JP2009073717A - Ferrite sintered compact, production method thereof, and electronic component - Google Patents
Ferrite sintered compact, production method thereof, and electronic component Download PDFInfo
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Abstract
Description
本発明は、高周波用磁性材料に係るもので、特に数ＭＨｚから数ＧＨｚまでの高周波帯域においてチョークコイル、ノイズ除去素子、アンテナなどの電子部品や電波吸収体に使用される六方晶Ｚ型フェライトに関する。 The present invention relates to a magnetic material for high frequency, and particularly relates to a hexagonal Z-type ferrite used in electronic components such as choke coils, noise removing elements, and antennas and radio wave absorbers in a high frequency band from several MHz to several GHz. .
近年、携帯電話や無線ＬＡＮ、パソコンなどの信号の高周波化に伴い、装置内部で使用される素子もまた高周波で使用可能なものが要求されている。このような要求に対し、従来用いられてきたスピネル系フェライトでは高周波帯域においてスネークの限界と呼ばれる周波数限界が存在するため使用することが困難となる。そこで六方晶系の結晶構造を有する六方晶フェライトがかかる周波数限界を超える高周波用材料として検討されている。 In recent years, with the increase in the frequency of signals from mobile phones, wireless LANs, personal computers, etc., elements used inside the apparatus are also required to be usable at high frequencies. In response to such demands, spinel ferrites conventionally used are difficult to use because there is a frequency limit called a snake limit in the high frequency band. Therefore, hexagonal ferrite having a hexagonal crystal structure has been studied as a high frequency material exceeding the frequency limit.
六方晶系フェライトの中でも特にＣｏを含有したＺ型フェライトが比較的高い初透磁率を有し優れた高周波特性を示すことが知られている。例えば特許文献１には、ＢａＯを過剰な組成とした、初透磁率などの磁気特性に優れたＺ型フェライトが開示されている。 Among hexagonal ferrites, it is known that a Z-type ferrite containing Co in particular has a relatively high initial permeability and exhibits excellent high frequency characteristics. For example, Patent Document 1 discloses a Z-type ferrite having an excessive composition of BaO and excellent in magnetic characteristics such as initial permeability.
しかしながら、特許文献１に記載されたＺ型フェライトも、初透磁率は十分な水準とは言えず、さらに高い初透磁率を有する六方晶Ｚ型フェライトが望まれていた。よって、本発明はこの点を解決することを目的とする。 However, the Z-type ferrite described in Patent Document 1 cannot be said to have a sufficient initial permeability, and a hexagonal Z-type ferrite having a higher initial permeability has been desired. Therefore, an object of the present invention is to solve this point.
本発明のフェライト焼結体は、六方晶Ｚ型フェライトのフェライト焼結体であって、１８〜２１ｍｏｌ％のＢａＯ、９〜１１．５ｍｏｌ％のＣｏＯ、残部をＦｅ２Ｏ３を主成分とし、前記焼結体の断面観察において、空孔を除いた観察面積に対する、スピネル型フェライト相の面積比率およびＢａＦｅ２Ｏ４相の面積比率が共に１％以下であることを特徴とするフェライト焼結体である。かかる構成によって高い初透磁率を示すフェライト焼結体を得ることができる。 Ferrite sintered body of the present invention, there is provided a ferrite sintered body of hexagonal Z-type ferrite, and 18～21Mol% of BaO, 9~11.5mol% of CoO, the main component Fe 2 O 3 and the remainder, In the cross-sectional observation of the sintered body, the area ratio of the spinel ferrite phase and the area ratio of the BaFe 2 O 4 phase to the observation area excluding the voids are both 1% or less, It is. With this configuration, a ferrite sintered body having a high initial permeability can be obtained.
また、前記フェライト焼結体において、焼結体密度が５.０５×１０３ｋｇ／ｍ３以上であることが望ましい、焼結体密度の向上に伴い、初透磁率も向上し、これを用いた電子部品の高性能化に寄与する。 In the ferrite sintered body, it is desirable that the sintered body density is 5.05 × 10 3 kg / m 3 or more. As the sintered body density is improved, the initial permeability is also improved. This contributes to higher performance of electronic components.
さらに、前記フェライト焼結体において、体積抵抗率が１×１０３Ω・ｍ以上であることが好ましい。フェライト焼結体が高い初透磁率と高絶縁性を併せ持つことで、該焼結体を用いて構成する電子部品の小型化を図ることができる。 Furthermore, the ferrite sintered body preferably has a volume resistivity of 1 × 10 3 Ω · m or more. Since the ferrite sintered body has both high initial permeability and high insulation, it is possible to reduce the size of an electronic component that is configured using the sintered body.
更に、前記フェライト焼結体において、１００ｋＨｚでの初透磁率μｉが５０以上である方向を有することが望ましい。かかる構成とすることでそれを用いた電子部品の高性能化に寄与する。 Furthermore, it is desirable that the ferrite sintered body has a direction in which an initial permeability μ i at 100 kHz is 50 or more. Such a configuration contributes to higher performance of electronic components using the same.
前記フェライト焼結体を用いることにより高性能な電子部品を提供することが可能となる。 By using the ferrite sintered body, a high-performance electronic component can be provided.
本発明のフェライト焼結体の製造方法は、混合した素原料を仮焼する仮焼工程と、前記仮焼工程で得られた仮焼粉を粉砕する粉砕工程と、前記粉砕工程で得られた粉砕粉を成形する成形工程と、前記成形工程で得られた成形体を焼結する焼結工程とを有する、ＢａＯ、ＣｏＯおよびＦｅ２Ｏ３を主成分とする六方晶Ｚ型フェライトのフェライト焼結体の製造方法であって、前記フェライト焼結体の組成は、Ｚ型フェライトの化学量論組成よりもＢａＯリッチであるとともに、前記仮焼工程において前記混合した素原料を酸素中雰囲気で１３００℃以上に加熱することを特徴とする。かかる条件で仮焼を行なうことにより、異相の含有率が少ない、初透磁率の高いフェライト焼結体を得ることができる。 The method for producing a ferrite sintered body according to the present invention was obtained by the calcination step of calcining the mixed raw materials, the pulverization step of pulverizing the calcined powder obtained in the calcination step, and the pulverization step. Ferrite sintering of hexagonal Z-type ferrite mainly composed of BaO, CoO and Fe 2 O 3 , which has a forming step for forming pulverized powder and a sintering step for sintering the formed body obtained in the forming step. In the method of manufacturing a sintered body, the composition of the ferrite sintered body is BaO richer than the stoichiometric composition of Z-type ferrite, and the mixed raw material in the calcining step is 1300 in an oxygen atmosphere. It is characterized in that it is heated to a temperature not lower than ° C. By performing calcination under such conditions, it is possible to obtain a ferrite sintered body having a low initial phase permeability and a low heterogeneous content.
