Electron compound

Electronic compounds are composed of the first family or transition family element Composed with Group II to IV elements compound They don't obey The law of valency But meet certain Electron concentration Although electronic compounds are available Chemical formula However, the actual composition can vary in a certain range and can dissolve a certain amount of Solid solution .

interphase A class of, also known as Hume phase . alloy A class of compounds whose composition and structure depend on electron concentration.

In general, electron compounds with electron concentrations of 3/2 have Body centered cubic structure ( Beta brass construction ); Electron compounds with an electron concentration of 21/13 have Complex cubic structure ( Gamma brass construction ); Electron compounds with an electron concentration of 21/12 have Close-packed hexagonal structure (εbrass structure). Performance ten Hard and brittle , yes Alloy structure One of the important components of the phase ^[1] .

Electron Compounds, or Electron Phases, are special classes that have the same electron concentration Intermetallic compound . This type of phase usually forms between precious metals with similar atomic size and electronegativity, such as copper, zinc, gold, silver and other B group metals, and the electron concentration plays the most important role in the formation and stability of this type of intermetallic compounds. They are not only ideal objects for studying the effects of electrons on structures, but also important strengthening phases in materials. As the concept of electron compounds expands from crystal phases to quasicrystals and their approximate phases, as well as bulk Metallic glass The study of its stable physical mechanism has great practical significance. As early as the 1920s, the study of Intermetallic Compounds aroused interest. At that time, it was already known that inorganic compounds usually have valence electrons that form stable orbitals and are saturated, thus having certain stoichiometric ratios, and generally do not have electrical conductivity. Since the theory of metal bond has not been established, intermetallic compounds with special stoichiometric ratios have conductive properties, which arouse people's research interest ^[2] .

(1) A ligand compound formed by an electron-deficient atom with a compound of multi-electron atoms, such as [F 3 B←NH 3 ], Al 2 Cl 6 BeCl 2 Chain polymer containing delocalized π bonds.

(2) An electron-deficient molecule formed by the combination of an electron-deficient atom with an isoelectron atom, such as B 2 H 6 According to the classical structural formula, 7 covalent bonds and 14 valence electrons are needed, and 2 are missing, which forms a multi-center bond lacking electrons.

(3) The bond type of a compound formed by the combination of an electron-deficient atom and an electron-deficient atom has gradually transited to a metallic bond ^[2] .

Preparation of porous electronic compounds of calcite

Electron compound is a kind of special ionic crystal material with electron as anion, and traditional Metallic material In contrast, the electrons in electron compounds are not randomly distributed freely, and their distribution has a certain region. The difficult-to-control electron concentration and its low thermal stability in electronic compounds have been the main factors limiting the development of electronic compounds.

Calcium aluminite is a new kind of two-phase composite ceramic material, which is an insulating material, but can be transformed into an ideal electron compound with high electron concentration and stability at room temperature through a certain way. This unique property comes from the special cage structure in its crystal structure, each calcium aluminite single crystal has 12 special cage structure composition, of which 2 O 2 - (Free oxygen ions) randomly occupied two of the 12 cage-like structures. Since the free oxygen ions are very unstable in the cage structure, they are easily replaced by particles with suitable ionic radii. When the particles that replace the free oxygen ions are electrons, calciferite can be transformed into an ideal electron compound that is stable at room temperature.

It was first discovered in 1936, and over the next few years its special crystal structure was successfully deduced. In 2003, a method for the preparation of electron compounds of aluminite stable at room temperature was reported for the first time Electron paramagnetic resonance Spectroscopic method (EPR) confirmed the form of the C12A7 electron compound. Subsequently, a variety of electronic compounds of calcite were synthesized by different methods.

However, conductive porous C12A7 with interconnected macropores and a cocontinuous skeleton has been rarely reported. The space provided by the large pore structure allows a variety of chemical reactions to proceed fully and reduces the resistance of liquid flow. This stable conductive material with a large pore structure inside can be applied to porous electrodes, Catalyst support And a series of electrochemical reactions and other fields.

However, since calcium itself is a very active metal element in calcium aluminite electronic compounds, it will have a certain impact on the overall electron concentration and compound stability. Therefore, on the basis of preparing a porous calcium aluminite electronic compound, the use of other more stable metal ions to replace a certain amount of calcium element sites. The thermal stability and electrical conductivity of the electronic compounds were strengthened, and the effects of Cd doping on the microstructure, crystal changes and electrical properties of the calcium aluminite were investigated ^[3] .