JP3837721B2 - Molecular magnetic material and method for producing the same - Google Patents

Molecular magnetic material and method for producing the same Download PDF

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JP3837721B2
JP3837721B2 JP2003035780A JP2003035780A JP3837721B2 JP 3837721 B2 JP3837721 B2 JP 3837721B2 JP 2003035780 A JP2003035780 A JP 2003035780A JP 2003035780 A JP2003035780 A JP 2003035780A JP 3837721 B2 JP3837721 B2 JP 3837721B2
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aqueous solution
magnetic material
kcl
molecular magnetic
temperature
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JP2004247517A (en
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雅史 花輪
浩 守友
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Japan Science and Technology Agency
National Institute of Japan Science and Technology Agency
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Japan Science and Technology Agency
National Institute of Japan Science and Technology Agency
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Description

【0001】
【産業上の利用分野】
本発明は、磁化特性が温度ヒステリシスを有さない分子磁性材料、及びその製造方法に関する。
【0002】
【従来の技術】
温度または光照射によって磁化率が変化する分子磁性材料と呼ばれる物質がある。このような特性を有する分子磁性材料は、例えば、光メモリ、温度センサ等のデバイス材料として使用することができ、また分子設計によって特性を種々に調整できるため、今後の機能性材料として注目されている。
温度または光照射によって磁化率が変化する分子磁性材料としては、アルカリ金属を含有したコバルト−鉄シアノ錯体化合物が知られている(特許文献1,2参照)。この物質の結晶構造は図3に示すように、FeとCoがCNを媒介として結合した面心立方格子を形成しており、アルカリ金属は格子間位置に存在している(例えば、非特許文献1参照)。
この分子磁性材料は、温度または光励起をトリガーとして格子の再配列が起こり、CoイオンとFeイオンと間で電荷移動が生じ、磁化状態が変化すると考えられている(例えば、非特許文献2参照)。
【0003】
【特許文献1】
特開平9−246044号公報
【特許文献2】
特開2000−269013号公報
【非特許文献1】
O. Sato 他3名,"Photoinduced Magnetization of a Cobalt-IronCynaide", Science, 3 May 1996 ,Vol.272, pp.704-705, (pp.704-705,Fig.1-5)
【非特許文献2】
N. Shimamoto他4名," Control of Charge-Transfer-Induced Spin Transition Temperature on Cobalt-Iron Prussian Blue Analogues",InorganicChemistry, American Chemical Society, Published on Web 01/2002, Vol.41, No.4, pp.678-684, (p.679, Fig.3, Fig.4, Fig.6, Fig.7)
【0004】
特許文献1の図1には、アルカリ金属として、Naを含有させたコバルト−鉄シアノ錯体化合物からなる分子磁性材料の温度による磁気ヒステリシス特性が示されている。この特性によれば、光照射によって温度を上昇させて磁化率が高い状態を書き込み、温度を下げて磁化率が低い状態を書き込むことが可能であるから、書き換え可能な光メモリ材料として使用することができる。
ところで、上記の分子磁性材料はヒステリシス特性を有しているために、光メモリ材料としては有用であるが、温度に対し磁化率が2値を有するため、温度センサのように温度履歴によらずに磁化率が確定する必要がある用途には不向きである。
【0005】
【発明が解決しようとする課題】
しかしながら従来、温度によって磁化率が変化し、かつ、温度履歴によらずに磁化率が確定する、すなわちヒステリシス特性を有しない分子磁性材料は知られていない。
また、温度センサとして使用する場合には、室温付近で磁化率が大きく変化する分子磁性材料が好ましいが、従来、室温付近で磁化率が大きく変化する分子磁性材料は知られていない。
【0006】
本発明は上記課題に鑑み、室温付近で磁化率の温度に対する変化率が大きく、かつ温度ヒステリシス特性を有しない分子磁性材料、及びその製造方法を提供することを目的とする。
【0007】
【課題を解決するための手段】
上記目的を達成するために、本発明の分子磁性材料は、化学組成式Kx Coy [Fe(CN)6 ]・zH2 O(ただし、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる分子磁性材料であって、この分子磁性材料の温度磁化特性が温度ヒステリシスを有さないことを特徴とするものである。
