Paramagnetism, conductivity

Pol VG (2010) Upcycling converting waste plastics into paramagnetic, conducting, solid, pure carbon microspheres. Environ Sci Technol 44(12) 4753 759... 

Both the polymers are dark in color and exhibit semiconductivity and paramagnetism. The electric conductivity measurements are performed on peUets and on thin films in sandwich and surface ceUs. 

Nickel is a malleable, ductile, tenacious, slightly magnetic, silvery white metal, which conducts heat and electricity fairly well. It is ferromagnetic at ordinary temperatures but becomes paramagnetic at elevated temperatures. Nickel is closely related in chemical properties to iron and cobalt. While sulphidic sources of nickel account for the world s major nickel supplies, it may be pointed out that lateritic nickel deposits (which essentially constitute an oxidic source of the metal) are more extensive than the sulphidic sources. 

Although relaxation measurements have been widely used in nuclear magnetic resonance studies of solid catalysts and adsorbed molecules, they have not found such favor in similar ESR work. Relaxation phenomena, however, do play a very important role in any magnetic resonance experiment, whether or not this aspect of the problem is studied. In fact, the temperature at which most ESR experiments are conducted is dictated by the relaxation process. Furthermore, even qualitative data on relaxation times can be used as supporting evidence in the identification of a paramagnetic species. 

A range of metals including iron, copper, cobalt, permalloy and nickel were used to form conductive and paramagnetic coatings on the halloysite clay. These conductive small particles may then be used in polymeric systems to form composites with interesting electromagnetic properties. 

Sulfur vapor consists of a mixture of species that includes S8, S6, S4, and S2 (which like 02 is paramagnetic). Because the S8 molecule is nonpolar, it is soluble in liquids such as CS2 and C6H6. Selenium also consists of cyclic molecules that contain eight atoms, and tellurium is essentially metallic in character. In their vapors, several species are found that contain 2, 6, or 8 atoms. Both are useful as semiconductors, and selenium has been used in rectifiers. Because the electrical conductivity of selenium increases as the intensity of illumination increases, it has been used to operate electrical switches that open or close as a light beam is broken. Selenium was also used in light meters, but other types of meters are now available that are more sensitive. Table 15.1 gives a summary of the properties of the group VIA elements. 

The 29Si relaxation rate 7j"1 at 1.6 K vs donor concentration nD shows a sharp decrease between nD = 2.5 x 1018 cm 3 and nu = 6 x 1018 cm 3. This reflects the fact that in the semiconducting regime (lower donor concentrations), the unionized donors are paramagnetic point sources of relaxation for the 29Si nuclei. Their localized electron spins are more effective in inducing relaxation than the itinerant electrons found in a conduction band at the higher donor concentrations [18]. 

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