Abstract: The invention provides certain novel metal oxide materials which exhibit superconductivity at elevated temperatures and/or which are useful in electrode, electrolyte, cell and sensor applications, or as electrochemical catalysts.

Abstract: The invention provides certain novel metal oxide materials which exhibit superconductivity at elevated temperatures and/or which are useful in electrode, electrolyte, cell and sensor applications, or as electrochemical catalysts.

Abstract: The invention provides certain novel metal oxide materials which exhibit superconductivity at elevated temperatures and/or which are useful in electrode, electrolyte, cell and sensor applications, or as electrochemical catalysts. The metal oxide materials are generally within the formulaR.sub.n+1-u-s A.sub.u M.sub.m+e Cu.sub.n 0.sub.w (1)where n.gtoreq.0 and n is an integer or a non-integer, 1.ltoreq.m.ltoreq.2, 0.ltoreq.s.ltoreq.0.4, 0.ltoreq.e.ltoreq.4, and 2n+(1/2)<w<(5/2)n+4, with the provisos that u is 2 for n.ltoreq.1, u is n+1 for 0.ltoreq.

Abstract: The invention comprises a method for determining the hole or electron concentration, transition temperature, ratio T.sub.c /T.sub.c (max), or state of doping of a material capable of exhibiting superconductivity when cooled below its critical temperature, by measuring the thermopower of a sample of the material above the critical temperature of the material and determining from the thermopower the hole or electron concentration, transition temperature, ratio T.sub.c /T.sub.c (max), or state of doping of the material as to whether it is underdoped, overdoped or optimally doped. The sample may be differentially heated and/or cooled to generate a temperature difference across the sample, the temperature difference across the sample measured, the voltage across the sample measured, and the hole concentration or similar determined from the measured temperature difference and the measured voltage. Means for determining the hole concentration, transition temperature, or doping of the material is also claimed.

Abstract: The invention comprises a process of heat treatment to produce a high T.sub.c superconductor with increased flux pinning. A precursor compound is subjected to temperature and oxygen pressure conditions at which the precursor compound decomposes or converts partially or completely to the high T.sub.c superconductor and precipitated non-superconducting compounds which are dispersed through the structure of the high T.sub.c superconductor and which are effective to pin lines of magnetic flux. The precursor compound may or may not itself be a high T.sub.c superconductor. In the YBCO system, 2-4-7 may be converted to 1-2-3 or 1-2-3 to 2-4-7 and flux pinning copper oxides dispersed through the structure, for example, various other transformations are possible.