KR20120045712A - Co2z type ferrite for rf application, method of preparing the same and antenna employing the same - Google Patents

Abstract

PURPOSE: A Co2 type ferrite for high frequency application, manufacturing method thereof, and an antenna using thereof are provided to maintain high level of permittivity and magnetic permeability by substituting Mn and Zn for Co. CONSTITUTION: A Co2 type ferrite for high frequency application is represented by chemical formula 1. The chemical formula 1 is same as follow: Ba3Co2-2 x (Mn, Zn) 2xFe24O41 (x=0.1-0.5). The ferrite is sintered at 1200-1300 deg. Celsius. A dielectric constant of the ferrite and value of the magnetic permeability are 15 or greater, and difference between the dielectric constant and magnetic permeability is within ±5 range. The high frequency device includes Co2Z type ferrite for high frequency application. The high frequency device is antenna.

Description

Co2Z type ferrite for RF application, method for manufacturing and antenna using same {Co2Z type Ferrite for RF Application, Method of preparing the same and Antenna employing the same}

The present invention relates to a Co ₂ Z-type ferrite for high frequency applications, a method of manufacturing the same and an antenna using the same. Specifically, as Mn and Zn are substituted at Co, both permittivity and permeability can be kept above a certain level, thereby miniaturizing the device without reducing bandwidth or loss of tangent.

The size of RF components such as antennas depends on the wavelength length at the operating frequency. As described above, various methods have been tried for miniaturization of the antenna depending on the wavelength length, and the most common method is to use a dielectric substrate having a high dielectric constant which can reduce the length of the wavelength. However, due to the high dielectric constant of the substrate, the energy delivered to the antenna tends to be trapped in the dielectric, thereby reducing the impedance bandwidth or the efficiency in applying the patch antenna.

In addition, recently used polymers also cannot be used as a high frequency antenna substrate due to bandwidth problems. In order to overcome this problem, studies on magnetic-dielectric materials such as ferrite are being actively conducted. High dielectric constant or high permeability is known to be useful for reducing the size of the device, but high dielectric constant and high permeability lead to a decrease in bandwidth or an increase in tangent loss, respectively, so materials with only one of the high permittivity and permeability are effective. Can not do it.

Therefore, there is an urgent need for a high frequency material which can be used in a high frequency band and has a high permeability compared to a low dielectric constant material.

An object of the present invention can maintain both the dielectric constant and permeability higher than a certain level, to provide a Co ₂ Z-type ferrite for high frequency applications that can achieve the miniaturization of the device without reducing the bandwidth or tangent loss, providing a method for manufacturing the same will be.

Still another object of the present invention is to provide an antenna in which miniaturization and wideband are simultaneously implemented.

The invention of claim 1 is a Co ₂ Z-type ferrite for high frequency applications, applicable at high frequency, and is represented by the following general formula (1).

[Formula 1]

Ba ₃ Co _{2 -2x} (Mn, Zn) _{2 x} Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5)

According to the Co ₂ Z-type ferrite for the high frequency application of claim 1, the dielectric constant and permeability are increased simultaneously as Mn and Zn are substituted in the Co site, and excellent microwave characteristics can be maintained even at high frequencies, thereby miniaturizing RF components. Becomes possible.

The invention of claim ₂ is a Co ₂ Z-type ferrite for high frequency applications of claim 1, the ferrite is sintered at 1200 ℃ to 1300 ℃.

According to claim 2 of the ferrite Co ₂ Z-type for high-frequency applications, Z-shaped stage with no secondary phase can be produced Co ₂ Z-type ferrite having a day-to-day.

According to a third aspect of the present invention, there is provided a Co ₂ Z-type ferrite for the high frequency application of claim 1, wherein the values of permittivity and permeability of the ferrite are 15 or more, and the difference between the permittivity and permeability is within a range of +5 .

According to the Co ₂ Z-type ferrite for high frequency applications according to claim 3, both the permittivity and permeability are more than a certain level, which is more effective for miniaturization of high frequency devices, and in particular, it can be used in broadband because the difference in permittivity and permeability is not large. .

A fourth aspect of the invention is a high frequency device and includes a Co ₂ Z type ferrite for the high frequency application of any one of claims 1 to 3.

The high frequency device of claim 4 can be miniaturized and can be used in a wide band.

The invention of claim 5 comprises a Co ₂ Z type ferrite for the high frequency application of any one of claims 1 to 3.

According to the antenna of claim 5, it can be miniaturized and can be used in a wide band.

And claims the sixth aspect of the invention is a method of producing a Co ₂ Z-type ferrite, BaCO _3, Mixing the materials using CoO, Fe ₂ O ₃ , MnO and ZnO as starting materials; Calcining the mixed material at 600 ° C to 1000 ° C; And sintering the calcined material at 1200 ° C to 1300 ° C.

According to the manufacturing method of Co ₂ Z-type ferrite of claim 6, it is possible to manufacture a hexagonal Z-type ferrite without secondary phase, can be applied to high frequency equipment and can be used in a wide band, thereby achieving miniaturization of the device.

The invention according to claim 7 is a method for producing a Co ₂ Z type ferrite according to claim 6, wherein the starting material is used after being weighed in accordance with a stoichiometric ratio so as to be a ferrite of the formula (1) by mixing and dispersing the organic solvent as a dispersion medium.

According to the manufacturing method of Co ₂ Z-type ferrite of claim 7, Mn, Zn is appropriately substituted with Co, Co ₂ Z-type ferrite having a high permeability and a high dielectric constant can be produced, so that a smaller and smaller device can be manufactured. Can be.

Co ₂ Z-type ferrite according to an embodiment of the present invention because both the permeability and the dielectric constant exhibits a high value of a predetermined value or more, it is possible to manufacture a small device without reducing the bandwidth.

The high frequency device according to an embodiment of the present invention can be used in a wide band even when manufactured in a small device.