前記フェライト焼結体の製造方法において、前記粉砕粉の比表面積が３．５４ｍ２／ｇ以上であることが好ましい。かかる範囲の比表面積を有する粉砕粉を用いることで高い焼結体密度及び初透磁率を持つＺ型フェライト焼結体を得ることができる。 In the method for producing a ferrite sintered body, it is preferable that a specific surface area of the pulverized powder is 3.54 m 2 / g or more. By using pulverized powder having a specific surface area in such a range, a Z-type ferrite sintered body having a high sintered body density and initial permeability can be obtained.
本発明によれば、高い初透磁率を有するＺ型フェライト焼結体を提供することができ、それを用いたチョークコイル、インダクタ、アンテナ、電波吸収体などの電子部品の高性能化を可能にする。 According to the present invention, it is possible to provide a Z-type ferrite sintered body having a high initial permeability and to improve the performance of electronic components such as a choke coil, an inductor, an antenna, and a radio wave absorber. To do.
以下、本発明を実施例によって具体的に説明するが、本発明はこれらの実施例によって限定されるものではない。本発明に係るフェライト焼結体は、混合した素原料を仮焼する仮焼工程と、前記仮焼工程で得られた仮焼粉を粉砕する粉砕工程と、前記粉砕工程で得られた粉砕粉を成形する成形工程と、前記成形工程で得られた成形体を焼結する焼結工程とを有する、フェライトの製造に適用される通常の粉末冶金的方法によって製造することができる。すなわち、素原料を例えば湿式のボールミルにて混合し、電気炉などを用いて仮焼することにより仮焼粉を得る。また得られた仮焼粉を湿式のボールミルなどを用いて粉砕し、得られた粉砕粉をプレス機により成形し例えば電気炉などを用いて焼成を行い、六方晶Ｚ型フェライトのフェライト焼結体を得る。 EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The ferrite sintered body according to the present invention includes a calcining step of calcining the mixed raw materials, a crushing step of crushing the calcined powder obtained in the calcining step, and a pulverized powder obtained in the crushing step It can be manufactured by an ordinary powder metallurgical method applied to the manufacture of ferrite, which has a forming step for forming the sintered body and a sintering step for sintering the formed body obtained in the forming step. That is, the raw materials are mixed in a wet ball mill, for example, and calcined using an electric furnace or the like to obtain calcined powder. Further, the obtained calcined powder is pulverized using a wet ball mill, etc., and the obtained pulverized powder is molded by a press machine and fired using, for example, an electric furnace, and a ferrite sintered body of hexagonal Z-type ferrite. Get.
六方晶Ｚ型フェライトのフェライト焼結体では、Ｚ相が生成し易い温度域において本焼成を行っても十分な初透磁率を得ることが難しい。これはＺ相が生成し易い温度域において十分焼結が進まず焼結体密度が低いためである。逆に高い温度域で焼成を行うとＺ相が生成しにくく、著しく特性が劣化する。したがって、高い初透磁率を有する六方晶Ｚ型フェライトのフェライト焼結体を得るためには、Ｚ相が安定な温度域において十分高い焼結体密度を得られるようにすることが必要である。 In a ferrite sintered body of hexagonal Z-type ferrite, it is difficult to obtain a sufficient initial permeability even if the main firing is performed in a temperature range in which a Z phase is easily generated. This is because the sintering does not proceed sufficiently in the temperature range where the Z phase is easily generated, and the sintered body density is low. On the other hand, if firing is performed in a high temperature range, the Z phase is hardly generated and the characteristics are remarkably deteriorated. Therefore, in order to obtain a ferrite sintered body of hexagonal Z-type ferrite having high initial permeability, it is necessary to obtain a sufficiently high sintered body density in a temperature range where the Z phase is stable.
高い焼結体密度を有する場合でも、焼結体中にスピネル型フェライト相（以下、単にスピネル相ともいう）やＢａＦｅ２Ｏ４相が生成する場合があり、これを所定の範囲に低減することによって、さらに高い初透磁率が得られる。すなわち、フェライト焼結体の組成を１８〜２１ｍｏｌ％のＢａＯ、９〜１１．５ｍｏｌ％のＣｏＯ、残部Ｆｅ２Ｏ３を主成分とし、焼結体の断面観察において、空孔を除いた観察面積に対する、スピネル型フェライト相の面積比率およびＢａＦｅ２Ｏ４相の面積比率を共に１％以下にすることで更に高い初透磁率を持つフェライト焼結体を得ることができること見出した。 Even when the sintered body has a high density, a spinel ferrite phase (hereinafter also simply referred to as a spinel phase) or a BaFe 2 O 4 phase may be generated in the sintered body, and this should be reduced to a predetermined range. As a result, a higher initial permeability can be obtained. That is, the composition of the ferrite sintered body is 18 to 21 mol% BaO, 9 to 11.5 mol% CoO, and the remaining Fe 2 O 3 as main components, and in the cross-sectional observation of the sintered body, the observation area excluding voids It was found that a ferrite sintered body having a higher initial magnetic permeability can be obtained by setting both the area ratio of the spinel type ferrite phase and the area ratio of the BaFe 2 O 4 phase to 1% or less.
ＢａＯが化学量論組成よりも過剰な前記組成とすることでＺ相が安定な温度域で高い焼結体密度を得ることができる。しかしＢａＯを過剰とするとＢａＦｅ２Ｏ４相が生成し、初透磁率が発現しにくくなる。これはＢａＦｅ２Ｏ４相が非磁性相であるためである。ＢａＦｅ２Ｏ４相は１％を超えると全体の組成バランスが崩れ、特性が大きく低下するため、１％以下であることが望ましい。 By setting the BaO in excess to the stoichiometric composition, a high sintered body density can be obtained in a temperature range where the Z phase is stable. However, when BaO is excessive, a BaFe 2 O 4 phase is generated, and the initial permeability is hardly exhibited. This is because the BaFe 2 O 4 phase is a nonmagnetic phase. If the BaFe 2 O 4 phase exceeds 1%, the overall composition balance is lost and the characteristics are greatly deteriorated, so that it is preferably 1% or less.
