JPH042656A - Porcelain composition having high dielectric constant - Google Patents

Abstract

PURPOSE:To reduce dielectric loss by blending BaTiO3 with Nb2O5 and CoO in a specific molar ratio to give a composition and adding CaZrO3 to the composition. CONSTITUTION:A blend of BaCO3 and TiO2 in a molar ratio of 1/1 is prepared as a starting raw material, dehydrated, dried, temporarily molded and calcined to form BaTiO3. A main component obtained by blending 95.0-99.9mol% ground BaTiO3 with 0.5-3.0mol% Nb2O5 and 0.5-3.0mol % CoO is mixed with 0.2-5.0wt.% CaZrO3, further optionally <=3wt.% MnO and <=0.5wt.% Nd2O3 and dried. Then the mixture is incorporated with a proper amount of an organic binder, kneaded, molded under pressure and burnt to give a porcelain composition having high dielectric constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high dielectric constant porcelain composition that has a small change in dielectric constant over a wide temperature range of 2%.

This invention relates to an excellent high dielectric constant ceramic composition with low dielectric loss.

[Conventional technology]

Conventionally, barium titanate (BaTiO3) has been used as a dielectric ceramic composition with a high dielectric constant and a small temperature change in the dielectric constant.
Bisousus vs. compounds 9 such as Bi2O3@8nO2 and B
i20a * ZrO2 and Ta205 * Nb2O5
etc., to reduce the rate of change in temperature characteristics.

[Problem to be solved by the invention]

However, when the dielectric constant of a composition containing these components is increased, the rate of change in capacitance increases.

There was naturally a limit to increasing the dielectric constant. Therefore, when these compositions were used in capacitors, it was difficult to obtain large capacitance with a small size.

In addition, in compositions containing bismuth compounds such as those mentioned above, the bismuth component evaporates during firing, causing the porcelain composition body to bend or pinholes to form, resulting in a dense porcelain composition. Difficult.

Furthermore, there was a problem in that the electrical characteristics also varied.

Furthermore, when a multilayer ceramic capacitor is made from barium titanate containing bismuth, the palladium or silver-palladium alloy that is the internal electrode reacts with the bismuth that is a component of the dielectric and loses its function as an electrode. Expensive platinum must be used for the electrodes, which increases the cost of multilayer ceramic capacitors.

Therefore, an object of the present invention is to provide an excellent high-permittivity ceramic composition that exhibits little change in dielectric constant over a wide temperature range and has low dielectric loss.

[Means to solve the problem] In order to achieve the above object, the inventors of the present invention have conducted extensive research.

BaTi0a: 94.0 mol% to 99.0 mol%1
'Jb2Q5: 0.5 mol% to 3.0 mol%
Coo: It has been found that a ceramic composition containing 0.2% to 5.0% by weight of CaZrO3 based on 0.5% to 3.0% by mole of the main component satisfies the above objective.

Also required (2) MnO is less than 0.3 weight and Nd2
It has been found that the properties are further improved by containing O3 at 0.5 weight or less. [Function] By using the dielectric ceramic composition of the composition of the present invention,
It has a high dielectric constant value of approximately 2000 to 4700 at room temperature, and the dielectric loss (-δ) is a small value of 1.2% or less. X7R characteristics (-55℃~
It was possible to obtain a high-permittivity ceramic composition with excellent characteristics such that the change in dielectric constant within the temperature range of +125°C was within ±15% with respect to 25°C.

〔Example〕

An embodiment of the present invention will be described using FIGS. 1 to 3.

Figure 1 is a ternary composition diagram of the high dielectric constant ceramic composition of the present invention, Figure 2 is a manufacturing process diagram of the high dielectric constant ceramic composition of the present invention, and Figure 3 is a diagram of the manufacturing process of the high dielectric constant ceramic composition of the present invention.
The figure shows the temperature characteristic curve of capacitance.

Starting material and LTE, BaCO3 and TiO2 in 1:1 ratio
(See Figure 2 I).

The prepared starting materials are subjected to dehydration and drying treatment (see Figure 2 I).

Next, these raw materials were temporarily molded and stabilized at 1000 to 1200°C for 2 hours to carry out a chemical reaction.

Preliminary firing is performed to form 13aT ios (see FIG. 2I).

This BaT i03 is pulverized using, for example, an atomizer (see FIG. 2 ff).

Pulverized BaTiO3, Nb2O5, Coo, Nd
2O3.

Weigh CaZrO3 and MnCO3 so that the composition after firing is as shown in Table 1, wet mix and dry (Fig. 2
reference).

An appropriate amount of organic binder was added to this and molded at a molding pressure of about 3 tons/d, with a diameter of 16.5 wm and a thickness of about 0.6 m.
Create a disc-shaped molded product of m. Next, this molded product is 122
Stabilize at 0°C to 1340°C for 2 hours and carry out main firing (second
(See figure ■).

Silver electrodes are baked on both ends of the obtained porcelain composition body to form a capacitor (see Figure 2).

The electrical characteristics of these capacitors are measured at a frequency of lKH2, a DC voltage of IV, and a room temperature of 20°C (see Figure 2).

The results of each measurement are shown in Table 1.

