JP5670094B2 - Method for producing magnetite nanoparticles - Google Patents

Method for producing magnetite nanoparticles Download PDF

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JP5670094B2
JP5670094B2 JP2010109165A JP2010109165A JP5670094B2 JP 5670094 B2 JP5670094 B2 JP 5670094B2 JP 2010109165 A JP2010109165 A JP 2010109165A JP 2010109165 A JP2010109165 A JP 2010109165A JP 5670094 B2 JP5670094 B2 JP 5670094B2
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magnetite
aqueous solution
iron hydroxide
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優子 一柳
優子 一柳
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Yokohama National University NUC
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本発明は、アモルファスSiO2に包含されたマグネタイトナノ微粒子の製造方法に関する。 The present invention relates to a method for producing magnetite nanoparticles contained in amorphous SiO 2 .

マグネタイト微粒子は、化学的に安定で比較的大きな磁化を有する微粒子であることから、これまで磁気記録媒体、磁性流体または磁性トナーなどの様々な用途に広く利用されてきた。さらに、近年では、例えば免疫測定における磁気濃縮・分離担体などの用途として、医療やバイオテクノロジーの分野にマグネタイト微粒子を応用することが注目されている。そして、湿式法を用いてマグネタイト微粒子を得る方法が開示されている(例えば、特許文献1参照)。
又、磁気微粒子表面をシリカ被覆すると、SiO2を介して官能基を導入することができ、薬剤等の修飾や、細胞、組織内へ容易に取り込むことが可能である。このようなことから、FeCl2を含む水溶液と、Na2SiO3を含む水溶液とを混合し、アモルファスSiO2からなるシェルを有する磁気微粒子を湿式法で製造することが記載されている(例えば、特許文献2、3、非特許文献1参照)。
Magnetite fine particles are fine particles that are chemically stable and have a relatively large magnetization, and thus have been widely used in various applications such as magnetic recording media, magnetic fluids, and magnetic toners. Furthermore, in recent years, attention has been paid to the application of magnetite fine particles in the fields of medicine and biotechnology, for example, as a magnetic concentration / separation carrier in immunoassay. And the method of obtaining magnetite microparticles | fine-particles using a wet method is disclosed (for example, refer patent document 1).
In addition, when the surface of the magnetic fine particles is coated with silica, a functional group can be introduced through SiO 2, and can be easily incorporated into a modification of a drug or the like, or into a cell or tissue. For this reason, it is described that an aqueous solution containing FeCl 2 and an aqueous solution containing Na 2 SiO 3 are mixed to produce magnetic fine particles having a shell made of amorphous SiO 2 by a wet method (for example, (See Patent Documents 2 and 3 and Non-Patent Document 1).

特開平9-169525号公報Japanese Unexamined Patent Publication No. 9-19525 特開2007−269770号公報(段落0021)JP 2007-269770 A (paragraph 0021) 特開2003−252618号公報Japanese Patent Laid-Open No. 2003-252618 J.Thermal Analysis and Calorimetory, 69(2002)919-923.J. Thermal Analysis and Calorimetory, 69 (2002) 919-923.

しかしながら、上記従来技術においては、マグネタイトとなる微粒子を湿式法で製造する際、2価鉄イオンの酸化を防ぐことが困難であり、マグネタイトのナノ微粒子は安定的に得ることが難しいという問題がある。
従って、本発明の目的は、アモルファスSiO2に包含されたマグネタイトナノ微粒子を安定して製造する方法を提供することにある。
However, in the above prior art, it is difficult to prevent oxidation of divalent iron ions when magnetite fine particles are produced by a wet method, and there is a problem that it is difficult to stably obtain magnetite nanoparticles. .
Accordingly, an object of the present invention is to provide a method for stably producing magnetite nanoparticles contained in amorphous SiO 2 .

