KR102608246B1 - Magnetic sintered ceramic, method of making the same, and antenna device comprising the magnetic sintered ceramic - Google Patents

Abstract

A magnetic ceramic sintered body including a Z-type phase and expressed by the following formula (1), a manufacturing method thereof, and an antenna including the magnetic ceramic sintered body are provided.
[Formula 1]
Ba _1.5-x Sr _1.5-x Ca _2x M ₂ Fe ₂₄ O ₄₁
(M and x in the chemical formula are as defined in the detailed description of the invention.)

Description

Magnetic ceramic sintered body, manufacturing method thereof, and antenna comprising the magnetic ceramic sintered body {MAGNETIC SINTERED CERAMIC, METHOD OF MAKING THE SAME, AND ANTENNA DEVICE COMPRISING THE MAGNETIC SINTERED CERAMIC}

It relates to a magnetic ceramic sintered body, a manufacturing method thereof, and an antenna including the magnetic ceramic sintered body.

Recently, with the development of mobile communication and information technology, the use of electronic devices such as mobile phones and laptops for the production, transmission, and preservation of information has increased, and miniaturization of electronic devices has become a hot topic. Accordingly, antennas used in electronic devices are also required to be miniaturized and have higher frequencies in accordance with the trend toward miniaturization of electronic devices.

In order to miniaturize and increase the frequency of antennas, it is common to reduce the length of the wavelength at the operating frequency by using a magnetic material with a high dielectric constant. However, if the energy transmitted to the antenna is trapped within the dielectric due to the high dielectric constant of the magnetic material, it causes a decrease in impedance bandwidth or efficiency in the low frequency band.

Depending on the type of electronic device, the required frequency band ranges from high frequency bands above about 1 GHz to relatively low frequency bands below about 1 GHz, but currently, the focus is on increasing the frequency of antennas that absorb electromagnetic waves in the high frequency band. Tailored research is mainly in progress.

Accordingly, the need for an antenna that has excellent electromagnetic wave absorption performance in a wide range of frequency bands, not only in the high frequency band but also in the low frequency band, is increasing.

One embodiment seeks to provide a magnetic ceramic sintered body that has excellent magnetic properties in both low-frequency and high-frequency bands and stable magnetic properties in the low-frequency band.

Another embodiment seeks to provide a method of manufacturing the magnetic ceramic sintered body.

Another embodiment seeks to provide an antenna including the magnetic ceramic sintered body.

According to one embodiment, a magnetic ceramic sintered body including a Z-type phase and represented by the following Chemical Formula 1 is provided.

[Formula 1]

Ba _1.5-x Sr _1.5-x Ca _2x M ₂ Fe ₂₄ O ₄₁

In Formula 1, M is one or more elements selected from Co, Ni, Cu, Mg, Mn, Ti, Al, Mn, Zn, and Zr, and 0 ≤ x ≤ 0.3.

In Formula 1, M is Co, and 0 < x ≤ 0.3.

The Z-shaped phase may be 90% or more based on the total phase of the magnetic ceramic sintered body.

The magnetic ceramic sintered body may be composed of a Z-type single phase.

The porosity of the magnetic ceramic sintered body may be 5% by volume or less.

The magnetic saturation of the magnetic ceramic sintered body may be 49 emu/g to 64 emu/g.

The coercive force of the magnetic ceramic sintered body may be greater than 0 and less than or equal to 200 Oe.

The magnetic ceramic sintered body may have a dielectric loss tangent (tan δ ₁ ) of 0.04 or less in the frequency band of 300 MHz to 500 MHz.

The magnetic ceramic sintered body may have a magnetic loss tangent (tan δ ₂ ) of 0.2 or less in the frequency band of 300 MHz to 500 MHz.

Meanwhile, according to another embodiment, in the method of manufacturing the magnetic ceramic sintered body according to the above embodiment, an iron (Fe)-containing precursor is calcined at 850 ° C to 1200 ° C to obtain an intermediate, the intermediate is pressure molded, and A method for manufacturing a magnetic ceramic sintered body is provided, in which the pressure-molded intermediate is sintered at 1100° C. to 1300° C. to obtain a magnetic ceramic sintered body represented by Chemical Formula 1.

In the method for producing the magnetic ceramic sintered body, an intermediate can be obtained by calcining the iron-containing precursor at 900 ° C to 1100 ° C, and the intermediate can be sintered at 1100 ° C to 1250 ° C to obtain an intermediate represented by the following formula (2). .

[Formula 2]

Ba _1.2 Sr _1.2 Ca _0.6 Co ₂ Fe ₂₄ O ₄₁

Meanwhile, according to another embodiment, an antenna including the magnetic ceramic sintered body according to the above embodiment is provided.