【0008】
前記化学組成式Kx Coy [Fe(CN)6 ]・zH2 Oとしては、好ましくは、化学組成式K0.44Co1.21[Fe(CN)6 ]・5.54H2 O、K0.52Co1.15[Fe(CN)6 ]・5.52H2 O、K0.53Co1.18[Fe(CN)6 ]・4.45H2 O、K0.58Co1.24[Fe(CN)6 ]・4.17H2 Oのいずれか1つであらわされる分子磁性材料である。
【0009】
上記の本発明の分子磁性材料は、室温付近で磁化率の温度に対する変化率が大きく、かつヒステリシス特性を有さないので、例えば、室温近傍の高感度な温度センサ等の用途に好適である。
【0010】
また、本発明の分子磁性材料の製造方法は、化学組成式K x Co y [Fe(CN) 6 ]・zH 2 O(ただし、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる分子磁性材料の製造方法であって、CoCl2 とKClからなる水溶液(以下、A水溶液と称する)及びK3 [Fe(CN)6 ]とKClからなる水溶液(以下、B水溶液と称する)を撹拌して混合する工程と、A水溶液とB水溶液との混合水溶液を所定時間放置し混合水溶液からの生成物を沈殿させる工程と、沈殿物を濾過する工程とからなり、上記A水溶液は、CoCl2 を10ミリモル/リットル、KClをxモル/リットル(ただし、x=1,2,3または4)、そしてH2 Oを90ミリリットルの割合で混合した水溶液であり、また、B水溶液は、K3 [Fe(CN)6 ]を10ミリモル/リットル、KClをxモル/リットル(ただし、x=1,2,3または4)、そしてH2 Oを50ミリリットルの割合で混合した水溶液であることを特徴とする。上記A水溶液とB水溶液とを、容積比で1.8:1の割合で混合することが好ましい。
【0011】
上記の本発明の製造方法による沈殿物は、Kx Coy [Fe(CN)6 ]・zH2 O(ここで、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる分子磁性材料である。本発明の製造方法は、撹拌、混合、沈殿及び濾過からなり、また、室温で製造できるから、極めて低コストで製造し得る。
【0012】
【発明の実施の形態】
以下、本発明の分子磁性材料及びその製造方法を実施例に基づいて詳細に説明する。
初めに、本発明の分子磁性材料の製造方法を説明する。
最初に、以下に示す組成のA水溶液、及びB水溶液を作製する。
A水溶液はCoCl2 とKClの水溶液であり、CoCl2 が10ミリモル/リットル(mol/l)、KClがXモル/リットル(Xは、0.5 から5程度がよい)、及びH2 Oが90ミリリットルの混合割合になるように混合する。
B水溶液は、鉄シアノカリウム塩、すなわちK3 [Fe(CN)6 ]とKClの水溶液であり、K3 [Fe(CN)6 ]が10ミリモル/リットル、KClがXモル/リットル(Xは、0.5 から5程度がよい)、及びH2 Oが50ミリリットルの混合割合となるように混合する。
A水溶液及びB水溶液は、試薬と水を混合した後、試薬が完全に溶解するように約1時間半撹拌し、かつ、24時間放置する。
【0013】
次に、A水溶液とB水溶液とを容積比で1.8:1の割合で混合する。混合の際、B水溶液を撹拌しながら、B水溶液全量に対しA水溶液を約10分間かけて撹拌しながら少しずつ混合していく。さらに、混合した後も約1時間半撹拌を続ける。その後、約24時間放置して生成物を完全に沈殿させる。
【0014】
次に、得られた生成物を適当な孔径を有するフィルターで濾過する。その後、フィルター上の生成物を蒸留水で所定回数洗浄し、空気中や乾燥窒素中において乾燥することにより、固形物として、本発明の化学組成式Kx Coy [Fe(CN)6 ]・zH2 O(ここで、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる本発明の分子磁性材料が得られる。この磁性材料は、Kを含有したコバルト−鉄シアノ錯体化合物であり、Kはコバルト−鉄シアノ錯体化合物のfcc格子の格子間に存在している。
【0015】
次に、本発明の分子磁性材料の製造方法の特徴について説明する。
従来のコバルト−鉄シアノ錯体化合物の合成は、鉄シアノナトリウム塩Na3 [Fe(CN)6 ]を原料として合成していた。しかしながら、Na3 [Fe(CN)6 ]は潮解性が大きく、合成に際しては、Na3 [Fe(CN)6 ]の潮解を防ぐための様々な工程を必要としていたため、コバルト−鉄シアノ錯体化合物を低コストで合成することができなかった。
本発明の製造方法に使用する[K3 Fe(CN)6 ]は潮解性が小さく、取り扱いが容易であるため、低コストでコバルト−鉄シアノ錯体化合物を合成することができる。
【0016】
また、Na3 [Fe(CN)6 ]を原料として使用した場合には、潮解性の課題のみでなく、合成されたコバルト−鉄シアノ錯体化合物中にNaが残留してしまうという課題があり、そのためKのみを格子間にドープしたコバルト−鉄シアノ錯体化合物の合成が困難であるという課題があった。
本発明の方法によれば、[K3 Fe(CN)6 ]を原料として使用するので、Kのみドープされたコバルト−鉄シアノ錯体化合物を容易に合成することができる。
【0017】
以下に、上記方法で製造した本発明の分子磁性体の実施例を示す。
(実施例1)
A溶液として、0.117gのCoCl2 と、6.719gのKClを、90ミリリットルのH2 Oに混合し、CoCl2 とKClの濃度比が10mM(ミリモル)/1M(モル)の水溶液を作製した。
また、B溶液として、0.164gのK3 [Fe(CN)6 ]と、3.728gのKClを50ミリリットルのH2 Oに混合し、K3 [Fe(CN)6 ]とKClの濃度比が10mM(ミリモル)/1M(モル)のB水溶液を作製した。
A水溶液及びB水溶液それぞれを、約1時間撹拌して、その後、各水溶液中の試薬を完全に溶解させるために約24時間放置した。
【0018】
次に、A水溶液とB水溶液とを、1.8:1の容積比割合で、A水溶液の全量をB水溶液の全量に対して約10分間かけてゆっくり加えた。ここで、B水溶液を最初から撹拌し、A水溶液の全量がB水溶液に加えられた後、さらに撹拌を約1時間継続した。
