Anomalous behavior of Bi-system superconductors in the normal state and their correlation with superconductivity

Our experiments show that Bi-system samples exhibit two parameter anomalies and two heat and weight anomalies in normal state. For the samples of (Bi,Pb)(2)Sr2CaCu2Oy, as the superconducting volume is over 65%, two anomalies of heat and weight at about 400 degrees C and 750 degrees C, respectively, are significantly observed; as the superconducting volume of the samples is under 50%: or the samples are non-superconducting the anomaly at about 400 degrees C is hardly observed. For the samples of (Bi,Pb)(2)Sr2Ca2Cu3Oy, as the superconducting volume is over 65%, they exhibit two anomalies at about 300 degrees C and 750 degrees C, respectively; as the superconducting volume is under 50%, the anomaly at about 300 degrees C disappears, and as the samples are non-superconducting it shows a quite opposite behavior to the superconducting samples at about 300 degrees C. We develop a computer program based on calculation of lattice energy to simulate the experimental results, it is found that the change of the lattice energy can well explain the anomalous phenomena in the samples.Physics, AppliedSCI(E)EI