Metals, properties electroconductivity

At the end of this section let us cite the opinion of Sachtler 461), on the subjects in question work function, Volta potential, photoelectrical emission, field emission microscopy, film electroconductivity, magnetic properties of small particles, and IR spectra indicate, according to Sachtler, that the chemisorption bond between the metal and the adsorbate is similar to the bond in the bulk, with both bond strengths differing by not more than 10%. In chemisorption the metal atom partly loses its metallic properties the result is a change of electroconductivity and magnetizing ability. The Me—Me bond is broken and a bond with the adsorbate is formed a mobility of the metal atoms on the surface is the result. All these considerations are consistent with the conclusions from the multiplet theory. 

The mechanical properties of a conductive material play an important role when selection is performed for any particular textile application. Metallic filaments usually compromise good electroconductive characteristics with poorer mechanical properties. A very high stiffness and lower stretchability of metallic fibers not only makes the woven or knitting process difficult but also reduces their service life. On the other hand, polymeric fibers or yams exhibit good elongation and recovery properties. The combination of nonstretchable metallic fibers with stretchable polymeric yams creates a new class of metal-based electroconductive fibers, which is known as co-spun polymeric-metal yams (Fig. 28.3). 

As mentioned earlier, the addition of powdered metals to polymeric materials eliminates electrostatic charges on their surface. But electric properties of materials such as vulcanized rubbers filled this way are not stable for this reason, powdered metals are used only for polymer-based electroconducting varnishes [5,6] and adhesives [7]. In these cases, the powdered metals (Ag, Au, Ni, Al, Cu) are impregnated with epoxy resins or added to polyamides, PVC, silicones, etc. [1,5,8]. 

An electron with half-integer spin is a fermion, i.e., it has to obey Fermi-Dirac statistics. All the usual metal electroconductivity properties are in agreement with these statistics. However, in some cases two electrons can produce the so-called Cooper s pairs with compensated spin, the spin of the Cooper pairs is zero. Therefore, such pairs transform electrons from fermions to bozons. There are no Pauli s exclusion principles for bozons they can be condensed, i.e., they occupy all the levels, and nearly all participate in electroconductivity. Superconductivity can then take place. 

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