wt % of polyvinyl alcohol as a binder to the powder-1 obtained in Example 1, it was molded and sintered in the same manner as in Example 1. The sintered body density of this sintered body is 8.
The dielectric constant was 18 g/cm3 (according to Archimedes method) and 13,200 (measurement temperature: 25°C).

Comparative Example 2 To 120 g of the powder obtained in Example 1, 0.1 g of polyvinyl alcohol and 0.1519 g of nickel acetate tetrahydrate were added.
.

After adding 10 g of distilled water and wet-mixing using a pestle for 5 minutes, drying with hot air produced PT-PM with an excess of 3 wt% Ni component.
An N-PNN powder composition was obtained.

The obtained powder composition was molded and sintered in the same manner as in Example 1. The sintered body density of this sintered body is 8.15g/eI1
3 (according to Archimedes method), relative permittivity is 14.800
(Measurement temperature: 25°C).

Comparative Example 3 After adding 0.5 νt% of polyvinyl alcohol as a binder to the powder-3 obtained in Example 2, it was molded and sintered in the same manner as in Example 1. The sintered body density of this sintered body is 8
．． 21 gleI13 (according to the Archimedes method), and the relative dielectric constant was 15,100 (measurement temperature: 25° C.).

Comparative Example 4 To 120 g of the powder obtained in Example 1, 0.1 g of polyvinyl alcohol and 0.04 g of magnesium acetate tetrahydrate were added.
38 g, 10 g of distilled water was added, wet-mixed using a pestle for 5 minutes, and then dried with hot air to obtain P with an excess of 3 wt% Mg component.
A T-PMN-PNN powder composition was obtained.

The obtained powder composition was molded and sintered in the same manner as in Example 1. The sintered body density of this sintered body is 815g/cn+3
(based on Archimedes method), relative permittivity is 14.500
(Measurement temperature: 25°C).

Claims (1)

[Claims] 1) Pb(Mg_1_/_3Nb_2_/_3)O_ containing Mg component and Ni component in excess of the stoichiometric amount
3-Pb(Ni_1_/_3Nb_2_/_3)O_3
composite oxide powder composition. 2) Pb(Mg_1_/_3Nb_2_/_3)O_ containing Mg component and Ni component in excess of the stoichiometric amount
3-Pb(Ni_1_/_3Nb_2_/_3)O_3
Composite oxide sintered body. 3) Pb(Mg_1_/_3Nb_2_/_3)O_3
- A method for producing a composite oxide sintered body, comprising sintering a powder composition containing a Pb(Ni_1_/_3Nb_2_/_3-based composite oxide powder, an Mg component, and a Ni component.