1 is a manufacturing process diagram of a ferrite according to an embodiment of the present invention.
Figure 2a is a Ba ₃ Co ₂ Fe ₂₄ O ₄₁ powder with calcination and sintering temperature, Figure 2b is a graph showing the X-ray diffraction pattern of calcination and sintered Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics.
3 is a phase diagram of a BaO—CoO—Fe ₂ O ₃ system.
4 is a graph showing the density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics according to the sintering temperature.
5A to 5C are micrographs of microstructures of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics at sintering temperatures of 1150 ° C. (5a), 1300 ° C. (5b), and 1350 ° C. (5c), respectively.
6 is a schematic diagram of an apparatus for measuring microwave characteristics of ferrite according to an embodiment of the present invention.
7A and 7B are graphs showing dielectric constants 7a and dielectric losses 7b of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, respectively.
8A and 8B are graphs showing the permeability (8a) and the permeation loss (8b) of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, respectively.
9A and 9B are X-ray diffraction patterns of X-ray diffraction patterns (x = 0.1 and 0.2) of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics, respectively, according to the sintering temperature. .
Figs. 10a and 10b is _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) X- ray diffraction appearance (x = 0.3, 0.4) of the ceramic according to the sintering temperature.
Figure 11 is a _{Ba 3 Co 1 .0 Mn 1 .0} Fe 24 O 41 ceramic (FIG. 11a) _{and, Ba 3 Co 2-2x Mn 2x Fe} 24 O 41 ceramic (FIG. 11b) sintered at 1350 according to the sintering temperature X-ray diffraction pattern.
12 is a micrograph showing the microstructure (x = 0.1, 0.2, 0.3) of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics according to the sintering temperature.
13 is a micrograph showing the microstructure (x = 0.4, 0.5) of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics according to the sintering temperature.
14 is a graph showing the sintering density and relative density of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics according to the sintering temperature.
Figs. 15a and 15b are graphs showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) dielectric constant (x = 0.1, 0.2) of the ceramics according to each sintering temperature and composition.
16A and 16B are graphs showing dielectric constants (x = 0.3 and 0.4) of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics according to sintering temperatures and compositions, respectively.
Figure 17a and Figure 17b is _{Ba 3 Co 1 .0 Mn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature It is a graph showing the dielectric constant of.
Figure 18a and Figure 18b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) The dielectric loss (x = 0.1, 0.2) of the ceramic according to the sintering temperature and composition.
Figure 19a and Figure 19b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) The dielectric loss (x = 0.1, 0.2) of the ceramic according to the sintering temperature and composition.
Figure 20a and Figure 20b is _{Ba 3 Co 1 .0 Mn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature A graph showing the dielectric loss of.
Figure 21a and Figure 21b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) permeability (x = 0.1, 0.2) of the ceramic according to the sintering temperature and composition.
Figure 22a and Figure 22b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) permeability (x = 0.3, 0.4) of the ceramic according to the sintering temperature and composition.
Figure 23a and Figure 23b is _{Ba 3 Co 1 .0 Mn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature A graph showing the permeability of.
Figure 24a and Figure 24b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) investment loss (x = 0.1, 0.2) of the ceramic according to the sintering temperature and composition.
Figure 25a and Figure 25b is a graph showing the _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) investment loss (x = 0.3, 0.4) of the ceramic according to the sintering temperature and composition.
Figure 26a and Figure 26b is _{Ba 3 Co 1 .0 Mn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature Is a graph showing the investment loss.
27A and 27B are X-ray diffraction patterns (y = 0.1, 0.2) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature.
28A and 28B are X-ray diffraction patterns (y = 0.3, 0.4) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature.
Figure 29a and 29b are in accordance with the sintering temperature of _{Ba 3 Co 1 .0 Zn 1 .0} Fe 24 O 41 ceramic (a) and a Ba ₃ sintered at _{1350 ℃ Co 2 -2 y Zn 2y} Fe 24 O 41 ceramics, (b X-ray diffraction pattern.
30 is a micrograph showing the microstructure (y = 0.1, 0.2, 0.3) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature.
31 is a micrograph of the microstructure (y = 0.4, 0.5) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature.
32 is a graph showing the sintering density and relative density of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature.
33A and 33B are graphs showing dielectric constants (y = 0.1, 0.2) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
34A and 34B are graphs showing dielectric constants (y = 0.3 and 0.4) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
Figure 35a and 35b are of _{Ba 3 Co 1 .0 Zn 1 .0} Fe 24 O 41 ceramic (a) and a Ba ₃ Co _{2 -2} sintered at 1250 _x Mn _2x Fe ₂₄ O ₄₁ ceramics, (b) according to the sintering temperature It is a graph showing the dielectric constant.
36A and 36B are graphs showing dielectric losses (y = 0.1, 0.2) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
37A and 37B are graphs showing dielectric losses (y = 0.3, 0.4) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
Figure 38a and Figure 38b is _{Ba 3 Co 1 .0 Zn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 y Zn 2y} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature A graph showing the dielectric loss of.
39A and 39B are graphs showing magnetic permeability (x = 0.1, 0.2) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
40A and 40B are graphs showing magnetic permeability (x = 0.3, 0.4) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
Figure 41a and 41b are in accordance with the sintering temperature of _{Ba 3 Co 1 .0 Zn 1 .0} Fe 24 O 41 ceramic (a) and a Ba ₃ sintered at _{1250 ℃ Co 2 -2 y Zn 2y} Fe 24 O 41 ceramics, (b ) Is a graph showing the magnetic permeability.
42A and 42B are graphs showing investment losses (y = 0.1, 0.2) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature and composition.
43A and 43B are graphs showing investment losses (y = 0.3, 0.4) of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature and the composition.
Figure 44a and Figure 44b is _{Ba 3 Co 1 .0 Zn 1 .0} Fe 24 O 41 ceramic (a) and a _{Ba 3 Co 2 -2 y Zn 2y} Fe 24 O 41 ceramics, (b) Sintered at 1250 according to the sintering temperature Is a graph showing the investment loss.
45 is a schematic diagram showing the structure of a 2x2 array antenna.
46 is a graph showing the reflection loss result of the 2x2 array antenna.
47A and 47B are graphs showing a radiation pattern of a 2x2 array antenna, FIG. 47A is an FM band, and FIG. 47B is a DMB band.

Hereinafter, the present invention will be described in more detail. However, this is to aid the understanding of the present invention and the scope of the invention is not limited thereto.

Ferrite according to an embodiment of the present invention is applicable at a high frequency,

It is represented by the following formula (1).

[Formula 1]

Ba ₃ Co _2-2x (Mn, Zn) _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5)

Ferrite may be defined as a magnetic material composed of oxides including iron and other metals. The crystal structure has a positively charged metal ion is charged with 2 ^{(Fe 3 +, M 2 +} , M = Co, Mn, Zn , etc.) and sound consists of the network structure of the oxygen ion. The arrangement of ions and the crystal structure of ferrite play an important role in explaining magnetic properties and magnetic interactions. Magnetic ferrite is classified into cubic ferrite and hexagonal ferrite according to the crystal structure.

Magnetic bodies are divided into three types, spinels, garnets, and hexagonal ferrites, depending on the shape of the crystal structure. Spinel ferrites are representative of nickel-zinc (Ni-Zn) and manganese-zinc (Mn-Zn) magnetic bodies. Ferrites have a relationship between permeability and magnetic resonance frequency by Snoek's law. In other words, spinel ferrite with high permeability has a low magnetic resonance frequency.