The antenna may be at least one of a communication service antenna between medical implant devices, an electronic tag antenna, and a mobile broadcast antenna.

A magnetic ceramic sintered body having excellent magnetic properties in both low-frequency and high-frequency bands and stable magnetic properties in the low-frequency band, and a method for manufacturing the same can be provided.

In addition, it is possible to provide an antenna that includes the magnetic ceramic sintered body and has very stable magnetic properties in a low frequency band.

1 is a scanning electron microscope (SEM) image showing a magnetic ceramic sintered body of one embodiment;
Figure 2 is an XRD analysis graph for examples,
Figure 3 is an SEM image of Examples 1-1 to 1-3 arranged according to sintering temperature conditions;
Figure 4 is an SEM image of Examples 2-1 to 2-3 arranged according to sintering temperature conditions;
Figure 5 is an SEM image of Examples 3-1 to 3-4 arranged according to sintering temperature conditions;
Figure 6 is a hysteresis curve graph for Example 1-3, Example 2-3, Example 3-2, and Example 3-5;
Figure 7 is a graph showing the dielectric loss tangent for Examples 1-3, 2-3, and 3-2;
Figure 8 is a graph showing magnetic loss tangent for Examples 1-3, 2-3, and 3-2.

Hereinafter, examples will be described in detail so that those skilled in the art can easily perform them. However, it may be implemented in various different forms and is not limited to the embodiment described herein.

In the drawing, the thickness is enlarged to clearly express various layers and areas. Throughout the specification, similar parts are given the same reference numerals. When a part of a layer, membrane, region, plate, etc. is said to be “on” another part, this includes not only cases where it is “directly above” the other part, but also cases where there is another part in between. Conversely, when a part is said to be “right on top” of another part, it means that there is no other part in between.

Additionally, the singular includes the plural, unless specifically stated in the phrase.

Hereinafter, the composition and schematic structure of the magnetic ceramic sintered body according to one embodiment will be described with reference to FIG. 1.

1 is a scanning electron microscope (SEM) image showing a magnetic ceramic sintered body of one embodiment.

The magnetic ceramic sintered body of one embodiment may have two or more hexagonal ferrites including a Z-type phase aggregated to form an aggregate as shown in FIG. 1 .

That is, generally, Z-type hexagonal ferrite has a structure in which a plurality of hexagonal plate-shaped units are dispersed in the form of flakes, but in the magnetic ceramic sintered body according to one embodiment, a plurality of hexagonal plate-shaped units are cohesive and sintered. It has a modified structure.

For example, referring to Figure 1, two or more hexagonal plate-shaped units may be aggregated together to form a lamellar shape. However, the microstructure of the magnetic ceramic sintered body according to one embodiment is not necessarily limited to the shape shown in FIG. 1.

Meanwhile, the magnetic ceramic sintered body according to the above embodiment may be expressed by the following formula (1).

[Formula 1]

Ba _1.5-x Sr _1.5-x Ca _2x M ₂ Fe ₂₄ O ₄₁

In the above formula, M is one or more elements selected from Co, Ni, Cu, Mg, Mn, Ti, Al, Mn, Zn, and Zr, and 0 ≤ x ≤ 0.3.

In one embodiment, in addition to the Z-type phase, the magnetic ceramic sintered body may further have one or more of an M-type phase, a Y-type phase, a W-type phase, and a CoFe ₂ O ₄ phase (spinel structure). That is, the magnetic ceramic sintered body may be composed of two or more mixed phases in which the Z-type phase and other phases are mixed.

However, the embodiment is not necessarily limited to this, and the magnetic ceramic sintered body may be made of a Z-type single phase. The phase of the magnetic ceramic sintered body may have different aggregation speed and agglomerated form of the hexagonal plate-shaped unit structures depending on changes in calcination temperature and/or sintering temperature during the manufacturing process of the magnetic ceramic sintered body.

The phases of the magnetic ceramic sintered body, phase changes depending on the manufacturing process, and physical properties that change as a result will be described later.

The magnetic ceramic sintered body according to one embodiment may have a higher density compared to a case where hexagonal plate-shaped unit structures are gathered and simply compressed.

That is, the magnetic ceramic sintered body according to one embodiment promotes the cohesion of the hexagonal plate-shaped unit structures through the firing process, so that the spaces existing inside or outside the magnetic ceramic sintered body are filled during the firing process to have a high density. Accordingly, spaces or micropores existing inside and outside the magnetic ceramic sintered body according to one embodiment can be removed through a sintering process.

In one embodiment, the porosity of the micropores formed inside and outside the magnetic ceramic sintered body is, for example, 10 vol% or less, for example, 7 vol% or less, for example, 5 vol% or less, based on the total volume of the magnetic ceramic sintered body. It may be less than 3% by volume, for example less than 3% by volume.

