Electrical conductivity, of metals

The easy movement of the electrons gives the high electrical conductivity of metals. The metallic bond has no directionality, so that metal ions tend to pack to give simple, high-density structures, like ball-bearings shaken down in a box. 

The high electrical conductivity of metals as well as the high electron (and hole) mobility of inorganic covalently bound semiconductors have both been clarified by the band theory [I9, which slates that the discrele energy levels of individual atoms widen in the solid stale into alternatively allowed and forbidden bands. The... 

The metallic structure essentially consists of atomic nuclei and associated core electrons, surrounded by a sea of free electrons. The high electrical conductivity of metals is derived from the presence of these free electrons. In addition to high electrical conductivity, the free electrons provide the metals with good thermal conductivity as well. The electrical resistivity of a metal increases with temperature. 

Y. Zhao, J. Wei, R. Vajtai, P. M. Ajayan, E. V. Barrera, Iodine doped carbon nanotube cables exceeding specific electrical conductivity of metals, Scientific Reports 1 83, 2011. 

Interest in the electrical conductivity of metal-chain complexes is increasing. Several studies have been made of the mixed valence complex K2Pt(CN)4BtQ 3 -2.3H2O. One reports that the conductivity in the direction of the Pt-atom chain is 100 times greater than at right angles to the chain. However, another study indicated considerable experimental scatter, which was attributed to variable water content from sample to sample. Small amounts of water were shown to increase the conductivity by a factor of up to It has also... 

Metals consist of a regular array of metal cations surrounded by a sea of electrons. These electrons occupy the space between the cations, binding them together, but are able to move under the influence of an external field, thus accounting for the electrical conductivity of metals. 

Extensions of this model in which the atomic nuclei and core electrons are included by representing them by a potential function, V, in Equation (4.1) (plane wave methods) can account for the density of states in Figure 4.3 and can be used for semiconductors and insulators as well. We shall however use a different model to describe these solids, one based on the molecular orbital theory of molecules. We describe this in the next section. We end this section by using our simple model to explain the electrical conductivity of metals. 

When discussing the electrical conductivity of metals, we described them in terms of ionic cores and delocalised valence electrons. The core electrons contribute a diamagnetic term to the magnetic susceptibility, but the valence electrons can give rise to paramagnetism or one of the cooperative effects we have described. 

The ionisation potential for electrons in arsenic vapour has been calculated to be 9-04 volts 3 the value previously accepted was 11-54 volts.4 The inelastic collision potential is 4-69 volts, and the resonance potential 4-7 volts.5 The electrical conductivity of metallic arsenic at 0° C. is 0-00285 mho.6 The yellow and amorphous forms do not conduct electricity appreciably. The specific resistance of grey arsenic has been determined 7 at various temperatures as follows ... 

The first conference of this group is the 4th Solvay Conference on The Electrical Conductivity of Metals held in April 1924.84 The conference was in some way premature. It took place just before the advent of quantum mechanics, in particular 2 years in advance of the first formulation... 

This picture, by the way, finds a most important application in the description of bonding in metals. Take, for instance, sodium, with one electron per atom for four orbitals. It is quite clear that here there is a vast excess of orbitals over electron pairs, and electrons in solid sodium, as in all metals, are effectively delocalized over the whole metal crystal. This idea can account satisfactorily for the electrical conductivity of metals. A more detailed discussion of metals would go beyond the space available here. 

How does band theory account for the electrical conductivity of metals ... 

Starting point for this paragraph is the electrical conduction of metals, a phenomenon with which everyone will be familiar. A simplified crystal structure of metals was already discussed in chapter 3, in the paragraph on Chemical bonds . In a metal, there is question of an electron cloud which moves between the metal ions. When the metal is connected... 

For metallic materials, charges are conducted by electrons or holes because most of the energy bands of metals are partially filled. A common equation for the electrical conductivity of metals can be derived from the following simple model. Applying Newton s second law to an electron in a crystal, it yields... 

In the temperature interval of —70 to 0°C and in the low-frequency range, an unexpected dielectric relaxation process for polymers is detected. This process is observed clearly in the sample PPX with metal Cu nanoparticles. In sample PPX + Zn only traces of this process can be observed, and in the PPX + PbS as well as in pure PPX matrix the process completely vanishes. The amplitude of this process essentially decreases, when the frequency increases, and the maximum of dielectric losses have almost no temperature dependence [104]. This is a typical dielectric response for percolation behavior [105]. This process may relate to electron transfer between the metal nanoparticles through the polymer matrix. Data on electrical conductivity of metal containing PPX films (see above) show that at metal concentrations higher than 5 vol.% there is an essential probability for electron transfer from one particle to another and thus such particles become involved in the percolation process. The minor appearance of this peak in PPX + Zn can be explained by oxidation of Zn nanoparticles. 

Metals are subject to electrochemical corrosion in the presence of water Metal atoms lose electrons to become positively charged metal ions that go into solution. These then react with other chemical species in the soil ground-water to form solid corrosion products (e.g., metal oxides, hydroxides, sulfates). It is these solid corrosion products that often form a colored matrix with soil particles around the corroding object (Cronyn 1990). The initial formation of the metal ions takes place at a site on the metal known as the anode, whereas the electrons produced consumed by another reaction with an electron acceptor (the cathode). Due to the electrical conductivity of metals the location of the anode and cathode can be at different locations on the metal surface. In the presence of water and oxygen the cathodic reaction is... 