Although it has a relatively weak ferrimagnetic than spinel ferrite, Garnet ferrite can also be considered for use in the ultra-high frequency band. However, although garnet ferrite has a low magnetic loss tangent above the magnetic resonance frequency, the permeability (μ ') is already close to 1 in the 300 MHz band, and thus sufficient permeability for antenna miniaturization cannot be obtained.

Therefore, in one embodiment of the present invention to provide a hexagonal ferrite structure of the formula (1), it is possible to use in the high frequency band to provide a high frequency material having a high permeability compared to the low dielectric constant material.

Ba ferrite having a hexagonal structure according to an embodiment of the present invention, Ba ₃ Co _{2 -2x} (Mn, Zn) _{2 x} by replacing Mn and Zn in Co sites of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) Ceramics are manufactured by the general firing method.

According to one embodiment of the present invention, it is preferable to sinter at 1200 ° C to 1300 ° C. If the sintering temperature is out of range, the secondary phase is not preferable.

According to one embodiment of the invention, the value of the permittivity and permeability of the ferrite is 15 or more, and the difference between the permittivity and permeability is preferably within the range of ± 5. Similar permittivity and permeability allow the device to be reduced in size without reducing bandwidth when used as a magnetic dielectric material.

According to an embodiment of the present invention, there is provided a high frequency device, for example an antenna using a Co ₂ Z-type ferrite according to the present invention.

According to an embodiment of the present invention, BaCO ₃ , Mixing the materials using CoO, Fe ₂ O ₃ , MnO and ZnO as starting materials; Calcining the mixed material at 600 ° C to 1000 ° C; And it provides a method for producing a ferrite comprising the step of sintering the calcined material at 1200 ℃ ~ 1300 ℃.

Specifically, the starting material is weighed according to the stoichiometric ratio so as to be ferrite of Chemical Formula 1, and then mixed and dispersed with an organic solvent as a dispersion medium, dried until the organic solvent is volatilized, and then subjected to 1 ~ at 600 ° C to 1000 ° C. Calculate for 5 hours. After sintering the calcined powder, it is put in a mold again and pressurized and molded, and the molded body is sintered at 1200 ° C to 1300 ° C for 1-5 hours.

Hereinafter, the present invention will be described in detail through examples. However, this is for the purpose of illustrating the invention and should not be construed in a way that limits the scope of the invention.

Example  1: Preparation of Specimen

Substitution of Mn and Zn Co in place of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics were prepared by the _{Ba 3 Co 2 -2x (Mn,} Zn) 2x Fe 24 O 41 (x = 0.1 ~ 0.5) to the normal ceramic firing process Table 1 shows the purity of the samples used in the manufacture of the specimens and the manufacturers.

matter water(%) manufacturer BaCO ₃ 99.9 Kojundo Chemical Co. Inc. CoO 99.9 Kojundo Chemical Co. Inc. Fe ₂ O ₃ 99.9 Kojundo Chemical Co. Inc. MnO 99 up Kojundo Chemical Co. Inc. ZnO 99 up Kojundo Chemical Co. Inc.

Sample purity and manufacturer.

Using the starting materials shown in Table 1, Ba ₃ Co _{2 -2x} (Mn, Zn) _{2 x} Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) was weighed according to the stoichiometric ratio, and then zirconia was used as the alcohol as a dispersion medium. The mixture was ground for 24 hours using a ball.

Mixed pulverized Ba ₃ Co _{2 -x} (Mn, Zn) _x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) was dried in an electric oven at 100 ° C. for 24 hours, dried and placed in an alumina crucible 600 for volatilization of organic matter. After maintaining for 1 hour at ℃ and finally calcined for 3 hours at 1000 ℃.

The calcined Ba ₃ Co _{2 -x} (Mn, Zn) _x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) powder was mixed and ground again to dry, and the dried powder was sieved.

The sifted powder was placed in a donut-shaped mold (φ _out = 10, φ _in = 5) and molded at a pressure of 800 kg / cm 2, and the molded body was sintered at 1150 ° C. to 1400 ° C. for 3 hours. The temperature increase rate at the time of calcination and sintering was 5 degree-C / min. The above manufacturing process is shown in FIG.

Experimental Example  1: according to composition and temperature change Calcination Powder Sintered specimen  Observation of solid solution formation and crystal structure

X-ray diffraction analysis was carried out using an X-ray diffractometer (Rigaku, RINT2000) to observe the formation of solid solution and crystal structure of calcined powder and sintered specimens according to the composition and temperature. CuKα1 (λ = 1.542A) is used, and the step width and scanning speed are 0.1deg. And 2deg./min. In the diffraction angle (2θ) of 20 ° to 70 °, respectively. The synthesized phase was examined from the position of the diffraction peak. The results are shown in Figures 2a and 2b.

As can be seen from Figures 2a and 2b, Ba ₃ Co ₂ Fe ₂₄ O ₄₁ powder at all calcination temperature conditions, Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase (Z-type) and Ba ₂ Co ₂ Fe ₁₂ O ₂₂ phases (Y-type) coexisted. This is illustrated by MA Vinnik and Zh. Neorg. The results were consistent with Khim's report on the phase equilibrium of BaO-CoO-Fe ₂ O ₃ system.

Under the calcination temperature of 600 ° C.-850 ° C., there was an unidentified secondary phase thought to be a BaFe ₁₂ O ₁₉ phase (M-type) together with the Ba ₂ Co ₂ Fe ₁₂ O ₂₂ phase. Secondary phases decreased at higher calcination conditions, 900-1350 ℃ and 1000-1350 ℃. In addition, a new Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase appeared and the diffraction intensity increased. As the calcination temperature increases, secondary phases such as Ba ₂ Co ₂ Fe ₁₂ O ₂₂ and BaFe ₁₂ O ₁₉ phases receive thermal energy and combine with each other to form Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase, which is a hexagonal structure. It is thought to be formed. Despite the decrease of the secondary phase and the increase of the Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase, the calcination temperature conditions of 900 ° C-1350 ° C and 1000 ° C-1350 ° C are the target temperature range (1150 ° C-1400 ° C) as the sintering temperature in this experiment. It is difficult to determine the calcining temperature because it is a high temperature in comparison with. Therefore, in this experiment, the calcination temperature condition of 600 ℃-1000 ℃ was determined as the calcination temperature to form Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase.

