在 (BaTiO3) n /(SrTiO3) n超级格子中的工程放松行为
Eduardo Lupi1,2, Robert B Wexler3,4, Derek Meyers1,5
1Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA.
Advanced materials (Deerfield Beach, Fla.)
|July 11, 2023
概括
复杂的氧化物超级网表现出类似放松器的行为,这是由于可调节的双极配置. 这项研究展示了超格子周期性如何控制这些结构,为先进的介电材料提供了设计策略.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 固态化学 固态化学
背景情况:
- 复杂的氧化物超级格子通过精确的层控制和界面相互作用来实现新兴现象.
- 众所周知,铁电和介电超级网格拥有新的铁电,二极纹理和域结构.
研究的目的:
- 为了研究 (BaTiO3) n/(SrTiO3) n超级格子中类似放松剂的行为.
- 为了将超级格子周期性与观察到的介电性质和极性模式相关联.
- 阐明这些工程结构中放松器行为的潜在机制.
主要方法:
- 制造具有不同周期性的 (BaTiO3) n/(SrTiO3) n超级格子 (n=4-20单元细胞).
- 介电谱学和Vogel-Fulcher分析用于研究频率分散和介电常量.
- 债券价值分子动力学模拟以建模放松者行为.
- 极点图案的二维离散波形变换分析.
主要成果:
- 在 (BaTiO3) n/(SrTiO3) n超级格子中观察到类似于Relaxor的行为,通常与化学不均有关.
- 对于较小的周期性 (较小的n) 发现了增强的介电常数和更强大的放松器行为.
- 模拟预测了放松器行为,与短时间内双极配置的形状变化有关,与较长时间内反极域形成对比.
结论:
- 超级格子周期性提供了一个设计策略,以诱导和控制类似放松者的行为.
- 可调节的二极体配置,受超级格子分层的影响,是实现所需介电性质的关键.
- 这种方法扩大了复杂的氧化物系统中控制新出现现象的可能性.
相关概念视频
02:42Valence Bond Theory
8.8K
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...
8.8K
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
43.1K
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,...
43.1K
01:23Atomic Nuclei: Nuclear Relaxation Processes
683
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis.
683
02:54Trends in Lattice Energy: Ion Size and Charge
24.0K
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
24.0K
01:16Thermal Sigmatropic Reactions: Overview
2.1K
Sigmatropic rearrangements are a class of pericyclic reactions in which a σ bond migrates from one part of a π system to another. These are intramolecular rearrangements where the total number of σ and π bonds remain unchanged.
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in...
Sigmatropic shifts are classified based on an order term [i, j ], where i and j indicate the number of atoms across which each end of the σ bond migrates. Below are examples of a [3,3] sigmatropic shift in...
2.1K
02:58Crystal Field Theory - Octahedral Complexes
26.9K
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...
26.9K