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関連する概念動画

Valence Bond Theory02:42

Valence Bond Theory

Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
Colors and Magnetism03:02

Colors and Magnetism

Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
Diamagnetism01:26

Diamagnetism

Materials consisting of paired electrons have zero net magnetic moments. However, when these materials are placed under an external magnetic field, the moments opposite to the field are induced. Such materials are called diamagnets. Diamagnetism is the response of the diamagnets when placed in an external magnetic field.
Diamagnetism was discovered by Anton Brugmans in 1778 when he observed that bismuth gets repelled by magnetic fields, thus theorizing that diamagnets get repelled by magnets.
Types Of Superconductors01:28

Types Of Superconductors

A superconductor is a substance that offers zero resistance to the electric current when it drops below a critical temperature. Zero resistance is not the only interesting phenomenon as materials reach their transition temperatures. A second effect is the exclusion of magnetic fields. This is known as the Meissner effect. A light, permanent magnet placed over a superconducting sample will levitate in a stable position above the superconductor. High-speed trains that levitate on strong...
Ferromagnetism01:31

Ferromagnetism

Materials like iron, nickel, and cobalt consist of magnetic domains, within which the magnetic dipoles are arranged parallel to each other. The magnetic dipoles are rigidly aligned in the same direction within a domain by quantum mechanical coupling among the atoms. This coupling is so strong that even thermal agitation at room temperature cannot break it. The result is that each domain has a net dipole moment. However, some materials have weaker coupling, and are ferromagnetic at lower...
Paramagnetism01:30

Paramagnetism

Paramagnets are materials with unpaired electrons that possess a finite magnetic moment. In the absence of a magnetic field, these moments are randomly oriented, and thus the net moment is zero. Under an external field, a torque acting on the moments tends to align them along the field's direction. However, the random thermal motion of electrons produces a torque opposite to the external field and tries to disorient the moments. These two competing effects align only a few moments along the...

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関連する実験動画

Updated: Jun 24, 2026

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene
08:25

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Published on: July 3, 2015

CaB2C2における高温フェロマグネティズム

J Akimitsu1, K Takenawa, K Suzuki

  • 1Department of Physics, Aoyama-Gakuin University, Tokyo 157-8572, Japan. jun@phys.aoyama.ac.jp

Science (New York, N.Y.)
|August 11, 2001
PubMed
まとめ
この要約は機械生成です。

研究者らはCaB2C2という新しい高キュリー温度鉄磁石を発見した. この材料は,過渡金属なしで最大770ケルヴィンまでのフェロ磁性を示し,高温磁性に関する以前の理論に異議を唱える.

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High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings
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High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
08:55

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

関連する実験動画

Last Updated: Jun 24, 2026

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene
08:25

Chemical Vapor Deposition of an Organic Magnet, Vanadium Tetracyanoethylene

Published on: July 3, 2015

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings
09:01

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Published on: April 16, 2017

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
08:55

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses

Published on: June 7, 2018

科学分野:

  • 材料科学 材料科学とは
  • 凝縮物質物理学 凝縮物質物理学
  • 固体化学 固体化学

背景:

  • 高キュリー温度フェロマグネチズムは,通常,移行金属や希土元素と関連付けられています.
  • ドーピングされた二価ヘクサボリドは,Ca{1-x}La{x}B6のように,鉄磁性を表しますが,特定の構造的および電子的性質を持っています.
  • 高温鉄磁性の背後にあるメカニズムを理解することは,高度な磁性材料の開発に不可欠です.

研究 の 目的:

  • 新しい高キュリー温度フェロマグネット,CaB2C2.2.の発見と特徴を報告する.
  • CaB2C2における鉄磁性の起源を調査し,特に磁性イオンがない場合.
  • CaB2C2の磁気特性と電子構造を,二価ヘクサボリドのような既知の磁気材料と比較する.

主な方法:

  • CaB2C2.2.の実験合成と特徴づけ
  • 磁気特性の測定は,鉄磁気移行温度 (Tc) を含む.
  • 第一原則 電子構造計算.

主要な成果:

  • CaB2C2は,約770ケルビン程度の高鉄磁気移行温度 (Tc) を表しています.
  • 室温でのCaB2C2のオーダーされた磁気モーメントは,単位の式ごとに10〜4のボア磁気単位で非常に小さい.
  • 電子構造の計算により,二価ヘクサボリドとフェルミレベルに近い類似性が明らかになったが,CaB2C2はCaB6に見られる特定の帯域のポケットなしに四角形構造を有している.
  • この結果は,フェルミレベルに近い特殊な分子軌道が,高Tcフェロ磁性にとって決定的であり,立方体の構造の3倍退化ではないことを示唆している.

結論:

  • CaB2C2は,過渡金属や稀土イオンが欠けているにもかかわらず,高キュリー温度フェロマグネットです.
  • CaB2C2の鉄磁性は,立方ヘクサボリドに見られる三重変性のような構造的特徴ではなく,フェルミレベルに近い特定の分子軌道に起因する.
  • この発見は,高温フェロマグネティズムに関する従来の理解に挑戦し,新しい磁気材料の設計のための新しい道を開きます.