本発明者は、ＢａＯが化学量論組成よりも過剰な前記組成に対して、仮焼工程において、混合した素原料を酸素中雰囲気で１３００℃以上に加熱するという反応が進みやすい条件を採用することで、高密度を有し、ＢａＦｅ２Ｏ４相の生成も抑制されたＺ型フェライト焼結体が得られることを見出した。焼結体密度の向上により、高い初透磁率を持つ焼結体が得られるようになる。仮焼を行なう雰囲気は酸素中であることが望ましく、１３００℃以上の温度で一定時間保持を行なうことが望ましい。十分な反応のためには保持時間は３０分以上であることが望ましく、保持時間が長すぎると反応が進みすぎ粉体の解砕が困難になるため、１０時間以下が望ましい。なお、仮焼温度は、それが高くなりすぎると融解が生じるので、１３８０℃以下とすることがより好ましい。 The present inventor adopts a condition in which the reaction in which the mixed raw material is heated to 1300 ° C. or higher in an oxygen atmosphere in the calcination step is easy for the above composition in which BaO is more than the stoichiometric composition. Thus, it has been found that a Z-type ferrite sintered body having a high density and suppressing the formation of the BaFe 2 O 4 phase can be obtained. By improving the density of the sintered body, a sintered body having a high initial permeability can be obtained. The atmosphere in which the calcination is performed is preferably in oxygen, and it is desirable to hold at a temperature of 1300 ° C. or higher for a predetermined time. For a sufficient reaction, the holding time is desirably 30 minutes or longer, and if the holding time is too long, the reaction proceeds so much that it becomes difficult to disintegrate the powder, and therefore it is desirable that the holding time is 10 hours or less. The calcination temperature is more preferably set to 1380 ° C. or lower because melting occurs when the temperature is too high.
上記のような高温での仮焼を行なった場合、化学量論組成ではスピネル相が生成してしまう。これに対して、化学量論組成よりもＢａＯが過剰な組成を用いることによって、スピネル相の生成を抑制することができる。スピネル相はＺ型フェライトよりも低い周波数で初透磁率が減衰するため、かかるスピネル相を１％以下にすることで、初透磁率の向上を図ることができる。以上の観点から、高初透磁率を得るために望ましい主成分組成範囲は、ＢａＯ換算で１８〜２１ｍｏｌ％、ＣｏＯ換算で９〜１１．５ｍｏｌ％、残部をＦｅ２Ｏ３である。また該範囲を外れると初透磁率が低下する一方、２１．０ｍｏｌ％を超えると反応が過剰に進み粉砕前の仮焼粉の解砕が困難になるという問題も発生する。一方、ＣｏＯ含有量の含有量が極端に低下するとＺ型フェライトの周波数特性が劣化するため９ｍｏｌ％以上が望ましい。また残部となるＦｅ２Ｏ３の一部をＭｎＯで置換することにより体積抵抗率が著しく増加し、初透磁率の周波数特性が改善される。ＭｎＯの量は、２（ＭｎＯ）換算で主成分全体の０．１ｍｏｌ％未満では効果が十分発揮されず、４.０ｍｏｌ％超としてもそれ以上の効果は発揮されない。したがって、ＭｎＯの量は、主成分全体に対して、２（ＭｎＯ）換算で０.１〜４.０ｍｏｌ％の範囲が好ましい。また置換する元素はＭｎＯのみではなく、ＮｉＯ、ＭｇＯ、ＺｎＯ、ＣｕＯなど他の２価の金属イオンを用いることも可能である。また、本発明の効果が損なわれない範囲でＳｉＯ２等の添加物を含んでもよいし、ＢａＯやＣｏＯの一部を他の元素の酸化物で置換してもよい。 When calcining at a high temperature as described above, a spinel phase is generated in the stoichiometric composition. On the other hand, by using a composition in which BaO is more excessive than the stoichiometric composition, the generation of the spinel phase can be suppressed. Since the initial permeability of the spinel phase is attenuated at a frequency lower than that of the Z-type ferrite, the initial permeability can be improved by setting the spinel phase to 1% or less. From the above viewpoint, the main component composition range desirable for obtaining a high initial permeability is 18 to 21 mol% in terms of BaO, 9 to 11.5 mol% in terms of CoO, and the balance is Fe 2 O 3 . Further, if the content is out of the range, the initial magnetic permeability is lowered. On the other hand, if it exceeds 21.0 mol%, there is a problem that the reaction becomes excessive and it becomes difficult to disintegrate the calcined powder before pulverization. On the other hand, if the CoO content is extremely lowered, the frequency characteristics of the Z-type ferrite are deteriorated, so 9 mol% or more is desirable. Further, by replacing a part of the remaining Fe 2 O 3 with MnO, the volume resistivity is remarkably increased, and the frequency characteristics of the initial permeability are improved. If the amount of MnO is less than 0.1 mol% of the whole main component in terms of 2 (MnO), the effect is not sufficiently exhibited, and even if it exceeds 4.0 mol%, no further effect is exhibited. Therefore, the amount of MnO is preferably in the range of 0.1 to 4.0 mol% in terms of 2 (MnO) with respect to the entire main component. The element to be substituted is not limited to MnO, and other divalent metal ions such as NiO, MgO, ZnO, and CuO can be used. In addition, an additive such as SiO 2 may be included as long as the effects of the present invention are not impaired, and a part of BaO or CoO may be substituted with an oxide of another element.
前記主成分組成範囲にて高温で仮焼を行なってフェライト焼結体を作製することにより、異相の抑制及び焼結体の高密度化が図られ、５．０５×１０３ｋｇ／ｍ３以上の焼結体密度を得ることができる。これは、初透磁率の向上に寄与する。また、５．０５×１０３ｋｇ／ｍ３以上の焼結体密度とすることで種々の加工にも耐え、所望の電子部品への加工を容易とする充分な強度を得ることができる。より好ましくは５．１×１０３ｋｇ／ｍ３以上、さらに好ましくは５．１５×１０３ｋｇ／ｍ３以上である。また前記スピネル相は、焼結体の断面観察における面積比較で、空隙よりも少ない方が望ましい。これは、空隙と異なり、スピネル相が磁気損失を有するためである。特に高周波において低損失が望まれる場合、焼結体密度またはＺ型フェライト相を同じとすれば、スピネル相が空隙よりも少ない方が有利である。 By performing calcination at a high temperature in the main component composition range to produce a ferrite sintered body, it is possible to suppress heterogeneous phases and increase the density of the sintered body, and to be 5.05 × 10 3 kg / m 3 or more. The sintered body density can be obtained. This contributes to an improvement in initial permeability. Further, by setting the sintered body density to 5.05 × 10 3 kg / m 3 or more, it is possible to withstand various processing and to obtain a sufficient strength that facilitates processing into a desired electronic component. More preferably, it is 5.1 × 10 3 kg / m 3 or more, and further preferably 5.15 × 10 3 kg / m 3 or more. Further, it is desirable that the spinel phase is smaller than the voids in the area comparison in the cross-sectional observation of the sintered body. This is because, unlike the voids, the spinel phase has a magnetic loss. In particular, when low loss is desired at a high frequency, if the sintered body density or the Z-type ferrite phase is the same, it is advantageous that the spinel phase is smaller than the voids.
