概括
射线吸收光谱显示,Fe2+) 协调率从晶体费亚利特中的6降至Fe2SiO4液体中的4. 这种结构变化影响了地球上的融化特性和元素分区.
科学领域:
- 地质化学 地质化学
- 材料科学 材料科学 材料科学
- 矿物物理 矿物物理
背景情况:
- 了解酸盐化的结构对于解释地球上的地物理观测和地化学过程至关重要.
- 铁 (Fe) 是许多地质材料的关键组成部分,其协调状态显著影响融特性.
- 以前的酸盐液体中的Fe2+模型在相关温度和压力下缺乏详细的结构信息.
研究的目的:
- 通过使用X射线吸收光谱学来确定化Fe(2) SiO(4) (fayalite) 中Fe(2+) 的局部结构环境.
- 为了研究化时协调号和Fe2+) -O键长度的变化.
- 开发一个结构模型Fe(2+) 在橄素组成的融及其对地质系统的影响.
主要方法:
- 进行X射线吸收光谱 (XAS) 对Fe(2) SiO(4) 液体在1575 K和10−4 GPa时进行.
- 分析涉及对液体结构中的不协调性进行核算.
- 对光谱数据与结点上的晶体法雅石进行比较.
主要成果:
- 在Fe(2) SiO(4) 液体中Fe(2+) -O 键的长度为1.98 ± 0.02 Å,比晶体费亚利特要短得多 (约1.98 ± 0.02 Å). 2.22 Å) 的时间.
- 平均Fe2+) 协调数从晶体法雅石中的6个下降到液体的4个.
- 这种协调变化类似于某些离子盐的化诱导的变化.
结论:
- 基于观察到的协调下降,开发了一种Fe2+中等范围结构环境的模型.
- 这些发现解释了Fe(2) SiO(4) 液体的关键性质,包括密度,粘度和Fe-Ni分区.
- 该模型对理解地球地和地幔中化的酸盐有意义.
更多相关视频
相关概念视频
03:02Colors 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.
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.
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...
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...
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...
03:45Formation of Complex Ions
A type of Lewis acid-base chemistry involves the formation of a complex ion (or a coordination complex) comprising a central atom, typically a transition metal cation, surrounded by ions or molecules called ligands. These ligands can be neutral molecules like H2O or NH3, or ions such as CN− or OH−. Often, the ligands act as Lewis bases, donating a pair of electrons to the central atom. These types of Lewis acid-base reactions are examples of a broad subdiscipline called coordination...
01:17Precipitation and Co-precipitation
Precipitation and coprecipitation methods can be used to separate a mixture of ions in a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent are separated based on the differences in solubility products. For example, consider the separation of Cu(II) and Fe(II) ions by precipitation as insoluble sulfides. First, copper(II) sulfide is precipitated by the addition of acidic H2S, where the dissociation of H2S is suppressed. Adding H2S...