JP2007122883A - Electron emitting source and its manufacturing method - Google Patents
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本発明は、酸化鉄ウィスカーからなる電子放出源およびその製造方法に関する。 The present invention relates to an electron emission source comprising iron oxide whiskers and a method for producing the same.
画像表示装置や照明用光源の電子放出源として、従来はシリコンやモリブデンからなる針状電極、いわゆるスピント型電極が使用されてきた。これに対して、より長寿命かつ低真空稼動という特性に着目してカーボンナノチューブが検討されている（たとえば特許文献１，２，３，４）。一方、酸化鉄ウィスカーは磁気記録媒体、炭酸ガス分解触媒の原料として有用であるため、湿式法により製造されたものが広く使用されている（たとえば特許文献５〜１３）が、シリコンやカーボンナノチューブと同様の優れた電子放出源であることは知られていなかった。
Conventionally, needle-like electrodes made of silicon or molybdenum, so-called Spindt-type electrodes, have been used as electron emission sources for image display devices and illumination light sources. On the other hand, carbon nanotubes have been studied by paying attention to the characteristics of longer life and low vacuum operation (for example, Patent Documents 1, 2, 3, and 4). On the other hand, since iron oxide whiskers are useful as raw materials for magnetic recording media and carbon dioxide gas decomposition catalysts, those produced by a wet method are widely used (for example,
従来知られていた材料であるシリコンやモリブデンと比較して、カーボンナノチューブは電子放出源としての寿命や駆動環境に優れていると期待されているが、電子放出が不均一、基板との密着強度が不充分という問題がある。本発明はこのような問題を解決するために、新たに酸化鉄ウィスカーを電子放出源として提案するものである。 Compared to silicon and molybdenum, which are conventionally known materials, carbon nanotubes are expected to have excellent lifetime and driving environment as an electron emission source, but electron emission is uneven and adhesion strength to the substrate There is a problem of insufficient. In order to solve such problems, the present invention proposes a new iron oxide whisker as an electron emission source.
本発明者らは、酸化鉄ウィスカーが電子放出材料として優れていることを新たに見出した。中でも、酸化雰囲気中で鉄系材料を高温度で酸化させることにより、基板上に直接成長させた酸化鉄ウィスカーが電子放出源として優れた性質を有することを見出し、本発明に至った。
即ち、本発明は、
（１）酸化鉄ウイスカーからなる電界放出による電子放出源であり、
（２）鉄系材料からなる基板の表面に直接酸化鉄ウィスカーを立設したことを特徴とする電界放出による電子放出源の形態を採ることができるものであり、
（３）その製法として、酸素を含有する気体雰囲気と高温度の鉄系材料基板とを接触させることにより、該気体から供給される酸素と該基板から供給される鉄とから、酸化鉄ウイスカーを析出成長させることを特徴とする、請求項２記載の電子放出源の製造方法であり、
（４）これらの酸化鉄ウイスカーが、直径５ｎｍから２μｍ、長さ０．１μｍから１ｍｍ、アスペクト比５から１０万であることができる。
The present inventors have newly found that iron oxide whiskers are excellent as electron emission materials. In particular, the present inventors have found that an iron oxide whisker directly grown on a substrate has excellent properties as an electron emission source by oxidizing an iron-based material at a high temperature in an oxidizing atmosphere.
That is, the present invention
(1) An electron emission source by field emission composed of iron oxide whiskers;
(2) It can take the form of an electron emission source by field emission, characterized in that iron oxide whiskers are erected directly on the surface of a substrate made of an iron-based material,
(3) As a manufacturing method thereof, an iron oxide whisker is produced from oxygen supplied from the gas and iron supplied from the substrate by contacting a gas atmosphere containing oxygen and a high-temperature iron-based material substrate. The method for producing an electron emission source according to claim 2, wherein the growth is performed by precipitation.
(4) These iron oxide whiskers can have a diameter of 5 nm to 2 μm, a length of 0.1 μm to 1 mm, and an aspect ratio of 5 to 100,000.