また、フェライト焼結体の製造方法において、粉砕粉の比表面積が３．５４ｍ２／ｇ以上であることが好ましい。同一条件で粉砕を行なった場合、粉砕粉比表面積はＢａＯ過剰な組成とすることで増加する。比表面積の増加に伴い、粉体が活性化し、焼結体の密度も向上する。即ち５．０５×１０３ｋｇ／ｍ３以上の高い焼結体強度を得るためには、比表面積は３．５４ｍ２／ｇ以上が好ましい。焼結体密度の向上の観点からは比表面積の上限はこれを特に限定するものではないが、比表面積が大きくなりすぎると、異常粒成長が生じやすいため、６.５ｍ２／ｇ以下であることが好ましい。 Moreover, in the manufacturing method of a ferrite sintered compact, it is preferable that the specific surface area of a grinding | pulverization powder is 3.54 m < 2 > / g or more. When pulverization is performed under the same conditions, the specific surface area of the pulverized powder is increased by setting the BaO-excess composition. As the specific surface area increases, the powder is activated and the density of the sintered body is improved. That is, in order to obtain a high sintered body strength of 5.05 × 10 3 kg / m 3 or more, the specific surface area is preferably 3.54 m 2 / g or more. From the viewpoint of improving the density of the sintered body, the upper limit of the specific surface area is not particularly limited. However, if the specific surface area becomes too large, abnormal grain growth is likely to occur, and therefore it is 6.5 m 2 / g or less. It is preferable.
更に、前記フェライト焼結体において焼結体の体積抵抗率が１０３Ω・ｍ以上であることが好ましい。フェライト焼結体が高い絶縁性を備えることで、フェライト焼結体に巻き線を施す場合でも、被覆などの絶縁層を省略することができるため、電子部品の小型化を図ることができる。また、体積抵抗率の向上に伴い、初透磁率の周波数特性も改善し、これを用いた電子部品の高性能化に寄与する。 Furthermore, in the ferrite sintered body, the volume resistivity of the sintered body is preferably 10 3 Ω · m or more. Since the ferrite sintered body has high insulation, even when the ferrite sintered body is wound, an insulating layer such as a coating can be omitted, so that the electronic component can be downsized. In addition, with the increase in volume resistivity, the frequency characteristics of initial permeability are also improved, which contributes to higher performance of electronic components using the same.
前記の主成分範囲、仮焼条件で作製した粉体を粉砕し、一定濃度のスラリーとし磁界中で結晶を配向させることにより、更に高い初透磁率を発揮させることができる。配向処理としては、一定方向に磁界を印加し、各結晶粒子のＣ面を磁界印加方向に平行に揃える一方向配向、及び回転磁界などで各結晶粒子のＣ面同士も平行に揃える面配向を採用することができる。一方向配向では磁界印加方向、面配向では回転磁界を印加した面に平行な任意の方向の初透磁率が特に高くなる。前記の条件にて作製した粉砕粉を配向させることにより初透磁率μｉが５０以上のＺ型フェライト焼結体を得ることもできる。特に初透磁率μｉが５０以上のＺ型フェライト焼結体は、電子部品の材料として特に好適である。更に主成分組成を１８〜２１ｍｏｌ％のＢａＯ、１０〜１１．５ｍｏｌ％のＣｏＯ、残部Ｆｅ２Ｏ３とすることで、更に高い初透磁率を持つフェライト焼結体を得ることができ、初透磁率μｉが６０以上のＺ型フェライト焼結体を得ることもできる。なお、混合した素原料を酸素中雰囲気で１３００℃以上に加熱する仮焼工程を経た粉砕粉は、配向性も良好であるため、成形工程において上記配向処理を行う場合に特に好適である。 Higher initial permeability can be exhibited by pulverizing the powder prepared under the above-mentioned main component range and calcining conditions to obtain a slurry having a constant concentration and orienting crystals in a magnetic field. As the orientation treatment, a unidirectional orientation in which a magnetic field is applied in a certain direction and the C-plane of each crystal grain is aligned in parallel with the magnetic field application direction, and a plane orientation in which the C-planes of each crystal grain are aligned in parallel with a rotating magnetic field, etc. Can be adopted. In the unidirectional orientation, the initial magnetic permeability is particularly high in the direction in which the magnetic field is applied, and in the plane orientation, the magnetic permeability in any direction parallel to the surface to which the rotating magnetic field is applied is particularly high. A Z-type ferrite sintered body having an initial permeability μ i of 50 or more can be obtained by orienting the pulverized powder produced under the above conditions. In particular, a Z-type ferrite sintered body having an initial permeability μ i of 50 or more is particularly suitable as a material for electronic components. Further, by setting the main component composition to 18 to 21 mol% BaO, 10 to 11.5 mol% CoO, and the balance Fe 2 O 3 , a ferrite sintered body having a higher initial permeability can be obtained. A Z-type ferrite sintered body having a magnetic permeability μ i of 60 or more can also be obtained. In addition, since the pulverized powder which passed through the calcining process which heats the mixed raw material to 1300 degreeC or more in oxygen atmosphere has favorable orientation, it is especially suitable when performing the said orientation process in a formation process.