続いて、A水溶液とB水溶液との混合溶液を約24時間放置して、生成物を完全に沈殿させた。このようにして得られた生成物を1.2μm孔のニトロセルロース系有機ポリマーフィルターで濾過した。さらに、フィルター上の生成物を50ミリリットルの蒸留水で2回洗浄し、空気中で乾燥することにより、固形状の本発明の分子磁性材料、約0.22gを得た。
【0019】
このようにして得られた本発明の分子磁性材料の組成比を化学分析で調べたところ、K0.44Co1.21[Fe(CN)6 ]・5.54H2 Oであった。
【0020】
(実施例2)
A水溶液及びB水溶液のKClを2M(モル)にした以外は、実施例1と同一条件で、本発明の分子磁性材料を合成した。得られた本発明の分子磁性材料の組成を、上記の実施例1と同様に化学分析したところ、組成は、K0.52Co1.15[Fe(CN)6 ]・5.52H2 Oであった。
【0021】
(実施例3)
A水溶液及びB水溶液のKClを3M(モル)にした以外は、実施例1と同一条件で、本発明の分子磁性材料を合成した。得られた本発明の分子磁性材料の組成を上記実施例1と同様に化学分析したところ、組成は、K0.53Co1.18[Fe(CN)6 ]・4.45H2 Oであった。
【0022】
(実施例4)
A水溶液及びB水溶液のKClを4M(モル)にした以外は、実施例1と同一条件で、本発明の分子磁性材料を合成した。得られた本発明の分子磁性材料の組成を上記実施例1と同様に化学分析したところ、組成は、K0.58Co1.24[Fe(CN)6 ]・4.17H2 Oであった。
【0023】
次に、本発明の分子磁性材料の温度に対する磁化特性を示す。
図1は、本発明の分子磁性材料の磁化率と温度の関係を示す図である。図の横軸は温度(K)で、縦軸は磁化率×温度(χT)である。測定に用いた試料は、上記の実施例1から実施例4において作製した試料であり、A水溶液及びB水溶液のKClの量を、それぞれ1M(モル)、2M、3M、4Mとして得られた、化学組成式がK0.44Co1.21[Fe(CN)6 ]・5.54H2 O、K0.52Co1.15[Fe(CN)6 ]・5.52H2 O、K0.53Co1.18[Fe(CN)6 ]・4.45H2 O、及びK0.58Co1.24[Fe(CN)6 ]・4.17H2 Oで表される本発明の分子磁性材料に対応する。
【0024】
図からわかるように、本発明の分子磁性材料は、50Kから350Kまでの温度領域において、温度上昇と共に、χTが増加すると共に、ヒステリシス特性がないことが分かる。また、KClの量が1Mと2Mの本発明の分子磁性材料の場合には、室温付近でχTの温度に対する変化率が大きいことが分かる。
図1の結果から、上記した本発明の分子磁性材料は、室温付近で磁化率の温度に対する変化率が大きく、かつ温度ヒステリシス特性を有さないことがわかる。従って、例えば、室温近傍の高感度な温度センサ等の用途に好適である。
【0025】
次に、本発明の分子磁性材料の温度に対する磁化率の変化がヒステリシスを有さないことを実証する他の測定データを示す。
図2は、本発明の分子磁性材料の格子定数の温度変化を示す図である。図の横軸は温度(K)を示し、縦軸は格子定数(Å)を示している。約100Kから約350Kまで昇温させ、各温度でディフラクトメーターの2θスキャンを行いながら測定した。図において、□(白四角)は、KClが1M(モル)の試料のLS相の格子定数を示し、■(黒四角)はHS相の格子定数を示す。同様に、△(白三角)及び▲(黒三角)は、KClが2Mの試料のLS相とHS相の格子定数を示している。
【0026】
ここで、LS相とHS相について説明する。
アルカリ金属としてNaを含有したコバルト−鉄シアノ錯体化合物においては、スピン状態が異なる2つの相が存在することが知られている(上記非特許文献2参照)。すなわち、二価のFeイオンと三価のCoイオンからなるスピンが小さいLS相と、三価のFeイオンと二価のCoイオンからなるスピンが大きいHS相とが存在し、LS相とHS相とが、おおきな熱ヒステリシスを有して相転移することが知られている。本発明の分子磁性材料は、アルカリ金属としてNaではなくKを含有するコバルト−鉄シアノ錯体化合物であるが、Naを含有したコバルト−鉄シアノ錯体化合物と同様にLS相とHS相とが存在する。
【0027】
図2からわかるように、低温領域ではLS相(□、△)のみが存在し、高温領域においてはHS相(■、▲)のみが存在し、図1の磁化率が急激に変化する温度250K近傍の両相が共存する温度範囲は狭く、特に、KClが1M(モル)の試料(□、■)では極めて狭いことがわかる。このことは、本発明のKを含有したコバルト−鉄シアノ錯体化合物の相転移は、温度によるヒステリシスが極めて小さいことを示している。これは、磁化特性の温度ヒステリシスが極めて小さくなることを意味している。
【0028】
本発明は、上記実施例に限定されることなく、特許請求の範囲に記載した発明の範囲内で種々の変形が可能であり、それらも本発明の範囲内に含まれることはいうまでもない。例えば、上記実施の形態で説明した、Kx Coy [Fe(CN)6 ]・zH2 Oの製造方法において、水溶液(A)と水溶液(B)との組成と混合比などは、Kx Coy [Fe(CN)6 ]・zH2 Oの組成に応じて、適宜に調整できることは勿論である。
【0029】
【発明の効果】
上記説明から理解されるように、本発明の分子磁性材料は、磁化率の温度ヒステリシスを有しておらず、また室温付近において磁化率の温度変化率が大きい。従って、温度履歴によらずに磁化率が確定する必要がある用途、例えば温度センサなどに最適な材料である。また、温度変化が磁化率の変化に変換されるので、磁気抵抗効果デバイスの構成要素として使用すれば、極めて高機能なデバイスが実現できる。
本発明の分子磁性材料の製造方法は、極めて簡便であり、従って低コストで本発明の分子磁性材料を提供することができる。また、本発明の製造方法は、鉄シアノカリウム塩、すなわちK3 [Fe(CN)6 ]を原料として用いるので、純粋にKのみがドープされた分子磁性材料を実現することができる。
【図面の簡単な説明】
【図1】本発明の分子磁性材料の磁化率と温度の関係を示す図である。
【図2】本発明の分子磁性材料の格子定数の温度変化を示す図である。
【図3】コバルト−鉄シアノ錯体化合物の結晶構造を示す図である。