本発明の酸化鉄ウィスカーからなる電界電子放出源は、均一な電子放射特性と、高い耐久性とがあり、また容易に所定の形態、寸法が得られるため電子放出プローブから、ＦＥＤ用或いは照明用など幅広い応用が可能である。 The field electron emission source comprising the iron oxide whisker of the present invention has uniform electron emission characteristics and high durability, and can easily obtain a predetermined form and size, so that the electron emission probe can be used for FED or illumination. A wide range of applications are possible.
以下に本発明の内容について具体的に説明する。本発明の電子放出源は、鉄系材料を酸化雰囲気中で高温度で酸化させることによって得られる、図１に示すような酸化鉄ウィスカーからなることが、望ましい。
本発明で言う酸化鉄とはウスタイト（FeO、Fe0.98O、 Fe0.94O）、ヘマタイト（Fe2O3）、マグヘマイト（Fe2O3）、マグネタイト（Fe3O4）、カチオン欠陥マグネタイト（Fe3-δO4）、カチオン過剰マグネタイト（Fe3O4-δ）、鉄―酸素の全ての二元系化合物（FexOyかつ０＜x≦３、０＜y≦４）の各々の単体、及びここに述べた鉄―酸素化合物を複数（２種類以上）含む混合物をも指す。加えて鉄と酸素以外の原子を高だか１０ａｔ％含む、望ましくは８ａｔ％以下、理想的には０．５ａｔ％以下しか含まないものが良い。鉄と酸素以外の不純物原子を１０ａｔ％以上含むと、結晶内の相当量の欠陥により、ウィスカーの強度が低下する弊害が起こる。
なお、基板にＳＵＳ３０４鋼の、厚み１ｍｍの板を用いて、図２に示す構成で大気中で生成した、マグネタイトウィスカーの元素分析を、透過型電子顕微鏡に搭載されている空間分解能が一桁ナノメートルのエネルギー分散型エックス線分光器で行ったところ、鉄と酸素以外の原子は検出されなかった。該エックス線分光器の最小検出限界は、比重が鉄に近い７から９の原子（クロム、マンガン、コバルト、ニッケル、銅、亜鉛、ニオブなど）で、０．５ａｔ％である。
The contents of the present invention will be specifically described below. The electron emission source of the present invention is preferably composed of an iron oxide whisker as shown in FIG. 1 obtained by oxidizing an iron-based material at a high temperature in an oxidizing atmosphere.
The iron oxide referred to in the present invention is wustite (FeO, Fe 0.98 O, Fe 0.94 O), hematite (Fe 2 O 3 ), maghemite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), cation defect magnetite (Fe 3- δO 4 ), cation-rich magnetite (Fe 3 O 4- δ), iron-oxygen binary compounds (FexOy and 0 <x ≦ 3, 0 <y ≦ 4), and each Also refers to a mixture containing a plurality (two or more) of the iron-oxygen compounds described in. In addition, it is preferable to contain atoms other than iron and oxygen at high or 10 at%, desirably 8 at% or less, ideally 0.5 at% or less. When impurity atoms other than iron and oxygen are contained in an amount of 10 at% or more, a detrimental amount in the crystal causes a problem that the strength of the whisker is lowered.
The elemental analysis of magnetite whiskers produced in the atmosphere with the structure shown in FIG. 2 using a SUS304 steel plate with a thickness of 1 mm was used as the substrate. When conducted with a meter-dispersive X-ray spectrometer, no atoms other than iron and oxygen were detected. The minimum detection limit of the X-ray spectrometer is 0.5 at% with 7 to 9 atoms (chromium, manganese, cobalt, nickel, copper, zinc, niobium, etc.) whose specific gravity is close to that of iron.
