Low-Temperature Effects in Electrochemical Systems with High- T _c Superconductors

Abstract

Low-temperature electrochemical measurements were carried out on interfaces between different polycrystalline high-Tc superconductors (YBa2Cu3O7-δ with 0 ⩽ δ ⩽ 0.5, YBa2Cu3(1-x)Zn3xO7-δ with 0 ⩽ x ⩽ 0.06, Tl2Ba2CaCu2O8, Tl2Ba2Ca2Cu3O10) and Ag β′′-alumina as a solid electrolyte. By using a special transient routine, cell currents were measured vs. time at a constant potential. From the d.c. limits of the transients, a significant increase of the current is observed around Tc which cannot be explained by a specific property of the solid electrolyte. This effect must be correlated to Cooper pairs changing the electrochemical double-layer structure and possibly penetrating the energy barrier at the interface HTSC/solid electrolyte. The results are interpreted as an enhancement of the electrode kinetics or a proximity effect.

Liquid Phase Electrochemistry at Ultralow Temperatures

“…Tremendous advances in the synthesis of high-temperature superconductors have pushed superconducting critical temperatures (To) above that of liquid nitrogen (-196~ (27, 28). There are no reports on electrochemistry at these new materials in fluid electrolytes at temperatures below their Tc values, but interesting electrochemical effects have been observed at Tc in experiments using solid electrolytes (29)(30)(31). Use of a suitably low temperature fluid electrolyte would improve contact to the superconducting electrode interface (as compared to solid-solid contacts) and could potentially provide access to a greater range of electrochemical reactions and experimental techniques to study the electrochemistry of superconductor electrodes such as YBa2Cu~O7 (T~ = -180~ Bi2Sr2Ca2Cu3010 (Tc = - 163~ and T12Ba2Ca2Cu3010 (To = -148 ~ in their superconducting states.…”

Electrochemistry of high-temperature superconductors. Challenges and opportunities

“…To conduct electrochemical measurements by using high-Tc electrodes at temperatures below 120 K, a number of formidable technical problems must be overcome. Lorenz and co-workers (28)(29)(30)(31) developed the first successful strategy by using solid electrolyte systems such as Agdoped p"-alumina in contact with a variety of high-Tc ceramic samples. Following potential step excursions, the quasi -dc limits of the resultant current flow across the superconductor-electrolyte interface were monitored as a function of temperature.…”

“…More recent results (31) acquired by using electrochemical impedance spectroscopy with RbAg4I6 / YBaaCugO^* assemblies suggest that both the interfacial charge-transfer resistance and the double-layer capacitance values are slightly reduced at temperatures very close to Tc. Superconducting quantum electrochemical phenomena are thought to be responsible for such effects (28)(29)(30)(31).…”

Electrochemistry of High-Temperature Superconductors

“…More recent results (31) acquired by using electrochemical impedance spectroscopy with RbAg4I5 / YBa2Cu307_4 assemblies suggest that both the interfacial charge-transfer resistance and the double-layer capacitance values are slightly reduced at temperatures very close to T". Superconducting quantum electrochemical phenomena are thought to be responsible for such effects (28)(29)(30)(31).…”