The X-ray diffraction pattern of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics sintered at 1200 ~ 1350 ℃ was similar to the X-ray diffraction pattern of commercial Z-type hexagonal ferrite from Trans-tech. As a result, it could be confirmed that Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase can be formed at a calcination temperature of 600 ° C.-1000 ° C. and a sintering temperature of 1150 ° C. to 1400 ° C. selected in the present invention. The Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase appeared as the main phase at all sintering temperatures, but the secondary phase appeared at the sintering temperatures of 1150 ° C and 1400 ° C, which is thought to be the BaCo ₂ Fe ₁₂ O ₂₂ phase.

At sintering temperature of 1200 ℃ ~ 1350 ℃, the diffraction intensity of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase increased with increasing sintering temperature, and the maximum value of diffraction intensity (2 = 30.8) was shown at sintering temperature of 1300 ℃. At the sintering temperature of 1400 ℃, the excess sintering caused by the high sintering temperature reduced the diffraction intensity of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ phase and reprecipitation of the secondary phase.

Experimental Example  2: Ba ₃ Co ₂ Fe ₂₄ O ₄₁  Sintered Density and Relative Density of Ceramics

The bulk density of the sintered specimens was measured by the method specified in ASTM 373-72.

When the sintered body is put into distilled water and boiled for 2 hours, water penetrates into the sintered body and the weight increases. At this time, the weight of air is W _d , the weight of suspension in water is W _ss , and the weight of air in the air of sintered body If W _s , the specimen density is expressed as

(g/㎠) (1)

(g / ㎠) (1)

4 shows the sintered density and relative density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics according to the sintering temperature.

As the sintering temperature increased, the sintered density increased. This is thought to be because sufficient thermal energy was supplied to the specimen to increase densification and grain growth and pore reduction. Ba ₃ Co ₂ Fe ₂₄ O ₄₁ on a diffraction intensity increases Ba ₃ Co ₂ Fe ₂₄ O ₄₁ X- ray diffraction pattern (Fig. 2 (b)) of the ceramic with a dense microstructure (Fig. 5) an increase in sintered density that Supported. The decrease in sintered density at 1400 ° C. is considered to be due to oversintering. In fact, in this experiment, the specimen sintered at 1400 ℃ was found to melt the specimen by oversintering. The specimen sintered at 1350 ° C exhibited the highest sintered density of 90.73% relative to the theoretical density (5.356 g / cm ³ ) of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. As a result, it can be seen that Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics were sufficiently sintered at a sintering temperature of 1200 ° C to 1350 ° C.

Experimental Example  3: Examining the Microstructure of Grain

The surface of the sintered specimens was polished with 0.3 µm alumina abrasive, and the ultrasonic cleaner was used to remove impurities in the form of small particles on the surface and then thermally etched to obtain microstructures such as crystal grains, grain boundaries, and pores. Scanning Electron Microscopy (SEM) was used and the results are shown in FIG. 5.

Experimental Example  4: Microwave Characterization

The permittivity (ε '), permeability (μ'), and loss tangents (ε "/ ε ', μ" / μ') were measured using the coaxial air line method. The HPE5071B Network Analyzer was used to measure the scattering parameters for mathematical calculations. The coaxial air track method is the most commonly used transmission line method for measuring the dielectric constant and permeability of materials.

Toroidal specimens for measurement in the coaxial air track method were inserted between the inner and outer conductors of the coaxial track.

Coaxial air track is also known as the easiest way to measure both permittivity and permeability simultaneously. The permittivity and permeability in the microwave band are represented by equations (2) and (3) by Nicolson, Ross and Weir.

In order to calculate the permittivity and permeability using the NRW algorithm, the S-parameters of S ₁₁ and S ₂₁ were measured through the measuring jig as shown in FIG.

(2)

(2)

(3)

(3)

Experiment Result 1: Ba ₃ Co ₂ Fe ₂₄ O ₄₁  Dielectric constant and dielectric loss of ceramics

The dielectric constant and dielectric loss of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics according to the sintering temperature and frequency are shown in FIG. 7.

As the sintering temperature increased, the dielectric constant of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics increased. This is thought to be due to the increased porosity of the specimens.

In the case of dielectric constant with frequency, it decreased with increasing frequency.

In the case of dielectric loss, the dielectric constant was opposite to that of dielectric constant. Dielectric losses decreased with sintering temperature and increased with frequency. This is thought to be due to the increase in densification as the sintering temperature increases and the reduction of microstructural defects such as pores which cause dielectric loss. In addition, the dielectric loss with frequency is thought to increase because the dielectric dispersion is larger as the frequency is increased. In the frequency band above 800 MHz, the dielectric loss was saturated and showed a constant value.

Experiment result 2: Ba ₃ Co ₂ Fe ₂₄ O ₄₁  Permeability and Loss of Ceramics

8 shows the permeability and permeability of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics according to the sintering temperature and frequency. The permeability of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics does not change significantly with the sintering temperature. However, specimens sintered at 1350 ° C showed relatively low values. This phenomenon is thought to be due to the overgrowth of the grain size and the reduction of the magnetic domain. The permeability with frequency showed a sharp decrease after 210 MHz. In general, the magnetic permeability of the magnetic material decreases rapidly above the magnetic resonance frequency band. As a result, the magnetic resonance frequency of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics is considered to be 210 MHz.

The investment loss of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics increased with frequency. This phenomenon is similar to the dielectric loss, and is thought to be due to the increase in dispersion with increasing frequency. In addition, the investment loss according to the sintering temperature showed similar values without significant change. This is because, unlike the dielectric properties, the microstructure of specimens such as pores and grain size have little influence on the magnetic properties.

The dielectric constant, dielectric loss, permeability and permeability of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics sintered at 1300 ° C were 19.896, 0.172, 14.218 and 0.205 at 210 MHz, respectively.

Experiment Result 3: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) X-ray of ceramics diffraction  analysis

X-ray diffraction analysis of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics was performed according to the sintering temperature, and the results are shown in FIGS. 9 to 11.

In the calcined powder, the Z-, Y- and W-phases coexisted. This is considered to be because it is difficult to form a Z-type single phase at the calcination temperature of 600 ° C-1000 ° C because the Z-type phase has a very complicated crystal structure.

At sintering temperatures of up to 1200 ° C, the three phases coexisted as in the calcined powder. It is thought that the sintering temperature of 1200 ° C. or less does not supply enough thermal energy to form a Z-type single phase, so that a Y-type phase and a W-type phase having a relatively simple crystal structure are formed.

As the sintering temperature was increased, the diffraction intensity of the Y- and W-forms gradually decreased and the diffraction intensity of the Z-types increased. This phenomenon is thought to be due to the sufficient growth of Z-shape with sufficient heat energy supply with increasing sintering temperature.

In addition, a new diffraction peak corresponding to a Z-type began to appear at a sintering temperature of 1200 ° C., which is thought to be due to the formation of a Z-type by combining a Y-type and a W-type with increasing sintering temperature.