酸化鉄の結晶の単位格子の寸法は、正方晶系のマグヘマイト（Ｆe2Ｏ3）のｃ軸方向が最も長く、２．５ｎｍある。ここにおいて、酸化鉄のウィスカーの直径が小さくなると、ある直径を境にして指数関数的に強度が低下することがわかった。この制約によって請求項にいう直径５ｎｍ以上が規定される。その物理的な理由は、球形のマイクロクラスターにおいて明らかにされている以下に述べる理由と同様であると本発明者らは考えている。すなわち、少数の原子が結晶構造をとっているマイクロクラスターは直径５０ｎｍ程度の大きさになると、結晶表面にある結合手が切れた原子の割合が結晶全体の原子数に対して増加することにより不安定になり、原子同士の結合力が弱くなる。ウィスカーのような一次元（線状）物質では上記の効果が、一次元に連なる結合によってある程度緩和されるので、結合力の低下が現れる寸法上の下限が低下する。酸化鉄ウィスカーでは実用上許容される直径の下限が請求項で言う直径５ｎｍであることが明らかになった。 The unit cell dimension of the iron oxide crystal is 2.5 nm, which is the longest in the c-axis direction of tetragonal maghemite (Fe 2 O 3 ). Here, it was found that when the iron oxide whisker diameter becomes smaller, the strength decreases exponentially at a certain diameter. Due to this restriction, a diameter of 5 nm or more as defined in the claims is defined. The present inventors believe that the physical reason is the same as the reason described below, which is clarified in the spherical microcluster. That is, when a microcluster having a crystal structure with a small number of atoms is about 50 nm in diameter, the proportion of atoms with broken bonds on the crystal surface increases with respect to the total number of atoms in the crystal. It becomes stable and the bonding force between atoms becomes weak. In the case of a one-dimensional (linear) material such as a whisker, the above effect is moderated to some extent by bonding that is one-dimensionally connected, so that the lower dimensional lower limit in which a decrease in bonding force appears. It became clear that the lower limit of the practically acceptable diameter for iron oxide whiskers is 5 nm in the claims.
上限の直径２μｍの値は、酸化鉄ウィスカーの直径が２μｍを越えると、電子放出材料としての耐久性が劣ることから規定される。ウィスカーの長さは、製造設備と操業時間の制約が無ければ２ｍｍ、３ｍｍ、５ｍｍ、１０ｍ、１００ｍといくらでも連続して長くできるが、電子放出源としては長さが０．１μｍから１ｍｍの範囲で充分である。 The upper limit value of 2 μm is defined because the durability as an electron-emitting material is inferior when the diameter of the iron oxide whisker exceeds 2 μm. Whisker length can be continuously increased as long as 2mm, 3mm, 5mm, 10m, and 100m as long as there are no restrictions on manufacturing equipment and operating time, but the length of the electron emission source is in the range of 0.1μm to 1mm. It is enough.
本発明でいうウィスカーの構造は、カーボンナノチューブに見られるような、断面が単層環状型、多層環状型、渦巻き環状型のものをも含み、さらに炭素繊維に見られるような、断面がオニオン型、ラジアル型の構造、また、だるま落としの玩具ように長さ方向に結晶を繋ぎ合わせた多結晶構造をも含む。また、ウィスカーの外観形状は高いアスペクト比を示しながらも、直線には限定されず、全体が渦を巻いたような螺旋構造、糸同士が無秩序に絡まり合ったフエルトのような構造のものをも含む。さらに、一点より多数のウィスカーが成長したもの、樹枝状に形成したもの、折線状に成長したものも含まれる。 The whisker structure referred to in the present invention includes a single-walled ring type, a multilayered ring type, and a spiral ring type as seen in a carbon nanotube, and a cross-section as seen in a carbon fiber. In addition, it includes a radial structure and a polycrystalline structure in which crystals are connected in the length direction like a daruma drop toy. Whisker has a high aspect ratio but is not limited to a straight line. The whisker has a spiral structure that is entirely swirled or a felt-like structure in which yarns are entangled randomly. Including. Furthermore, those in which a larger number of whiskers have grown from a single point, those in the form of dendrites, and those in the form of broken lines are included.
一方、電子放出材料として表面の仕事関数を低下させるためには、上記酸化鉄ウィスカーに異原子を蒸着して蒸着原子の最外殻電子をウィスカーに電荷移行させ、ウィスカー表面に電気二重層を形成させることが有効である。そのような異原子として、リチウム、ナトリウム、カリウム、ルビジウムなどがあげられる。
また、負性電子親和力を有する異種の材料；例えば窒化ホウ素、カーボン系材料（ダイヤモンド、ダイヤモンドライクカーボンなど）など；を酸化鉄ウィスカーに被覆することは閾値電界を低減させることに有効である。
On the other hand, in order to lower the work function of the surface as an electron emission material, foreign atoms are vapor-deposited on the iron oxide whiskers, and the outermost electrons of the deposited atoms are transferred to the whiskers, forming an electric double layer on the whisker surface. It is effective to make it. Such heteroatoms include lithium, sodium, potassium, rubidium and the like.
