JPS63288917A - Metal oxide for electroceramics - Google Patents

Abstract

PURPOSE:To increase the mechanical strength, such as transverse strength, etc. by incorporating a metal atom in the amt. smaller than the stoichiometric amt. in the specified perovskite metal oxide for electroceramics. CONSTITUTION:In the perovskite metal oxide shown by the formula, A(B, C)xDyO3, the metal element shown by B is incorporated in the amt. smaller than the stoichiometric amt. by 1-25atom.% to obtain the aimed metal oxide for electroceramics. In the formula, A is a bivalent metal element having 12 oxygen coordination number or >=2 kinds of metal elements incorporated in such ratio that the mean valency is controlled to two. In addition, C is a metal element having 6 oxygen coordination number, and D is a 4 valent metal element having 6 oxygen coordination number or >=2 kinds of metal elements incorporated in such ratio that the mean valency is controlled to four. Besides, the B element and C element are incorporated so that the mean valency of the elements is controlled to four, (x) is >=0.05, and the sum of (x) and (y) is 0.95-1.05.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Separation> The present invention relates to a metal oxide for electroceramics, particularly a C perovskite type metal oxide for electroceramics containing an iron group element. These metal oxides possess dielectric, piezoelectric and electrostrictive properties, making them ideal for capacitors,
Widely used in actuators, spark plugs, pumps, filters, etc.

<Conventional technology and its problems> Recently, the usage conditions of electroceramics have become harsher,
With the increase in output, there is a growing demand for higher strength. However, conventional electroceramics do not have sufficient strength when repeatedly applied voltage, high output, or when mechanical L force is applied. However, there were problems such as insufficient reproducibility and variation in the amount of distortion during use.

The present invention specifically seeks to provide metal oxides for electroceramics that are resistant to mechanical stress.

Elaborate Means to Solve the Problems In order to achieve the above object, the present inventors investigated various metal oxides and found that Fe, which is an iron group element,
Co'! 7'c shows that mechanical strength can be improved without impairing electrical properties by reducing the content of iron group elements below the stoichiometric amount in N1-containing perovskite metal oxides. This led to the present invention.

That is, the present invention provides a perovskite metal oxide represented by the formula A(B,C)xDyO3 containing 1 to 25 atomic % less ○ and Y
This is a characteristic metal oxide for electroceramics.

(However, A is a metal element with oxygen 12 coordination and a divalent valence, or is contained in a ratio such that the average valence is divalent.)
Metal element with fc2m or more, B is iron element, C is oxygen 6
Coordination metal element, D is a metal element with 6 oxygen coordination and a valence of 4, or a metal element containing two or more types of metal elements in a ratio such that the linear average valence is 4, 0 is a metal element with a valence of 4; ′# is prime and B
The average valence of element and C element is 4, but X is 0.05 or more, and the sum of X and y is 0.95 or more and 1.05. Must be below. ) Hereinafter, the present invention will be explained in detail. In the present invention, A
Examples of metal elements with 12-coordination of oxygen are Pb,
Examples include 5rXBa, Ca, and la.

When using a metal element other than divalent, 2/(valence) is applied as a correction coefficient. For example, in the case of trivalent La, it is blended as 2/3 L''.

The iron group element represented by B is at least one of Fe, Co, and Ni, and the metal element with oxygen hexacoordination represented by C has an average valence of 4 when combining elements B and C. An example of this is NbN, a pentavalent metal element.
"b% T' SBi and WXT which is a hexavalent metal element
8. Examples include Re.

The content ratio of B element and C element is, for example, B 1/3 C2/3 when B element is divalent and C element is pentavalent;
If the element is divalent and C element is hexavalent, B 1/2 C1/2
It is. 'tftz B element is trivalent and C element is 5111
In case of II, it is B 1/2 CI/2, and when B element is hexavalent and C element is hexavalent, it is B 2/3 C1/3. B
The total amount X of the element and C element must be 0.05 or more. If X is less than 0.05, the object of the present invention, which is to improve the mechanical strength of the metal oxide or its sintered body, cannot be achieved.

The metal element with oxygen hexacoordination and having a valence of 4, represented by D, is a tetravalent metal element such as Ti or Zr, or a 2a or more metal element containing at a ratio such that the average valence is 4. It is a metallic element. In this way, to combine two or more metal elements to obtain an average valence ytA, for example, CD"" 1/3
D5" 2/3), (D" 1/2 D5+
1/2), CD" 1/2 D" 1/2), CD"
2/3 D” 173), (D” 1/4 D”
There are combinations based on ratios such as 3/4). (However, D+ is Ll, Cu, etc., and Dg+ is Mg, Z
nlMn, 5nSC (sp in l etc., D"1MnX5
k), Al, 'i'b, In, Se, Y, etc., and D5+ is Nl), St).

'I'a, 131, etc., and D6+ is w, 're, R
13 etc. ) The total amount (X+7) of the above-mentioned B element and mouth system Z combination 'fc amount X and content jty of D element is 0.95 or more 1.05
Must be less than or equal to The sum of X and 1 is 0.95
If it is less than or exceeds 1.05a', the electrical properties of the resulting metal oxide will deteriorate.