The diffraction intensity of Z-type main peak (2θ = 30.8 °) showed the maximum value at sintering temperature of 1300 ℃ in all compositions.

At the sintering temperature of 1400 ° C., the diffraction intensity of the Z-shaped phase decreased and the W-shaped phase began to reappear. It is thought that the Z-shaped diffraction intensity is reduced and the W-shaped secondary phase is reprecipitated because of defects such as excessive growth of crystal grains due to excessive sintering due to high sintering temperature.

X-ray diffraction pattern of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics sintered at 1350 ° C in FIG. 10 (b) to analyze the change of crystal structure according to Mn addition amount Indicated. The diffraction intensity of the specimen did not change significantly with the addition of Mn. This is because even if Mn is substituted in Co site of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) does not have a significant effect on the sinterability of ceramics. do. However, as Mn was added, the diffraction angle shifted to the low angle (2θ = 23.8 °, 30.8 °, 56.3 °). This is because the crystal structure of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics is modified as Mn having an atomic radius of 0.112 nm is substituted at Co site having an atomic radius of 0.125 nm. I think because. However, because the difference in atomic radius is not large, I think there will be no big change in crystal structure. Also, with the addition of Mn, new diffraction peaks appeared at compositions of x = 0.4 and x = 0.5. (2θ = 32.1 °) This phenomenon is also thought to be due to the minute change of the crystal structure due to Mn substitution.

The addition of Mn showed a slight change in the X-ray diffraction pattern, but the overall X-ray diffraction pattern was similar to that of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics.

Experimental Result 4: Composition and Sintering Temperature Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) Microstructure of Ceramic Specimens

Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) according to the composition and sintering temperature were investigated for 3 hours at each sintering temperature. Specimens were photographed using a scanning electron microscope, and the results are shown in FIGS. 12 and 13).

12 is a microstructure of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1, 0.2, 0.3) ceramics according to sintering temperature. In all compositions, at a sintering temperature of 1150 ° C., no clear grains were observed (a, d) or (g) microstructures were found to have many pores. As can be seen from the X-ray diffraction analysis of FIGS. 8 and 9, the thermal energy supplied to the specimen at the sintering temperature of 1150 ° C is Ba ₃ Co _2-2x Mn _2x Fe ₂₄ O ₄₁ (x = 0.1, 0.2, 0.3) ceramics. I think that is because it is not enough to densify. As the sintering temperature was increased, the microstructure without pores was shown at the sintering temperature of 1300 ℃. Moreover, the shape of a crystal grain has shown the rectangular shape. This is thought to be due to the supply of sufficient thermal energy to promote the growth of grains to reduce the pore. In addition, it is considered that a Z-shaped phase having a complicated crystal structure is smoothly formed to exhibit rectangular crystal grains. However, at 1400 ℃ sintering temperature, the microstructures with excessive grain growth due to oversintering appeared.

13 is a microstructure of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.4, 0.5) ceramics according to sintering temperature. Similar to the composition of x = 0.1 ~ 0.3, the microstructure showed a lot of pores at the sintering temperature of 1150 ℃ and a dense microstructure with rectangular grains at the 1300 sintering temperature. At a sintering temperature of 1400 ° C., overgrown grains appeared. In addition, in the composition of x = 0.4, deformation of grain boundaries due to grain breakdown was observed as a result of oversintering. This is considered to be due to the recording of the specimen due to the high sintering temperature. The microstructure of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1, 0.2, 0.3) ceramics sintered at 1150 ° C. increased the amount of pores as the amount of Mn added increased. This is considered to be because crystallization energy increases as Mn is substituted at Co site.

Experimental Result 5: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) Sintered and Relative Density of Ceramics

Figure 14 shows the sintering density and relative density of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics according to the sintering temperature. As the sintering temperature increased, the sintered density increased and reached the maximum value at the temperature of 1350 ℃. As can be seen from the X-ray diffraction analysis results of FIGS. 9 to 11 and the microstructures of FIGS. 12 and 13, as the sintering temperature increases, the supply of thermal energy increases, so that grains grow and pores decrease. I think.

At the sintering temperature of 1400 ° C, the sintered density was decreased due to the fracture of grains by excessive sintering. Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics is the theoretical density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics (5.356g / cm) at 1350 ℃ which shows the maximum value of sintered density. ³ ) The relative density was 89.77% ~ 95.80% according to the composition. Since Mn with different molecular weight was added to Co site, the relative density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics was _calculated from Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) It is difficult to judge the sinterability directly. However, X- ray as can be seen in the diffraction _{analysis, Ba 3 Co 2 -2 x Mn} 2x Fe 24 O 41 (x = 0.1 ~ 0.5) crystal structure of the ceramic is in the addition of _{Mn Ba 3 Co 2 Fe 24 O} 41 ceramic It has a high relative density with respect to the theoretical density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics even though Mn (MW: 54.94) having a molecular weight smaller than that of Co (MW: 58.93) is added without showing a large difference with the crystal structure of Therefore, it can be seen that Ba ₃ Co _{2 -2x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics were sufficiently sintered under the sintering conditions of the present experiment.

Experimental Result 6: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) dielectric constant of ceramics

According to the sintering temperature, the composition and the frequency _{Ba 3 Co 2 -2 x Mn 2x} Fe 24 O 41 (x = 0.1 ~ 0.5) exhibited a dielectric constant of the ceramic to 15 to 17.

The dielectric constant of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics increased with increasing sintering temperature in all compositions.

This is because densification proceeds and pores with low permittivity (e _r = 1) decrease as can be seen from structural characteristics such as X-ray diffraction analysis and microstructure.

As the frequency increases, as in the case of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics (Fig. 7 (a)), the dielectric constant of the Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics decreases. It was. This is thought to be because dielectric dispersion increases with increasing frequency.

However, the decrease in dielectric constant with frequency in Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics with Mn differs from that in pure Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. Indicated. In the case of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, the decrease in dielectric constant started as soon as the frequency was increased, but with Mn added Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) The dielectric constant was relatively high up to the frequency band.

As the amount of Mn added increased, the frequency band at which the dielectric constant began to decrease increased. This is considered to be because the dielectric loss factor inherent in the material is reduced by the effect of Mn substituted at the Co site.

It is thought that the sintering temperature of 1350 ° C. increases the structural defects due to the excessive growth of grains, so that the decrease in the dielectric constant appears in the lower frequency band than other sintering temperatures. 17 (b) shows the dielectric constant of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics sintered at 1250 ° C. As the amount of Mn added increased, the dielectric constant slightly increased. 12, as can be seen in the photo of the microstructure _{13 Ba 3 Co 2 -2 x Mn} 2x Fe 24 O 41 (x = 0.1 ~ 0.5) ceramics exhibited a dense structure all at a sintering temperature of 1250 ℃ ~ 1300 ℃. Therefore, the increase in permittivity with increasing amount of Mn is thought to be due to the effect of Mn being substituted, not due to the reduction of porosity.