本発明者らは、前述の課題を解決すべく鋭意検討した結果、マグネタイトとなる微粒子を湿式法で製造する際、2価鉄イオンを含む水溶液に還元剤を加えると、2価鉄イオンの酸化を抑制してマグネタイトナノ微粒子を安定して製造できることを見出した。
すなわち本発明のマグネタイトナノ微粒子の製造方法は、メタ珪酸ナトリウムを含むアルカリ水溶液と、2価鉄イオン及びC 6 H 8 O 6 からなる還元剤を含む2価鉄イオン水溶液とを混合し、2価の水酸化鉄からなるコアと、該コアを覆うアモルファスSiO2からなるシェルを有する水酸化鉄微粒子を生成させる水酸化鉄微粒子生成工程と、前記水酸化鉄微粒子を不活性ガス雰囲気下で600〜1100℃で焼成し、前記シェルに覆われたマグネタイトナノ微粒子を生成する工程と、を有する。
As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention, when producing fine particles to be magnetite by a wet method, when a reducing agent is added to an aqueous solution containing divalent iron ions, oxidation of divalent iron ions is performed. It was found that magnetite nanoparticles can be stably produced while suppressing the above.
That is, the method for producing magnetite nanoparticles according to the present invention comprises mixing an alkaline aqueous solution containing sodium metasilicate with a divalent iron ion aqueous solution containing a divalent iron ion and a reducing agent comprising C 6 H 8 O 6. a core consisting of iron hydroxide, and iron hydroxide particle generation step of generating the iron hydroxide microparticles having a shell made of amorphous SiO 2 covering the core, said iron hydroxide particles in an inert gas atmosphere 600 Firing at 1100 ° C. to produce magnetite nanoparticles covered by the shell.

前記マグネタイトナノ微粒子の粉末X線回折パターンからシェラーの式によって得られる一次粒径を2〜20nmの範囲で調整することが好ましい。 It is preferable to adjust the primary particle size obtained by the equation of Scherrer from the powder X-ray diffraction pattern of the magnetite nanoparticles in the range of 2 to 20 nm.

本発明によれば、アモルファスSiO2に包含されたマグネタイトナノ微粒子を安定して製造することができる。 According to the present invention, magnetite nanoparticles included in amorphous SiO 2 can be stably produced.

600℃〜1100℃の間の各焼成温度における焼成粉末の粉末X線回折パターンを示す図である。It is a figure which shows the powder X-ray-diffraction pattern of the baked powder in each calcination temperature between 600 degreeC-1100 degreeC . 600℃〜1100℃の間の各焼成温度における焼成粉末の粉末X線回折パターンから、シェラーの式によって求めた焼成粉末の一次粒径を示す図である。It is a figure which shows the primary particle size of the baked powder calculated | required by the Scherrer formula from the powder X-ray-diffraction pattern of the baked powder in each calcination temperature between 600 degreeC-1100 degreeC. 各焼成温度と一次粒径との関係を示す図である。It is a figure which shows the relationship between each baking temperature and a primary particle size. 850℃で焼成して得られたマグネタイトナノ微粒子の透過型電子顕微鏡(TEM)像を示す図である。It is a figure which shows the transmission electron microscope (TEM) image of the magnetite nanoparticle obtained by baking at 850 degreeC. 図4のTEM像の個々のマグネタイトナノ微粒子の粒径を測定した粒径分布を示す図である。It is a figure which shows the particle size distribution which measured the particle size of each magnetite nanoparticle of the TEM image of FIG.

以下、本発明の実施形態について説明する。
まず、メタ珪酸ナトリウム(Na2SiO3)を含むアルカリ水溶液を調製する。通常、メタ珪酸ナトリウムは、Na2SiO3・9H2Oの形で存在するので、これを純水等に溶解させてアルカリ水溶液を得ることができる。メタ珪酸ナトリウムの濃度は特に限定されないが、0.1〜0.3モル/L程度である。
Hereinafter, embodiments of the present invention will be described.
First, an alkaline aqueous solution containing sodium metasilicate (Na 2 SiO 3 ) is prepared. Usually, sodium metasilicate exists in the form of Na 2 SiO 3 .9H 2 O, so that it can be dissolved in pure water or the like to obtain an alkaline aqueous solution. The concentration of sodium metasilicate is not particularly limited, but is about 0.1 to 0.3 mol / L.

同様に、2価鉄イオン及び還元剤を含む2価鉄イオン水溶液を調製する。2価鉄イオンとしてはFeCl2を用いることができ、通常、FeCl2・4H2Oを純水等に溶解させて2価鉄イオン水溶液を得ることができる。さらに、この水溶液に還元剤を添加して2価鉄イオンの酸化を抑制する。還元剤としては水溶性還元剤が好ましく、水溶性還元剤としては、アスコルビン酸(C6H8O6)、カテキン(C15H14O6で表されるフラボノイド)が例示されるがこれらに限られない。特に、マグネタイトナノ微粒子を医療に応用できるようにするため、人体に無害なアスコルビン酸が好ましい。還元剤の濃度は特に限定されないが、数モル/L程度である(例えば、6.25モル/L)。 Similarly, a divalent iron ion aqueous solution containing divalent iron ions and a reducing agent is prepared. As the divalent iron ion, FeCl 2 can be used. Usually, FeCl 2 · 4H 2 O can be dissolved in pure water or the like to obtain a divalent iron ion aqueous solution. Furthermore, a reducing agent is added to this aqueous solution to suppress the oxidation of divalent iron ions. The reducing agent is preferably a water-soluble reducing agent, and examples of the water-soluble reducing agent include ascorbic acid (C 6 H 8 O 6 ) and catechin (flavonoid represented by C 15 H 14 O 6 ). Not limited. In particular, ascorbic acid that is harmless to the human body is preferable in order to make it possible to apply the magnetite nanoparticles to medicine. The concentration of the reducing agent is not particularly limited, but is about several mol / L (for example, 6.25 mol / L).