前述したような面配向または一方向配向などの配向処理によって異方性が付与されたフェライト焼結体の初透磁率は、以下に述べるような手法で評価する。その概念図を図１に示した。図に示したように、初透磁率が５０００以上の、リング形状の高透磁率フェライト１にギャップを形成し、巻線を施す（以降ヨーク部と呼ぶ）。巻線したフェライトのインダクタンスはインピーダンスアナライザ３にて評価する。後述の実施例ではヨーク部として１００kHzでμｉ＝８１００のＭｎ−Ｚｎフェライトを用いた。標準試料として初透磁率が０〜６０の範囲の既知の初透磁率を持つ磁性体を用意する。後述の実施例では、無配向の六方晶フェライト（μｉ＝２.８、５.７、１２.９）、圧粉金属（μｉ＝４５、６０）、スピネルフェライト（μｉ＝１４.０、１９.２、２９.３、３２.８、５０.０、５５.０）を用意した。それらを図１のようにヨーク部のギャップ部位と断面形状が一致するように加工した後、ギャップ部位に挿入し、１００ｋＨｚにおけるインダクタンス値を測定した。標準試料の初透磁率は既知であるので、これにより０〜６０までの初透磁率とインダクタンスの関係を得る。すなわち、初透磁率およびインダクタンスの対応関係を６次の多項式によって近似し、近似曲線を得る。上記標準試料の場合と同様に、図１に示すギャップ部位に収まるように、初透磁率が未知の焼結体４を加工して測定試料２を得る。該測定試料２の１００ｋＨｚでのインダクタンスＬを測定し、得られたインダクタンスＬの値から上記の近似曲線を用い初透磁率を算出する。ここで得られた初透磁率は測定試料２の厚み方向の初透磁率となる。以降、本手法をギャップ法と呼ぶことにする。 The initial permeability of the ferrite sintered body to which anisotropy is imparted by the orientation treatment such as the plane orientation or the unidirectional orientation as described above is evaluated by the method described below. The conceptual diagram is shown in FIG. As shown in the figure, a gap is formed in the ring-shaped high permeability ferrite 1 having an initial permeability of 5000 or more, and winding is performed (hereinafter referred to as a yoke portion). The inductance of the wound ferrite is evaluated by the impedance analyzer 3. In examples described later, Mn—Zn ferrite of μi = 8100 at 100 kHz was used as the yoke portion. As a standard sample, a magnetic material having a known initial permeability in the range of 0 to 60 is prepared. In the examples described later, non-oriented hexagonal ferrite (μi = 2.8, 5.7, 12.9), dust metal (μi = 45, 60), spinel ferrite (μi = 14.0, 19. 2, 29.3, 32.8, 50.0, 55.0). These were processed so that the cross-sectional shape coincided with the gap part of the yoke portion as shown in FIG. 1, and then inserted into the gap part, and the inductance value at 100 kHz was measured. Since the initial permeability of the standard sample is known, the relationship between the initial permeability of 0 to 60 and the inductance is thereby obtained. That is, the correspondence relationship between the initial magnetic permeability and the inductance is approximated by a sixth-order polynomial to obtain an approximate curve. As in the case of the standard sample, the measurement sample 2 is obtained by processing the sintered body 4 whose initial permeability is unknown so as to fit in the gap portion shown in FIG. An inductance L at 100 kHz of the measurement sample 2 is measured, and an initial permeability is calculated from the obtained inductance L value using the above approximate curve. The initial permeability obtained here is the initial permeability in the thickness direction of the measurement sample 2. Hereinafter, this method is referred to as a gap method.
また、本発明に係る上記のフェライト焼結体において、測定範囲が２θ＝２０〜８０°であるＸ線回折パターンにおいて、六方晶Ｚ型フェライトの全ての回折ピークの積分強度和をΣＩ（ＨＫＬ）とし（但し、Ｉ（ＨＫＬ）は指数（ＨＫＬ）で表される回折ピークの積分強度を示す）、Ｌ＝０であるすべての（ＨＫ０）の回折ピークの積分強度和をΣＩ（ＨＫ０）とした場合、ｆｃ＝ΣＩ（ＨＫ０）／ΣＩ（ＨＫＬ）で与えられる配向度ｆが０.３以上であるｃ軸配向面を有することが好ましい。かかる配向度ｆが０．３以上となると焼結体の方向が、特に初透磁率の高い方向になり、初透磁率μｉが５０以上の材料を得ることも可能となる。配向度ｆが０．３未満では無配向状態に近く初透磁率向上の効果は小さいため、配向度ｆは０．３以上が望ましい。 In the ferrite sintered body according to the present invention, in the X-ray diffraction pattern in which the measurement range is 2θ = 20 to 80 °, the integrated intensity sum of all diffraction peaks of the hexagonal Z-type ferrite is ΣI (HKL) (Where I (HKL) indicates the integrated intensity of the diffraction peak represented by the index (HKL)), and the integrated intensity sum of all (HK0) diffraction peaks where L = 0 is ΣI (HK0). In this case, it is preferable to have a c-axis orientation plane in which the orientation degree f given by fc = ΣI (HK0) / ΣI (HKL) is 0.3 or more. When the degree of orientation f is 0.3 or more, the direction of the sintered body is particularly high in the initial permeability, and a material having an initial permeability μ i of 50 or more can be obtained. If the degree of orientation f is less than 0.3, the orientation degree f is preferably 0.3 or more because the effect of improving the initial magnetic permeability is small because it is close to the non-oriented state.
また本発明にて得られたフェライトは１０ＭＨｚ〜１０ＧＨｚまでで使用される高周波用電子部品材料として特に好適である。例えば本発明のフェライト焼結体をコアとして用いるコイル部品を作製すれば、１０ＭＨｚ〜１０ＧＨｚにおいて高いインピーダンスを生じ、コモンモードチョークコイルなどのノイズ除去素子、高周波用アンテナとして好適に用いることができる。特に初透磁率μｉが５０以上の材料を用いれば電子部品として優れた特性を示す。 Moreover, the ferrite obtained in the present invention is particularly suitable as a high frequency electronic component material used in a frequency range from 10 MHz to 10 GHz. For example, if a coil component using the ferrite sintered body of the present invention as a core is produced, high impedance is generated at 10 MHz to 10 GHz, and it can be suitably used as a noise removing element such as a common mode choke coil and a high frequency antenna. In particular, when a material having an initial permeability μ i of 50 or more is used, excellent characteristics as an electronic component are exhibited.
比較例１〜３、実施例１〜３の試料については、主成分組成が表１に示す割合となるように、Ｆｅ２Ｏ３、ＢａＣＯ３、ＣｏＯを秤量し、湿式ボールミルにて１６時間混合した。混合後１３３０℃において酸素中で３時間仮焼し、仮焼粉を湿式ボールミルにて１８時間粗粉砕し、更にメディア・回転数を変え４時間微粉砕した。得られたスラリーを沈降させ上澄み液を除去し、スラリー濃度６８％になるように調整し、一方向の静磁界中で湿式成形を行った。得られた成形体を１３００℃において酸素中で３時間焼成し焼結体を得た。比較例４、５の試料については、主成分組成が表１に示す割合となるように、Ｆｅ２Ｏ３、ＢａＣＯ３及びＣｏＯを秤量し、湿式ボールミルにて１６時間混合した。混合後１２００℃において大気中で２時間仮焼し、仮焼粉を湿式ボールミルにて１８時間粉砕した。作製した粉砕粉にバインダー（ＰＶＡ）を添加し、造粒した。造粒後圧縮成形し、その後、酸素雰囲気中、１３４０℃で３時間焼結した。 For the samples of Comparative Examples 1 to 3 and Examples 1 to 3, Fe 2 O 3 , BaCO 3 and CoO were weighed so that the main component composition had the ratio shown in Table 1, and mixed for 16 hours in a wet ball mill. did. After mixing, the mixture was calcined in oxygen at 1330 ° C. for 3 hours, and the calcined powder was coarsely pulverized in a wet ball mill for 18 hours, and further pulverized for 4 hours while changing the medium and the rotational speed. The resulting slurry was allowed to settle and the supernatant was removed, adjusted to a slurry concentration of 68%, and wet-molded in a unidirectional static magnetic field. The obtained molded body was fired in oxygen at 1300 ° C. for 3 hours to obtain a sintered body. For the samples of Comparative Examples 4 and 5, Fe 2 O 3 , BaCO 3 and CoO were weighed so that the main component composition had the ratio shown in Table 1, and mixed for 16 hours in a wet ball mill. After mixing, the mixture was calcined in the atmosphere at 1200 ° C. for 2 hours, and the calcined powder was pulverized in a wet ball mill for 18 hours. A binder (PVA) was added to the prepared pulverized powder and granulated. After granulation, compression molding was performed, followed by sintering at 1340 ° C. for 3 hours in an oxygen atmosphere.