[0001]
[Industrial application fields]
The present invention relates to a molecular magnetic material whose magnetization characteristics do not have temperature hysteresis, and a manufacturing method thereof.
[0002]
[Prior art]
There is a substance called a molecular magnetic material whose magnetic susceptibility changes with temperature or light irradiation. Molecular magnetic materials having such characteristics can be used as device materials for optical memories, temperature sensors, etc., and can be adjusted in various ways by molecular design. .
Cobalt-iron cyano complex compounds containing an alkali metal are known as molecular magnetic materials whose magnetic susceptibility changes with temperature or light irradiation (see Patent Documents 1 and 2). As shown in FIG. 3, the crystal structure of this substance forms a face-centered cubic lattice in which Fe and Co are bonded via CN, and the alkali metal exists in the interstitial position (for example, non-patent document). 1).
In this molecular magnetic material, it is considered that lattice rearrangement takes place triggered by temperature or photoexcitation, charge transfer occurs between Co ions and Fe ions, and the magnetization state changes (for example, see Non-Patent Document 2). .
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-246044 [Patent Document 2]
JP 2000-269013 A [Non-Patent Document 1]
O. Sato and three others, "Photoinduced Magnetization of a Cobalt-IronCynaide", Science, 3 May 1996, Vol.272, pp.704-705, (pp.704-705, Fig.1-5)
[Non-Patent Document 2]
N. Shimamoto et al., “Control of Charge-Transfer-Induced Spin Transition Temperature on Cobalt-Iron Prussian Blue Analogues”, InorganicChemistry, American Chemical Society, Published on Web 01/2002, Vol.41, No.4, pp. 678-684, (p.679, Fig.3, Fig.4, Fig.6, Fig.7)
[0004]
FIG. 1 of Patent Document 1 shows magnetic hysteresis characteristics depending on the temperature of a molecular magnetic material made of a cobalt-iron cyano complex compound containing Na as an alkali metal. According to this characteristic, it is possible to write a state with a high magnetic susceptibility by raising the temperature by light irradiation and write a state with a low magnetic susceptibility by lowering the temperature, so that it can be used as a rewritable optical memory material. it can.
By the way, the above-mentioned molecular magnetic material is useful as an optical memory material because it has a hysteresis characteristic. However, since the magnetic susceptibility has a binary value with respect to temperature, it does not depend on the temperature history like a temperature sensor. It is not suitable for applications where the magnetic susceptibility needs to be determined.