Further, coating different types of materials having negative electron affinity; for example, boron nitride, carbon-based materials (diamond, diamond-like carbon, etc.) on iron oxide whiskers is effective in reducing the threshold electric field.
以下に述べることは本発明を限定するものではないが、本特許出願までに明らかにされた、酸化鉄ウィスカーを担持させる基板に推奨される条件である。
本発明で言うウィスカーを生成させる基板となる鉄系材料は次のようなものである。
１）純鉄。この純鉄には例えば走査型トンネル顕微鏡のプローブで鉄原子一つ一つを並 べて得られるような、原子オーダーで文字通り１００％の純鉄から、不可抗力の 不純物を微量に含む工業的な冶金で得られる純鉄までも含む。
２）鉄原子を重量比で１０％以上９９．９９９％以下含む合金で、０．００１重量％以 上９０重量％以下含まれる鉄以外の原子が以下に列挙される原子のどれか１種か あるいは２種類以上を含む化合物や混合物。
鉄以外の原子とは、原子番号３番（リチウム）から１０３番（ローレンシウム ）までの全ての原子でかつこれらからVIII族(希ガス)原子と鉄原子とを除いた ものである。これらの原子には天然同位体比で同位体を含むものや、同位体分離 によって質量数の同じ原子のみからなるものも含む。
３）鉄原子を重量比で０．００１重量％以上１０％未満含むもので、鉄以外に含まれる 原子は、その酸化物が温度５０℃から１５００℃の間で平衡解離圧がヘマタイト （Ｆｅ2Ｏ3）よりも高いもの。この様な原子には、例えばコバルト、ニッケル 、銅などがあり、そのような性質をもつ原子を１種もしくは２種類以上を含む鉄 化合物もしくは鉄混合物。
４）上記１，２、３で述べた材料を層状や傾斜成分状に組み合わせたり、部分的にはめ 込んで組み合わせたり、混合させたり、共析物とさせている材料。
Although the following description is not intended to limit the present invention, it is a recommended condition for a substrate carrying iron oxide whiskers, which has been clarified up to the present patent application.
The iron-based material used as a substrate for generating whiskers in the present invention is as follows.
1) Pure iron. This pure iron is an industrial metallurgical metal that contains trace amounts of impurities of force majeure from literally 100% pure iron in atomic order, which can be obtained with a scanning tunneling microscope probe. Including even pure iron obtained in.
2) Is an alloy containing 10% or more and 99.999% or less of iron atoms in a weight ratio, and any atom other than iron that is contained by 0.001% or more and 90% or less by weight is one of the atoms listed below? Or the compound and mixture containing two or more types.
Atoms other than iron are all atoms from atomic number 3 (lithium) to 103 (lorensium), and from which VIII (rare gas) atoms and iron atoms are excluded. These atoms include those containing isotopes in the natural isotope ratio and those consisting only of atoms with the same mass number by isotope separation.
3) It contains 0.001% by weight or more and less than 10% by weight of iron atoms, and atoms contained in addition to iron have an equilibrium dissociation pressure of hematite between the temperature of 50 ° C. and 1500 ° C. (Fe 2 Higher than O 3 ). Examples of such atoms include cobalt, nickel, copper, and the like, and iron compounds or iron mixtures containing one or more kinds of atoms having such properties.
4) Materials in which the materials described in the above 1, 2 and 3 are combined in a layered form or a gradient component form, or partially embedded and combined, mixed, or made into a eutectoid.
上記２）、３）、４）の基板を用いると、生成するウィスカー内に鉄以外の金属原子が拡散して混入する場合があり、このときの混入量は高だか１０at%であり、これを不可避的不純物原子と呼ぶ。
基板の形状は問わない、板・箔状でもワイヤー・棒状でも、機械加工もしくは鋳物や接着・熔接で複雑な形状に仕上げられたものでも、上記条件を満たすもので、固体であればどんな形でも良い。上記の方法によって作成される酸化鉄ウィスカーは、湿式で得られるウィスカーのような樹枝状粒子が全く混在しておらず、かつその細さと強度の高さから電界電子放出源に適している。
When the substrates of 2), 3) and 4) are used, metal atoms other than iron may be diffused and mixed in the whisker to be generated. The amount of mixing at this time is at most 10 at%. Called inevitable impurity atoms.