上記のように作製した比較例１〜５、実施例１〜３の焼結体の焼結体密度を評価し、表２に示した。また内部断面を鏡面研磨して撮影した１０００倍のＳＥＭ写真により、観察面積を４００００μｍ２としてスピネル相、ＢａＦｅ２Ｏ４相の面積を測定し、これらの面積を空孔を除いた観察領域全体の面積で除して各相の生成率を面積比率として算出した。表２に各相の面積比率を併せて示した。なお、本実施例の１０００倍のＳＥＭ写真では、Ｚ型フェライト相、スピネル型フェライト相及びＢａＦｅ２Ｏ４相以外の相が確認されなかったため、ここで述べる面積比率は、実質的に、焼結体中のＺ型フェライト相、スピネル型フェライト相及びＢａＦｅ２Ｏ４相の全体に対するスピネル型フェライト相またはＢａＦｅ２Ｏ４相の割合に相当する。図２〜４に比較例１、比較例５および実施例２のＳＥＭ写真を示した。図２には写真大部分を占めるＺ型フェライト相５の他に、周囲より暗く見えるスピネル相６及び空孔７が存在していることが分かる。また図３には周囲よりも明るいコントラストを示すＢａＦｅ２Ｏ４相８が存在していることが確認できる。また、図４に示す実施例２の試料ではこれら異相が観察されず、ポアの他にはＺ型フェライト相のみが観察された。なお、これらの相は、ＸＲＤ（Ｘ線回折パターン）及びＥＤＸ（エネルギー分散型蛍光Ｘ線分析装置）を用いて同定した。 The sintered body density of the sintered bodies of Comparative Examples 1 to 5 and Examples 1 to 3 prepared as described above was evaluated and shown in Table 2. In addition, from the SEM photograph of 1000 times taken by mirror polishing the internal cross section, the area of the spinel phase and BaFe 2 O 4 phase was measured with an observation area of 40000 μm 2 , and these areas were taken out of the entire observation region excluding the voids Dividing by the area, the generation rate of each phase was calculated as the area ratio. Table 2 also shows the area ratio of each phase. In addition, in the 1000 times SEM photograph of this example, no phase other than the Z-type ferrite phase, the spinel-type ferrite phase and the BaFe 2 O 4 phase was confirmed. This corresponds to the ratio of the spinel ferrite phase or the BaFe 2 O 4 phase to the entire Z-type ferrite phase, spinel ferrite phase and BaFe 2 O 4 phase in the body. The SEM photograph of the comparative example 1, the comparative example 5, and Example 2 was shown to FIGS. In FIG. 2, it can be seen that in addition to the Z-type ferrite phase 5 occupying most of the photograph, there are spinel phases 6 and holes 7 that appear darker than the surroundings. Moreover, it can be confirmed in FIG. 3 that there is a BaFe 2 O 4 phase 8 showing a brighter contrast than the surroundings. Moreover, in the sample of Example 2 shown in FIG. 4, these different phases were not observed, but only the Z-type ferrite phase was observed in addition to the pores. These phases were identified using XRD (X-ray diffraction pattern) and EDX (energy dispersive X-ray fluorescence analyzer).
表２より、１３３０℃において酸素中で仮焼を行なった場合、ＢａＯが１８ｍｏｌ％未満である比較例１を除き何れもスピネル相及びＢａＦｅ２Ｏ４相の面積比率は１％以下であった。実施例１〜３の試料では、スピネル相及びＢａＦｅ２Ｏ４相の面積比率は０％であった。すなわち、実質的にスピネル相及びＢａＦｅ２Ｏ４相が生成していないことがわかる。また、焼結体密度はＢａＯを１８ｍｏｌ％以上とすることで、５．０５×１０３ｋｇ／ｍ３以上となることが分かる。一方、１２００℃において大気で仮焼を行なった比較例５では、Ｂａリッチな組成を用いたことにより、５．２１×１０３ｋｇ／ｍ３の高い焼結体密度が得られるが、１％を超えるＢａＦｅ２Ｏ４相の生成が確認された。なお、１２００℃において大気で仮焼を行なった、ＢａＯが１８ｍｏｌ％未満である比較例４では異相の生成は見られなかったものの焼結体密度が低く、望ましい焼結体が得られないことが分かる。 From Table 2, when calcined in oxygen at 1330 ° C., the area ratio of the spinel phase and the BaFe 2 O 4 phase was 1% or less except for Comparative Example 1 in which BaO was less than 18 mol%. In the samples of Examples 1 to 3, the area ratio of the spinel phase and the BaFe 2 O 4 phase was 0%. That is, it can be seen that a spinel phase and a BaFe 2 O 4 phase are not substantially formed. Further, the sintered body density by a BaO and 18 mol% or more, it can be seen that a 5.05 × 10 3 kg / m 3 or more. On the other hand, in Comparative Example 5, which was calcined in the atmosphere at 1200 ° C., a high sintered body density of 5.21 × 10 3 kg / m 3 can be obtained by using the Ba-rich composition. It was confirmed that the BaFe 2 O 4 phase was exceeded. In Comparative Example 4 where BaO was less than 18 mol%, which was calcined in the atmosphere at 1200 ° C., no heterogeneous phase was formed, but the sintered body density was low and a desirable sintered body could not be obtained. I understand.
