Amorphous superconductors

In metallic amorphous solids the observation of the linear specific heat term is obscured by the large electronic contribution. It seems possible to detect it, though, in amorphous superconductors when the measurements are extended to temperatures sufficiently below the superconducting transition temperature 7. Such measurements were reported by Graebner et al. (1977) on amorphous ZrPd. In amorphous rare earth base materials the presence of such low-lying excitations were found in LaQ7QCuQ3o by Daudin (1981) by means of thermal conductivity studies below 7J,. 

The gradient value is about one-tenth as large as that (about 2.0 T/K) (Johnson 1978 and Inoue et al. 1981) for amorphous superconductors in Zr-, Nb- and Mo-based alloys. This significant difference is thought to reflect the difference in electrons contributing to superconductivity, i.e., heavy d-electrons for the M-based amorphous alloys and s- and p-electrons for the Al-based amorphous alloys. 

The materials described below include diamond, cubic BN (the hardest material next to diamond), SrCu02 (from which two types of superconductors have been derived by compositional modification), MgSiOs (a geologically interesting perovskite), and Ge02 (amorphized underpressure at room temperature). 

Case d Amorphous balloons, Le., hollow amorphous spherical particles several microns in diameter, were observed in some cases. They are characterized by various expansion degrees. We observed that the balloons diameter increases with CO2 density. Examples of this morphology were observed during the study of the precipitation of Yttrium acetate (YAc) (superconductor precursors) from DMSO at 120 bar and 40 °C (Figure 3) and of Cefonicid (antibiotic) from DMSO at 150 bar and 60... 

D.M. Smyth, Defects and structural changes in perovskite systems from insulators to superconductors. Ciyst. Latt. Def. Amorph. Mat., 18 (1989) 355-375. 

As the understanding about the states of matter became deeper, people had found that in addition to the above mentioned well-known three states, there exist other states of matter in nature, such as the plasma state, amorphous solid, liquid crystal state, superconductor, neutron state, etc. Among them the liquid crystal state is the subject of this book. 

The citrate gel method was developed by Marcilly et al. (99) and can be illustrated by the synthesis of the ceramic superconductor YBa2Cu307 (100). Nitrate solutions of Y, Ba, and Cu were added to citric acid solution, and the pH was kept at 6 to prevent precipitation of barium nitrate. Heating the solution at 75°C in air produced a viscous liquid containing polybasic chelates. Further heating at 85°C in a vacuum produced an amorphous solid that was pyrolyzed in air at 900°C to produce a crystalline powder. 

It was shown in fig. 38 that the gradient of Hd in the vicinity of Tc for Al-La-M amorphous alloys is about 10% of that (Johnson 1978, Inoue and Masumoto 1981) of amorphous alloy superconductors in M-based systems. Equation (1) indicates that the gradient is dependent on pn, N(Ef) and A. One of the reasons for the extremely low gradient values is probably the low electrical resistivities which are about 50% of those (200 to 300pQcm) (Rao 1983, Mizutani et al. 1989) for M-based amorphous... 

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