Since the micropores deteriorate the magnetic properties of the magnetic material, when a magnetic material containing many micropores is used as a device for transmitting/receiving radio waves, such as an antenna for wireless communication, the stability of transmitting/receiving radio waves may be reduced.

However, the magnetic ceramic sintered body according to one embodiment can improve both the magnetic properties and stability of the magnetic ceramic sintered body by minimizing internal and/or external micropores within the above range to improve the density of the magnetic ceramic sintered body. In other words, it can be applied to various wireless communication devices (antennas, etc.) that require stable transmission/reception of radio waves.

The magnetic saturation of the magnetic ceramic sintered body may be, for example, 80 emu/g or less, for example, 70 emu/g or less, for example, 65 emu/g or less, for example, 64 emu/g or less. . Additionally, the magnetic saturation of the magnetic ceramic sintered body may be, for example, 30 emu/g or higher, for example, 40 emu/g or higher, for example, 45 emu/g or higher, for example, 49 emu/g or higher.

In addition, the coercive force of the magnetic ceramic sintered body is, for example, 500 Oe or less, for example, more than 0 and 490 Oe or less, for example, more than 0 and 250 Oe or less, for example, more than 0 and 200 Oe or less, e.g. For example, it can be greater than 0 and less than or equal to 100 Oe.

When the magnetic saturation and coercivity of the magnetic ceramic sintered body are within the above range, the magnetic ceramic sintered body can exhibit excellent soft magnetic properties.

Meanwhile, the magnetic ceramic sintered body can minimize both dielectric loss and magnetic loss in a low frequency band of less than 1 GHz, for example, a frequency band of 300 MHz to 500 MHz.

For example, the magnetic ceramic sintered body may have a dielectric loss tangent (tan δ ₁ ) of 0.07 or less, for example, 0.05 or less, for example, 0.04 or less in the 300 MHz to 500 MHz frequency band.

Additionally, the magnetic ceramic sintered body may have a magnetic loss tangent (tan δ ₂ ) of 0.5 or less, for example, 0.3 or less, for example, 0.2 or less in the 300 MHz to 500 MHz frequency band.

As above, the magnetic ceramic sintered body according to one embodiment has a very low porosity and exhibits strong soft magnetic properties, while minimizing the dielectric loss tangent and magnetic loss tangent in the 300 MHz to 500 MHz frequency band, respectively, within the above range. .

Meanwhile, the magnetic ceramic sintered body may have a ratio of permeability to dielectric constant in the frequency band of 300 MHz to 500 MHz, for example, 0.3 or more, for example, 0.33 or more, for example, 0.37 or more, for example, 0.5 or more. When the ratio of permeability to dielectric constant in the low frequency band satisfies the above range, the intrinsic impedance of the magnetic ceramic sintered body increases, so the bandwidth of the magnetic ceramic sintered body including the magnetic ceramic sintered body will be improved. You can.

However, the magnetic ceramic sintered body according to one embodiment not only minimizes dielectric loss and magnetic loss in a low frequency band of less than 1 GHz, but also exhibits excellent magnetic properties in a high frequency band of 1 GHz or more. That is, one embodiment can provide a magnetic ceramic sintered body that can be used as an antenna over a wide bandwidth from low frequencies and bands to high frequency bands.

As discussed above, according to one embodiment, the magnetic ceramic sintered body has excellent magnetic properties (soft magnetic properties), for example, less than 1 GHz, for example, 400 MHz to 800 MHz, for example, 300 MHz to 500 MHz. For example, it is possible to provide a magnetic ceramic sintered body with minimized dielectric loss and magnetic loss in a low frequency band of 400 MHz to 410 MHz.

Meanwhile, hereinafter, an antenna including the above-described magnetic ceramic sintered body will be described.

An antenna including the magnetic ceramic sintered body may be processed into various shapes depending on the purpose of the antenna.

An antenna including a magnetic ceramic sintered body according to an embodiment exhibits excellent magnetic properties over a wide frequency band from a low frequency band to a high frequency band, and is therefore used in electrical devices that must transmit/receive electromagnetic waves in both low and high frequency bands together. , electrical devices that must stably absorb electromagnetic waves in the low-frequency band, such as transmitters/receivers of electronic tags (radio frequency identification, RFID) widely used in security or distribution fields, and for mobile broadcasting (digital multimedia broadcasting, DMB) It can be widely applied to channel transmitters/receivers, etc.

