Conductors in Solid Materials
The conductors are characterized by overlapping of either (i) partially filled valence band and the conduction band (Figure: a) or (ii) completely filled valence band and empty conduction band (Figure: b). Case (b) is a metal, but not a good conductor as in case (a).
Fig: (a) overlap between a conduction band and a partly filled valence band
Under the influence of an applied electric field the vacant levels within the topmost valence band are to receive electrons from the originally filled levels giving a ‘drift’ of charge through the lattice. This corresponds to the conduction of electricity. The conduction may also result from the promotion of electrons from the valence hand to the conduction band by the applied electric field.
Fig: (b) overlap between a conduction band and a filled band
An electrical conductor is a substance in which electrical charge carriers, usually electrons, move easily from atom to atom with the application of voltage. Conductivity, in general, is the capacity to transmit something, such as electricity or heat.