そして、上記したアルカリ水溶液と2価鉄イオン水溶液とを混合、攪拌すると、2価の水酸化鉄からなるコアと、該コアを覆うアモルファスSiO2からなるシェルを有する水酸化鉄微粒子を沈殿物として生成することができる。各水溶液の混合は常温で行うことができ、混合時間は特に限定されないが、1時間〜数時間程度である。混合時に上記した還元剤が存在するので、2価鉄イオンの酸化を抑制して水酸化鉄微粒子(ひいてはマグネタイトナノ微粒子)を安定して製造できる。
得られた沈殿物を、ろ過、遠心分離等によって混合液から分離回収し、純水等で適宜洗浄した後、乾燥させると、ガラス状の塊が得られる。そして、このガラス状の塊を粉砕することにより、水酸化鉄微粒子の粉末が得られる。
When the above alkaline aqueous solution and divalent iron ion aqueous solution are mixed and stirred, iron hydroxide fine particles having a core made of divalent iron hydroxide and a shell made of amorphous SiO 2 covering the core are precipitated. Can be generated. Each aqueous solution can be mixed at room temperature, and the mixing time is not particularly limited, but is about 1 hour to several hours. Since the reducing agent described above is present at the time of mixing, iron hydroxide fine particles (and magnetite nanoparticle) can be stably produced by suppressing oxidation of divalent iron ions.
The obtained precipitate is separated and recovered from the mixed solution by filtration, centrifugation, etc., washed with pure water or the like, and then dried to obtain a glassy lump. And the powder of iron hydroxide microparticles | fine-particles is obtained by grind | pulverizing this glass-like lump.

次に、水酸化鉄微粒子を不活性ガス雰囲気下で焼成し、水酸化鉄を酸化物(Fe3O4)に変化させ、アモルファスSiO2からなる上記シェルに覆われたマグネタイトナノ微粒子を生成する。不活性ガス雰囲気としては、例えば、アルゴン、窒素を例示できる。又、焼成温度は、473〜1373K(200〜1100℃)程度であり、600〜1100℃が好ましい。焼成時間は、数時間〜10時間程度である。焼成温度が1100℃以上になると、目的物質以外のαFe2O3やSiFe2O4が生成する。
焼成で得られるマグネタイトナノ微粒子の一次粒径は、1.3〜50nm程度であり、3.0〜50nmが好ましい。マグネタイトナノ微粒子の一次粒径は、シェラー(Scherrer)の式を用いて見積もることが出来る。なお、本発明では、シェラーの係数(K)を0.9とした。
Next, iron hydroxide fine particles are baked in an inert gas atmosphere, and iron hydroxide is changed to oxide (Fe 3 O 4 ) to produce magnetite nanoparticles covered with the above-mentioned shell made of amorphous SiO 2. . Examples of the inert gas atmosphere include argon and nitrogen. The firing temperature is about 473 to 1373 K (200 to 1100 ° C.), preferably 600 to 1100 ° C. The firing time is about several hours to 10 hours. When the firing temperature is 1100 ° C. or higher, αFe 2 O 3 and SiFe 2 O 4 other than the target substance are generated.
The primary particle size of the magnetite nanoparticles obtained by firing is about 1.3 to 50 nm, preferably 3.0 to 50 nm. The primary particle size of the magnetite nanoparticles can be estimated using the Scherrer equation. In the present invention, the Scherrer coefficient (K) is set to 0.9.