上記比較例１〜５、実施例１〜３の試料の１００ｋＨｚの初透磁率、体積抵抗率、配向度および粉砕粉の比表面積を表３に示した。１００ｋＨｚの初透磁率は前述したギャップ法を用いて最も初透磁率が高くなる方向で評価した。該方向は本実施例では成形中に磁界を印加した方向に相当する。粉砕粉の比表面積はＭａｃｓｏｒｂ社製Ｍｏｄｅｌ−１２０１を用いてガス吸着法（ＢＥＴ法）により評価した。体積抵抗率は２端子法にて評価した。配向度ｆは作製した焼結体の中で最もＣ面から回折線強度：Ｉ（００Ｌ）が弱くなるような断面が得られるよう焼結体を切断し、切断面におけるＸ線回折（ＸＲＤ：Ｘ ｒａｙ ｄｉｆｆｒａｃｔｉｏｎ）測定を行い、配向度ｆを評価した。本実施例においては、磁界を印加した方向を法線に持つ面を用いて、Ｘ線回折パターンを取得した。２θ＝２０〜８０°の測定範囲でＸＲＤを行い、得られたＸ線回折パターンにおいて、六方晶Ｚ型フェライトの全ての回折ピークの積分強度和をΣＩ（ＨＫＬ）とし、Ｌ＝０であるすべての（ＨＫ０）の回折ピークの積分強度和をΣＩ（ＨＫ０）とした。ｆｃ⊥＝ΣＩ（ＨＫ０）／ΣＩ（ＨＫＬ）の式から配向度ｆｃ⊥を算出した。なお、Ｉ（ＨＫＬ）とは（ＨＫＬ）)面の回折線のピーク角度をθ（ＨＫＬ）とした時、θ（ＨＫＬ）−０.４°からθ（ＨＫＬ）＋０.４°までの範囲で積分した値である。 Table 3 shows the initial permeability at 100 kHz, the volume resistivity, the degree of orientation, and the specific surface area of the pulverized powder of the samples of Comparative Examples 1 to 5 and Examples 1 to 3. The initial permeability at 100 kHz was evaluated in the direction of the highest initial permeability using the gap method described above. This direction corresponds to a direction in which a magnetic field is applied during molding in this embodiment. The specific surface area of the pulverized powder was evaluated by a gas adsorption method (BET method) using Model-1201 manufactured by Macsorb. The volume resistivity was evaluated by a two-terminal method. The degree of orientation f is such that the sintered body is cut from the C-plane so that the cross section where the diffraction line intensity: I (00L) is weakest is obtained from the C-plane, and X-ray diffraction (XRD: X ray diffraction) measurement was performed to evaluate the orientation degree f. In this example, an X-ray diffraction pattern was acquired using a surface having a normal to the direction in which a magnetic field was applied. XRD is performed in the measurement range of 2θ = 20-80 °, and in the obtained X-ray diffraction pattern, the integrated intensity sum of all diffraction peaks of hexagonal Z-type ferrite is ΣI (HKL), and all L = 0 The sum of integrated intensities of diffraction peaks of (HK0) was ΣI (HK0). fc ⊥ = ΣI (HK0) / ΣI was calculated degree of orientation fc ⊥ from the equation (HKL). Note that I (HKL) is the (HKL)) diffraction line peak angle θ (HKL) and θ (HKL) −0.4 ° to θ (HKL) + 0.4 °. The integrated value.
表３に示したように配向処理を行なった比較例１〜３及び実施例１〜３は何れも配向度ｆが０．６を超え、配向処理を行なわなかった比較例４，５は共に０．３未満であった。初透磁率は比較例１〜３で４０以上、実施例１〜３で５０以上であったが、比較例４，５では２０以下であった。より詳細には、１８〜２１ｍｏｌ％のＢａＯ、１０〜１１．５ｍｏｌ％のＣｏＯ、残部Ｆｅ２Ｏ３の主成分組成を有する、実施例１〜３の試料では、初透磁率は６０以上であり、比較例の試料に比べて大幅に初透磁率が向上していることがわかる。さらに、配向度が０.７以上の実施例１および２では６５以上の非常に高い初透磁率が得られた。また、粉砕粉の比表面積は組成がＢａＯ過剰側にて増加する傾向があり、比表面積が３．５４ｍ２／ｇを超えると５．０５×１０３ｋｇ／ｍ３以上の焼結体密度が得られていることが分かる。 As shown in Table 3, in Comparative Examples 1 to 3 and Examples 1 to 3 in which the orientation treatment was performed, the orientation degree f exceeded 0.6, and Comparative Examples 4 and 5 in which the orientation treatment was not performed were both 0. .3 or less. The initial permeability was 40 or more in Comparative Examples 1 to 3, and 50 or more in Examples 1 to 3, but 20 or less in Comparative Examples 4 and 5. More specifically, in the samples of Examples 1 to 3 having a main component composition of 18 to 21 mol% BaO, 10 to 11.5 mol% CoO, and the balance Fe 2 O 3 , the initial permeability is 60 or more. It can be seen that the initial permeability is significantly improved as compared with the sample of the comparative example. Furthermore, in Examples 1 and 2 having an orientation degree of 0.7 or higher, a very high initial magnetic permeability of 65 or higher was obtained. Further, the specific surface area of the pulverized powder tends to increase on the BaO excess side, and when the specific surface area exceeds 3.54 m 2 / g, the sintered body density is 5.05 × 10 3 kg / m 3 or more. You can see that it is obtained.
実施例１〜３、比較例１〜３の組成に対し、Ｆｅ２Ｏ3の一部をＭｎＯで置換した組成の焼結体試料を作製した（比較例６〜８、実施例４〜６）。その組成を表４に示した。また、表５に比較例６〜８、実施例４〜６の試料のスピネル相及びＢａＦｅ２Ｏ４相の面積比率及び焼結体密度を示した。表５に示すように、比較例６の試料では４．８％のスピネル相が生成したが、他の比較例７、８、実施例４〜６の試料にはスピネル相及びＢａＦｅ２Ｏ４相ともに観察されなかった。また表６に上記手法にて評価した１００ｋＨｚの初透磁率、体積抵抗率、配向度、粉砕粉の比表面積を示した。 Sintered body samples having compositions in which a part of Fe 2 O 3 was substituted with MnO for the compositions of Examples 1 to 3 and Comparative Examples 1 to 3 were prepared (Comparative Examples 6 to 8 and Examples 4 to 6). . The composition is shown in Table 4. Table 5 shows the area ratio and sintered body density of the spinel phase and BaFe 2 O 4 phase of the samples of Comparative Examples 6 to 8 and Examples 4 to 6. As shown in Table 5, 4.8% of the spinel phase was produced in the sample of Comparative Example 6, but the spinel phase and BaFe 2 O 4 phase were produced in the samples of other Comparative Examples 7 and 8 and Examples 4 to 6. Neither was observed. Table 6 shows the initial permeability, volume resistivity, orientation degree, and specific surface area of the pulverized powder evaluated at 100 kHz by the above-described method.
