Studies on the Composite System of Bi-2212 Glass Ceramic and MgB2 Superconductors
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The composites of glass ceramic Bi-2212 and MgB2 superconductors were prepared at ambient conditions. The transmission electron microscopy images of the composite samples illustrate the presence of glass ceramic inclusions in bulk MgB2. Temperature-dependent magnetization of the composite samples shows two superconducting transitions: one at 80 K corresponding to the Bi-2212 phase and a second one at 39 K corresponding to the MgB2 phase, suggesting that the two superconducting phases are separated with clear boundaries. The critical current density (J c) and pinning force values are increased in composite systems by an order of magnitude compared to that of individual samples. The pinning mechanism in the composite sample is the same as in the matrix phase. Reduced field maxima (h max) are observed at 0.15 for composite samples. A low value of h max for composite samples indicates the random orientation of grain boundaries and repulsive pinning force in the composite samples.
KeywordsHigh-Tc superconductors Glass ceramics Composite system Surface morphology Critical current density Pinning mechanism
M. Padmavathi acknowledges University Grant Commission (UGC), India, for providing financial assistance under Basic Science Research (BSR) fellowship.
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