水酸化鉄微粒子の焼成温度が高くなるほど、マグネタイトナノ微粒子が成長し、その一次粒径が大きくなる。従って、要求される粒径に応じ、水酸化鉄微粒子の焼成温度を上記範囲で調整することで、マグネタイトナノ微粒子の一次粒径を管理することができる。   As the firing temperature of the iron hydroxide fine particles increases, the magnetite nanoparticle grows and its primary particle size increases. Therefore, the primary particle size of the magnetite nanoparticles can be controlled by adjusting the firing temperature of the iron hydroxide fine particles within the above range according to the required particle size.

なお、マグネタイトナノ微粒子のコアが、アモルファスSiO2からなるシェルで覆われていることの確認は、焼成後の粉末のX線回折を行うとアモルファスSiO2とマグネタイトの回折線が観測されること、及びマグネタイトナノ微粒子の一次粒子径が上記X線回折の半値幅から予想される程度の値であること、から行うことができる。
水酸化鉄微粒子についても同様にして、表面がアモルファスSiO2からなるシェルで覆われていることを確認することができる。又、水酸化鉄微粒子のコアが2価の水酸化鉄からなることは、X線回折のパターンでFe(OH)2を同定することで確認できる。
Note that the core of magnetite nanoparticles are confirmation that is covered with a shell made of amorphous SiO 2 is amorphous SiO 2 and a diffraction line of magnetite is observed when performing the X-ray diffraction of the powder after firing, And the primary particle diameter of the magnetite nanoparticle is a value that is expected from the half width of the X-ray diffraction.
Similarly, it can be confirmed that the surface of iron hydroxide fine particles is covered with a shell made of amorphous SiO 2 . Further, it can be confirmed that the core of the iron hydroxide fine particles is composed of divalent iron hydroxide by identifying Fe (OH) 2 by the X-ray diffraction pattern.

以上のように、アモルファスSiO2に包含されたマグネタイトナノ微粒子を安定して製造することができる。又、磁気特性が優れ、しかも工程中に界面活性剤を添加せずにマグネタイトナノ微粒子を得ることができる。そして、アモルファスSiO2は官能基との結合が容易であるので、医療やバイオテクノロジーなどの広い分野での使用に適したマグネタイトナノ微粒子が得られる。 As described above, magnetite nanoparticles included in amorphous SiO 2 can be stably produced. Moreover, it has excellent magnetic properties, and magnetite nanoparticles can be obtained without adding a surfactant during the process. The amorphous SiO 2 is because it is easy to bond with a functional group, magnetite nanoparticles suitable for use in a wide range of fields such as medicine and biotechnology are obtained.

以下に、実施例によって本発明を更に具体的に説明するが、本発明は以下の実施例に限定されるものではない。   EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

500mlのフラスコに純水250mlを満たし、さらにアルカリとしてNa2SiO3・9H2Oを5mモル加え、Na2SiO3水溶液(アルカリ水溶液)を作製した。又、純水80mlにFeCl2・4H2Oを5mモル加え、FeCl2水溶液を得た。これに、還元剤としてC6H8O6を2.5mモル加えることにより、還元作用を有する2価鉄イオン水溶液を得た。各水溶液をそれぞれスターラーにより約15分間攪拌した。
その後、上記アルカリ水溶液に2価鉄イオン水溶液を混合して約1時間攪拌し、水酸化鉄微粒子を沈殿物として生成させた。この沈殿物を遠心分離によって回収し、純水にて洗浄した。洗浄後、約80℃の乾燥炉にて乾燥させたところ、ガラス状の塊が得られた。このガラス状の塊を乳鉢で粉砕することにより、水酸化鉄微粒子の粉末を得た。
次に、この粉末をArガス雰囲気の電気炉中で焼成した。図1に示すように600℃〜1100℃の間で焼成温度を、変化させ、焼成時間は各10時間とした。各焼成温度で得られた焼成粉末の粉末X線回折を行った結果、いずれの場合も、アモルファスSiO2とマグネタイトの回折線が観測された。
A 500 ml flask was filled with 250 ml of pure water, and 5 mmol of Na 2 SiO 3 .9H 2 O was added as an alkali to prepare an aqueous Na 2 SiO 3 solution (alkali aqueous solution). Further, 5 mmol of FeCl 2 .4H 2 O was added to 80 ml of pure water to obtain an FeCl 2 aqueous solution. A divalent iron ion aqueous solution having a reducing action was obtained by adding 2.5 mmol of C 6 H 8 O 6 as a reducing agent. Each aqueous solution was stirred with a stirrer for about 15 minutes.
Thereafter, a divalent iron ion aqueous solution was mixed with the alkaline aqueous solution and stirred for about 1 hour to produce iron hydroxide fine particles as a precipitate. The precipitate was collected by centrifugation and washed with pure water. After washing, it was dried in a drying furnace at about 80 ° C. to obtain a glassy lump. This glassy lump was pulverized in a mortar to obtain iron hydroxide fine particle powder.
Next, this powder was fired in an electric furnace in an Ar gas atmosphere. As shown in FIG. 1, the firing temperature was changed between 600 ° C. and 1100 ° C., and the firing time was 10 hours each. As a result of performing powder X-ray diffraction of the fired powder obtained at each firing temperature, diffraction lines of amorphous SiO 2 and magnetite were observed in all cases.

