Resistance temperature curve

Figure 12.6. Resistance-temperature curves for electrodeposited nickel films about 20 [xm thick.

Figure 6.9 Properties of superconductors (a) resistivity-temperature curve for a pure (solid) and an impure (broken) superconductor (b) magnetization as a function of external field for type I superconductor (c) magnetization curve for a type II superconductor.

The electrical conductivity of a pure arsenic crystal has been measured 3 at temperatures down to 2-42° Abs. The resistance-temperature curve is similar to those of pure metals. There is evidence of definite residual resistance being maintained at low temperatures, but arsenic does not exhibit the abnormally high residual resistance shown by bismuth, nor does it show superconductivity. The resistance is by no means proportional to the absolute temperature. It has been estimated that the electrical resistance of liquid arsenic at the melting point is about 0-4 of that of the solid phase.4... 

In many cases this procedure would suffice, but not in all. At high temperatures the resistance-temperature curve no longer has any universal character.f For example, the metals platinum, palladium, and tantalum at high temperatures exhibit a retarded rise in the resistance, which is very striking but so far is completely unexplained, while the ferromagnetic metals iron, nickel, and cobalt... 

The volume resistivity/temperature curve clearly illustrates the strong difference in the temperature dependency of the volume resistivity of a polymer in its glassy phase and in its rubbery phase. The Tg-value, obtained by drawing two tangents near this glass-rubber transition, is determined at 1000/T 3.58 or 6°C. This Tg-value is a real static Tg-value and its hypothetical frequency [f(h)l in the frequency/temperature plane will be lower than the f(h) = lxB-2 to lxE-4 claimed by Phillips [12] for dilatometric experiments. A good fit on the Arrhenius plot was obtained assuming an f(h) of lxE-6 for this Tg-value, see below. 

Atoji has previously reported that PrC2 is an antiferromagnet with a Neel temperature of 15 2 K by neutron diffraction techniques at zero field. In order to clarify the discrepancy between the two results, the temperature dependency of the resistivity was examined (Sakai et al. 1981a). The change in the slope of the resistivity-temperature curve occurred at about 18 K, which is close to the Neel temperature reported by Atoji. This finding indicates that PrC2 possesses a metamagnetic transition in fields below 700 Oe. 

It was Takagi et al. (1992) and then Nakamura and Uchida (1993) who noticed that the resistivity-temperature curve deviates from linearity and starts decreasing sharper towards lower temperatures below T. More recent results were summarized by Nakano et al. (1994). 

Additives and their effects on PTC characteristics are listed in Table 2.1.1. The transition temperature Tc can be lowered or elevated from its original value (120°C) by substitution of Sr + and Pb + at the Ba + site. Figure 2.1.5 shows the typical resistivity-temperature curves of PTC thermistors with various Tc. 

FIGURE 2.21 Typical resistance/temperature curve for a PTC resistor. 

All materials exhibit a change in resistance with material, either positive or negative, and many are nonlinear to a high degree. By definition, the TCR at a given temperature is the slope of the resistance-temperature curve at that temperature. The TCR of thick-film resistors is generally linearized over one or more intervals of temperature, typically in the range from —55 to- -125°C, as shown in Eq. (11.4) as... 

The TES is composed of an absorber, thermometer of the superconducting film, thermal link and heat bath. Fig. 2(a) and 2(b) are schematic and photograph of the TES device, respectively. The superconducting film is used as a thermometer because the temperature range between normal state to superconducting state (called as superconducting transition edge) has the steepness for resistance-temperature curve. 

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