Copper-oxygen bonding

In one case pulse-radiolysis techniques were employed to study the effect of pressure on such reactions. The oxidation of [Cu lphenhl by dioxygen proceeds via a Cu1—02 transient in which a copper—oxygen bond is formed, followed by the rapid formation of [Cun(phen)2] and 02 (110). This process is characterized by a AV of 22 cm3 mol1, which is close to the reaction volume expected for the binding of dioxygen. 

Even though the yttrium and barium (and any of the other elements that show up in the various mixes) are important—they donate electrons for Cooper pairing and may simply act as glue to hold the structure together—it is the copper-oxygen bond that seems to form the hot wire of this rig. Since the distances between the copper and oxygen atoms in the layers are not great, electron transfer, and thus the flow of electric current between them, occurs fairly easily. 

Table 2. Copper-oxygen bond-lengths Rg and Rj involving off-z-axis ligands, R, —Rs and T = Rs/R ...

In any application, the new oxide superconductors will have to coexist in intimate contact with other materials. However, the copper-oxygen bonds common to all presently known oxide superconductors with Tc above 40K are relatively weak. This means that elements that form much stronger bonds with oxygen, such as Si, will be chemically unstable when in contact with the copper-oxide superconductors. In this paper, we will establish procedures and guidelines that will enable workers to choose materials that will not react chemically with the oxide super-conductors. These should enable researchers working in all applications areas to avoid unnecessary empirical searches for suitable substrate or host materials by eliminating the most thermodynamically unfavorable choices. In particular, we have determined which of the elemental metals should be most stable in contact with the copper-oxide semi-conductors, and examined schemes for integrating these superconductors into Si devices. 

---