図1は、600℃〜1100℃の間の各焼成温度における焼成粉末の粉末X線回折パターンを示す。アモルファスSiO2とマグネタイトの回折線が観測された。又、焼成温度の上昇に伴ってピークが鋭くなり、粒子径の成長が確認できた。
図2は、600℃〜1100℃の間の各焼成温度における焼成粉末の粉末X線回折パターンから、シェラーの式によって焼成粉末の一次粒径Dを求めた結果を示す。又、図3は、図2の各焼成温度と一次粒径Dとの関係を表にしたものである。焼成温度を600℃〜1100℃の間で調整することにより、3.5〜32nmの範囲で焼成粉末の一次粒径を制御することができた。
FIG. 1 shows a powder X-ray diffraction pattern of the calcined powder at each calcining temperature between 600 ° C. and 1100 ° C. Amorphous SiO 2 and magnetite diffraction lines were observed. Further, the peak became sharper as the firing temperature increased, and the growth of the particle diameter was confirmed.
FIG. 2 shows the result of determining the primary particle diameter D of the fired powder from the powder X-ray diffraction pattern of the fired powder at each firing temperature between 600 ° C. and 1100 ° C. according to Scherrer's equation. FIG. 3 is a table showing the relationship between each firing temperature and the primary particle size D of FIG. By adjusting the firing temperature between 600 ° C. and 1100 ° C., the primary particle size of the fired powder could be controlled in the range of 3.5 to 32 nm.

図4は、850℃で焼成して得られたマグネタイトナノ微粒子の透過型電子顕微鏡(TEM)像を示す。図4の中央付近の黒丸がマグネタイトナノ微粒子を示す。
又、図5は、図4のTEM像の個々の黒丸(マグネタイトナノ微粒子)の粒径を測定した粒径分布を示す。画像解析によって黒丸を円に換算したときの直径を個々の粒子の粒径とし、500-1000個の粒子の粒径分布を得た。画像解析による粒径分布は、X線回折による半値幅から求めた粒径と同程度であった。TEM像から得られた粒径分布は正規分布で6.2±1.1nmであり、上記X線回折の半値幅から予想される値(6.5nm)に近似した。これらの結果から、得られたマグネタイトナノ微粒子は、アモルファスSiO2に包含されたマグネタイトナノ微粒子であると判断することができる。
FIG. 4 shows a transmission electron microscope (TEM) image of magnetite nanoparticles obtained by firing at 850 ° C. The black circle near the center of FIG. 4 shows the magnetite nanoparticles.
FIG. 5 shows a particle size distribution obtained by measuring the particle size of each black circle (magnetite nanoparticle) in the TEM image of FIG. The diameter of the black circle converted into a circle by image analysis was used as the particle size of each particle, and a particle size distribution of 500-1000 particles was obtained. The particle size distribution by image analysis was almost the same as the particle size obtained from the half width by X-ray diffraction. The particle size distribution obtained from the TEM image was 6.2 ± 1.1 nm as a normal distribution, and approximated to a value (6.5 nm) expected from the half-value width of the X-ray diffraction. From these results, it can be determined that the obtained magnetite nanoparticles are magnetite nanoparticles included in amorphous SiO 2 .

