JP2004247517A - Molecular magnetic material and method for manufacturing the same - Google Patents
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Abstract
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、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、とからなることを特徴とする。
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 applications]
The present invention relates to a molecular magnetic material whose magnetization characteristics do not have temperature hysteresis, and a method for manufacturing the same.
[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 and temperature sensors, for example, and can be variously adjusted in characteristics by molecular design, so that they are attracting attention as future functional materials. .
As a molecular magnetic material whose magnetic susceptibility changes with temperature or light irradiation, a cobalt-iron cyano complex compound containing an alkali metal is known (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 at an interstitial position (for example, see Non-Patent Document 1).
In this molecular magnetic material, lattice rearrangement is triggered by temperature or photoexcitation, charge transfer occurs between Co ions and Fe ions, and the magnetization state is considered to change (for example, see Non-Patent Document 2). .
[0003]
[Patent Document 1]
Japanese Patent Application Laid-Open No. Hei 9-246044 [Patent Document 2]
Japanese Patent Application Laid-Open No. 2000-269013 [Non-Patent Document 1]
O. Sato et al., "Photoinduced Magnetization of a Cobalt-IronCynide", Science, 3 May 1996, Vol. 272 pp. 704-705, (pp. 704-705, FIG. 1-5)
[Non-patent document 2]
N. Shimamoto and 4 others, "Control of Charge-Transfer-Induced Spin Translation Temperature on Cobalt-Iron Plush Business Pharmaceutical Business Analogues, Pharmaceuticals and Pharmaceuticals. 41, no. 4, pp. 678-684, (p.679, FIG. 3, FIG. 4, FIG. 6, FIG. 7).
[0004]
FIG. 1 of Patent Document 1 shows the magnetic hysteresis characteristics of a molecular magnetic material comprising a cobalt-iron cyano complex compound containing Na as an alkali metal depending on the temperature. According to this characteristic, it is possible to write a state with a high magnetic susceptibility by raising the temperature by light irradiation and to 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 molecular magnetic material is useful as an optical memory material because it has a hysteresis characteristic, but since the magnetic susceptibility has two values with respect to temperature, it does not depend on the temperature history like a temperature sensor. It is not suitable for applications where the susceptibility needs to be determined.
[0005]
[Problems to be solved by the invention]
However, conventionally, there is no known molecular magnetic material in which the magnetic susceptibility changes depending on the temperature and the magnetic susceptibility is determined without depending on the temperature history, that is, has no hysteresis characteristics.
When used as a temperature sensor, a molecular magnetic material whose magnetic susceptibility changes greatly near room temperature is preferable, but a molecular magnetic material whose magnetic susceptibility changes largely near room temperature has not been known.
[0006]
In view of the above problems, it is an object of the present invention to provide a molecular magnetic material having a large rate of change in magnetic susceptibility at room temperature near room temperature and having no temperature hysteresis characteristics, and a method for manufacturing 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 of K x Co y [Fe (CN) 6 ] · zH 2 O (provided that 0.44 ≦ x ≦ 0.58, 1.18) ≤ y ≤ 1.24, 4.17 ≤ z ≤ 5.54), characterized in that the temperature magnetization characteristics of the molecular magnetic material have no temperature hysteresis. .
[0008]
As the chemical composition formula K x Co y [Fe (CN) 6 ] · zH 2 O, preferably, the chemical composition formula K 0.44 Co 1.21 [Fe (CN) 6 ] · 5.54H 2 O, K 0.52 Co 1.15 [Fe (CN) 6 ] .5.52 H 2 O, K 0.53 Co 1.18 [Fe (CN) 6 ] .4.45 H 2 O, K 0.58 Co 1 .24 [Fe (CN) 6 ] .4.17H 2 O is a molecular magnetic material.
[0009]
The above-described molecular magnetic material of the present invention has a large rate of change in magnetic susceptibility to temperature near room temperature and does not have hysteresis characteristics, and thus is suitable for use as a highly sensitive temperature sensor near room temperature, for example.
[0010]
The method for producing a molecular magnetic material according to the present invention includes an aqueous solution comprising CoCl 2 and KCl (hereinafter, referred to as A aqueous solution) and an aqueous solution comprising K 3 [Fe (CN) 6 ] and KCl (hereinafter, referred to as B aqueous solution). A) stirring and mixing, a step of allowing a mixed aqueous solution of the A aqueous solution and the B aqueous solution to stand for a predetermined time to precipitate a product from the mixed aqueous solution, and a step of filtering the precipitate. I do.
The aqueous solution A is an aqueous solution obtained by mixing CoCl 2 at 10 mmol / l, KCl at x mol / l (where x = 1, 2, 3, or 4), and H 2 O at a ratio of 90 ml. , B aqueous solution at a rate of 10 mmol / L of K 3 [Fe (CN) 6 ], x mol / L of KCl (x = 1, 2, 3, or 4), and 50 mL of H 2 O. It is a mixed aqueous solution. It is preferable that the aqueous solution A and the aqueous solution B are mixed at a volume ratio of 1.8: 1.
