Transport properties temperature-dependent resistivity

The lower carrier density of the 80-nm nanowires compared to bulk bismuth is due to the smaller band overlap in the former. For the 40-nm bismuth nanowires, the carrier density has a temperature dependence similar to bulk bismuth at high temperatures, but it drops rapidly with decreasing temperature at low temperatures. Because the carrier density is highly dependent on wire diameter, the transport properties of bismuth nanowires are expected to be highly sensitive to wire diameter, as will be shown experimentally in the section temperature-dependent resistivity of nanowires. ... 

Transport properties (continued.) semiclassical model, 192-193 temperature-dependent resistivity of nanowires, 193-198 Triplet sites on supports, 63-64 Tungsten species, SiC>2-supported, 63 Turnover numbers (TON), nanostructured materials, 6... 

LaPtBi Transport and thermoelectric properties have been measured on single crystals of LaPtBi (Jung et al., 2001). With only a weakly temperature dependent resistivity (1.2 mf2 cm at room temperature) and a small positive Hall coefficient (1.4 cm /C at 4.2 K), LaPtBi is a low hole-carrier concentration semimetal. The band structure and Fermi surface have been calculated (Oguchi, 2001). 

Special attention is paid to transport properties (resistance and Hall effect) because they are very sensitive to external parameters being the base for working mechanisms in many types of sensors and devices. The magnetic field and temperature dependences of resistance and Hall effect are considered in the framework of the percolation theory. Various types of magnetoresistances such as giant and anisotropic ones as well as their mechanisms are under discussion. 

The Au films formed at the interface show interesting electrical transport properties that are dependent on the reaction temperature (see Figure 4).24 Four-probe electrical resistance measurements on the nanocrystalline films show a metal to insulator transition, metallic behavior being shown by the films formed at high temperatures (>45 °C). The films formed at lower temperatures (<45 °C) show insulating behavior. 

It is interesting to compare the transport properties of available metallic polymers with those of the underdoped High T superconductors at doping levels where k l 1. Eor example, when YBa2Cu307 8 is underdoped to values of 8 such that the resistivity increases as the temperature is lowered with Pr=p(1.4K)/ p(300 K) 2 (i.e. with temperature dependence similar to that found in the best metallic polymers), the disorder associated with the random occupation of the oxygen sites quenches the superconductivity [273]. 

The investigations of SOEs with oxygen ion conductivity (mainly based on zirconia, ceria and gallates) and with protonic conductivity (mainly cerates and zirconates) included detailed studies of their ceramic and transport properties, contact resistance of grains in SOE, ageing processes depending on the mode of fabrication, temperature, composition of material, impurities, gas atmosphere, and other factors. 

A common feature of R-amorphous alloys and transition metal-metalloid alloys is that they show similar transport properties such as high resistivities with weak temperature dependence and often at low temperature a logarithmic variation with temperature (Kastner et al., 1980). The magnetic R-alloys often show additional transport behaviour. We will now discuss this in detail for several R-amorphous alloys. 

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