In addition, the antenna including the magnetic ceramic sintered body according to one embodiment exhibits excellent and stable magnetic characteristics while minimizing dielectric loss and magnetic loss in the low frequency band of 300 MHz to 500 MHz, thereby enabling stable radio wave transmission/reception. It can be applied to various required wireless communication devices (antennas, etc.). For example, an antenna including a magnetic ceramic sintered body according to one embodiment is an antenna for transmitting/receiving communication services between medical implant devices (about 402 MHz to 405 MHz frequency band), where radio wave transmission/reception stability is emphasized. It can also be applied to wireless communication devices.

Meanwhile, the following will describe a method of manufacturing the magnetic ceramic sintered body.

A method of manufacturing a magnetic ceramic sintered body according to an embodiment includes a process of calcining an iron (Fe)-containing precursor at 850°C to 1200°C to obtain an intermediate (calcination process), a process of pressurizing and molding the intermediate (molding process), and It includes a process (sintering process) of sintering the pressure-molded intermediate at 1100°C to 1300°C to obtain a magnetic ceramic sintered body represented by the above-mentioned Chemical Formula 1.

First, prepare a precursor containing iron (Fe). The precursor contains at least iron (Fe), but may further contain barium (Ba) and strontium (Sr), and may further contain calcium (Ca), and in addition, cobalt (Co), nickel (Ni), and copper. It may be a powder-type precursor that further contains one or more elements among (Cu), magnesium (Mg), manganese (Mn), titanium (Ti), aluminum (Al), zinc (Zn), and zirconium (Zr). . The stoichiometric ratio of the above elements in the precursor is as shown in Chemical Formula 1 described above.

Then, as a preliminary step for calcination, the precursor mixed with the above elements is placed in a dispersion medium, mixed, pulverized, and dried to obtain a precursor with the pulverized elements.

Thereafter, in the calcination step, the pulverized precursor is calcined at a temperature of 850°C to 1200°C. In one embodiment, the precursor may be calcined for 1 hour to 8 hours, such as 2 hours to 8 hours, such as 4 hours to 8 hours.

In the calcination step, elements inside the precursor form chemical bonds to form particle-shaped intermediates, and as calcination progresses, the intermediate particles gradually grow. The particles have different phases depending on the specific calcination temperature. For example, when the calcination temperature is adjusted close to about 850°C to about 1100°C, two-phase, three-phase or more intermediate particles including the M-type phase may be formed in the precursor after the calcination is completed. In addition, for example, when the calcination temperature is adjusted close to about 1200° C., after calcination is completed, two-phase, three-phase or more intermediate particles further including a Z-type phase may be formed in the precursor.

Thereafter, in the molding step, the intermediate particles formed through the calcination are put into a mold and pressed. Through the pressurizing step, the space between the intermediate particles can be minimized before the sintering step, while the intermediate particles can be molded into various required shapes.

For example, in the pressing step, the intermediate particles can be formed into pellet-shaped specimens by uniaxial pressing or cold isostatic compression. However, the pressing step and the shape of the molded intermediate according to one embodiment are not necessarily limited to this molding method or pellet shape, and may be molded using various known pressing methods or formed into a belt depending on the field to which the magnetic ceramic sintered body will be applied. It can be molded into various shapes, such as shape, rod shape, and chip shape.

Thereafter, in the sintering step, the molded intermediate specimen is sintered at 1100° C. to 1300° C., thereby obtaining a magnetic ceramic sintered body according to one embodiment. In one embodiment, the specimen may be sintered for 1 hour to 12 hours, such as 4 hours to 10 hours, such as 5 hours to 8 hours.

The magnetic ceramic sintered body formed through the sintering step may be a magnetic material represented by the following formula (2).

[Formula 2]

Ba _1.2 Sr _1.2 Ca _0.6 Co ₂ Fe ₂₄ O ₄₁

However, the magnetic ceramic sintered body according to one embodiment is not limited to that represented by Formula 2, and the magnetic ceramic sintered body may include various magnetic materials represented by Formula 1 above.

The intermediate specimen formed in the calcination step undergoes a phase change through sintering. Additionally, the intermediate particles have different phases depending on the specific sintering temperature. The phase change in the calcination step and the phase change in the sintering step depend on both the change in the state of the particles depending on the temperature and the stoichiometric ratio of the precursor, which is the starting material. For example, the above-described intermediate specimen can be sintered at, for example, 1100°C to 1250°C, and thus a magnetic ceramic sintered body exhibiting excellent magnetic properties can be manufactured.

The phase changes of particles that occur during calcination and sintering and the resulting effects will be described later.

The obtained magnetic ceramic sintered body may be in the form of an aggregate with very low porosity.

The method for manufacturing a magnetic ceramic sintered body according to an embodiment controls the calcination temperature and the sintering temperature according to the stoichiometric ratio of iron-containing precursor elements, thereby manufacturing a magnetic ceramic sintered body with minimized dielectric loss and magnetic loss as described above. there is.

