Question
Asked 18th Mar, 2015

Why is copper a better conductor than other metals, say nickel?

Just as I said in the question. I have looked at copper and nickel's band structure. For copper, Fermi level is within 3d, but for Nickel Fermi energy is higher than 3d band. My understanding is that for copper there is a higher chance for copper's electron to be excited for conduction. Is this correct? Or is there any other interpretation?

Most recent answer

25th Mar, 2015
Sajjad Jannesar Malakooti
Iranian Mines & Mining Industries Development & Renovation (IMIDRO) (IMPASCO) (Tabas Coal Mines Complex)
Dear Yuan Yao
Copper Is one of conductive metal in the industries. This manner is because its  molecular structure and metallic band, Electron concentration and mobility in the copper is very high.
Kind Regards 
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Popular Answers (1)

23rd Mar, 2015
Jorge Morales Pedraza
Morales Project Consulting
Electrical conductivity is a measure of how well a material transports an electric charge. This is an essential property in electrical wiring systems. Copper has the highest electrical conductivity rating of all non-precious metals: the electrical resistivity of copper = 16.78 nΩ•m at 20 °C. Specially-pure Oxygen-Free Electronic (OFE) copper is about 1% more conductive (i.e., achieves a minimum of 101% IACS).
In a copper atom, the outermost 4s energy zone, or conduction band, is only half filled, so many electrons are able to carry electric current. When an electric field is applied to a copper wire, the conduction of electrons accelerates towards the electropositive end, thereby creating a current. These electrons encounter resistance to their passage by colliding with impurity atoms, vacancies, lattice ions, and imperfections. The average distance travelled between collisions, defined as the “mean free path,” is inversely proportional to the resistivity of the metal. What is unique about copper is its long mean free path (approximately 100 atomic spacings at room temperature). This mean free path increases rapidly as copper is chilled.
Because of its superior conductivity, annealed copper became the international standard to which all other electrical conductors are compared.
The main grade of copper used for electrical applications is electrolytic-tough pitch (ETP) copper . This copper is at least 99.90% pure and has an electrical conductivity of at least 101% IACS. ETP copper contains a small percentage of oxygen (0.02 to 0.04%). If high conductivity copper needs to be welded or brazed or used in a reducing atmosphere, then oxygen-free copper may be used.
Several electrically conductive metals are less dense than copper, but require larger cross sections to carry the same current and may not be usable when limited space is a major requirement.
 Aluminium has 61% of the conductivity of copper. The cross sectional area of an aluminium conductor must be 56% larger than copper for the same current carrying capability. The need to increase the thickness of aluminium wire restricts its use in several applications, such as in small motors and automobiles. In some applications such as aerial electric power transmission cables, copper is rarely used.
Silver, a precious metal, is the only metal with a higher electrical conductivity than copper. The electrical conductivity of silver is 106% of that of annealed copper on the IACS scale, and the electrical resistivity of silver = 15.9 nΩ•m at 20°C. The high cost of silver combined with its low tensile strength limits its use to special applications, such as joint plating and sliding contact surfaces, and plating for the conductors in high-quality coaxial cables used at frequencies above 30 MHz.
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All Answers (4)

23rd Mar, 2015
Rinat Khisamov
Institute for Metals Superplasticity Problems of Russian Academy of Sciences
The conductivity of a metal depends on the electron concentration and mobility of electrons: S [conductivity]=n [electron concentration]*e [electron charge]*M [electron mobility]. M=e*L [the mean free path]/m [electronic mass]*U [the average thermal velocity]. Thus:  S=ne2L/mU. For example: n(Cu)=0.85*1029 m-3, n(Al)=0.83*1029 m-3. L (Cu) (at 273 K)=2.65*10-10 m, L (Al)=1.64*10-10 m. m=9.1*10-31 kg. U~105 m/s. e=1.6*10-19 С. SCu/SAl=nCu*LCu/nAl*LAl=1.65. From Wiki SCu=55-58*106 S/m, SAl=37*106 S/m.
3 Recommendations
23rd Mar, 2015
Jorge Morales Pedraza
Morales Project Consulting
Electrical conductivity is a measure of how well a material transports an electric charge. This is an essential property in electrical wiring systems. Copper has the highest electrical conductivity rating of all non-precious metals: the electrical resistivity of copper = 16.78 nΩ•m at 20 °C. Specially-pure Oxygen-Free Electronic (OFE) copper is about 1% more conductive (i.e., achieves a minimum of 101% IACS).
In a copper atom, the outermost 4s energy zone, or conduction band, is only half filled, so many electrons are able to carry electric current. When an electric field is applied to a copper wire, the conduction of electrons accelerates towards the electropositive end, thereby creating a current. These electrons encounter resistance to their passage by colliding with impurity atoms, vacancies, lattice ions, and imperfections. The average distance travelled between collisions, defined as the “mean free path,” is inversely proportional to the resistivity of the metal. What is unique about copper is its long mean free path (approximately 100 atomic spacings at room temperature). This mean free path increases rapidly as copper is chilled.
Because of its superior conductivity, annealed copper became the international standard to which all other electrical conductors are compared.
The main grade of copper used for electrical applications is electrolytic-tough pitch (ETP) copper . This copper is at least 99.90% pure and has an electrical conductivity of at least 101% IACS. ETP copper contains a small percentage of oxygen (0.02 to 0.04%). If high conductivity copper needs to be welded or brazed or used in a reducing atmosphere, then oxygen-free copper may be used.
Several electrically conductive metals are less dense than copper, but require larger cross sections to carry the same current and may not be usable when limited space is a major requirement.
 Aluminium has 61% of the conductivity of copper. The cross sectional area of an aluminium conductor must be 56% larger than copper for the same current carrying capability. The need to increase the thickness of aluminium wire restricts its use in several applications, such as in small motors and automobiles. In some applications such as aerial electric power transmission cables, copper is rarely used.
Silver, a precious metal, is the only metal with a higher electrical conductivity than copper. The electrical conductivity of silver is 106% of that of annealed copper on the IACS scale, and the electrical resistivity of silver = 15.9 nΩ•m at 20°C. The high cost of silver combined with its low tensile strength limits its use to special applications, such as joint plating and sliding contact surfaces, and plating for the conductors in high-quality coaxial cables used at frequencies above 30 MHz.
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