[0011]
The precipitate obtained by the above-mentioned 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 comprises stirring, mixing, precipitation and filtration, and can be produced at room temperature, so that it can be produced at extremely low cost.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the molecular magnetic material of the present invention and the method for producing the same will be described in detail based on examples.
First, a method for producing a molecular magnetic material of the present invention will be described.
First, an aqueous solution A and an aqueous solution B having the following composition are prepared.
The aqueous solution A is an aqueous solution of CoCl 2 and KCl. CoCl 2 is 10 mmol / L (mol / L), KCl is X mol / L (X is preferably about 0.5 to 5), and H 2 O is Mix to a mixing ratio of 90 ml.
The aqueous solution B is an aqueous solution of iron cyano potassium salt, ie, 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) and H 2 O in a mixing ratio of 50 ml.
After mixing the aqueous solution A and the aqueous solution B with the reagent, the mixture is stirred for about one and a half hours so that the reagent is completely dissolved, and left for 24 hours.
[0013]
Next, the A aqueous solution and the B aqueous solution are mixed at a volume ratio of 1.8: 1. At the time of mixing, the aqueous solution A is gradually mixed with the total amount of the aqueous solution B over about 10 minutes while stirring the aqueous solution B while stirring. Further, after the mixing, stirring is continued for about one and a half hours. The product is then left to precipitate completely for about 24 hours.
[0014]
Next, the obtained product is filtered through a filter having an appropriate pore size. Thereafter, the product on the filter is washed with distilled water a predetermined number of times, and dried in air or dry nitrogen, so that the solid composition is represented by the chemical composition formula of K x Co y [Fe (CN) 6 ] · of the present invention. The molecular magnetic material of the present invention represented by zH 2 O (here, 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 lattices of the fcc lattice of the cobalt-iron cyano complex compound.
[0015]
Next, features of the method for producing a molecular magnetic material of the present invention will be described.
In the synthesis of a conventional cobalt-iron cyano complex compound, iron cyano sodium salt Na 3 [Fe (CN) 6 ] was used as a raw material. However, since Na 3 [Fe (CN) 6 ] has a large deliquescent property and requires various steps for preventing the deliquescent of Na 3 [Fe (CN) 6 ] during the synthesis, the cobalt-iron cyano complex is used. The compound could not be synthesized at low cost.
[K 3 Fe (CN) 6 ] used in the production method of the present invention has low deliquescence and is easy to handle, so that a cobalt-iron cyano complex compound can be synthesized at low cost.
[0016]
In addition, 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 in addition to the problem of deliquescent. Therefore, there has been a problem that it is difficult to synthesize a cobalt-iron cyano complex compound in which only K is interstitial-doped.
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]
Hereinafter, examples of the molecular magnetic material of the present invention produced by the above method will be described.
(Example 1)
As an A solution, 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 in which the concentration ratio of CoCl 2 to KCl is 10 mM (mmol) / 1 M (mol). did.
As a B solution, 0.164 g of K 3 [Fe (CN) 6 ] and 3.728 g of KCl are mixed with 50 ml of H 2 O, and the concentrations of K 3 [Fe (CN) 6 ] and KCl are mixed. A B aqueous solution having a ratio of 10 mM (mmol) / 1 M (mol) was prepared.
The aqueous solution A and the aqueous solution B were stirred for about 1 hour, and then allowed to stand for about 24 hours to completely dissolve the reagent in each aqueous solution.
[0018]
Next, the aqueous solution A and the aqueous solution B were slowly added to the total amount of the aqueous solution B over about 10 minutes at a volume ratio of 1.8: 1. Here, the B aqueous solution was stirred from the beginning, and after the entire amount of the A aqueous solution was added to the B aqueous solution, the stirring was further continued for about 1 hour.
Subsequently, the mixed solution of the aqueous solution A and the aqueous solution B was left for about 24 hours to completely precipitate the product. The product thus obtained was filtered through a nitrocellulose-based organic polymer filter having a pore size of 1.2 μm. Further, the product on the filter was washed twice with 50 ml of distilled water and dried in air to obtain about 0.22 g of a solid molecular magnetic material of the present invention.
[0019]
When the composition ratio of the molecular magnetic material of the present invention thus obtained was examined by chemical analysis, it was 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 KCl of the aqueous solution A and the aqueous solution B was changed to 2 M (mol). The composition of the obtained molecular magnetic material of the present invention was chemically analyzed in the same manner as in Example 1 described above, and the composition was found to be K 0.52 Co 1.15 [Fe (CN) 6 ] .5.52H 2 O. Met.
[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 solutions A and B was changed to 3 M (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 0.53 Co 1.18 [Fe (CN) 6 ] .4.45H 2 O. Was.
[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 solutions A and B was changed to 4 M (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. Was.