表６に示したように比較例６〜８、実施例４〜６はいずれも配向度ｆが０．６以上となっているが、初透磁率は比較例６〜８では４０未満となり、実施例４〜６では、４０以上の初透磁率が得られている。また、同時にＦｅ２Ｏ３の一部をＭｎＯで置換することによって、１０3Ω・ｍを以上の高い体積抵抗率が得られている。実施例４〜６の試料は、実施例１〜３に比べて、初透磁率がやや低いものの、４０以上の高透磁率と１０3Ω・ｍ以上の高体積抵抗率の併せ持ち、優れた特性を具備している。特に、１９〜２０ｍｏｌ％のＢａＯ、１０〜１０．５ｍｏｌ％のＣｏＯ、２〜３ｍｏｌ％の２（ＭｎＯ）、残部Ｆｅ２Ｏ３の主成分組成範囲に入る実施例５の試料は、５０以上の初透磁率と１０3Ω・ｍ以上の高体積抵抗率を示した。 As shown in Table 6, in Comparative Examples 6-8 and Examples 4-6, the degree of orientation f is 0.6 or more, but the initial permeability is less than 40 in Comparative Examples 6-8. In Examples 4 to 6, an initial permeability of 40 or more is obtained. At the same time, by replacing part of Fe 2 O 3 with MnO, a high volume resistivity of 10 3 Ω · m or more is obtained. Although the samples of Examples 4 to 6 have slightly lower initial permeability than Examples 1 to 3, they have both high permeability of 40 or more and high volume resistivity of 10 3 Ω · m or more, and excellent characteristics. It has. In particular, the sample of Example 5 that falls within the main component composition range of 19-20 mol% BaO, 10-10.5 mol% CoO, 2-3 mol% 2 (MnO), and the balance Fe 2 O 3 is 50 or more. The initial magnetic permeability and high volume resistivity of 10 3 Ω · m or more were exhibited.
実施例２、実施例５の焼結体よりリング形状の試料を切り出し、インピーダンスメータ４２９１Ｂ（Ａｇｉｌｅｎｔ社製）にて１０ＭＨｚ〜１.８ＧＨｚまでの複素比初透磁率を測定した。得られた初透磁率に対し１００ＭＨｚの初透磁率実数部が２０％低下する周波数を評価したところ実施例２、実施例５ではそれぞれ５．7０ＧＨｚ、８．２５ＧＨｚとＦｅ２Ｏ３の一部をＭｎＯで置換することにより初透磁率の周波数特性が改善することが分かった。ＭｎＯに置換することにより１００ｋＨｚの初透磁率は同組成のＭｎＯを置換しなかった場合に比べ、１０〜２０程度低下するが上記のように体積抵抗率・周波数特性向上の効果が発揮された。 A ring-shaped sample was cut out from the sintered bodies of Example 2 and Example 5, and the complex ratio initial permeability from 10 MHz to 1.8 GHz was measured with an impedance meter 4291B (manufactured by Agilent). When the frequency at which the real part of the initial permeability of 100 MHz is reduced by 20% with respect to the obtained initial permeability was evaluated, in Examples 2 and 5, 5.70 GHz, 8.25 GHz, and a part of Fe 2 O 3 were respectively used. It was found that the frequency characteristics of the initial permeability were improved by substituting with MnO. By substituting with MnO, the initial magnetic permeability at 100 kHz was reduced by about 10 to 20 compared with the case where MnO having the same composition was not substituted, but the effect of improving the volume resistivity / frequency characteristics was exhibited as described above.
また、比較例６及び実施例２の観察領域全体の面積をＡmm2、スピネル相の面積をＢmm2、空隙の面積をＣmm2としたとき、観察領域全体に占めるスピネル相の割合（Ｂ／Ａ）を観察領域全体に占める空隙の割合（Ｃ／Ａ）で除して、空隙の面積に対するスピネル相の面積の比を算出したところそれぞれ１．０２及び０となった。すなわち比較例６では空隙よりもスピネル相の方が多くなっていた。 Further, Amm 2 the area of the entire observation region in Comparative Example 6 and Example 2, Bmm the area of the spinel phase 2, when the area of the voids was Cmm 2, the ratio of the spinel phase in the entire observation region (B / A ) Divided by the ratio of the voids in the entire observation region (C / A), the ratio of the area of the spinel phase to the area of the voids was calculated to be 1.02 and 0, respectively. That is, in Comparative Example 6, the spinel phase was larger than the voids.
１：高透磁率磁性体 ２：測定試料 ３：インピーダンスアナライザ ４：焼結体
５：スピネル相 ６：空孔 ７：ＢａＦｅ２Ｏ４相 ８：Ｚ型フェライト相
1: High permeability magnetic material 2: Measurement sample 3: Impedance analyzer 4: Sintered body 5: Spinel phase 6: Hole 7: BaFe 2 O 4 phase 8: Z-type ferrite phase
Claims (7)
前記フェライト焼結体の組成は、Ｚ型フェライトの化学量論組成よりもＢａＯリッチであるとともに、
前記仮焼工程において、前記混合した素原料を酸素中雰囲気で１３００℃以上に加熱することを特徴とするフェライト焼結体の製造方法。 A calcining step of calcining the mixed raw materials, a crushing step of crushing the calcined powder obtained in the calcining step, a molding step of molding the pulverized powder obtained in the crushing step, and the molding step A method for producing a ferrite sintered body of hexagonal Z-type ferrite mainly composed of BaO, CoO, and Fe 2 O 3 , comprising a sintering step of sintering the formed body obtained in step 1).
The composition of the ferrite sintered body is richer in BaO than the stoichiometric composition of Z-type ferrite,
In the calcining step, the mixed raw material is heated to 1300 ° C. or higher in an oxygen atmosphere.
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| JP2006306693A (en) * | 2005-03-31 | 2006-11-09 | Hitachi Metals Ltd | Ferrite sintered body and method for manufacturing same |
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| JPS5428800A (en) * | 1977-08-09 | 1979-03-03 | Kagaku Gijutsucho Mukizai | Method of making hexagonal barium ferrite *bafe 12 o12* single crystal |
| JP2005047783A (en) * | 2003-07-31 | 2005-02-24 | Hitachi Metals Ltd | Hexagonal system z-type ferrite and method of manufacturing the same |
| JP2006076872A (en) * | 2003-12-24 | 2006-03-23 | Hitachi Metals Ltd | Hexagonal z type ferrite |
| JP2006306693A (en) * | 2005-03-31 | 2006-11-09 | Hitachi Metals Ltd | Ferrite sintered body and method for manufacturing same |
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