Systematics of the physical properties of compounds

A study of systematics was carried out on compounds by replacing Ca with Nd ions. The dependence of on structural parameters, oxygen content and hole carrier concentration was observed as a function of Nd concentration. X-ray diffraction patterns show the single phase (2212) nature of the samples. Lattice parameters have been calculated and the results show an increase in a-axis with a simultaneous decrease in c-axis. Oxygen content was estimated from the iodometric titration method and was shown to increase with x. The measured (0) and (onset) obtained from resistivity and susceptibility data were found to decrease with increasing Nd concentration. Vacuum annealing was found to improve . The materials exhibited superconductivity in the concentration range, and for higher concentrations of Nd they became semiconducting. In the semiconducting region, the conduction was found to be due to the 3D variable range hopping (VRH) mechanism. The initial susceptibility dM/dH relating to the superconducting volume, has shown a continuous decrease with increasing Nd concentration. The hole carrier concentration was computed from thermoelectric power data and found to decrease with increasing Nd ion concentration. The results are presented and discussed in comparison with those obtained from system.