単一成分分子結晶の室温以上の鉄電性である
Sachio Horiuchi1, Yusuke Tokunaga, Gianluca Giovannetti
1National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8562, Japan. s-horiuchi@aist.go.jp
Nature
|February 12, 2010
まとめ
研究者は,電場と分子極性を並べて結晶クロコニック酸で鉄電性を達成した. この有機物質は高自発的偏極化を示し,新しい電子アプリケーションの道を開く.
科学分野:
- マテリアルサイエンス 材料科学
- オーガニック・エレクトロニクス
- クリスタルグラフィーです.
背景:
- 鉄電性材料は,切り替え可能な極性,火電性,およびピエゾ電性などのユニークな電気活性特性を発揮します.
- 柔軟な電子機器には有機鉄電性が望ましいが,高自発的偏極化を達成することは依然として課題である.
- 五角形の分子であるクロコニン酸は,結晶状態では水素結合の極性構造を有する.
研究 の 目的:
- 結晶クロコニン酸の鉄電性を,電場誘発の分子配列によって実証する.
- トポロジカル・パイ・ボンド・スイッチングによるポラライゼーション・スイッチングのメカニズムを調査する.
- この有機鉄電力の自発的偏極化と熱安定性を特徴づける.
主な方法:
- クロコニック酸の結晶における分子極性の一貫した調整を誘導するために,電場を適用する.
- 光学第2ハーモニックの生成を測定し,偏振の調整を確認します.
- 室温での偏極化ヒステレスループの観測.
- 第一原理の電子構造計算を実行する.
主要な成果:
- 電気フィールドの適用により,クロコニン酸の分子極性が一貫して整列され,光学第2ハーモニックの生成が増加したことが証明されています.
- 室温でよく定義された偏極化ヒステレスループが観測され,鉄電性を確認した.
- 分子結晶は,同期された陽子伝送に起因する有機鉄電学の中で最も高い自発的偏振 (約20μC cm−2) を表した.
- 高極化は400Kまで維持された.
結論:
- 結晶クロコニック酸は,電場誘発の同期型陽子移転,ピ・ボンドトポロジーのスイッチングを通じて鉄電化することができる.
- この有機鉄電気材料は,その分子サイズに対して,非常に高い自発的偏振を示しています.
- 400Kまでの強固な鉄電特性により,有機電子のためのアクティブコンデンサと非線形光学における潜在的な応用が示唆されています.
関連する概念動画
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
02:54Molecular and Ionic Solids
Crystalline solids are divided into four types: molecular, ionic, metallic, and covalent network based on the type of constituent units and their interparticle interactions.
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
Molecular Solids
Molecular crystalline solids, such as ice, sucrose (table sugar), and iodine, are solids that are composed of neutral molecules as their constituent units. These molecules are held together by weak intermolecular forces such as London dispersion forces, dipole-dipole interactions, or hydrogen bonds, which...
02:42Valence 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...
02:58Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
01:31Ferromagnetism
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...
01:18Fermi Level
The Fermi-Dirac function is represented by an S-shaped curve indicating the probability of an energy state being occupied by an electron at a given temperature. The Fermi level is the energy level at which there is a fifty percent chance of finding an electron, and it is positioned between the lower-energy valence band and the higher-energy conduction band.
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...
At absolute zero temperature, electrons fill all energy states up to the Fermi level, leaving upper states empty. As the temperature rises,...