Metallic structure and bonding are characterized by delocalized valence electrons, which are responsible for the high electrical conductivity of metals. This contrasts with ionic and covalent bonding in which the valence electrons are localized on particular atoms or ions and hence are not free to migrate through the solid. The physical data for some solid materials are shown in Table 4.3.1. 

Electrical conductivity of metals is very high and is of the order of 106 108 ohm-1 cm-1 while that of insulators is of the order of 10-12 ohm-1 cm-1. Semi-conductors have intermediate conductivity which lies in the range 102 10-9 ohm-1 cm1. Electrical conductivity of solids may arise through the motion of electrons and positive holes (electronic conductivity) or through the motion of ions (ionic conductivity). The conduction through electrons is called n-type conduction and through positive holes is called p-type conduction. Pure ionic solids where conduction can take place only through motion of ions are insulators. However, the presence of defects in the crystal structure increases their conductivity. 

HYDROGEN CONCENTRATION DEPENDENCE ON THERMAL AND ELECTRICAL CONDUCTIVITIES OF METAL-HYDRIDE COMPOSITE MATERIALS... 

Electrical Conductivity of Metal—Molten Salt Mixtures... 

A serious problem with these categories of electrodes in molten salts is the dissolution of the metal into melts having the same cation, and thus the melts may have a significant electronic conduction. (See Section I.B.4, Electrical Conductivity of Metal-Molten Salt Mixtures .)... 

The current efficiency would be 100% if the recombination reaction of sodium with chlorine did not occur. Although the diaphragm prevents sodium droplets formed at the cathodes to react with the chlorine bubbles formed at the anodes, another phenomenon causes the decrease in current efficiency. Thus, the slight solubility of sodium in the melt causes the melt to become a partial electronic conductor (see Section I.B.4 Electrical Conductivity of Metal-Molten Salt Mixtures ). This electronic conductivity and the recombination reaction of sodium and chlorine dissolved in the electrolyte decrease the current efficiency. 

In a metal, certainly the transition metals, the electrons are more or less free to move in conduction bands. This fact is responsible for the high electrical conductivity of metals. When hydrogen atoms are present in the holes between the atoms, the movement of the electrons is somewhat impaired. As a result, the metal hydrides of this class are poorer conductors than the pure metals. The presence of hydrogen atoms makes the metal atoms less mobile and more restricted to particular lattice sites. Accordingly, the interstitial metal hydrides are more brittle than the parent metal. Also, the inclusion of the hydrogen atoms causes a small degree of lattice expansion so that the interstitial hydrides are less dense than the parent metal alone. 

The most important clue to understanding the nature of the metallic bond is the high electrical conductivity of metals. Like most substances held together by ionic or covalent bonds, pure salt and pure water do not conduct electricity well. But pure copper does. Scientists could not make much sense of this difference until J.J. Thomson discovered the electron in 1897. Soon afterward,... 

Halifax Regional School Board. Electrical Conductivity of Metals, Including Some Alloys. Available online. URL http // www.myhrsb.ca/Functions/Curriculum/eng/science/9/ SupplementaryPages/MetalsElectConductivity.htm. Accessed on July 24, 2007. 

A series of AgF+ salts (AgFMF4 with M = B, Au and AgFMF6 with M = As, Au, Ir, Ru, Sb, Bi) have been prepared. The first was AgFAsF6 [9] made by the interaction of AgF2 with AsF5 in aHF. They all have the weak, temperature independent paramagnetism indicative of a partially filled band and suggestive of metallic character [12]. In no case however has electrical conductivity of metallic type been demonstrated in any one of these solids. A wide variety of synthetic routes have been demonstrated for the preparation of (Ag—F)]]+ salts. 

The existence of empty MOs close in energy to filled MOs explains the thermal and electrical conductivity of metal crystals. Metals conduct electricity and heat very efficiently because of the availability of highly mobile electrons. For example, when an electrical potential is placed across a strip of metal, for current to flow electrons must be free to move from the negative to the positive areas of the metal. In the band model for metals, mobile electrons are furnished when electrons in filled MOs are excited into empty ones. The conduction electrons are free to travel throughout the metal crystal as dictated by the potential imposed on the metal. The MOs occupied by these conducting electrons are called conduction bands. These mobile electrons also account for the efficiency of the conduction of heat through metals. When one end of a metal rod is heated, the mobile electrons can rapidly transmit the thermal energy to the other end. 

Metals are used in a wide variety of applications. The excellent electrical conductivity of metals such as copper, makes them a good choice for transmitting electrical power. Ductility and malleability allow metals to be formed into coins, tools, fasteners, and wires. 

Responsible for characteristic luster and light reflectivity properties of a metal -> Accounts for malleability, ductility, and electrical conductivity of metals... 

Adhesion of positively and negatively charged latex was used to estimate the IEP of stainless steel (original and heated in air for 2 hours at 1000°C) [688], Adhesion occurs when the signs of the charge of the studied surface and of the latex are opposite. The same method has been used for other metals [689], The nonzero electrical conductivity of metals excludes measurements of their IEP by means of standard methods. 

Values of j3v have been successfully calculated from Rubens reststrahlen " (Einstein, Nernst, and Lindemann), from the elastic properties (Sutherland, Einstein, Debye, Bom and v. Karman, Eucken), from the electrical conductivity of metals (Nernst, Kamerlingh-Onnes, Schiemank), and from thermal expansion (Griineisen). ... 

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