The present invention is characterized in that the iron group element contained in B is less than the stoichiometric amount.

The ratio of less content, that is, the reduction in weight, is 1~
It is not insignificant at 25 atomic %, preferably 2 to 20 atomic %. Even if the reduction rate is less than 1 atomic %, or conversely even if it exceeds 25 atomic %, there is no effect on improving mechanical strength.

The raw materials for these metal elements may be simple metals, alloys, or metal compounds, but metal oxides are generally particularly preferred. Perovskite-type metal oxides are produced from mixtures containing these gold maple elements! To produce 1', the above-mentioned mixing 4[--calcination and/or sintering may be carried out. Calcining is heating the raw material mixture @ at a temperature of 700 to 1000°C, and sintering is heating the raw material mixture or calcined powder Y
The powder is crushed to a particle size of 6 μm or less, and the resulting powder bed is molded by pressure molding, sheet molding, etc., and heated at a temperature of 900 to 1 μm.
This is a method of sintering at 300°C.

Hereinafter, the present invention will be specifically explained with reference to Examples.

<Example> Examples 1 to 5 and Comparative Examples 1 to 2 pbo, Coo, Nb2O6, zro2 and TlO2
Each powder 'k Pt+(Co 1 /3 Nt) 2/
3) Weigh and mix in the ratio of o, 2Zro, 'r1o,. However, at this time, the amount of C00 was made smaller than the stoichiometric amount by the reduction rate shown in Table 1.

This mixture? ! 1 asoo ~ 900' in the in-matsufuru furnace
Calcinate for 1 hour at C to form Pb (Co1/3 Nb2/3)
Peropskite type metal oxide binder indicated by δ o, aZro, 4T1o, 40s.

Particle size is 0.5 after being crushed for 5 hours with this temporary/Akatsuki ball mill.
~2μffi powder, this is Y1000kg/3”
Pressure molded into a disc with a diameter of 201 m at a pressure of 110 m.
It was sintered at 0-1200°C.

From the above sintered body, width 5mm, depth Q 3mm, feldspar 251m
After cutting out the test piece and polishing it, a 6-point bending test was performed with a span of 10 gm using a testing machine (SV3 model manufactured by Imada Seisakusho Co., Ltd.) to measure the bending strength.The results are shown in Table 1. Those containing 1 to 25 atomic % less iron group elements than the stoichiometric amount had higher bending strength.

Examples 6-10 and Comparative Examples 3-4 pbo, Nt)20. , zr02 and TlO2 powders Pb(Ni 1/2 Nb2/3)o, IZro
, 4ISTio, +5, and then weighed 1 mm:% MnO2Y of each of the above powders and mixed these powders. In this case, the amount of NiO should be less than the stoichiometric amount by the reduction rate shown in Table 1. Hereinafter, one calcining process was performed in the same manner and under the same conditions as in Examples 1 to 4 and Comparative Examples 1 to 2, and perovskite metal oxides having the formula % were formed. Test pieces were cut out from this calcined product in the same manner and under the same conditions as in Examples 1 to 4 and Comparative Examples 1 to 2, and the bending strength was measured.

As a result, as shown in Table 1, materials containing 1 to 25 atomic percent less iron group elements than the theoretical amount had a higher flexural strength.

Examples 11-13 and Comparative Examples 5-7 Pb0, 3rCO3, cao X'ra2o, , T
Each powder of i0g, ZnO, and Nt)205 was weighed and mixed in the ratio of the metal elements of the metal oxide shown in Table 2. It is a friend, and the old man of C00 is shown in Table 2. Examples 11 to 16
was 10% less than the stoichiometric amount, and Comparative Examples 5 to 7 were made at the full stoichiometric amount.

The mixture @#1ltJ of Gore et al. was calcined at a temperature of 800 to 900° C. for 1 hour to obtain the full range oxide shown in Table 2. These calcined bodies were ground in a Z-mill for 5 hours to obtain a powder with a particle size of 0.5 to 2 μm. /cm" pressure to form a disc with a diameter of 20 mm, and at a temperature of 1100 to 1200.
'C sintered.

As a result of determining the bending strength of the disc using the @force distribution method, as shown in Table 2, it contains less iron group elements! ：The transverse flexural strength was low.

Table 1 <Effects of the Invention> The metal oxide for electroceramics or the sintered body thereof of the present invention has an effect that its mechanical strength is particularly high.

Claims (1)

[Claims] In the perovskite metal oxide represented by the formula A(B,C)_xD_yO_3, B is 1 less than the stoichiometric amount.
A metal oxide for electroceramics, characterized in that the content is less than ~25 atomic %. (However, A is a metal element with oxygen 12 coordination and a divalent valence, or two or more metal elements contained in a ratio such that the average valence is divalent, B is an iron element, and C is an iron element. D is a metal element with 6 oxygen coordinations and a valence of 4, or 2 or more metal elements contained in a ratio such that the average valence is 4, O is oxygen The B element and the C element are contained in a ratio such that their average valence is 4, and x is 0.05 or more, and the sum of x and y is 0.95 or more and 1.05. The following must be true.)