[0023]
Next, the magnetization characteristics of the molecular magnetic material of the present invention with respect to temperature will be described.
FIG. 1 is a diagram showing the relationship between the magnetic susceptibility and the temperature of the molecular magnetic material of the present invention. The horizontal axis of the figure is temperature (K), and the vertical axis is susceptibility × temperature (ΔT). The samples used for the measurement were the samples prepared in Examples 1 to 4 above, and the amounts of KCl in the aqueous solution A and the aqueous solution B were obtained as 1 M (mol), 2 M, 3 M, and 4 M, respectively. The chemical composition formula 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 ] .4.45 H 2 O and K 0.58 Co 1.24 [Fe (CN) 6 ] .4.17 H 2 O Corresponds to magnetic materials.
[0024]
As can be seen from the figure, the molecular magnetic material of the present invention shows that ΔT increases as the temperature rises in the temperature range from 50 K to 350 K, and has no hysteresis characteristics. In addition, in the case of the molecular magnetic material of the present invention in which the amount of KCl is 1M and 2M, it can be seen that the change rate of ΔT with respect to the temperature is large near room temperature.
From the results shown in FIG. 1, it is understood that the molecular magnetic material of the present invention described above has a large rate of change in magnetic susceptibility to temperature near room temperature and does not have temperature hysteresis characteristics. Therefore, for example, it is suitable for use as a highly sensitive temperature sensor near room temperature.
[0025]
Next, other measurement data showing that the change of the magnetic susceptibility with respect to the temperature of the molecular magnetic material of the present invention has no hysteresis will be described.
FIG. 2 is a diagram showing a temperature change of the lattice constant of the molecular magnetic material of the present invention. The abscissa in the figure indicates the temperature (K), and the ordinate indicates the lattice constant (Å). The temperature was raised from about 100K to about 350K, and measurement was performed while performing a 2θ scan of a diffractometer at each temperature. In the figure, □ (open square) indicates the lattice constant of the LS phase of the sample having 1 M (mol) of KCl, and ■ (black square) indicates the lattice constant of the HS phase. Similarly, △ (open triangle) and ▲ (closed triangle) indicate the lattice constants of the LS phase and the HS phase of the sample having KCl of 2M.
[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). That is, there is an LS phase having a small spin composed of divalent Fe ions and trivalent Co ions, and an HS phase having a large spin composed of trivalent Fe ions and divalent Co ions. Is known to undergo a phase transition with large 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 has an LS phase and an HS phase similarly to the cobalt-iron cyano complex compound containing Na. .
[0027]
As can be seen from FIG. 2, only the LS phase (□, △) exists in the low temperature region, and only the HS phase (■, 存在) exists in the high temperature region. It can be seen that the temperature range in which both nearby phases coexist is narrow, and in particular, the sample (□, Δ) in which KCl is 1 M (mol) is extremely narrow. This indicates that the phase transition of the K-containing cobalt-iron cyano complex compound of the present invention has extremely low hysteresis with temperature. This means that the temperature hysteresis of the magnetization characteristics becomes extremely small.
[0028]
The present invention is not limited to the above embodiments, and various modifications are possible within the scope of the invention described in the claims, and it goes without saying that they 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 the mixing ratio of the aqueous solution (A) and the aqueous solution (B) are 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 temperature hysteresis of magnetic susceptibility, and has a large temperature change rate of magnetic susceptibility near room temperature. Therefore, it is an optimal material for applications where the magnetic susceptibility needs to be determined without depending on the temperature history, for example, a temperature sensor. Further, since a change in temperature is converted into a change in magnetic susceptibility, an extremely high-performance device can be realized if used as a component of a magnetoresistive device.
The method for producing a molecular magnetic material of the present invention is extremely simple, and therefore can provide the molecular magnetic material of the present invention at low cost. In addition, the production method of the present invention uses an iron cyano potassium salt, that is, K 3 [Fe (CN) 6 ] as a raw material, so that a molecular magnetic material purely doped with only K can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the magnetic susceptibility and the temperature of the molecular magnetic material of the present invention.
FIG. 2 is a diagram showing a temperature change of a lattice constant of a molecular magnetic material of the present invention.
FIG. 3 is a view showing a crystal structure of a cobalt-iron cyano complex compound.
Claims (5)
（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), whose magnetization characteristics have a temperature hysteresis. A molecular magnetic material, characterized by not being subjected to any treatment.
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,
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.
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、からなることを特徴とする、分子磁性材料の製造方法。Stirring and mixing an aqueous solution comprising CoCl 2 and KCl and an aqueous solution comprising K 3 [Fe (CN) 6 ] and KCl;
Leaving a mixed aqueous solution of the aqueous solution of CoCl 2 and KCl and the aqueous solution of K 3 [Fe (CN) 6 ] and KCl for a predetermined period of time to precipitate a product from the mixed aqueous solution;
Filtering the precipitate. A method for producing a molecular magnetic material, comprising:
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