又、SQUID磁束計を用い、それぞれ850℃、1000℃の各温度で焼成して得られたマグネタイトナノ微粒子の磁気測定を行った。その結果、それぞれ850℃、1000℃度で焼成したマグネタイトナノ微粒子の飽和磁化はそれぞれ83.1および95.1emu/gとなり、いずれもナノ微粒子であるにもかかわらす、バルクのマグネタイト結晶(粒径1μm以上)が持つ飽和磁化値に近い大きな値を示した。
なお、飽和磁化の測定は、以下の分子飽和磁気モーメントの測定によって行った。
分子飽和磁気モーメント:磁気ナノ微粒子分散体の粉末サンプルにつき、SQUID磁束計(超伝導量子干渉装置:Quantum Design社製のMPMS)で、印加磁場±3.95×10A/m(±50kOe)、温度範囲5K〜300Kで測定した。なお、粉末サンプルをアクリル製の内径4mmのサンプルケースに入れ、(アピエゾングリス)キムワイプで固定したのち、SQUIDのサンプルホルダーに取りつけた。このようにして、磁化−磁場曲線(M-H曲線)を測定し、曲線上の最大磁場におけるy軸(M:磁気モーメント)の最大値を分子飽和磁気モーメントとした。
In addition, using a SQUID magnetometer, magnetic measurements were performed on the magnetite nanoparticles obtained by firing at temperatures of 850 ° C. and 1000 ° C., respectively. As a result, the saturation magnetization of the magnetite nanoparticles fired at 850 ° C. and 1000 ° C., respectively, was 83.1 and 95.1 emu / g, respectively. It showed a large value close to the saturation magnetization value of 1 μm or more.
The saturation magnetization was measured by measuring the following molecular saturation magnetic moment.
Molecular saturation magnetic moment: For a powder sample of a magnetic nanoparticle dispersion, applied magnetic field ± 3.95 × 10 6 A / m (± 50 kOe) with a SQUID magnetometer (superconducting quantum interference device: MPMS manufactured by Quantum Design) , Measured in a temperature range of 5K-300K. The powder sample was put in an acrylic sample case with an inner diameter of 4 mm, fixed with (Apiezon grease) Kimwipe, and then attached to a SQUID sample holder. In this way, the magnetization-magnetic field curve (MH curve) was measured, and the maximum value of the y-axis (M: magnetic moment) at the maximum magnetic field on the curve was defined as the molecular saturation magnetic moment.

比較のため、FeCl2水溶液に還元剤を加えずに2価鉄イオン水溶液を調製し、上記と同様に混合したところ、γ-Fe2O3が生成した。γ-Fe2O3が生成すると酸化が進行した状態であり、目的物であるFe3O4が得られない。
又、FeCl2水溶液に、還元剤としてC6H8O6の代わりにそれぞれNaOH,NH3を2.5mモル加えて2価鉄イオン水溶液を調製し、上記と同様に混合したところ、やはりγ-Fe2O3が生成した。
For comparison, a divalent iron ion aqueous solution was prepared without adding a reducing agent to the FeCl 2 aqueous solution and mixed in the same manner as described above to produce γ-Fe 2 O 3. When γ-Fe2O3 is generated, the oxidation has progressed, and the target Fe 3 O 4 cannot be obtained.
In addition, a divalent iron ion aqueous solution was prepared by adding 2.5 mmol of NaOH and NH 3 instead of C 6 H 8 O 6 as a reducing agent to an FeCl 2 aqueous solution and mixing in the same manner as described above. Fe2O3 was formed.

Claims (2)

メタ珪酸ナトリウムを含むアルカリ水溶液と、2価鉄イオン及びC 6 H 8 O 6 からなる還元剤を含む2価鉄イオン水溶液とを混合し、2価の水酸化鉄からなるコアと、該コアを覆うアモルファスSiO2からなるシェルを有する水酸化鉄微粒子を生成させる水酸化鉄微粒子生成工程と、
前記水酸化鉄微粒子を不活性ガス雰囲気下で600〜1100℃で焼成し、前記シェルに覆われたマグネタイトナノ微粒子を生成する工程と、
を有するマグネタイトナノ微粒子の製造方法。
An alkaline aqueous solution containing sodium metasilicate and a divalent iron ion aqueous solution containing a reducing agent consisting of divalent iron ions and C 6 H 8 O 6 are mixed to form a core made of divalent iron hydroxide, An iron hydroxide fine particle producing step for producing iron hydroxide fine particles having a shell made of amorphous SiO 2 covering;
Firing the iron hydroxide fine particles at 600 to 1100 ° C. in an inert gas atmosphere to produce magnetite nanoparticles covered with the shell;
The manufacturing method of the magnetite nanoparticle which has this.
前記マグネタイトナノ微粒子の粉末X線回折パターンからシェラーの式によって得られる一次粒径を2〜20nmの範囲で調整する請求項1記載のマグネタイトナノ微粒子の製造方法。 The manufacturing method of the magnetite nanoparticle of Claim 1 which adjusts the primary particle size obtained by Scherrer's formula from the powder X-ray diffraction pattern of the said magnetite nanoparticle in the range of 2-20 nm .
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