Regardless of the shape of the substrate, whether it is a plate, foil, wire, or rod, machined or finished in a complicated shape by casting, bonding, or welding, it satisfies the above conditions and can be any solid shape. good. The iron oxide whisker produced by the above method does not contain any dendritic particles such as whisker obtained by a wet process, and is suitable for a field electron emission source because of its thinness and high strength.
以下、本発明の実施の形態を図面を参照しながら詳細に説明する。
メタンガスと酸素の予混合ガス炎と、厚み１ｍｍの純鉄基板とを用いて、図２に示す構成で、大気中でウィスカーの生成を行った。火口径１ｍｍのトーチを使用し、メタンガスと酸素ガスは化学量論比よりも酸素を７vol％減らして、これを総計毎分５リットル燃焼ガスとして供給した。炎の当たっていない側の基板表面の最高温度部が７００℃の状態で、５分間保持した。その結果、炎の当たっているのとは反対の側の基板表面に、直径１ｃｍの円状の範囲から１０μｍ四方当たり１００本の密度でマグネタイトウィスカーが生成し、個々のウィスカーは平均で長さ１０μｍ、直径３０ｎｍ、最も長いもので長さ２０μｍ、直径５０ｎｍであった。
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
Using a premixed gas flame of methane gas and oxygen and a pure iron substrate having a thickness of 1 mm, whiskers were generated in the atmosphere with the configuration shown in FIG. A torch with a crater diameter of 1 mm was used, and methane gas and oxygen gas reduced oxygen by 7 vol% from the stoichiometric ratio, and supplied this as a combustion gas of 5 liters per minute in total. The substrate was held for 5 minutes at a maximum temperature of 700 ° C. on the non-flammable substrate surface. As a result, magnetite whiskers are formed at a density of 100 per 10 μm square from a circular area having a diameter of 1 cm on the surface of the substrate opposite to the side where the flame is hit, and each whisker has an average length of 10 μm. The diameter was 30 nm, the longest was 20 μm in length, and the diameter was 50 nm.
こうして作成した、マグネタイトウィスカー担持純鉄基板を陰極にし、陽極の蛍光板を向かい合わせに５ｍｍ離して並行におき、真空中で電界電子放出特性を測定した。その結果を図３に示す。蛍光板は均一に発光し、局部的な輝度むらは認められなかった。５０００時間発光させたのちでも、電界電子放出特性と蛍光発光の均一性は変化しなかった。電子は、一本一本のマグネタイトウィスカーの先端からも側面からも放出されるが、この基板の場合は、ウィスカーの側面から放出される電子の寄与のほうが大きい。 The magnetite whisker-supported pure iron substrate prepared in this manner was used as a cathode, and the anode fluorescent plate was placed 5 mm away from each other in parallel, and field electron emission characteristics were measured in a vacuum. The result is shown in FIG. The fluorescent plate emitted light uniformly, and local brightness unevenness was not observed. Even after 5000 hours of light emission, the field electron emission characteristics and the uniformity of fluorescence emission did not change. Electrons are emitted from the tip and side of each magnetite whisker, but in the case of this substrate, the contribution of electrons emitted from the side of the whisker is greater.
以下、実施例を挙げて具体的な条件及び結果を説明する。
〔実施例１〕
純酸素雰囲気中で、基板としてＳＳ４００鋼、厚さ２ｍｍの板を用いて、図２に示す構成で、１０分間生成を行った。反応条件は上記した条件によった。その結果炎の当たっている面とは反対の基板面の、直径１ｃｍの円状の範囲から無数のマグネタイトとヘマタイトの混晶ウィスカーが生成し、最も長いものは長さ１０μｍ、直径４０ｎｍであった。この試料を陰極にし、陽極の蛍光板を向かい合わせに５ｍｍ離して並行におき、電界電子放出特性を測定した。その結果１８Ｖ/μmの電界下で、１５mＡ/cm2の電子放出電流が得られた。この試料の表面に、真空中でリチウムを５ｎｍ厚蒸着し、連続して真空中で電界電子放出特性を測定した。その結果８Ｖ/μmの電界下で、１６mＡ/cm2の放出電流が得られた。
Hereinafter, specific conditions and results will be described with reference to examples.