[0005]
[Problems to be solved by the invention]
Conventionally, however, no molecular magnetic material has been known in which the magnetic susceptibility changes with temperature and the magnetic susceptibility is determined without depending on the temperature history, that is, has no hysteresis characteristic.
When used as a temperature sensor, a molecular magnetic material whose magnetic susceptibility changes greatly near room temperature is preferable, but no molecular magnetic material whose magnetic susceptibility changes largely near room temperature has been known.
[0006]
In view of the above problems, an object of the present invention is to provide a molecular magnetic material that has a large rate of change of magnetic susceptibility with respect to temperature near room temperature and does not have temperature hysteresis characteristics, and a method for producing the same.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the molecular magnetic material of the present invention has a chemical composition formula K x Co y [Fe (CN) 6 ] · zH 2 O (where 0.44 ≦ x ≦ 0.58, 1.18). ≦ y ≦ 1.24, 4.17 ≦ z ≦ 5.54), characterized in that the temperature magnetization characteristic of this molecular magnetic material has no temperature hysteresis. .
[0008]
The chemical composition formula K x Co y [Fe (CN) 6 ] · zH 2 O is preferably the chemical composition formula K 0.44 Co 1.21 [Fe (CN) 6 ] · 5.54 H 2 O, K 0.52 Co 1.15. [Fe (CN) 6 ] · 5.52H 2 O, K 0.53 Co 1.18 [Fe (CN) 6 ] · 4.45H 2 O, K 0.58 Co 1.24 [Fe (CN) 6 ] · 4.17H 2 O It is a molecular magnetic material represented by any one.
[0009]
The above-described molecular magnetic material of the present invention has a large rate of change of magnetic susceptibility with respect to temperature near room temperature and does not have hysteresis characteristics.
[0010]
In addition, the method for producing the molecular magnetic material of the present invention has the chemical composition formula K x Co y [Fe (CN) 6 ] · zH 2 O (where 0.44 ≦ x ≦ 0.58, 1.18 ≦ y ≦ 1.24, 4.17 ≦ z ≦ 5.54), which is an aqueous solution composed of CoCl 2 and KCl (hereinafter referred to as A aqueous solution) and K 3 [Fe (CN) 6 ] and an aqueous solution comprising KCl (hereinafter referred to as B aqueous solution) with stirring, a step of allowing the mixed aqueous solution of A aqueous solution and B aqueous solution to stand for a predetermined time and precipitating the product from the mixed aqueous solution; the precipitate Ri Do and a step of filtering, the a aqueous solution, CoCl 2 10 mmol / l, the KCl x mol / l (where, x = 1, 2, 3 or 4), and 90 of H 2 O An aqueous solution mixed in milliliters And, B aqueous solution, the proportion of K 3 [Fe (CN) 6 ] 10 mmol / l, KCl and x mol / l (where, x = 1, 2, 3 or 4), and 50 ml of H 2 O It is the aqueous solution mixed by this. The aqueous solution A and aqueous solution B are preferably mixed at a volume ratio of 1.8: 1.
[0011]
The precipitate produced by the production method of the present invention is K x Co y [Fe (CN) 6 ] · zH 2 O (where 0.44 ≦ x ≦ 0.58, 1.18 ≦ y ≦ 1.24). 4.17 ≦ z ≦ 5.54). The production method of the present invention consists of stirring, mixing, precipitation and filtration, and can be produced at room temperature, so it can be produced at a very low cost.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the molecular magnetic material of the present invention and the production method thereof will be described in detail based on examples.
First, the method for producing the molecular magnetic material of the present invention will be described.
First, an A aqueous solution and a B aqueous solution having the following composition are prepared.
A aqueous solution is an aqueous solution of CoCl 2 and KCl, CoCl 2 is 10 mmol / liter (mol / l), KCl is X mol / liter (X is preferably about 0.5 to 5), and H 2 O is 90 ml. Mix to a mixing ratio of.
The aqueous B solution is an iron cyano potassium salt, that is, an aqueous solution of K 3 [Fe (CN) 6 ] and KCl, where K 3 [Fe (CN) 6 ] is 10 mmol / L, and KCl is X mol / L (X is , 0.5 to 5 is preferable), and H 2 O is mixed to a mixing ratio of 50 ml.
The aqueous solution A and aqueous solution B are mixed for approximately one and a half hours and mixed for 24 hours so that the reagent is completely dissolved after mixing the reagent and water.
[0013]
Next, the A aqueous solution and the B aqueous solution are mixed at a volume ratio of 1.8: 1. During mixing, the aqueous solution A is mixed little by little with stirring over about 10 minutes with respect to the total amount of aqueous solution B while stirring the aqueous solution B. Furthermore, stirring is continued for about 1 and a half hours after mixing. Thereafter, it is left for about 24 hours to completely precipitate the product.
