The resistivity-temperature behavior

The authors gratefully acknowledge the financial support of this work by the National Outstanding Youth Foundation of China (Contract No. 50925311). 

Narkis M, Ram A and Flashner F (1978) Electrical properties of carbon black filled polyethylene, Polym Eng Set 18 649-653. 

Mamunya Y P, Muzyehenko Y V, Pissis P, Lebedev E V and Shut M I (2002) Percolation phenomena in polymers containing dispersed iron, Polym Eng Sci 42 90-100. 

Zheng Q, Song Y H and Yi X S (1999) Piezoresistive properties of HDPE/graphite composites, J Mater Sci Lett 18 35-37. 

Chen J and Tsubokawa N (2000) Novel gas sensor from polymer-grafted carbon black vapor response of electric resistance of conducting composites prepared from poly(ethylene- block-ethylene oxide)-grafted carbon black, J Appl Polym Sci 77 2437-2447. 

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Carbon nanotubes since its discovery in 1991 have attracted much attention of researchers due to its unique properties, like high current density, chemical inertness, high mechanical strength, etc. Kaiser et al. [1] pointed out similarity between the resistivity temperature behavior p(T) observed in SWCNTs and that of highly conducting polymers, in particular the change in sign of the p(T) dependence from metallic to non-metallic as T was decreased. 

A wide variety of microstructures can be obtained by suitable alloying in Nb alloys and the oxidation resistance of Nb alloys can be dramatically improved by alloying. It is important to investigate the microstructural aspects associated with oxidation in order to establish the high temperature behavior of these alloys. Here an overview of the effects of alloying on microstructural development was illustrated and their effects on oxidation... 

FIGURE 26 High-pressure study of carbon films prepared from maleic anhydride at about 600"C. (a) Resistance decreases with pressure, (b) The low-temperature behavior of resistance is metallic at a different locked pressure [84],... 

Figure 13.6. The volume resistivity-temperature behavior for i-CB/PET/PE composite with different thermal treatment times at 180 °C. The heating rate is 2°C/min, and the applied voltage is fixed at 10 V [19]...

Figure 13.20. The volume resistivity-temperature behaviors of the ACPC sample in the parallel (a) and perpendicular (b) directions after different treatment time (2, 8, 16, 32 and 46 h). The inset shows the treatment time dependence of IpjQ and [41]...

At low plastic strain amplitudes (ACp/ 2<2xl0 ), the deformation is mainly accommodated by the softer austenitic phase of the duplex alloy. Movement of the screw dislocations in the a-phase is very difficult because of the low temperature behavior of this phase at 300 K. Cyclic deformation of the austenitic phase then controls the fatigue properties of the duplex alloy. Because of the large reversibility of the cyclic strain, delayed transgranular crack initiation occurs in this phase (Fig. 5-34a). This explains the good fatigue resistance of the two-phase alloy at Agp/2< 10" as shown in the Coffin-Manson curve (Fig. 5-33). 

Environmental resistance is a key concern for Ti-Al-based intermetallics. Examination of the elevated-temperature behavior of elemental Ti in oxygen- or nitrogen-... 

Fig. 7. The resistivity curves ofCCj,La, -j,Pbj for four different values of x to illustrate the effects of doping (Lee et al. 1986). The curves are normalized by the Ce concentration x. The temperature scale is expanded below 12 K, marked by the vertical dashed line, to show details of the low-temperature behavior.

In addition to the failure of the free electron gas model to properly account for the observed temperature behavior of resistivity of metals, there are serious problems when other properties are considered. First, let us make a few simple calculations to illustrate one of its major difficulties. Multiplying the collision time of 2.5 x 10 s by the thermal velocity 1 x 10 m/s, one gets a mean free path of 2.5 nm, which is on the order of a few lattice spacing. This seems incredibly small, especially considering that Cu is one of the... 

Even though there are a number of metals that appear suitable for resistance thermometry, platinum has come to occupy a predominant position, partly because of excellent characteristics, such as chemical inertness and ease of fabrication, and partly because of custom that is, certain desirable features such as ready availability in high purity and the existence of a large body of knowledge about its behavior have come into being as its use grew and have tended to perpetuate that use. Its sensitivity down to 20 K and its stability are excellent. Its principal disadvantages are low resistivity, insensitivity below about 10 K, and a variation of the form of the resistance-temperature relation from specimen to specimen below about 30 K. 

In other work, the impact of thermal processing on linewidth variation was examined and interpreted in terms of how the resist s varying viscoelastic properties influence acid diffusion (105). The authors observed two distinct behaviors, above and below the resist film s glass transition. For example, a plot of the rate of deprotection as a function of post-exposure processing temperature show a change in slope very close to the T of the resist. Process latitude was improved and linewidth variation was naininiized when the temperature of post-exposure processing was below the film s T. 

Melt Index or Melt Viscosity. Melt index describes the flow behavior of a polymer at a specific temperature under specific pressure. If the melt index is low, its melt viscosity or melt flow resistance is high the latter is a term that denotes the resistance of molten polymer to flow when making film, pipe, or containers. ASTM D1238 is the designated method for this test. 

High Temperature Properties. There are marked differences in the abihty of PGMs to resist high temperature oxidation. Many technological appHcations, particularly in the form of platinum-based alloys, arise from the resistance of platinum, rhodium, and iridium to oxidation at high temperatures. Osmium and mthenium are not used in oxidation-resistant appHcations owing to the formation of volatile oxides. High temperature oxidation behavior is summarized in Table 4. 

Fig. 4. Effect of dopant additions on the resistivity versus temperature behavior of BaTiO PTCR ceramics. A, undoped B, doped with 0.134 mol % Cr ...

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