[Example 1]
Generation | occurrence | production was performed for 10 minutes with the structure shown in FIG. 2 using SS400 steel and a 2 mm-thick board as a board | substrate in a pure oxygen atmosphere. The reaction conditions were as described above. As a result, innumerable mixed crystal whisker of magnetite and hematite was generated from a circular range of 1 cm in diameter on the substrate surface opposite to the surface on which the flame was hit, and the longest one was 10 μm long and 40 nm in diameter. . This sample was used as a cathode, and the anode fluorescent plate was placed 5 mm away from each other in parallel, and the field electron emission characteristics were measured. As a result, an electron emission current of 15 mA / cm 2 was obtained under an electric field of 18 V / μm. Lithium was deposited in a thickness of 5 nm on the surface of this sample in vacuum, and the field electron emission characteristics were measured continuously in vacuum. As a result, an emission current of 16 mA / cm 2 was obtained under an electric field of 8 V / μm.
〔実施例２〕
プロパンガスと酸素とアンモニア蒸気の予混合ガス炎を用い、基板にＳ１５Ｃ鋼の厚み１ｃｍの板を用いて、図２に示す構成で、大気中でウィスカーの生成を行った。ガス管に内径１ｍｍ管を使用し、これに毎分プロパン２リットル、酸素２リットル、アンモニア蒸気０．１リットル供給して燃焼ガスとした。炎の当たっていない側の基板表面の最高温度部が９８０℃の状態で、１時間保持した。その結果、炎の当たっているのとは反対の基板表面に無数のヘマタイトウィスカーが生成し、最も長いものは長さ２００μｍ、直径６０ｎｍであった。こうして作成した複数のヘマタイトウィスカー担持基板表面をポリプロピレン板の稜でしごいて、ウィスカーのみを分離した。このヘマタイトウィスカーを１０ｗｔ％の割合で溶融ポリプロピレンと混ぜて樹脂状ペレットとした後に、射出成型機により板状の成型体にした。この成型体を誘導加熱装置にて、大気中で６８０℃で１０分間加熱して、ポリプロピレン成分を炭化させた。その結果、炭化樹脂の表面からヘマタイトウィスカー端面が均一に露出した板が得られた。この板を陰極にし、陽極の蛍光板を向かい合わせに５ｍｍ離して並行におき、電界電子放出特性を測定した。その結果２０Ｖ/μmの電界下で、１８mＡ/cm2の電子放出電流が得られた。
[Example 2]
Using a premixed gas flame of propane gas, oxygen, and ammonia vapor, and using a 1 cm thick plate of S15C steel as the substrate, whiskers were generated in the atmosphere with the configuration shown in FIG. A 1 mm inner diameter pipe was used as the gas pipe, and 2 liters of propane, 2 liters of oxygen and 0.1 liter of ammonia vapor were supplied to the gas pipes per minute to obtain a combustion gas. The substrate was held for 1 hour at a maximum temperature of 980 ° C. on the non-flammable substrate surface. As a result, innumerable hematite whiskers were formed on the surface of the substrate opposite to the one on which the flame was hit, and the longest one was 200 μm long and 60 nm in diameter. The surface of the plurality of hematite whisker-supporting substrates thus prepared was rubbed with a ridge of a polypropylene plate to separate only the whiskers. This hematite whisker was mixed with molten polypropylene at a ratio of 10 wt% to form resin pellets, and then formed into a plate-like molded body by an injection molding machine. This molded body was heated in the atmosphere at 680 ° C. for 10 minutes with an induction heating device to carbonize the polypropylene component. As a result, a plate was obtained in which the hematite whisker end face was uniformly exposed from the surface of the carbonized resin. This plate was used as a cathode, and the anode fluorescent plate was placed 5 mm away from each other in parallel, and field electron emission characteristics were measured. As a result, an electron emission current of 18 mA / cm 2 was obtained under an electric field of 20 V / μm.
