ABSTRACT This work reports the mechanical properties of ab and a(b)c-plane of melt textured Y1-xPrxBa2Cu3O7-δ (x = 0.00 and 0.05) superconductor. Y1-xPrxBa2Cu3O7-δ have been prepared by top seeding technique. Hardness and elastic modulus were obtained by instrumented indentation. Independent of the plane, the hardness values were around 5.0-7.5 GPa. Young’s modulus was approximately the same for both samples for ab-plane, around 132 GPa at the deepest tip penetration. However, for a(b)c-plane, the value of Young’s modulus for x = 0.05 is higher than observed for x = 0.00 sample.

The substitution effects of Fe ion on the structure of the intermetallic Bi3Ni1-xFex (0 ≤ x ≤ 0.10) superconductor were studied. The morphology of samples consists of an inhomogeneous laminar slab-like microstructure. The main phase corresponds to Bi3Ni1-xFex with an orthorhombic structure (Pnma), but with very small quantities of impurities of BiNi and Bi as revealed by X-ray diffraction. SEM and AFM reveal that the Bi3Ni1-xFex phase consists of two regions. One region is Bi richer and Ni and Fe poorer than the other region. Raman spectroscopy revealed two phonon modes at room temperature. No significant changes were observed in the spectra with Fe doping and in different regions of the Bi3Ni1-xFex phase. Superconductivity is observed below a transition temperature TC = 4 K and regardless of iron doping.

We studied the effect of superconducting fluctuations on the electrical conductivity of granular samples of Y1 - xPr xBa2Cu3O7-delta superconductors, with x = 0.01, 0.03, 0.05, 0.07 and 0.10. Samples were prepared by the standard solid-state reaction technique, with two different types of calcination process, in air at 900 ºC ( x < 0.07 ) and in vacuum at 850 ºC ( 0.05 < x < 0.10 ). For the samples prepared in air, our results revealed a splitting of the bulk transition, denoted by T C1 and T C2, besides the coherence transition. It was observed fluctuation regimes above the highest transition ( T C1 ) and the lowest transition ( T C2 ). For the samples calcinated in vacuum and high concentrations of Pr, changes were observed in the critical region with chemical substitution of the Pr ion for the Y ion. In the regime of approach to the zero resistance state it was observed an occurrence of a coherence transition for all concentrations of praseodymium.