Superconducting ceramic

The electronic theory of metallic superconduction was established by Bardeen, Cooper and Schrieffer in 1957, but the basis of superconduction in the oxides remains a battleground for rival interpretations. The technology of the oxide ( high-temperature ) superconductors is currently receiving a great deal of attention the central problem is to make windable wires or tapes from an intensely brittle material. It is in no way a negative judgment on the importance and interest of these materials that they do not receive a detailed discussion here it is simply that they do not lend themselves to a superficial account, and there is no space here for a discussion in the detail that they intrinsically deserve. 

Superconductivity research has reached out to other branches of physics and materials science perhaps the strangest example of this is a study by Keusin-Elbaum 

This is by way of preliminary to an outline account of the genesis of the magnetic ferrites in the Philips Laboratory, before, during and just after World War ll. The presiding spirit was Jacobus Louis Snoek (1902-1950), a Dutch physicist whom we 

The intellectual stages baldly summarised here, and especially Neel s seminal role, are set out fully in an excellent historical treatment (Keith and Quedec 1992). 

Casimir, in his memoirs, mentions that the first Philips representative to visit Brookhaven gave the design team a set of guaranteed magnetic specifications which were too conservative, and Brookhaven was pleased to find that the material was better than they had been led to expect. Casimir reckons that Brookhaven must have concluded that Philips was dumb but honest . 

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Phase transitions are involved in critical temperature thermistors. Vanadium, VO2, and vanadium trioxide [1314-34-7] V2O3, have semiconductors—metal transitions in which the conductivity decreases by several orders of magnitude on cooling. Electronic phase transitions are also observed in superconducting ceramics like YBa2Cu30y but here the conductivity increases sharply on cooling through the phase transition. 

In addition, the copper industry s market development activities have resulted in appHcations such as clad ship hulls, sheathing for offshore platforms, automotive electrical systems including electric vehicles, improved automobde radiators, solar energy, fire sprinkler systems, parts for fusion reactors, semiconductor lead frames, shape memory alloys, and superconducting ceramics (qv) containing copper oxides. 

High temperature strength, 13 470 High temperature superconducting ceramic, 23 836-851... 

Assigning oxidation states of —2 to oxygen, + 3 to yttrium and + 2 to barium, one would obtain an oxidation state 7/3 for copper when jc = 0. The non-integer oxidation state of copper is interpreted as if 2/3 of the ions are present as Cu2+ and 1/3 as Cu3 +. This mixed-valent composition seems to be determinant for the occurrence of superconductivity. In fact, as noted in Table 1, all the superconducting ceramic oxides contain Cu in a non-stoichiometric composition. 

The re arch in catalysis is still one of the driving forces for interface science. One can certainly add to the topics of interface physics the whole new field of interface problems that is about to spring out of the new high Tc superconducting ceramics, i.e. the fundamental problem of the matching of the superconducting carriers wave-functions with the normal state metal or semiconductor electron states, the super-conductor-superconductor interfaces and so on, as well as the wide open discovery field for devices and applications. 

Gabovich, A.M., Moiseev, D.P. and Shpigel , A.S., Anomalous Behavior of the Thermodynamic Properties of the Superconducting Ceramic BaPbj xBixOs. Sov. Phys. Solid State 24(6) 1071 (1982). 

Evaporative decomposition erf solutions and spary pyrolysis have been found to be useful in the preparation of submicrometer oxide and non-oxide particles, including high temperature superconducting ceramics [819, 820], Allowing uniform aerosol droplets (titanium ethoxide in ethanol, for example) to react with a vapor (water, for example) to produce spherical colloidal particles with controllable sizes and size distributions [821-825] is an alternative vapor phase approach. Chemical vapor deposition techniques (CVD) have also been extended to the formation of ceramic particles [825]. 

In searching for new superconducting ceramics, there are guidelines that may be followed,33 some of which are as follows ... 

Until 1986 many experiments were carried out using metals and alloys. However, in 1986 Georg Bednorz and Alex Muller, two researchers of the IBM laboratory in Ruschlikon near Zurich, published an article in the Zeitschrift fur Physik in which they announced that they had made a superconducting ceramic material. It turned out to be a compound made of barium, copper, lanthanum and oxygen, which became superconducting at 35 K. They were awarded the Nobel prize for this discovery. After this, superconductors developed rapidly, at least as far as critical temperature is concerned. 

Floating superconducting ceramic disk (by ECN, Petten, Netherlands). 

Bazuev GV, Kurbatova LD / -Diketonate precursors for superconducting ceramics 1993 [55]... 

Routes to monomeric , mononuclear , monolanthanide alkoxides, enolates, siloxides and aryloxides - an expanded title which will put the scope of the article in a more concrete form. The synthesis of mononuclear alkoxides, in particularly homoleptic derivatives [1], was decisively stimulated by the discovery of high temperature superconducting ceramics based on YBa2Cu307<, where yttrium represents the lanthanide elements [2]. The support of volatile and highly soluble molecular precursors is a prerequisite for synthesizing thin films of these materials by means of MOCVD [3] and sol gel processes [4], respectively. More recently, lanthanide alkoxide reagents became established in... 

Since then there has been the totally unexpected breakthrough with the superconducting ceramics operating comfortably at liquid nitrogen temperature (77 K), and stimulating intensive R D efforts in the US, Japan and Europe. 

A significant step in the history of the HTSs was the discovery in 1966 of superconductivity in the oxygen-deficient perovskite SrTi03 5, containing some barium or calcium substituted for strontium. Although the Tc value was very low (0.55 K), in retrospect it can be seen as the first superconducting ceramic. In 1979 a Tc of approximately 13 K was discovered for BaPb075Bi025O3, which also has the perovskite structure. 

Raman spectroscopy has played a significant role in the characterization of electrical conductors, some of which have become superconductors. There are three general classes of compounds that have been investigated using Raman spectroscopy. These are the high- Tc superconducting ceramics the low-7 ... 

A magnet is levitated over a superconducting ceramic immersed in liquid nitrogen. 

The now-famous formula for the first superconducting ceramic lanthanum-barium-copper-oxide. 

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