Temperature dependent electrical conductivity

By producing PPy films, electrical conductivities up to 150 S/cm can be obtained. Electropolymerized PPy films differ in their molecular structure according to polymerization conditions such as the electrochemical parameters of the polymerization. At low current densities (l.c.d.) below 3 mA/cm one-dimensional polypyrrole chain structures are mainly produced [3]. Higher current densities predominantly lead to two-dimensional molecular polymer structures. The electronic state of such PPy films produced with high current density (h.c.d.) has been investigated by several solid-state spectroscopic methods such as ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS), as well as temperature-dependent electrical conductivity measurements [4-6]. 

Moreover, the hierarchical structure is formed by hydrogen bonding from the mixture (42) of poly[(styrene)- /ock-(4-vinylpyridine)] and methanesulfonic acid, which exhibits temperature-dependent electrical conductivity by the change of microphase-separated structure (Fig. 13) [96]. 

Fig. 2 Temperature-dependent electrical conductivity of the LB film of a 1 1 mixture of 3C10-Au and eicosanoic acid after electro-oxidation. The measurement was carried out by the dc 4-probe method in vacuum. The cooling rate was 0.5 K/min.

Mikrajuddin, Shi FG, Okuyama K (2001) Temperature-dependent electrical conduction in porous silicon Non-Arrhenius behavior. Europhys Lett 54 234 Parkutik VP (1996) Residual electrolyte as a factor influencing the electrical properties of porous silicon. Thin Solid Films 276 195... 

Many of the elements that lie along the zigzag diagonal hne that divides metals and nonmetals are metalloids and exhibit mixed properties. Several metalloids are also classified as semiconductors because of their intermediate (and highly temperature-dependent) electrical conductivity. Our ability to change and control the conductivity of semiconductors makes them useful to us in the manufacture of the electronic chips and circuits central to computers, cellular telephones, and many other modem devices. Good examples of metalloids include sihcon, arsenic, and antimony. 

Figure 5.5h shows the temperature-dependent electrical conductivity of pure and Ni-doped Cu2ZnSnS4 nanocrystals. Remarkably, Ni doping results in a dramatic increase of electrical conductivity for Cu2ZnSnS4 nanocrystals reaching 2316 m at 600 K, which is 4 times higher than that of pure sample (570... 

Since at low temperatures, the electrical conductivity is determined by the scattering on defects, whereas at room temperature it depends on the scattering on phonons, the RRR is a measure of the limiting defect scattering. It indicates how pure a material is. The RRR of particularly pure materials can be as high as 104. 

The electrical conductivity was obtained using the applied voltage and the measured current and dimension of the sample. The electrode was A1 plate. For dose dependence, the conductivity was measured at 300 K and at humidity of 40 % in air. For temperature dependence, the conductivity was measured in the temperature range from 300 to 393K in vacuum under pressure of 6xl0"5 Pa. 

In 1997, Anderson et al. reported that when more and more extra electrons are introduced into the zeolite hosts,[19] some zeolites indeed show an electrical conductivity increase. The loading of potassium into zeolite L increases the room-temperature conductivity of the latter by 10 000 times. Nevertheless, the measured temperature dependence of conductivity on temperature indicates that the conduction mechanism is characteristic of thermal activation, and therefore that the electrical conduction may involve the redox jump of the K32+/K3+ process (see Figure 9.7). The K/K-A host-guest compound exhibits interesting ferromagnetic behavior,1221 and this magnetism may be related with the formation of a superlattice.[231... 

The electrical transport of KCP was reported by Zeller et The room-temperature conductivity along the molecular stacking direction is 300-400 S cm , which is 10 greater than the conductivity perpendicular to the chain direction. The temperature dependence of conductivity along the chain direction shows metallic behaviour down to around 250 K and semiconducting behaviour below that temperature. The broad maximum of conductivity around 250 K is due to the one-dimensionality of the linear-chain system. The large anisotropy of conductivity in directions parallel and perpendicular to the chains confirms the onedimensional character of KCP. 

J 8 An electrical conductor 2 cm in diameter fits closely inside a long hollow cylinder having an inside diameter of 2 cm and an outside diameter of 6 cm. The material from which the cylinder is madehas a temperature-dependent thermal conductivity (Fig.2P-15). The outer surface of the cylinder is maintained at 1600 C, and the electrical conductor dissipates 500 W per m of length. Compute the temperature at the inside surface of the hollow cylinder. 

The Steenbeck-Raizer charmel model (Fig. 4-38) is based on the strong dependence of plasma electric conductivity on temperature (Saha equation, Section 3.1.3). At temperatures below 3000 K, plasma conductivity is low it grows signiflcantly only when the temperature exceeds 4000 K. The temperature decrease T (r) from the axis to the walls is gradual, whereas the conductivity change with radius a[T r)] is sharp. Thus, according to the model, arc current is located mostly in a charmel of radius ro. Temperature and electric conductivity are considered constant inside of the arc charmel and equal to their maximum value on the discharge axis Tm and a(7A). The total arc current can be then expressed as... 

Figure 7. Thickness-dependent electrical conductivity of YSZ thin fdms determined at different temperatures. Solid lines represent the results of fitting the experimental data to the model [31]...

While the temperature dependence of conductance can reveal fundamental transport mechanisms in CPNWs, current-voltage characteristics provide direct information on the electrical properties of CP materials. Kaiser and Park introduced an expression with which the nonlinear I-V characteristics of highly conductive CP materials can be treated as conduction through small barriers between metallic regions [100] ... 

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