JPH05330906A - Mn-zn-based ferrite - Google Patents

Abstract

PURPOSE:To develop a low-loss Mn-Zn-based ferrite having a high magnetic permeability by including specific amounts of CaO, Bi2O3 and SiO2 as secondary components in the Mn-Zn-based ferrite. CONSTITUTION:The Mn-Zn-based ferrite is obtained by adding 0.05-0.13wt.% CaO, <0.04wt.% Bi2O3 (with the proviso that 0wt.% is not included) and 0.01-0.02wt.% SiO2 (with the proviso that 0.01wt.% is not included) as secondary components to 52.5mol% Fe2O3, 25.5mol% MnO and 22.0mol% ZnO as principal components, producing a mixed raw material, calcining the mixed raw material at, e.g. 850 deg.C, then pulverizing the calcined material with a ball mill, compression forming the pulverized material into a ring shape and subsequently burning the formed compact. Thereby, the objective Mn-Zn-based ferrite having a high magnetic permeability to a high frequency of 500kHz and a small loss at the high frequencies is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to M having high magnetic permeability and low loss.
It is an object to provide an n-Zn ferrite.

[0002]

2. Description of the Related Art Mn--Zn type ferrite having a high magnetic permeability is mainly composed of Fe2O3, ZnO and MnO, and various additives (Bi, Ca,
It was a material to which V) was added.

This Mn--Zn ferrite is used as a magnetic core for transformers, noise filters and the like, and miniaturization of components is being promoted by utilizing its high magnetic permeability characteristics.

[0004]

For example, as a magnetic core for a noise filter, there is an increasing demand for a material having a high magnetic permeability up to a high frequency (up to 500 kHz).

However, in the case of the conventional Mn-Zn type ferrite, there is a problem that the frequency characteristic of magnetic permeability is poor, the magnetic permeability decreases at high frequency, and the loss at high frequency increases.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a Mn-Zn type ferrite having a high magnetic permeability and a small loss at a high frequency.

[0007]

According to the present invention, CaO is added as an auxiliary component in an amount of 0.05 to 0.5 in a Mn-Zn system ferrite.
0.13 wt%, Bi2O3 0.04 wt% or less (however, not including 0 wt% or less), SiO2 0.01 ~.
It is a Mn—Zn-based ferrite containing 0.02 wt% (excluding 0.01 wt%).

In the present invention, the reason for limiting the amounts of subcomponents is that if CaO, Bi2O3, and SiO2 are less than the predetermined amount, the loss increases, and if CaO is more than the predetermined amount, the magnetic permeability decreases and Bi2O3 and SiO2 are present. This is because if the amount is larger than the fixed amount, abnormal sintering will occur, which is not preferable.

[0009]

Examples Fe2O3 52.5 mol%, MnO2
5.5 mol% and ZnO 22.0 mol% as main components,
A raw material containing CaO, Bi2O3, and SiO2 in the amounts shown in Table 1 was prepared, and this was calcined at 850 ° C for 2 hours, then crushed in a ball mill for 8 hours, compression-molded into a ring, and 1380 ° C for 5 hours. It was fired at an oxygen partial pressure of 1%. The initial permeability of the core of 100 kHz and 500 kHz μi
And tan δ / μi at 100 kHz are shown in Table 1. In Table 1, those within the scope of the present invention are examples.
Those outside the range are comparative examples.

[0010]

[Table 1]

The frequency characteristics of magnetic permeability of Example 7 and Comparative Example 1 are shown in FIG. As shown in FIG. 1 and Table 1, it is understood that the examples of the present invention are materials having high magnetic permeability even at high frequencies. At the same time, it can be seen that the material has a small loss.

[0012]

According to the present invention, it is possible to obtain a Mn-Zn type ferrite which has a high magnetic permeability up to a high frequency and has a small loss even at a high frequency.

[Brief description of drawings]

FIG. 1 is a frequency characteristic of magnetic permeability of an example according to the present invention and a comparative example.

Claims (1)

[Claims] 1. A Mn—Zn-based ferrite containing CaO as an accessory component in an amount of 0.05 to 0.13% by weight and Bi2O.
3 is 0.04% by weight or less (however, 0% by weight is not included), and SiO2 is 0.01 to 0.02% by weight (however,
The Mn—Zn-based ferrite is characterized by containing 0.01% by weight).