Experiment result 7: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) Dielectric Loss of Ceramics

18 to Ba ₃ in Fig. 20 according to the sintering temperature, the composition and the frequency _{Co 2 -2 x Mn 2x Fe 24} O 41 (x = 0.1 ~ 0.5) shows the dielectric loss of the ceramic.

Dielectric losses increased with increasing frequency at all compositions and sintering temperatures. This phenomenon is consistent with the result of permittivity of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics shown in FIGS. 15 to 17 because the dielectric dispersion is greatly increased with increasing frequency. I think. In case of dielectric loss with sintering temperature, dielectric loss decreased with increasing sintering temperature in all compositions and showed minimum value at sintering temperature of 1250 ℃. This is thought to be due to the increase in densification as the sintering temperature increases and the reduction of microstructural defects such as pores which cause dielectric loss.

A Ba ₃ sintered at _{1250 ℃ Co 2 -2 x Mn 2x} Fe 24 O 41 is shown in 20 (b) the dielectric loss of the ceramic. As the amount of Mn added increased, the dielectric loss of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ ceramics did not show a big difference. This is because Mn substitution to Co site causes a slight change in crystal structure, but because it satisfies Hume-Rothery's law for formation of substitutional solid solution, it is thought that no microstructural defects such as crystal structure deformation affecting dielectric properties appear. do. Co and Mn have similar atomic radii of 0.125 nm and 0.112 nm and electronegativity of 1.8 and 1.5.

Experimental Result 8: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) Permeability of ceramics

Permeability of ceramics is shown in FIGS. 21 to 23. The permeability increased continuously with increasing sintering temperature in all compositions. This can be seen in the microstructure of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics of FIGS. 12 and 13, and as the sintering temperature increases, grains having magnetic zones grow to increase permeability. It is believed that this is increased. In addition, unlike in the case of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, as the Mn is substituted, the temperature of forming the Z-form is slightly increased, so that the excessive growth of grains does not appear even at the sintering temperature of 1350 ° C. Therefore, permeability is thought to increase continuously with sintering temperature. However, in the case of x = 0.1, the permeability increased with the sintering temperature and showed the maximum value at 1300 ℃.

In addition, the permeability decreased at the sintering temperature of 1350 ℃. This phenomenon is similar to that of pure Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, and because the amount of Mn is fine, the magnetic permeability decreases due to excessive growth of grains at 1350 sintering temperature. do. The permeability of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics with frequency decreased with increasing frequency. This is because magnetic dispersion increases with increasing frequency.

In the case of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics, the frequency band in which the permeability decreases sharply increased compared to Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. It can be seen that the magnetic resonant frequency of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 to 0.5) ceramics increases as Mn is added to this phenomenon. In the band above the self-resonant frequency, the investment characteristics deteriorate rapidly, so Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics are also used in the higher frequency band than Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. I think it will be possible. Mn-added specimens showed a slightly higher permeability than Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. This is by reducing the amount of spin to be canceled each other between the ferromagnetic ions in the crystal structure as the substituted Mn (3.4532μ / μ _N) having a smaller magnetic moment than _{Co (4.627μ / μ N) Ba} 3 Co 2 -2 x Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) Permeability seems to increase because it affects the magnetic momentum of ceramics.

Experiment Result 9: Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁  (x = 0.1 ~ 0.5) Investment loss of ceramics

Figure ₃ Ba according to the sintering temperature, the composition and the frequency 24 to _{26 Co 2 -2 x Mn 2x Fe} 24 O 41 (x = 0.1 ~ 0.5) showed the loss of the ceramic investment.

The investment losses of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics showed similar characteristics at all compositions and sintering temperatures.

The investment loss of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics remained low with increasing frequency and then rapidly increased above a certain frequency.

The rapid increase in investment loss, which tends to be similar to the investment loss characteristics of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, is thought to be due to the increase in dispersion with increasing frequency. However, Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics, unlike the investment loss of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, has a frequency of 600 MHz to 800 MHz, in which the loss value increases rapidly. Moved to the band. This is considered to be because the magnetic resonance frequency increased with the addition of Mn, as can be seen from the permeability characteristics of FIGS. 20 to 22. The investment loss according to the sintering temperature showed similar values without significant change. This is because, unlike the dielectric properties, the microstructure of specimens such as pores and grain size have little influence on the magnetic properties.

A Ba ₃ Co ₁ sintered at _{1250 ℃ .4 Mn 0 .6 Fe 24} O ₄₁ ceramic dielectric constant of the dielectric loss, permeability and investment loss was respectively 27.276, 0.171, 20.448 and 0.068 at 310 MHz.

Experiment Result 10: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) X-ray of ceramics diffraction  Analysis

27 to 29 show the results of X-ray diffraction analysis of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature. The X-ray diffraction pattern of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics in all compositions is Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ shown in FIGS. Similar results were obtained with the X-ray diffraction pattern of the ceramics. Powder calcined at 600 ℃ -1000 ℃ and Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics sintered at sintering temperature below 1200 ℃ Shape and W-shape coexisted. This is because the crystal structure of the Z-shaped phase is very complicated, so it is difficult to form a Z-shaped single phase at a sintering temperature of 600 ° C.-1000 ° C. and a sintering temperature of 1200 ° C. or lower. As the sintering temperature increased, the diffraction intensity of Y-type and W-type gradually decreased and the diffraction intensity of Z-type increased. At the sintering temperature of 1200 ° C, new diffraction peaks corresponding to the Z-form began to appear. This is considered to be due to the increase in the thermal energy transferred to the specimen as the sintering temperature is increased, the Z-shaped phase is sufficiently grown, and the Y-shaped phase and the W-shaped phase are combined to form a Z-shaped phase. As the sintering temperature increased, secondary phases corresponding to Y- and W-phases began to appear from 1300 ° C, respectively. At the sintering temperature of 1350 and 1400, the diffraction intensity of Z-type was decreased. It is thought that the Y- and W-phases are reprecipitated from the Z-type due to oversintering. It is also believed that the diffraction intensity of the Z-shaped phase decreases because the microstructure defect increases due to the high sintering temperature. 29 (b) shows an X-ray diffraction pattern of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics sintered at 1350 ° C. As the amount of Zn added increased, the diffraction intensity of the specimen did not change significantly. This is thought to be because it does not have a significant impact Ba ₃ Co ₂ Fe ₂₄ O, even if Zn is substituted in place of the Co ₄₁ ceramic _{Ba 3 Co 2 -2 y Zn 2y} Fe 24 O 41 (y = 0.1 ~ 0.5) , the sintering property of the ceramic do. However, as Zn was added, diffraction angles of 2θ = 23.8 °, 30.8 °, 32.5 °, and 56.3 ° were moved to the low angle. This is because the crystal structure of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics is deformed because Zn substituted at Co site has a different atomic radius (0.133 nm) from Co. think. However, because the difference in atomic radius is not large, I think there will be no big change in crystal structure. The addition of Zn showed a slight change in the X-ray diffraction pattern, but the overall X-ray diffraction pattern was similar to that of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics.