Below, specific embodiments of the present invention are presented. However, the examples described below are only for illustrating or explaining the invention in detail, and should not limit the scope of the invention.

Preparation of Intermediate 1

As starting raw materials, BaCO ₃ , SrCO ₃ , Co ₃ O ₄ , and Fe ₂ O ₃ were weighed and mixed in a molar ratio of Ba: Sr: Co: Fe = 1.5 : 1.5 : 2 : 24 to obtain an iron-containing precursor. manufacture. Thereafter, the iron-containing precursor is mixed with water or ethanol as a dispersion medium, ground for 24 hours using a ball mill, and then dried.

Thereafter, the pulverized precursor is calcined at a temperature of 1100° C. for 4 hours to obtain pulverized Intermediate 1 in powder form. In the obtained intermediate 1, a two-phase mixed phase of the M-type phase and the Y-type phase is formed through calcination.

Preparation of Intermediate 2

Weigh BaCO ₃ , SrCO ₃ , CaCO ₃ , Co ₃ O ₄ , and Fe ₂ O ₃ as starting raw materials so that the molar ratio is Ba: Sr: Ca: Co: Fe = 1.4 : 1.4 : 0.2 : 2 : 24, and By mixing, an iron-containing precursor is prepared.

Thereafter, the iron-containing precursor is mixed with water or ethanol as a dispersion medium, ground for 24 hours using a ball mill, and then dried.

Thereafter, the pulverized precursor is calcined at a temperature of 1100° C. for 4 hours to obtain Intermediate 2. In the obtained intermediate 2, a two-phase mixed phase of the M-type phase and the Y-type phase is formed through calcination.

Preparation of Intermediate 3

Weigh BaCO ₃ , SrCO ₃ , CaCO ₃ , Co ₃ O ₄ , and Fe ₂ O ₃ as starting raw materials so that the molar ratio is Ba: Sr: Ca: Co: Fe = 1.2 : 1.2 : 0.6 : 2 : 24, and By mixing, an iron-containing precursor is prepared.

Thereafter, the iron-containing precursor is mixed with water or ethanol as a dispersion medium, ground for 24 hours using a ball mill, and then dried.

Thereafter, the pulverized precursor is calcined at a temperature of 900° C. for 4 hours to obtain Intermediate 3. The obtained intermediate 3 has a three-phase mixed phase formed inside the M-type phase, Y-type phase, and CoFe ₂ O ₄ phase through calcination.

Preparation of Intermediate 4

Weigh BaCO ₃ , SrCO ₃ , CaCO ₃ , Co ₃ O ₄ , and Fe ₂ O ₃ as starting raw materials so that the molar ratio is Ba: Sr: Ca: Co: Fe = 1.2 : 1.2 : 0.6 : 2 : 24, and By mixing, an iron-containing precursor is prepared.

Thereafter, the iron-containing precursor is mixed with water or ethanol as a dispersion medium, ground for 24 hours using a ball mill, and then dried.

Thereafter, the pulverized precursor is calcined at a temperature of 1100° C. for 4 hours to obtain Intermediate 4. The obtained intermediate 4 has a three-phase mixed phase formed inside the M-type phase, Y-type phase, and CoFe ₂ O ₄ phase through calcination.

Example One- 1 of manufacturing

The above-described intermediate 1 is isostatically compressed at 200 MPa to prepare a pellet-shaped specimen. Thereafter, the obtained specimen was sintered at 1100°C for 4 hours to obtain the magnetic ceramic sintered body of Example 1-1.

Example Preparation of 1-2

The magnetic ceramic sintered body of Example 1-2 was obtained through the same method as Example 1-1 described above, except that the sintering temperature was changed to 1200°C.

Example Preparation of 1-3

The magnetic ceramic sintered body of Example 1-3 was obtained through the same method as Example 1-1 described above, except that the sintering temperature was changed to 1250°C.

The magnetic ceramic sintered bodies according to Examples 1-1 to 1-3 all contain Ba _{1 . 5} Sr _{1 . 5} Co ₂ Fe ₂₄ O ₄₁ It is a magnetic material expressed as .

Example Manufacturing of 2-1

The magnetic ceramic sintered body of Example 2-1 was obtained through the same method as Example 1-1 described above, except that Intermediate 2 was used instead of Intermediate 1.

Example Preparation of 2-2

The magnetic ceramic sintered body of Example 2-2 was obtained through the same method as Example 2-1 described above, except that the sintering temperature was changed to 1200°C.

Example Preparation of 2-3

The magnetic ceramic sintered body of Example 2-3 was obtained through the same method as Example 2-1 described above, except that the sintering temperature was changed to 1250°C.