[0014]
Next, the obtained product is filtered through a filter having an appropriate pore size. Thereafter, the product on the filter is washed a predetermined number of times with distilled water, and dried in air or dry nitrogen, so that the solid composition has the chemical composition formula K x Co y [Fe (CN) 6 ] · The molecular magnetic material of the present invention represented by zH 2 O (where 0.44 ≦ x ≦ 0.58, 1.18 ≦ y ≦ 1.24, 4.17 ≦ z ≦ 5.54) is obtained. This magnetic material is a cobalt-iron cyano complex compound containing K, and K exists between the fcc lattices of the cobalt-iron cyano complex compound.
[0015]
Next, features of the method for producing the molecular magnetic material of the present invention will be described.
A conventional cobalt-iron cyano complex compound has been synthesized using iron cyano sodium salt Na 3 [Fe (CN) 6 ] as a raw material. However, Na 3 [Fe (CN) 6 ] has great deliquescence, and the synthesis required various steps to prevent deliquescence of Na 3 [Fe (CN) 6 ], so that the cobalt-iron cyano complex The compound could not be synthesized at a low cost.
Since [K 3 Fe (CN) 6 ] used in the production method of the present invention has low deliquescence and is easy to handle, a cobalt-iron cyano complex compound can be synthesized at low cost.
[0016]
Moreover, when Na 3 [Fe (CN) 6 ] is used as a raw material, there is a problem that Na remains in the synthesized cobalt-iron cyano complex compound as well as a problem of deliquescence, Therefore, there has been a problem that it is difficult to synthesize a cobalt-iron cyano complex compound doped with only K between lattices.
According to the method of the present invention, since [K 3 Fe (CN) 6 ] is used as a raw material, a cobalt-iron cyano complex compound doped only with K can be easily synthesized.
[0017]
Examples of the molecular magnetic material of the present invention produced by the above method are shown below.
Example 1
As solution A, 0.117 g of CoCl 2 and 6.719 g of KCl are mixed with 90 ml of H 2 O to prepare an aqueous solution with a concentration ratio of CoCl 2 and KCl of 10 mM (mmol) / 1M (mol). did.
Further, as a solution B, 0.164 g of K 3 [Fe (CN) 6 ] and 3.728 g of KCl were mixed with 50 ml of H 2 O, and the concentrations of K 3 [Fe (CN) 6 ] and KCl were mixed. A B aqueous solution having a ratio of 10 mM (mmol) / 1 M (mol) was prepared.
Aqueous solution A and aqueous solution B were each stirred for about 1 hour, and then allowed to stand for about 24 hours in order to completely dissolve the reagents in each aqueous solution.
[0018]
Next, the A aqueous solution and the B aqueous solution were slowly added over about 10 minutes with respect to the total amount of the B aqueous solution in a volume ratio of 1.8: 1. Here, the aqueous B solution was stirred from the beginning, and after the entire amount of the aqueous A solution was added to the aqueous B solution, stirring was further continued for about 1 hour.
Subsequently, the mixed solution of the A aqueous solution and the B aqueous solution was allowed to stand for about 24 hours to completely precipitate the product. The product thus obtained was filtered through a 1.2 μm pore nitrocellulose organic polymer filter. Further, the product on the filter was washed twice with 50 ml of distilled water and dried in the air to obtain about 0.22 g of the solid molecular magnetic material of the present invention.
[0019]
The composition ratio of the molecular magnetic material of the present invention thus obtained was examined by chemical analysis and found to be K 0.44 Co 1.21 [Fe (CN) 6 ] · 5.54H 2 O.
[0020]
(Example 2)
The molecular magnetic material of the present invention was synthesized under the same conditions as in Example 1 except that the KCl of the aqueous solution A and aqueous solution B was changed to 2M (mol). The composition of the obtained molecular magnetic material of the present invention was chemically analyzed in the same manner as in Example 1. The composition was K 0.52 Co 1.15 [Fe (CN) 6 ] · 5.52H 2 O.
[0021]
Example 3
The molecular magnetic material of the present invention was synthesized under the same conditions as in Example 1 except that the KCl of the aqueous solution A and aqueous solution B was changed to 3M (mol). The composition of the obtained molecular magnetic material of the present invention was chemically analyzed in the same manner as in Example 1. As a result, the composition was K 0.53 Co 1.18 [Fe (CN) 6 ] · 4.45H 2 O.
[0022]
Example 4
The molecular magnetic material of the present invention was synthesized under the same conditions as in Example 1 except that the KCl of the aqueous solution A and aqueous solution B was changed to 4M (mol). When the composition of the obtained molecular magnetic material of the present invention was chemically analyzed in the same manner as in Example 1, the composition was K 0.58 Co 1.24 [Fe (CN) 6 ] · 4.17H 2 O.
[0023]
Next, the magnetization characteristic with respect to temperature of the molecular magnetic material of the present invention is shown.