Experiment Result 11: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Microstructure of Ceramics

30 and 31 show microstructure pictures of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to composition and sintering temperature. The microstructure according to the sintering temperature showed similar results as when Mn was substituted. All the compositions showed a microstructure with many pores at the sintering temperature of 1150 ℃. As can be seen from the X-ray diffraction analysis of FIGS. 27 to 29, the Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) lacked thermal energy supplied to the specimen at the sintering temperature of 1150 ° C. It is considered that the densification of ceramics is difficult. As the sintering temperature was increased, the microstructure without pores was shown at the sintering temperature of 1300 ℃. This is thought to be due to the supply of sufficient thermal energy to promote the growth of crystal grains to reduce the pore. In addition, the hexagonal Z-shaped phase having a complicated crystal structure was formed smoothly, indicating a rectangular crystal grain. At sintering temperature of 1400 ℃, Ba ₃ Co _2-2y Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics were over-sintered, resulting in microstructural fractures such as grain breakdown, grain boundary deformation and grain growth.

Experiment Result 12: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Sintered and Relative Density of Ceramics

32 shows the sintering density and relative density of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature. As the sintering temperature increased, the sintered density increased and reached the maximum value at the temperature of 1350 ℃. This phenomenon is characterized by densification as the sintering temperature increases, as shown by X-ray diffraction analysis and microstructure of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics. It is thought to be due to the growth and decrease of pores.

At a sintering temperature of 1350 ° C, Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics is about (5.356 g / cm ³ ) compared to the theoretical density of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics A relative density of 92% was shown. As with Mn, Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics were replaced with Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics because they replaced substances with different molecular weights. Density is not a direct factor in determining the sinterability of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics. However, it was confirmed from the X-ray diffraction analysis that there was no significant change in the crystal structure due to the substitution of Zn. Thus, Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics was sufficiently I think it was sintered. In addition, the molecular weight of Zn: Because (MW 65.39) Mn slightly larger than the molecular weight of _{Ba 3 Co 2 -2 y Zn 2y} Fe 24 O 41 (y = 0.1 ~ 0.5) the theoretical density ceramic Ba ₃ Co _{2 -2x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) It is thought to be larger than ceramics.

At the sintering temperature of 1400 ° C, the sintered density was decreased due to the fracture of grains by excessive sintering.

Experiment Result 13: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Dielectric constant of ceramics

The dielectric constant of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature, composition and frequency is shown in FIGS. 33 to 35.

The dielectric constant of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics increased with increasing sintering temperature in all compositions. This phenomenon is thought to be due to the growth of grains and the reduction of pores with increasing sintering temperature, as can be seen from the structural characteristics such as sinter density.

Also, the dielectric constant of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics decreased with increasing frequency. This is thought to be because dielectric dispersion increases with increasing frequency as in the case of other ceramics.

Like Z ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics, when Zn was added, the dielectric constant remained relatively high up to a certain frequency band. 35 (b) shows the dielectric constant according to the frequency of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics sintered at 1250 ° C. As the amount of Zn added increased, the dielectric constant increased.

As can be seen from the microstructures of FIGS. 30 and 31, Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics showed a compact structure at sintering temperatures of 1250 ° C to 1300 ° C.

Therefore, as in the case of Mn addition, the increase in dielectric constant of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics is thought to be due to the effect of substituted Zn, not due to the reduction of pores. do.

Experiment Result 14: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Dielectric Loss of Ceramics

36 to 38 show dielectric losses of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to sintering temperature, composition, and frequency. As with other ceramics, the dielectric loss of all compositions increased with increasing frequency. This is because the dielectric dispersion increases with increasing frequency, as can be seen from the dielectric constant of Ba ₃ Co _2-2y Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics.

In case of dielectric loss according to sintering temperature, dielectric loss decreased with increasing sintering temperature in all compositions as in the case of Mn addition. This is because densification increases as the sintering temperature increases, and microstructure defects such as pores which cause dielectric loss decrease.

At sintering temperatures above 1300 ° C, dielectric losses increased due to microstructure defects such as excessive grain growth. 38 (b) shows the dielectric loss of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics sintered at 1250 ° C. in order to investigate the dielectric loss depending on the amount of Zn added. As the amount of Zn added increased, the dielectric loss of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics did not show a big difference. This is because Co and Zn have similar atomic radius (Co: 0.125 nm, Zn: 0.133 nm) and similar electronegativity (Co: 1.8, Zn: 1.6), which satisfies Hume-Rothery's law for the formation of substituted solid solutions. I think.

Experiment 15 Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Permeability of ceramics

The permeability of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature, composition and frequency is shown in FIGS. 39 to 41.

At sintering temperatures below 1300 ° C, the permeability of the specimens increased with increasing sintering temperature. As can be seen from the microstructure of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics (Figs. 31 and 30), as the sintering temperature increases, grains having magnetic zones grow. Permeability seems to increase.

However, the permeability decreased at the sintering temperature of 1350 ℃. This is similar to the magnetic permeability characteristics of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics, and it is thought that the magnetic permeability decreases due to the excessive growth of grain and the magnetic permeability decreases due to microstructure defects.

The permeability of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics decreased with increasing frequency. This is because the magnetic dispersion increases as the frequency increases.

In the Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics, the frequency band in which the permeability decreases sharply increased compared to Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. This phenomenon is thought to be due to the increase in the magnetic resonance frequency of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics as in the case of adding Mn.

41 (b) shows the permeability of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics sintered at 1250 ° C. As the amount of Zn added increased, the permeability did not change significantly. However, the addition of Zn showed a slightly higher permeability than Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. The magnetic momentum of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics is reduced by reducing the amount of offset between the ferromagnetic ions in the crystal structure due to the difference in the magnetic moments of Zn and Co. It is considered that the magnetic moment of Zn is smaller than (0.875μ / μ _N ) Co and Mn, and the permeability is further increased.

