The metallurgical enhancement of type II superconductors

Abstract

Contents 1. Introduction . 1.1. Applications of type I1 superconductors 1.2. Properties required of commercial superconductors 2. Critical temperature . 2.1. BCS theory . 2.2. Matthias rules . 2.3. Theory of McMillan. . 2.4. Ternary A15 compounds . 3.1. Type I1 superconductivity. . 3.2. Effect of normal state resistivity . 3.3. Factors determining normal state residual resistivity 3.4. Paramagnetic limitation of upper critical field 4.1. Introduction . 4.2. Properties of the flux lattice 4.3. Flux flow. 4.4. Flux creep . 4.5. The critical state . 4.6. Microstructure and flux pinning. 4.7. Mechanisms of flux pinning .

Flux vortices and transport currents in type II superconductors

“…A similar mechanism has also been proposed to explain the peak e ects which sometimes occur when pinning is caused by dislocation cell structures Witcomb 1972). Figure 66 shows a cell structure occurring in a sample of deformed Nb±50%Ta (Coote 1970).…”

“…A possible explanation of these results is that the magnetization is determined by¯ux jumps, which will occur at di erent ®elds at di erent temperatures. The subject of¯ux jumps and instabilities in the critical state has recently been reviewed by Dew-Hughes (1972).…”

“…We shall for the main part restrict our discussion to experiments that can be subjected to a quantitative analysis, except for situations where no quantitative work has been done. Dew-Hughes (1971) gives an excellent general survey of the recent literature on pinning. Very comprehensive reviews have also been given by Livingston and Schadler (1964) and by Dew-Hughes (1966).…”

“…A second di culty lies in the fabrication of the material into a suitably stable form. We shall not consider this question here, the subject of stability has been recently reviewed by Dew-Hughes (1971).…”

“…For a more general introduction to the subject the reader is referred to the reviews by Livingston and Schadler (1964) and , and the book by St James et al (1969). More recently, Dew-Hughes (1971) has given an excellent comprehensive review of the subject.…”