Mercury superconducting critical temperature

In 1908, Kamerlingh Onnes succeeded in liquefying helium, and this paved the way for many new experiments to be performed on the behaviour of materials at low temperatures. For a long time, it had been known from conductivity experiments that the electrical resistance of a metal decreased with temperature. In 1911, Onnes was measuring the variation of the electrical resistance of mercury with temperature when he was amazed to find that at 4.2 K, the resistance suddenly dropped to zero. He called this effect superconductivity and the temperature at which it occurs is known as the (superconducting) critical temperature, Tc. This effect is illustrated for tin in Figure 10.1. One effect of the zero resistance is that no power loss occurs in an electrical circuit made from a superconductor. Once an electrical current is established, it demonstrates no discernible decay for as long as experimenters have been able to watch ... 

The phenomenon of superconductivity was discovered at the beginning of the twentieth century by the Dutch physicist H. Kamerlingh Onnes, during the first attempts to liquefy helium (which at atmospheric pressure boils at 4.2 K). After refining the technique of helium liquefaction, in 1911, Onnes attempted to measure the electrical resistance of metals at these extraordinary low temperatures, and realized that at 4 K the resistance of mercury, as well as that of other metals indicated in Figure 1, became too low to be measured. This change in electrical property became the indication of the new superconductive physical state. The temperature below which materials become superconducting is defined as the critical temperature, Tc. 

Fig. 5.10 The mass dependence of the critical temperature of the superconducting/resistive transition in isotopically enriched samples of mercury (Triangles Reynolds, C. A., et al. Phys. Rev. 78, 487 (1950). Circles Maxwell, E., Phys. Rev. 78, 477 (1950))...

While Onnes was experimenting on the liquefaction of helium in 1911, he found the resistance of mercury dropped dramatically from 0.08 at 4.2 K to less than 3 x 10 Q at 4 K over a temperature interval of 0.01 K (Figure 7.1). He named this phenomenon superconductivity. This behaviour is the most striking feature of superconducting materials, in which below a critical temperature, the electrical resistance suddenly drops to effectively zero. 

Superconductors are materials that have the ability to conduct electricity without resistance below a critical temperature above absolute zero. The phenomenon of superconductivity was first seen in mercury at liquid helium temperatures. Great interest developed in this area in the late 1980s, when Muller and Bednorz discovered that even ceramic-like materials can exhibit superconductivity. C. W. Chu subsequently found yttrium barium copper oxide (YBCO) to be superconducting above liquid nitrogen temperatures. Indeed, various books are devoted to this subject. > In the following subsections we highlight representative force field applications that have aided the understanding of static and dynamic properties of superconductors. 

Superconductivity was discovered in 1911 by Onnes who was awarded the Nobel Prize for Physics in 1913. Onnes observed that, upon cooling mercury to 4.2 K, its electrical resistance dropped abruptly to zero. Two properties characterize a superconductor on cooling to its critical temperature, a superconductor loses all electrical resistance, and it becomes a perfect diamagnetic material. If an external... 

Superconductivity is a phenomenon characterized by sudden and complete disappearance of electrical resistance in a substance when it is cooled below a certain tempeSrature, called the critical transition temperature, T. Superconductivity was discovered in 1911 by measuring the resistance of solid mercury (Hg) on cooling with a sharp discontinuity in resistance at about 4.2 K (see Fig. 1). In addition to the total loss... 

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