Experiment Result 16: Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁  (y = 0.1 ~ 0.5) Investment loss of ceramics

42 to 44 show the investment loss of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics according to the sintering temperature, composition, and frequency.

The investment losses of Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics showed similar characteristics at all compositions and sintering temperatures. It is similar to the investment loss of Ba ₃ Co _{2 -2 x} Mn _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) ceramics, and it keeps low value as the frequency increases, but rapidly increases above the specific frequency due to the increase of magnetic dispersion. I think to increase. However, the frequency of rapid increase in investment loss in Ba ₃ Co _{2 -2 y} Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 ~ 0.5) ceramics is higher than that of Ba ₃ Co ₂ Fe ₂₄ O ₄₁ ceramics. Moved to. This is thought to be due to the increase in the magnetic resonance frequency of Ba ₃ Co _2-2y Zn _2y Fe ₂₄ O ₄₁ (y = 0.1 to 0.5) ceramics as in the case of adding Mn.

The investment loss according to the sintering temperature showed similar values without significant change. This is because, unlike the dielectric properties, the microstructure of specimens such as pores and grain size have little influence on the magnetic properties.

44 (b) shows the investment loss of Ba ₃ Co _{2 −2 y} Zn _2y Fe ₂₄ O ₄₁ ceramics sintered at 1250 ° C. FIG. The investment loss according to the change of composition showed a constant value without significant change.

A Ba ₃ Co ₁ sintered at _{1250 ℃ .6 Zn 0 .4 Fe 24} O ₄₁ ceramic dielectric constant of the dielectric loss, permeability and investment loss was respectively 28.277, 0.193, 22.992 and 0.065 at 310 MHz.

Example  2: Microstrip Antenna Design

Microstrip antennas are popular antenna structures because they are thin, easy to attach to flat and non-planar surfaces, and are easy to manufacture and inexpensive when using modern printed circuit technology. In particular, selecting the patch shape and mode has the advantage of changing the resonant frequency, polarization, pattern and impedance.

Ba ₃ Co ₁ sintered at _{1250 ℃ .6 Zn 0 .4 Fe 24} O 41 ceramic the FM band using a ferrite substrate (88 MHz ~ 108 MHz, the center frequency: 98 MHz) and the DMB band (174 MHz ~ 216 MHz , Dual frequency 2x2 microstrip array antenna was designed and simulated to investigate the antenna characteristics at 195 MHz.

The spacing between the metal patches was designed at 0.76 m and 0.38 m, respectively, at 98 MHz and 195 MHz / 4 and fed using a probe.

In addition, the metal patch and the feeding structure are designed to show impedance matching as 50.

The structure of a dual band 2x2 microstrip array antenna using a ferrite substrate is shown in FIG.

Experimental Example  5: Return loss of a microstrip 2x2 array antenna

The dual band 2x2 microstrip array antenna of Example 2 was designed and frequency-resolved using HFSS, an electromagnetic wave (EM) circuit analysis tool.

The return loss of the dual band 2x2 microstrip array antenna of Example 2 is shown in FIGS. 46 and 47.

You can see the resonance at 100 MHz and 195 MHz.

Also, the return loss (S ₁₁ ) at the resonant frequencies of 100 MHz and 195 MHz was -33.928 dB and -30.408 dB, respectively. As a result, it can be seen that the 2x2 array antenna according to the present invention exhibits excellent characteristics in the FM band (88-108 MHz) and the DMB band (174-216 MHz).

47 shows a radiation pattern of a 2x2 array antenna.

When the antennas are arranged in order to implement a dual band in a single microstrip antenna, a radiation pattern having the same polarization characteristics and directivity without distortion is required in the two bands in which the array antenna operates. At the resonant frequencies of 100 MHz and 195 MHz, the radiation patterns exhibited direct radiation patterns. If the _{Ba 3 Co 1 .6 Zn 0 .4} Fe 24 O 41 ceramics sintered at 1250 ℃ above result was used as the substrate, it is considered that the production of the antenna exhibits good characteristics in the FM band and the DMB band possible.

From the above test results, it can be seen that the Co ₂ Z-type ferrite having a Z-type single phase without secondary phase at a sintering temperature of 1200 ℃ to 1300 ℃ can be produced.

In addition, the permittivity and permeability increased by substituting Mn and Zn at Co site, and it is possible to maintain excellent microwave characteristics at high frequencies as the magnetic resonance frequency moves from 200 MHz to 600 MHz band, so that the applicable frequency range of ferrite material It can be seen that is improved.

In addition, by using _{Ba 3 Co 1 .6 Zn 0 .4} Fe 24 O 41 ceramics it exhibits excellent properties as a substrate After a design the 2x2 array antenna can be seen that exhibits excellent characteristics in the FM frequency band and the DMB band.

Therefore, based on microwave characteristics such as permittivity, permeability, magnetic resonance frequency, and antenna simulation results as described above, it can be seen that Co ₂ Z-type ferrites containing Mn and Zn can be applied in a high frequency region.

Also, in the future, as the frequency of use of RF components shifts to several GHz bands, microwave materials will require higher frequency and smaller size.

Therefore, the Co ₂ Z ferrite according to the present invention has a high permeability and a high dielectric constant, and can be used in a variety of high frequency devices.

Claims (7)

Applicable at high frequency,
Co ₂ Z-type ferrite for high frequency applications, characterized in that represented by the formula (1).
[Formula 1]
Ba ₃ Co _{2 -2x} (Mn, Zn) _{2 x} Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5) The method of claim 1,
Co ₂ Z-type ferrite for high frequency applications, characterized in that the ferrite is sintered at 1200 ℃ ~ 1300 ℃. The method of claim 1,
The value of permittivity and permeability of the ferrite is 15 or more,
Co ₂ Z-type ferrite for high frequency applications, characterized in that the difference between the permittivity and the permeability is within ± 5 range. A high frequency device comprising a Co ₂ Z type ferrite for use in any of the high frequency applications of claim 1. The method of claim 4, wherein
And the high frequency device is an antenna. BaCO ₃ , Mixing the materials using CoO, Fe ₂ O ₃ , MnO and ZnO as starting materials;
Calcining the mixed material at 600 ° C to 1000 ° C; And
Method for producing a Co ₂ Z-type ferrite comprising the step of sintering the calcined material at 1200 ℃ ~ 1300 ℃. The method of claim 6,
The starting material is a method of producing a Co ₂ Z-type ferrite, characterized in that the basis weight in accordance with the stoichiometric ratio of the ferrite of the formula (1) and then mixed and dispersed using an organic solvent as a dispersion medium.
[Formula 1]
Ba ₃ Co _2-2x (Mn, Zn) _2x Fe ₂₄ O ₄₁ (x = 0.1 ~ 0.5)

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