energy band
In forming molecules, atomic orbitals constitute discrete energy levels of molecular orbitals with. By a large number of atoms in the crystal are ordered piled. The number of atomic orbitals molecular orbital constituted by the very large, so that the formation of molecular orbital energy level can be seen as a quasi-continuous, that the formation of the band. When 0K electron band filling in the highest occupied energy level is called the Fermi level. Solid band density of states can be said that it represents the number of intervals in the unit energy electron states. A zero density of states in the forbidden band zone is called the highest fully occupied band called the valence band, a minimum band is not fully occupied called the conduction band. The metallic material is partially filled conduction band, which has electron conductivity. Semiconductors and insulators are empty conduction band, the valence band is completely filled, the difference between the two is different from the width of the forbidden band. Solid Band width management mechanism also factors characterizing properties of solids, which is directly related to the size of the atomic orbital interaction between the crystals. The transition metal element, the d-orbital interaction between the first transition metal element is small, a narrow band gap is formed, the more the corresponding transition metal oxide semiconductor. The second and third transition series element d orbital interaction between the strong, wide band is formed, the corresponding compound having a normally metallic.
Physics terms. Electrons in the energy range of the crystal can have in physics often visualize a single horizontal lines represent the value of each energy electrons. Energy greater the higher the position of the line, within a certain energy range Many levels [apart from each other close] formed a band, called band. various crystal band number and width are not the same. energy range between two adjacent band called "energy gap" or "ban said partially occupied; belt. "crystal electrons can not have this kind of energy is completely occupied by electrons band said." filled with "electronic conductivity is not full band;. said to be fully occupied by the end of" empty zone " . "conduction band" of electrons to the conduction band conductivity; occupied valence electron band called "valence band" parity with low energy band generally the full band, the valence band can be a full band, it can be turned. band; such as is the conduction band in the metal, so the metal can conduct electricity in insulators and semiconductors are filled with a conductive, but they can not be very easy because of which the semiconductor impurities or outside influence [such as light, temperature, etc.], so. reducing the number of electrons in the valence band, or to some empty band of the conduction band electrons becomes, and thus can be conductive. |