FIG. 1 is a graph showing the relationship between the magnetic susceptibility and temperature of the molecular magnetic material of the present invention. In the figure, the horizontal axis represents temperature (K), and the vertical axis represents magnetic susceptibility × temperature (χT). The sample used for the measurement was the sample prepared in the above-described Example 1 to Example 4, and the KCl amounts of the A aqueous solution and the B aqueous solution were obtained as 1 M (mol), 2 M, 3 M, and 4 M, respectively. The chemical composition is K 0.44 Co 1.21 [Fe (CN) 6 ] · 5.54H 2 O, K 0.52 Co 1.15 [Fe (CN) 6 ] · 5.52H 2 O, K 0.53 Co 1.18 [Fe (CN) 6 ] 4.45H 2 O and K 0.58 Co 1.24 [Fe (CN) 6 ] · 4.17 H 2 O corresponding to the molecular magnetic material of the present invention.
[0024]
As can be seen from the figure, the molecular magnetic material of the present invention has no hysteresis characteristic as χT increases with increasing temperature in the temperature range from 50K to 350K. It can also be seen that the rate of change with respect to the temperature of χT is large near room temperature in the case of the molecular magnetic material of the present invention with the amount of KCl of 1M and 2M.
From the results of FIG. 1, it can be seen that the above-described molecular magnetic material of the present invention has a large rate of change of magnetic susceptibility with respect to temperature near room temperature and does not have temperature hysteresis characteristics. Therefore, for example, it is suitable for applications such as a highly sensitive temperature sensor near room temperature.
[0025]
Next, other measurement data demonstrating that the change in magnetic susceptibility with temperature of the molecular magnetic material of the present invention has no hysteresis will be shown.
FIG. 2 is a graph showing the temperature change of the lattice constant of the molecular magnetic material of the present invention. In the figure, the horizontal axis indicates temperature (K), and the vertical axis indicates lattice constant (Å). The temperature was raised from about 100 K to about 350 K, and measurement was performed while performing a 2θ scan of the diffractometer at each temperature. In the figure, □ (white square) indicates the lattice constant of the LS phase of the sample having KCl of 1 M (mol), and ■ (black square) indicates the lattice constant of the HS phase. Similarly, Δ (white triangles) and ▲ (black triangles) indicate the lattice constants of the LS phase and the HS phase of the sample with 2 M KCl.
[0026]
Here, the LS phase and the HS phase will be described.
It is known that a cobalt-iron cyano complex compound containing Na as an alkali metal has two phases having different spin states (see Non-Patent Document 2 above). That is, there are an LS phase having a small spin composed of a divalent Fe ion and a trivalent Co ion, and an HS phase having a large spin composed of a trivalent Fe ion and a divalent Co ion, and the LS phase and the HS phase. Are known to undergo phase transitions with significant thermal hysteresis. The molecular magnetic material of the present invention is a cobalt-iron cyano complex compound containing K instead of Na as an alkali metal, but an LS phase and an HS phase exist in the same manner as the cobalt-iron cyano complex compound containing Na. .
[0027]
As can be seen from FIG. 2, only the LS phase (□, Δ) exists in the low temperature region, and only the HS phase (■, ▲) exists in the high temperature region, and the temperature at which the magnetic susceptibility in FIG. It can be seen that the temperature range in which the two adjacent phases coexist is narrow, and in particular, the sample (□, ■) with 1 M (mol) KCl is extremely narrow. This indicates that the phase transition of the cobalt-iron cyano complex compound containing K of the present invention has extremely small hysteresis due to temperature. This means that the temperature hysteresis of the magnetization characteristics becomes extremely small.
[0028]
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that these are also included in the scope of the present invention. . For example, in the method for producing K x Co y [Fe (CN) 6 ] .zH 2 O described in the above embodiment, the composition and mixing ratio of the aqueous solution (A) and the aqueous solution (B) are expressed as K x Of course, it can be appropriately adjusted according to the composition of Co y [Fe (CN) 6 ] .zH 2 O.
[0029]
【The invention's effect】
As understood from the above description, the molecular magnetic material of the present invention does not have a magnetic susceptibility temperature hysteresis, and has a large temperature change rate of susceptibility near room temperature. Therefore, it is an optimal material for applications in which the magnetic susceptibility needs to be determined regardless of the temperature history, such as a temperature sensor. In addition, since a change in temperature is converted into a change in magnetic susceptibility, if it is used as a component of a magnetoresistive effect device, an extremely high performance device can be realized.
The method for producing the molecular magnetic material of the present invention is extremely simple, and therefore the molecular magnetic material of the present invention can be provided at a low cost. Further, since the production method of the present invention uses iron cyano potassium salt, that is, K 3 [Fe (CN) 6 ] as a raw material, it is possible to realize a molecular magnetic material purely doped with K.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the magnetic susceptibility and temperature of a molecular magnetic material of the present invention.
FIG. 2 is a graph showing a temperature change of a lattice constant of the molecular magnetic material of the present invention.
