Influence of simultaneous doping of Sb & Pb on phase formation, superconducting and microstructural characteristics of HgBa2Ca2Cu3O8+\delta

We describe three previously unreported superconductors, BaPb3, Ba0.89Sr0.11Pb3 and Ba0.5Sr0.5Pb3. These three materials, together with SrPb3, form a distinctive isoelectronic family of intermetallic superconductors based on the stacking of Pb planes, with crystal structures that display a hexagonal to cubic perovskite-like progression, as rarely seen in metals. The superconducting transition temperatures (Tc) are similar for all - 2.2 K for BaPb3, 2.7 K for Ba0.89Sr0.11Pb3 a...

Thin films of the high-temperature superconductor HgBa$_2$CaCu$_2$O$_{6+\delta}$ have been prepared on SrTiO$_3$ substrates by pulsed-laser deposition of precursor films and subsequent annealing in mercury-vapor atmosphere. The microstructural properties of such films can vary considerably and have been analyzed by x-ray diffraction and atomic force microscopy. Whereas the resistivity is significantly enhanced in samples with coarse-grained structure, the Hall effect shows li...

In the Bi cuprates, the presence of a near 1$\times$5 superstructure is well known. Usually, this superstructure is suppressed by the substitution of lead, but there have been reports of a phase separation in so called {\alpha} and {\beta} phases. This paper shows in high detail time how and why the phase separation develops and what happens to the quasi-1$\times$5 superstructure upon lead substitution. For this purpose, the lanthanum- and lead-substituted single-layered supe...

The enhanced performance of superconducting FeSe0.5Te0.5 materials with added microsized Pb and Sn particles is presented. A series of Pb and Sn added FeSe0.5Te0.5 (FeSe0.5Te0.5 + xPb + ySn; x = y = 0-0.1) bulks are fabricated by solid-state reaction method and characterized through various measurements. A very small amount of Sn and Pb additions enhance the transition temperature (Tconset) of pure FeSe0.5Te0.5 by 1 K, sharpening the superconducting transition and improving t...

Here we study the effect of Ca doping on charge transfer mechanism of polycrystalline YBa2Cu3O7-{\delta} compound. The samples of composition Y1-xCaxBa2Cu3O7-{\delta} (x = 0.00, 0.05, 0.10, 0.20 and 0.30) are synthesized through standard solid state reaction route. Carrier doping is controlled by annealing of samples in oxygen and subsequently in reducing atmosphere. Samples are investigated using resistivity, dc magnetization (M-T) and magnetization with field (M-H) measurem...

We have investigated the effects of lead (Pb) additions (x) up to 40 wt.% (x = 0-0.4) on the structure, electrical properties, and magnetic properties of FeSe0.5Te0.5 superconductor. The samples were prepared by the solid-state reaction method and characterized by various techniques. The parent compound (x = 0) showed the onset temperature Tc onset of 15 K, and zero-resistance temperature, Tc offset of 12 K. The addition of Pb enhances the metallic characteristics of FeSe0.5T...

The effect of Sr chemical pressure on superconductivity was investigated in Hg2(Ba1-ySry)2YCu2O8-d. The samples were synthesized at high pressure-high temperature from y = 0.0 to full substitution, y = 1.0. These Sr-substituted compounds are superconducting, without Ca doping on the Y site, and show an increasing Tc with Sr, reaching 42 K for y = 1.0. A detailed neutron powder diffraction study compares the structural changes induced by this chemical Sr/Ba substitution and th...

In the present investigation, the novel two-step electrochemical process of room temperature synthesis of Hg-1212 superconducting films has been developed and reported first time. Electrochemical parameters were optimized by studying cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry (CA) for the deposition of Hg-Ba-Ca-Cu alloy at room temperature. Current time transient showed progressive growth with hemispheriodal granules, which were then reveale...

This paper is published in Advanced Materials (available at http://www3.interscience.wiley.com/cgi-bin/abstract/113511105/ABSTRACT). It has been withdrawn from the cond-mat preprint archive in order to avoid a violation of the Journal's policy.

The recently discovered FeAs-based superconductors are a new, promising set of materials for both technological as well as basic research. They offer transition temperatures as high as 55 K as well as essentially isotropic and extremely large upper, superconducting critical fields in excess of 40 T at 20 K. In addition they may well provide insight into exotic superconductivity that extends beyond just FeAs-based superconductivity, perhaps even shedding light on the still per...