The magnetic ceramic sintered bodies according to Examples 2-1 to 2-3 are all magnetic materials expressed as Ba _1.4 Sr _1.4 Ca _0.2 Co ₂ Fe ₂₄ O ₄₁ .

Example Manufacturing of 3-1

The magnetic ceramic sintered body of Example 3-1 was obtained through the same method as Example 1-1 described above, except that Intermediate 3 was used instead of Intermediate 1.

Example Manufacturing of 3-2

The magnetic ceramic sintered body of Example 3-2 was obtained through the same method as Example 3-1 described above, except that the sintering temperature was changed to 1150°C.

Example Preparation of 3-3

The magnetic ceramic sintered body of Example 3-3 was obtained through the same method as Example 3-1 described above, except that the sintering temperature was changed to 1200°C.

Example Preparation of 3-4

The magnetic ceramic sintered body of Example 3-4 was obtained through the same method as Example 3-1 described above, except that the sintering temperature was changed to 1250°C.

Example Preparation of 3-5

The magnetic ceramic sintered body of Example 3-5 was obtained through the same method as Example 3-4 described above, except that Intermediate 4 was used instead of Intermediate 3.

The magnetic ceramic sintered bodies according to Examples 3-1 to 3-5 are all magnetic materials expressed as Ba _1.2 Sr _1.2 Ca _0.6 Co ₂ Fe ₂₄ O ₄₁ .

The XRD patterns for the above-described examples were measured and shown in FIG. 2. In addition, SEM images for Examples 1-1, 1-2, and 1-3 are shown in Figure 3, SEM images for Examples 2-1, 2-2, and 2-3 are shown in Figure 4, and Example 3- SEM images for 1, 3-2, 3-3, and 3-4 are shown in Figure 5, respectively.

Analysis 1: Examples XRD pattern and S.E.M. image

Figure 2 is an -3 is an SEM image arranged according to sintering temperature conditions, and Figure 5 is an SEM image of Examples 3-1 to 3-4 arranged according to sintering temperature conditions.

In FIGS. 2 to 5, the CoFe ₂ O ₄ phase is indicated as “S” for convenience.

Referring to Figures 2 and 3, it can be seen that the final formed phase and microstructure are different depending on the specific sintering temperature in Examples 1-1 to 1-3 in which the calcination temperature was set to the same 1100°C. You can.

For example, it can be confirmed that in Example 1-1 (sintering temperature 1100°C) and Example 1-2 (sintering temperature 1200°C), the M-Y two-phase mixed phase of Intermediate 1 continues to appear. However, it can be seen that the particles in Example 1-1 were more aggregated compared to Example 1-2. However, in Example 1-3 (sintering temperature 1250°C), it could be confirmed that the M-Y two-phase mixed phase of Intermediate 1 was changed to a Z single phase. In Example 1-3, as Z changes to a single phase, most of the particles of Intermediate 1 change to a hexagonal plate-shaped unit shape, but it can be seen that the units are aggregated as one body.

Referring to Figures 2 and 4, even in the case of Examples 2-1 to 2-3 in which the calcination temperature was set to the same 1100°C, the final formed phase and microstructure were different depending on the specific sintering temperature. can confirm.

For example, Example 2-1 (sintering temperature 1100 °C) still shows the M-Y two-phase mixed phase of intermediate 2, while Example 2-2 (sintering temperature 1200 °C) and Example 2-3 (sintering temperature 1250 °C) In the case of , it can be confirmed that the M-Y two-phase mixed phase of Intermediate 2 was changed into a Z single phase. In the case of Intermediate 2, it can be seen that the sintering temperature at which the Z-only phase is formed is relatively lower than in Examples 1-1 to 1-3 using Intermediate 1.

However, it can be seen that Example 2-3 has a higher degree of particle aggregation compared to Example 2-2. More specifically, particles with a hexagonal plate-like structure were formed under the sintering conditions of Example 2-2, but the sizes of the particles may be different. Accordingly, as shown in FIG. 4, relatively large particles aggregate to form a mountain range-shaped framework, and relatively small size particles aggregate between the framework to form a fine structure.

Meanwhile, in the case of Example 2-3, the size difference between particles was relatively small compared to the particles of Example 2-2, and the particles having a hexagonal plate-shaped structure were aggregated to form a lamellar shape. In this case, as shown in Figure 4, the thickness of each layer inside the lamella shape of Example 2-3 is relatively thick compared to the thickness of the mountain range shape skeleton of Example 2-2, and the particles between the layers have a relatively high density. You can see that it is cohesive.

Meanwhile, referring to FIGS. 2 and 5, unlike the above-described FIGS. 3 and 4, in the case of Examples 3-1 to 3-4 in which the calcination temperature was set to 900 ° C., depending on the specific sintering temperature, It can be confirmed that the final formed phase and microstructure are different.

