Ferrite with high permeability and high dielectric constant...

Details Ferrite with high permeability and high dielectric constant... Ferrite with high permeability and high dielectric constant...

2001-12-28

2003-05-27

Wood, Elizabeth D. (Department: 1755)

Compositions

Magnetic

Iron-oxygen compound containing

C252S062590, C252S062600, C252S062610, C252S062620, C252S062640

Reexamination Certificate

active

06569346

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to a ceramic material with both high permeability and high dielectric constant. More particularly, it relates to a ferrite with both high permeability and high dielectric constant and the manufacturing method for the same.
2. Related Art
Generally speaking, dielectric materials and ferrite materials are two kinds of substances with different properties and functions. The ferrite is a ferrimagnetic material, which, according to most studies, has a dielectric constant under 20. The dielectric materials, such as those used in capacitors, are not magnetic; that is, their permeabilities all equal 1. Therefore, if a layered element needs materials with both high permeability and high dielectric constant, e.g. LC-type layered elements or LC compound elements, different magnetic material and dielectric material are often needed to be sintered together. However, sintering two different materials usually causes many problems such as material compatibility, material match and breakdown of finished products. To conquer the problems due to sintering two different materials, one resolution is to find a material with both high permeability and high dielectric constant. In the prior art, the methods of obtaining materials with both high permeability and high dielectric constant proposed in the U.S. Pat. No. 5,029,043 “Chip type LC composite ceramic component”, the Japanese Pat. No. 62,147,703 “High permittivity oxide magnetic material” and the U.S. Pat. No. 5,856,770 “Filter with ferroelectric-ferromagnetic composite materials” all need to prepare magnetic material powders and dielectric material powders in advance in the manufacturing process. The magnetic material powders, such as ferrite, are obtained by sintering and grinding magnetic materials. The dielectric material powders, such as Ba/Sr—TiO
3
, are also obtained by sintering and grinding dielectric materials. These two different powders are then mixed, condensated, shaped, and sintering to obtain a compound material with magnetic and dielectric properties. However, when sintering these two types of powders, BaO and SrO in Ba/Sr—TiO
3
will combine with the ferrite to form barium ferrite and strontium Ferrite. These two ferrite are hard magnetic materials with a permeability close to 1. Therefore, the compound materials thus obtained have a very low permeability.
In summary, it is highly desirable to develop a new material with a high permeability and a high dielectric constant and its manufacturing method as well.
SUMMARY OF THE INVENTION
It is an objective of the invention to provide a ferrite with a high permeability and a high dielectric constant. It can not only be used as a magnetic material in an electronic element, e.g. LC-type elements, but also a dielectric material at the same time.
The ferrite with high permeability and dielectric constant disclosed in the specification has the following composition Ti
x
(MFe
2
O
4+2x/y
)
y
, where x+y=1 and 0<×<1. Here M is any one or more metals selected from the group of Mn, Ni, Cu, and Zn. Such a combination can form ferrite materials with a permeability between 2 and 2260 and a dielectric constant between 17 and 2775. Since the disclosed ferrite material is a single composite material mixed and formed from raw material powders of TiO
2
, Fe
2
O
3
and one or more metal selected from Mn, Ni, Cu or Zn in an appropriate proportion. It does not have a hard magnetic phase as in barium and strontium ferrites and thus have a high permeability and a high dielectric constant. It is particularly useful in elements requiring magnetic and dielectric materials, such as LC-type elements. It also avoids the problems of compatibility and breakdown of finished products due to mixing two different materials.
According to a manufacturing method for ferrites with high permeability and high dielectric constant of the invention, raw material powders of TiO
2
, oxide of metal M and Fe
2
O
3
are prepared according to the composition Ti
x
(MFe
2
O
4+2x/y
)
y
and homogeneously mixed, where x+y=1 and 0<×<1. The metal M can be any one or several metals selected from the group of Mn, Ni, Cu, Mg, Li and Zn. The homogeneously mixed material powders are preheated at, for example, 750° C. and ground into tiny powders, which are then compressed and made into needed shapes. Afterwards, a temperature between 840° C. and 1250° C. is used for sintering, forming a ferrite with a high permeability and a high dielectric constant. The ratio between x and y can be adjusted according to practical needs to obtain ferrite materials with different permeabilities and dielectric constants. They are applicable to various types of elements.


REFERENCES:
patent: 5029043 (1991-07-01), Kitahara et al.
patent: 5512196 (1996-04-01), Mantese et al.
patent: 5856770 (1999-01-01), Mantese et al.
patent: 62-147703 (1987-09-01), None

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