Preparation and physical properties of (Bi_(1.8)Pb_(0.4))Sr_2Ca_2Cu_3O_(10+δ) superconductors impregnated with mangano(ll)undecatungstosilicate nanomaterials

摘要

In this study, the effects of (K-6[(H2O)MnSiW11O39]center dot 21H(2)O, {MnSiW11}) polyoxometalate, with an average particle size of 48.46 nm, on (Bi1.8Pb0.4)Ca2Sr2Cu3O10+delta (Bi,Pb)-2223, superconducting samples, were investigated. Samples of type {MnSiW11}(x)(Bi1.8Pb0.4)Ca2Sr2Cu3O10+delta, 0.00 <= x <= 0.20 (wt%) were prepared using the conventional solid-state reaction technique. Manganese-containing polyoxometalates are considered as an attractive class of inorganic nanomaterials, because they have multiple oxidation states and many unpaired electrons. Consequently, the microstructure, morphology, optical and magnetic properties of the prepared {MnSiW11} nanoparticles were determined by powder X-ray diffraction (XRD), transmission electron microscopy, Fourier transform infrared spectroscopy and magnetic hysteresis loop measurements, respectively. The bulk of superconducting samples was characterised by XRD, scanning electron microscopy and energy dispersive X-ray spectroscopy. The XRD analysis showed that the addition of small amounts of {MnSiW11} nanoparticles improves (Bi,Pb)-2223 phase formation significantly. The lattice parameters (a and c) of (Bi,Pb)-2223 phase did not change with the addition of nanoparticles. Furthermore, the superconducting transition temperature (T-c) was determined from dc electrical resistivity (rho - T) as a function of temperature measurements. T-c was enhanced as x increased up to x = 0.12 wt%, then decreased gradually with a further increase in the concentration of nanoparticles. The (E) measurements were conducted at 77 K with 1 mu V/cm. It showed that the critical current density (J(c)) of the samples increased from about 301.9 to 728.4 A/cm(2) as x increased from 0.00 to 0.12 wt%. The suppression in T-c and J(c) for x > 0.12 wt% samples may be due to the decrease in the volume fraction of a high-T-c (Bi,Pb)-2223 phase and the increase of weak links connectivity among the grain boundaries.