For example, in Example 3-1 (sintering temperature 1100°C), the three-phase mixed phase of M-Y-S of Intermediate 3 continues to appear, but in Example 3-2 (sintering temperature 1150°C) it changes to a Z-only phase, and Example 3 It can be confirmed that -3 (sintering temperature 1200°C) and Example 3-4 (sintering temperature 1250°C) show a Z-W two-phase mixed phase. In the case of Intermediate 3, it can be seen that the sintering temperature at which the Z-containing phase is formed is relatively lower than in the case of Intermediate 1 or Intermediate 2.

Meanwhile, plate-shaped particles began to form from the sintering temperature (1100° C.) of Example 3-1, but in the case of Example 3-1, it can be seen that the size difference between particles was relatively large. On the other hand, in the case of Example 3-2, it can be seen that most of the particles grew to be plate-shaped. In the case of Example 3-2, it can be confirmed that it exhibits a microstructure similar to Examples 1-3, Example 2-2, and Example 2-3 having the above-described Z single phase. However, in the case of Examples 3-3 and 3-4, it can be seen that as the sintering temperature increases, the equilibrium particle shape gradually approaches a spherical shape. It can be confirmed that this is because part of the Z-shaped phase changes into a W-shaped phase.

As seen above, in the case of Examples 1-1 to 1-3 that do not contain Ca, and Examples 2-1 to 2-3 that contain a relatively small amount of Ca, the magnetic ceramic sintered body is Z-type. It can be seen that the calcination temperature and sintering temperature for change to the phase are somewhat high. Meanwhile, in the case of Examples 3-1 to 3-4, the Z-type phase may be changed at relatively low calcination and sintering temperatures, but as the sintering temperature increases, part of the Z-type phase may change into the W-type phase. You can confirm that it exists.

Analysis 2: Example 1-3, Example 2-3, Example 3-2 and Example 3-5 coercivity ( Hc ) and magnetic saturation (Ms)

Examples 1-3, 2-3, and 3-2 having a Z-only phase, and together with Example 3-2, are expressed by Formula 2, but are the same as Examples 1-3 and 2-3. The hysteresis curve for Examples 3-4 (calcining temperature 1100°C, sintering temperature 1200°C) prepared at the calcining and sintering temperatures is shown in Figure 6.

Figure 6 is a hysteresis curve graph for Examples 1-3, 2-3, 3-2, and 3-5.

Referring to FIG. 6, the coercivity under the same calcination and sintering conditions (calcination temperature of 1100°C, sintering temperature of 1200°C) is similar to that of Examples 1-3 and 2-3, each at 100 Oe or less. It can be seen that 3-5 is relatively high, at over 100 Oe and around 200 Oe. Meanwhile, although the calcination and sintering conditions are different, it can be confirmed that Example 3-2, which has a Z-only phase, has a coercive force of 100 Oe or less, similar to Examples 1-3 and Example 2-3.

This is presumed to be because, unlike Examples 1-3, 2-3, and 3-2, which have a Z-only phase, part of the internal Z-shaped phase in Example 3-5 was transformed into a W-type phase.

Meanwhile, the magnetic saturation under the same calcination and sintering conditions (calcination temperature 1100°C, sintering temperature 1200°C) was about 49 emu/g in Examples 1-3 and 2-3, whereas Example 3-5 showed It can be seen that it represents a relatively high value of about 64 emu/g. Meanwhile, although the calcination and sintering conditions are different, it can be seen that Example 3-2, which has a Z-type single phase, shows a magnetic saturation of about 64 emu/g, similar to Example 3-5.

It is assumed that compared to Examples 1-3 and 2-3, Examples 3-2 and 3-5, which contain more Ca, slightly increased the saturation magnetization value due to Ca. However, when compared to a general magnetic ceramic sintered body having a magnetic saturation exceeding 80 emu/g, all of Examples 1-3, 2-3, 3-2, and 3-5 were 64 emu/g or less. It can be confirmed that it represents a magnetic saturation of .

Accordingly, it can be confirmed that the magnetic ceramic sintered bodies of Examples 1-3, 2-3, 3-2, and 3-5 have both relatively low coercive force and magnetic saturation, and have excellent soft magnetic properties. there is.

Analysis 3: By frequency band Example 1-3, Example 2-3, Example Dielectric loss tangent and magnetic loss tangent change in 3-2

While changing the frequency, the dielectric loss tangent (tan δ ₁ ) and magnetic loss tangent (tan δ ₂ ) for each of the magnetic ceramic sintered bodies of Examples 1-3, Example 2-3, and Example 3-2 were measured, This is shown in Figures 7 and 8.

