関連する実験動画
Updated: Sep 10, 2025
09:25
Fabricating van der Waals Heterostructures with Precise Rotational Alignment
Published on: July 5, 2019
9.6K
Al-Ni-Co準結晶の準周期性カリウム添加層
Vipin Kumar Singh1, Marian Krajčí2, Pramod Bhakuni1
1UGC-DAE Consortium for Scientific Research, Khandwa Road, Indore 452001, Madhya Pradesh, India.
まとめ
研究者らは10角形のアルミニウム・ニッケル・コバルトの準結晶表面で形成される準周期的なカリウム単層を観察した. この半周期的な成長は,基板によって引き起こされます.
科学分野:
- 材料科学
- 表面科学
- 凝縮物質物理学
背景:
- 準周期性 (quasiperiodicity) は準結晶の重要な特徴であり,長距離の秩序を持つ物質であるが,変換対称性が欠けている.
- 準結晶表面でのアダトムの振る舞いを理解することは,それらのユニークな電子的および物理的性質を探求するために不可欠です.
研究 の 目的:
- 十角形のアルミニウム・ニッケル・コバルト (Al-Ni-Co) 準結晶の表面におけるカリウム (K) モノレイヤの形成と構造を調査する.
- 準周期的成長パターンを誘発する基質-アドソルベート相互作用の役割を解明する.
主な方法:
- スキャントンネル顕微鏡 (STM) による原子スケールの表面イメージング.
- 構造分析と対称性決定のための低エネルギー電子微分法 (LEED).
- 吸収物質と基質の相互作用をモデル化し,成長構造を予測するための密度関数理論 (DFT) の計算.
主要な成果:
- Al-Ni-Coの十角表面に準周期的なカリウム単層の形成を証明した.
- 低カバーで分散したKアダトムは観察され,高カバーで五角形と十角形のモチーフに結合します.
- LEEDパターンは十角対称性を確認し,STMの結果は,有利な準周期的な場所に結合するK adatomsのDFT予測と密接に一致しました.
結論:
- カリウムアダトムは,アドソルベートと基板の相互作用によって誘発される十角形のAl-Ni-Co準結晶に準周期的な単層を形成する.
- 準結晶基板の電子構造は,準周期的なカリウム添加層の成長を決定する.
- 実験結果は理論的予測と強く一致し,DFTモデルを検証しています.
関連する概念動画
02:42Ionic Crystal Structures
14.7K
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
14.7K
03:26Electron Configuration of Multielectron Atoms
54.2K
The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the 3s orbital, giving a 1s22s22p63s1 configuration. The electrons occupying the outermost shell orbital(s) (highest value of n) are called valence electrons, and those occupying the inner shell orbitals are called core electrons. Since the core electron shells correspond to noble gas electron configurations, we can abbreviate electron...
54.2K
02:37Metallic Solids
18.7K
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
18.7K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
44.4K
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
44.4K
02:42Valence Bond Theory
9.4K
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...
9.4K
02:33Lattice Centering and Coordination Number
9.9K
The structure of a crystalline solid, whether a metal or not, is best described by considering its simplest repeating unit, which is referred to as its unit cell. The unit cell consists of lattice points that represent the locations of atoms or ions. The entire structure then consists of this unit cell repeating in three dimensions. The three different types of unit cells present in the cubic lattice are illustrated in Figure 1.
Types of Unit Cells
Imagine taking a large number of identical...
Types of Unit Cells
Imagine taking a large number of identical...
9.9K