FIG. 3 is a view showing a crystal structure of a cobalt-iron cyano complex compound.

Claims (4)

化学組成式Kx Coy [Fe(CN)6 ]・zH2
(ただし、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる分子磁性材料であり、この磁化特性が温度ヒステリシスを有さないことを特徴とする、分子磁性材料。
Chemical composition formula K x Co y [Fe (CN) 6 ] .zH 2 O
(However, 0.44 ≦ x ≦ 0.58, 1.18 ≦ y ≦ 1.24, 4.17 ≦ z ≦ 5.54), and this magnetization characteristic has temperature hysteresis. A molecular magnetic material characterized by not.
前記分子磁性材料が、
0.44Co1.21[Fe(CN)6 ]・5.54H2 O、
0.52Co1.15[Fe(CN)6 ]・5.52H2 O、
0.53Co1.18[Fe(CN)6 ]・4.45H2 O、
0.58Co1.24[Fe(CN)6 ]・4.17H2 O、
のいずれか1つであることを特徴とする、請求項1に記載の分子磁性材料。
The molecular magnetic material is
K 0.44 Co 1.21 [Fe (CN) 6 ] · 5.54H 2 O,
K 0.52 Co 1.15 [Fe (CN) 6 ] · 5.52H 2 O,
K 0.53 Co 1.18 [Fe (CN) 6 ] .4.45H 2 O,
K 0.58 Co 1.24 [Fe (CN) 6 ] · 4.17H 2 O,
The molecular magnetic material according to claim 1, wherein the molecular magnetic material is any one of the following.
化学組成式K x Co y [Fe(CN) 6 ]・zH 2 O(ただし、0.44≦x≦0.58、1.18≦y≦1.24、4.17≦z≦5.54)で表わされる分子磁性材料の製造方法であって、
CoCl2 とKClからなる水溶液と、K3 [Fe(CN)6 ]とKClからなる水溶液とを撹拌して混合する工程と、
上記CoCl2 とKClからなる水溶液と、上記K3 [Fe(CN) 6]とKClからなる水溶液との混合水溶液を所定時間放置し、この混合水溶液からの生成物を沈殿させる工程と、
この沈殿物を濾過する工程、とからなり、
上記CoCl 2 とKClからなる水溶液は、CoCl 2 を10ミリモル/リットル、KClをxモル/リットル(ただし、x=1,2,3または4)、H 2 Oを90ミリリットルの割合で混合して成り、
上記K 3 [Fe(CN) 6 ]とKClからなる水溶液は、K 3 [Fe(CN) 6 ]を10ミリモル/リットル、KClをxモル/リットル(ただし、x=1,2,3または4)、H 2 Oを50ミリリットルの割合で混合して成ることを特徴とする、分子磁性材料の製造方法。
Chemical composition formula K x Co y [Fe (CN) 6 ] · zH 2 O (where 0.44 ≦ x ≦ 0.58, 1.18 ≦ y ≦ 1.24, 4.17 ≦ z ≦ 5.54) A method for producing a molecular magnetic material represented by:
Stirring and mixing an aqueous solution composed of CoCl 2 and KCl and an aqueous solution composed of K 3 [Fe (CN) 6 ] and KCl;
Leaving a mixed aqueous solution of the aqueous solution composed of CoCl 2 and KCl and the aqueous solution composed of K 3 [Fe (CN) 6 ] and KCl for a predetermined time, and precipitating a product from the mixed aqueous solution;
The step of filtering the precipitate, Do from the Ri,
The aqueous solution composed of CoCl 2 and KCl is obtained by mixing CoCl 2 at 10 mmol / liter, KCl at x mole / liter (where x = 1, 2 , 3 or 4) and H 2 O at a ratio of 90 ml. Consisting of
The aqueous solution composed of K 3 [Fe (CN) 6 ] and KCl is 10 mmol / liter of K 3 [Fe (CN) 6 ] and x mol / liter of KCl (where x = 1, 2, 3 or 4 ), A method of producing a molecular magnetic material , wherein H 2 O is mixed at a ratio of 50 ml .
前記CoCl2 とKClからなる水溶液およびK3 [Fe(CN)6 ]とKClからなる水溶液を撹拌して混合する工程は、上記CoCl2 とKClからなる水溶液および上記K3 [Fe(CN)6 ]とKClからなる水溶液を、容積比で、1.8:1の割合で混合することを特徴とする、請求項に記載の分子磁性材料の製造方法。The step of stirring and mixing the aqueous solution composed of CoCl 2 and KCl and the aqueous solution composed of K 3 [Fe (CN) 6 ] and KCl includes the aqueous solution composed of CoCl 2 and KCl and the K 3 [Fe (CN) 6. The method for producing a molecular magnetic material according to claim 3 , wherein the aqueous solution comprising KCl and KCl is mixed at a volume ratio of 1.8: 1.
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