Critical temperature , for superconductivity

Fig. 8. Critical temperatures for superconductivity, Tc, and for antiferromagnetic ordering, Tn, for RNijI C compounds with R = Lu, Tm, Er, Ho, Dy, Tb and Gd. DG is the de Gennes factor, g the Land factor and J the total angular momentum of the /t3+ Hund s rule ground stale. The straight lines represent rough linear...

Nanocrystalline materials comprising sub-100 / metal particles, when compressed to 50% of their bulk density, show properties (specific heat, thermal conductivity, saturation magnetization and critical temperature for superconductivity) provocatively different from those of their crystalline or glassy counterparts.(48) It is well known that the interfaces of mechanically reduced composites are effective in interacting with dislocations and with flux lines in superconducting composites. Precursor materials for the preparation of ultrafine filamentary composites can also be imagined. Here the combinations of interphasial boundaries and dislocations can... 

The second example is also from solid state physics. For many decades top physicists did advanced work on superconductivity, but in spite of their sophisticated theories they were unable to make materials having a critical temperature for superconductivity in excess of 23 K. The recent successes in constructing high-critical temperature superconductors were not the result of theoretical prediction but of laboratory work, done by solid state chemists with the wrong guidelines. 

The quest for a room temperature superconductor has spurred the development of thousands of compounds incrementally driving the critical temperature for superconduction to higher values. Table 3.21 shows various superconducting materials with corresponding... 

Superconducting only in thin films or under high pressure in a crystal modification not normally stable. Critical temperatures for those elements from [32, Chapter 12]. 

Figure 5. Phase diagram for Nj =2 quark matter in the NCQM. The critical temperature for color superconductivity (2SC phase) can be high enough for this phase to reach close to the tricritical point which shall be explored in future heavy-ion collision experiments.

Molecular superconductors are of more immediate practical interest. Experimental evidence indicates superconductivity is incipient at 30 K, a temperature above the critical temperature for other known materials. Superconductors have a major potential use in providing two distinguishable states associated with tunneling of electron pairs through a... 

Table I. Superconducting Critical Temperatures for the Samples Prepared in This Study as Determined by Resistivity vs.

Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials when cooled below some critical temperatures Tc- Superconductivity attracts attention of physicists and engineers because of prospects of its applications in industry. The matter is of research applications, defense and space, instruments for science and medicine, machine tools, materials processing, transportation, and energy. 

Technique for increasing the critical temperature of superconducting materials. Patent application no. 07/626,723. Application filed on December 12, 1990. 

Fig. 6. Log-log plot of the applied magnetic field H vs. (l-T IT ), where T is the irreversibility temperatiuE and Tc is the superconducting critical temperature for Smi jsCej i5Cu04 j,. The solid lines represent least-squares fits to the data. From Ahnasan et al. (1991).

Fig. 45. Critical temperatures and superconducting volume fractions in YBa CUjOj and TmBa CUjOj. (a) Critical temperatures triangles and squares for YBa CujOj at the midpoint of the superconducting transition (Graf et al. 1990) solid circles for TmBa2Cu30j j at the onset of the transition (Bakharev et al. 1994). (b) Superconducting volume fractions triangles and squares for YBa CojOj., (Graf et al. 1990) solid circles for TmBa2Cu30j (Bakharev et al. 1994) stars indicate results from the Gd " EPR intensity (Pekker et al. 1991, Rockenbauer et al. 1992, see eq. 300).

Critical Temperature of Superconductivity. Atypical value for pure titanium is 0.40 0.04 K (B.W. Roberts, Properties of Selected Superconducting Materials, 1978 Supplement, NBS Tfechnical Note 983). Critical temperatures as high as 0.56 K have been re-... 

Calculated values of critical temperature for the set of studied compounds are presented in Table 27.1. As it can be seen, the values of Tc for transition into antiadiabatic state are in a good agreement with corresponding experimental values of Tc for superconducting state transition of particular compounds [3,47,70]. 

Table 27.1 Calculated values of critical temperature for transition into antiadia-batic state (Tc-theor) and experimental values of critical temperature for transition into superconducting state (Tc-exp)...

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