In addition, material floor 1, 3-3.3-4.3-8.3 in Table 1
-12.6, 8, 9, 11, and 12 are not included in the scope of the present invention.

As is clear from Table 1 below, the dielectric ceramic composition of the present invention has e Ba'I"iQ3: 94.00 mol% to 99
．． 00 mol%, Nb2O5: 0.50 mol% ~ 3
．． 0 mol duck, Co.

:0.50 mol% to 3.0 mol% as a main component, and contains 0.2% to 5.0% by weight of CaZrOs based on the above main component, and if necessary, Nd2O3 is added to 0. The properties are further improved by adding 0.3 parts by weight or less of MnO.

Fig. 1 shows a ternary component diagram consisting of the composition of the above-mentioned main components, and the range connecting each point 2.7, 5.10 in Fig. 1 with a line is one ternary component of the present invention. The number of each point in FIG. 1 corresponds to the sample in Table 1.

Next, the reason for limiting the composition range of the present invention will be explained with reference to Table 1.

BaTiO3 is 94. If O is less than 0 mol%, the relative permittivity (1) will be low (see sample floor 6 in Table 1), 99.0
If it exceeds mol%, dielectric loss (1aJ1δ), temperature characteristic change rate (ΔC/C25°C) and sinterability will deteriorate (first
(See table sample floor 1).

Moreover, if Nb2O3 is less than 0.50 mol%, taa
If it exceeds 3.0 mol %, the dielectric constant becomes low (see, for example, sample Nl16 in Table 1).

607025°C becomes worse (for example, Table 1 sample strain 8°9
Reference) 0 Furthermore, if Coo is less than 0.5 mol%, tmδ and 6
For example, Table 1 sample Na
If it exceeds 3.0 mol %, the dielectric constant becomes low (for example, see sample N11l in Table 1).

601025° C. (see, for example, samples Na1l and 12 in Table 1).

Moreover, the content of CaZrOs is relative to the above main components.

If it is less than 0.2% by weight, 607025℃ will increase (for example, see sample floor 3-4 in Table 1), and even if it is 5.0% by weight or more, ΔC/C25℃ will increase (for example, sample floor 3 in Table 1). -8)).

There is no problem in use even if Nd203 is not added to the above ceramic composition (for example, see Sample Floor 3 in Table 1).

Addition of up to 0.5% by weight improves sinterability (see, for example, sample Nα3-1 in Table 1), and addition of 0.5% by weight or more improves sinterability.
/C25°C increases (for example, see sample floor 3-3 in Table 1).

The addition of MnO, like the addition of Nd2O3, poses no problem in use even if it is not added (for example, see sample floor 3-9 in Table 1).
．． Addition of up to 3% by weight prevents reduction (secondary).

-δ is improved and sinterability is also improved (for example, see sample 2 in Table 1). If it exceeds 0.3% by weight, ΔC/C25°C increases, sinterability deteriorates, and dense porcelain cannot be obtained (see, for example, sample Nα3-12 in Table 1).

FIG. 3 shows the capacitance temperature characteristic curve of the ceramic composition of the present invention. The curve numbers in FIG. 3 correspond to the sample floors in Table 1.

As is clear from FIG. 3, the compositions within the scope of the present invention, such as Nα3-1, are stable with little change in ΔC/C25°C.

〔Effect of the invention〕

By using the ceramic composition of the present invention, there is little change in dielectric constant over a wide temperature range.

In order to obtain an excellent high-permittivity ceramic composition with low dielectric loss (2).

In addition, its composition does not contain bismuth, which easily reacts with palladium or silver-palladium alloys.

When manufacturing a multilayer capacitor using this composition as a dielectric layer, palladium alone or a silver-palladium alloy can be used as the internal electrode. Therefore, there is no need to use expensive platinum or platinum-palladium alloy, and the cost of the product can be significantly reduced, resulting in immeasurable industrial benefits.

[Brief explanation of drawings]

FIG. 1 is a ternary composition diagram of the high dielectric constant ceramic composition of the present invention. FIG. 2 is a manufacturing process diagram of the high dielectric constant ceramic composition of the present invention. FIG. 3 is a temperature characteristic diagram of capacitance. Patent applicant: TDC Co., Ltd. Representative patent attorney: Akira Yamatani (1 other person) Te5Lper+atur
e Figure 3 Procedural amendment (voluntary) Contents of amendment January 16, 2022. Renka?

Claims (4)

[Claims] (1) BaTiO_3: 94.0 mol% to 99.0 mol% Nb_2O_5: 0.5 mol% to 3.0 mol% CoO
:0.5 mol% to 3.0 mol% of CaZrO_3 to a composition mainly composed of 0.2% by weight of CaZrO_3
A high dielectric constant ceramic composition containing ~5.0% by weight. (2) 0.3 MnO is added to the composition according to claim (1) above.
1. A high dielectric constant ceramic composition, characterized in that it contains not more than 0% by weight (excluding 0). (3) Nd_2O_3 in the composition according to claim (1) above.
A high dielectric constant ceramic composition comprising 0.5% by weight or less (excluding 0) of (4) Nd_2O_3 in the composition according to claim (2) above.
A high dielectric constant ceramic composition characterized in that it contains 0.5% by weight or less (excluding 0) of