FIG. 7 is a graph showing the dielectric loss tangent for Examples 1-3, 2-3, and 3-2, and FIG. 8 is a graph showing dielectric loss tangents for Examples 1-3, 2-3, and 3-2. This is a graph showing the magnetic loss tangent for Example 3-2. The x-axis and y-axis of FIGS. 7 and 8 are expressed in log scale.

Referring to FIG. 7, the dielectric loss tangent in the low frequency band of 1 GHz or less is generally the lowest in Example 2-3, and Examples 1-3 and 3-2 show similar levels. However, in the frequency band of about 400 MHz or more, the dielectric loss tangent of Example 2-3 increases rapidly, and it can be seen that in the frequency band of about 700 MHz or more, the dielectric loss tangent is larger than that of Examples 1-3 and Example 3-2. You can.

Meanwhile, in all of Examples 1-3, 2-3, and 3-2, the dielectric loss tangent in the 300 MHz to 500 MHz frequency band is all 0.04 or less, and in the case of Example 2-3, it is a value close to 0.01. It can be confirmed that it represents .

Referring to FIG. 8, the magnetic loss tangent in the low frequency band of 1 GHz or less is low in Examples 2-3 and 3-2, and is relatively high in Example 1-3. The magnetic loss tangent generally increases as the frequency band increases.

Meanwhile, in all of Examples 1-3, 2-3, and 3-2, the magnetic loss tangent in the 300 MHz to 500 MHz frequency band is all 0.2 or less, and in the case of Example 2-3, it is close to about 0.04. You can confirm that it represents a value.

That is, it can be confirmed that the magnetic ceramic sintered body according to one embodiment has both small dielectric loss tangent and magnetic loss tangent in the frequency band of 300 MHz to 500 MHz, and has excellent magnetic properties even in the high frequency band around 1 GHz. Accordingly, the magnetic ceramic sintered body according to one embodiment can also be applied to MICS transmission/reception antennas, etc., which must stably transmit/receive low-frequency band radio waves of 300 MHz to 500 MHz.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements can be made by those skilled in the art using the basic concept of the present invention as defined in the following claims. It falls within the scope of invention rights.

Claims (14)

A magnetic ceramic sintered body including a Z-type phase and expressed by the following formula (1).
[Formula 1]
Ba _1.5-x Sr _1.5-x Ca _2x M ₂ Fe ₂₄ O ₄₁
In Formula 1, M is one or more elements selected from Co, Ni, Cu, Mg, Mn, Ti, Al, Mn, Zn, and Zr, and 0 < x ≤ 0.3. In paragraph 1:
In Formula 1, M is Co. In paragraph 1:
The Z-shaped phase is 90% or more of the entire phase of the magnetic ceramic sintered body. In paragraph 1:
The magnetic ceramic sintered body is a magnetic ceramic sintered body composed of a Z-type single phase. In paragraph 1:
The magnetic ceramic sintered body has a porosity of 5% by volume or less. In paragraph 1:
The magnetic ceramic sintered body has a magnetic saturation of 49 emu/g to 64 emu/g. In paragraph 1:
The magnetic ceramic sintered body has a coercive force of more than 0 and 200 Oe or less. In paragraph 1:
The magnetic ceramic sintered body has a dielectric loss tangent (tan δ ₁ ) of 0.04 or less in the frequency band of 300 MHz to 500 MHz. In paragraph 1:
The magnetic ceramic sintered body has a magnetic loss tangent (tan δ ₂ ) of 0.2 or less in the frequency band of 300 MHz to 500 MHz. A method of manufacturing the magnetic ceramic sintered body according to any one of claims 1 to 9, comprising:
An iron (Fe)-containing precursor is calcined at 850°C to 1200°C to obtain an intermediate, the intermediate is pressure molded, and the pressure molded intermediate is sintered at 1100°C to 1300°C to produce a magnetic ceramic sintered body represented by Formula 1. Obtaining a method for producing a magnetic ceramic sintered body. In paragraph 10:
A method for producing a magnetic ceramic sintered body in which an intermediate is obtained by calcining the iron-containing precursor at 900°C to 1100°C. In paragraph 11:
A method of producing a magnetic ceramic sintered body in which the intermediate is sintered at 1100°C to 1250°C to obtain an intermediate represented by the following formula (2).
[Formula 2]
Ba _1.2 Sr _1.2 Ca _0.6 Co ₂ Fe ₂₄ O ₄₁ An antenna comprising the magnetic ceramic sintered body according to any one of claims 1 to 9. In paragraph 13:
The antenna is at least one of a medical implant communication service (MICS) antenna, an electronic tag (radio frequency identification, RFID) antenna, and a mobile broadcasting (digital multimedia broadcasting, DMB) antenna.

Images