Propriedades estruturais, microestruturais e supercondutoras de Ca0,5LaBa1,5[(CuO)1-x(MS)x]3O4-Â com M=Zn e Ni

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

Since their discovery doping and substitution studies of high temperature superconductors (HTSC) oxides have attracted attention of many researchers. These studies have contributed to the understanding of the superconductivity in these compounds. Studies of 3d -metal doping of HTSC have shown that it is possible to obtain an improvement in the critical current density of these materials, even with a depreciation of the critical temperature (Tc). In this work we study the effect of substitution of CuO by MS ( M = Zn and Ni) in the compound Ca0,5LaBa1,5Cu3O7−δ . Samples of the desired composition were prepared by solid-state reaction starting from high purity sulfites and oxides. The samples were characterized structurally by X-ray diffraction (XRD) with Rietveld analysis, microstructurally by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) and physically through transport and magnetic properties. XRD diffractograms show that the samples presented a tetragonal structure with independent of the doping concentration. SEM micrographs indicate that the samples presented rectangular shape and size that decrease with increasing dopant concentration. EDS analysis reveals that both NiS and ZnS are incorporated to the compound and also the presence of small amount of impurities in the samples. Eletrical resistivity, magnetization and ac susceptibility measurements show a severe depreciation of Tc in comparison with ZnO and NiO doped system

ASSUNTO(S)

supercondutividade supercondutores de alta temperatura crÃtica edx fisica anÃlise de rietveld microscopia eletrÃnica de varredura

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