〔実施例３〕
２００メッシュのステンレス網を基板とし、電気炉中の石英管（内径４cm、長さ７０cm）内でウィスカーを以下の条件で生成させた。アルゴンと酸素ガスの混合気体を１５ｃｃ／minで流し、排気流量を調整し気体の圧力を５００Ｐａに保ち、酸素分圧を１５０Ｐaとして、５分間で７５０℃に昇温し、３０分間その温度に保った。その後ガスを止め、石英管内を真空にして自然放冷させた。その結果ステンレス網表面に径５nm〜１００nm, 長さ約２００nm〜１μｍの酸化鉄ウィスカーが、ステンレス網全体に各ステンレス細線表面にほぼ垂直の向きで密集して成長した。この試料を陰極にし、陽極の蛍光板を向かい合わせに５ｍｍ離して並行におき、電界電子放出特性を測定した。その結果１８Ｖ/μmの電界下で、２０mＡ/cm2の電子放出電流が得られた。
Example 3
A whisker was generated under the following conditions in a quartz tube (inner diameter: 4 cm, length: 70 cm) in an electric furnace using a 200 mesh stainless steel net as a substrate. A mixed gas of argon and oxygen gas is flowed at 15 cc / min, the exhaust flow rate is adjusted, the gas pressure is kept at 500 Pa, the oxygen partial pressure is 150 Pa, the temperature is raised to 750 ° C. in 5 minutes, and the temperature is maintained for 30 minutes. It was. The gas was then stopped and the quartz tube was evacuated and allowed to cool naturally. As a result, iron oxide whiskers having a diameter of 5 nm to 100 nm and a length of about 200 nm to 1 μm were densely grown on the stainless steel mesh surface in a direction almost perpendicular to the surface of each stainless steel wire. This sample was used as a cathode, and the anode fluorescent plate was placed 5 mm away from each other in parallel, and the field electron emission characteristics were measured. As a result, an electron emission current of 20 mA / cm 2 was obtained under an electric field of 18 V / μm.
１０ 基板
１１ ウィスカー発生面
１２ 蓋円盤
１３ ドーナツ型円盤
１４ 受け台
１５ テーパー穴
１６ 炎
１７ バーナー
DESCRIPTION OF
Claims (4)
3. The electron emission source according to claim 1, wherein the iron oxide whisker has a diameter of 5 nm to 2 μm, a length of 0.1 μm to 1 mm, and an aspect ratio of 5 to 100,000.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009016281A (en) * | 2007-07-09 | 2009-01-22 | Asahi Kasei Corp | Field-emission type electron emission device |
| JP2009172467A (en) * | 2008-01-22 | 2009-08-06 | Nippon Steel Corp | Metal carrier, decomposition catalyst of carbon dioxide in gas, method of manufacturing the carrier and catalyst, and method for decomposition of carbon dioxide |
| JP2010056024A (en) * | 2008-08-29 | 2010-03-11 | Nippon Steel Corp | Spin-polarized electron source |
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| JP2003162955A (en) * | 2001-11-27 | 2003-06-06 | Sony Corp | Cold cathode field electron emission element, manufacturing method therefor, and cold cathode field electron emission display device |
| WO2005090651A1 (en) * | 2004-03-23 | 2005-09-29 | Kanazawa R And D Ltd. | Iron oxide whisker of high aspect ratio, titanium oxide whisker of high aspect ratio, structure containing these and process for producing them |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2003162955A (en) * | 2001-11-27 | 2003-06-06 | Sony Corp | Cold cathode field electron emission element, manufacturing method therefor, and cold cathode field electron emission display device |
| WO2005090651A1 (en) * | 2004-03-23 | 2005-09-29 | Kanazawa R And D Ltd. | Iron oxide whisker of high aspect ratio, titanium oxide whisker of high aspect ratio, structure containing these and process for producing them |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009016281A (en) * | 2007-07-09 | 2009-01-22 | Asahi Kasei Corp | Field-emission type electron emission device |
| JP2009172467A (en) * | 2008-01-22 | 2009-08-06 | Nippon Steel Corp | Metal carrier, decomposition catalyst of carbon dioxide in gas, method of manufacturing the carrier and catalyst, and method for decomposition of carbon dioxide |
| JP2010056024A (en) * | 2008-08-29 | 2010-03-11 | Nippon Steel Corp | Spin-polarized electron source |
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