Surface properties, high-temperature superconductors

For bulk dielectrics, a dielectric resonator can be formed by a cylindrically shaped piece of dielectric material. Dielectric thin films are more difficult to investigate, in particular when the loss tangent is very small. Planar resonator techniques as well as specially designed dielectric resonators can be used to examine their properties. For high-temperature superconductors both dielectric resonators and planar resonators represent an ideal tool to examine their surface impedance values. 

The (0001) surface of sapphire (a-alumina, corundum) is one of the most widely used substrate for the growth of metal, semi-conductor or high-temperature superconductor thin films. It is also used as a substrate in silicon on sapphire (SOS) technology. Moreover, its initial state is known to play a role on the overlayer properties [50]. 

Oleg Petrii and Galina Tsirlina describe a wide range of oxide high temperature superconductors, their electrochemical synthesis, their properties and degradation mechanisms, and analytical methods for the characterization of their surfaces and volumes. The recent advances in this field open new possibilities for elucidating the interface and charge-transfer at extremely low temperatures. 

Surface and Interface Properties of High-Temperature Superconductors... 

Bonn, D.A., and W.N. Hardy, 1996, Microwave surface impedance of high-7 superconductors, in Physical Properties of High Temperature Superconductors, VoL I, ed. D.M. Ginsbeig (World Scientific, Singapore). 

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