How temperature affects on electrical conductivity and is it increase or decrease the conductivity as temperature increase?
3.1. The normal metals (non-superconductors) - at the lowest temperatures, electrical conductivity is almost constant (limited by scattering from defects). When the temperature rises - see 2.1.
3.2. The superconductors - everything depends on the superconducting transition temperature (Tc), which can be either in the region of constant conductivity or in the region of its decrease (with increasing temperature). In a narrow temperature range below Tc, conductivity quickly (often abruptly) tends to an infinitely large value (electrical resistance ® 0), and remains so at all TTc – see 2.1.
3.3. Semiconductors - see 2.2.
Conductivity sigma can be expressed by the formula: sigma = qvn, where q is the charge of the particle, v is the mobility, and n is the concentration of charge carriers. In metals n does not depend on temperature; mobility v decrease with heating due to scattering by thermal vibrations. Therefore, conductivity in metals decreases with heating according to an approximately linear law.
In semiconductors, n increases with heating according to an exponential law. This dependence is much stronger than the linear law. Therefore, in semiconductors, conductivity increases with heating according to an approximately exponential law.
This question relates to charge transport and phonon excitation, which have different effect on metallic materials and semiconducting materials.
Alexander explains well the charge transport in electrical conductivity. Lattice vibration or phonons will be excited due to temperature. For metallic materials (not superconductors) the charge carriers will be scattered by thermal vibration or due to electron/hole-phonon interactions. Thus conductivity decreases with temperature. Oppositely, for semiconductors/insulators, thermal excitation makes more charge carriers to the conduction band, indicating that number of charge carriers increase with temperature. Thus, electrical conductivity increases with temperature in general.
Temperature affects the degree to which an electrolyte gets dissolved in a solution. It has been seen that higher temperature enhances the solubility of electrolytes and hence the concentration of ions which results in increased electrolytic conduction. When temperature increases, the vibration of metal ions increases. This results in increase in resistance of metal and hence, decreases in conductivity. In electrolytic conductors, the ions are charge carriers and with increase in temperature, ionization increases and hence, conductivity increases. The metal's resistivity increases as the temperature rises, giving it a positive temperature coefficient of resistance. A conductor's resistance increases and its conductivity decreases as the temperature rises. For every 1°C increase, conductivity values can increase 2-4% 3. Temperature affects conductivity by increasing ionic mobility as well as the solubility of many salts and minerals. The relationship between conductivity and temperature depends on the material: In conductors: As temperature increases and resistance increases, conductivity decreases. In semiconductors: As temperature increases and resistance generally decreases, conductivity increases. Conductivity of metal decreases with temperature while conductivity of electrolytic conductors increases with temperature. Because the electrons move faster as the temperature increases, the electrical conductivity increases. The electrons and holes involved in conduction in the semiconductor will increase significantly with the increase of temperature, the conductivity will increase, and the resistance will decrease.If electrical conductivity increases with the increase of temperature of a substance then that substance is a semiconductor.
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