Impact of sintering temperature and KMnO4 addition on the growth of Bi2212 ceramics

In this study, the highest volume fraction was obtained by the combined effect of KMnO4 doping and different sintering temperatures (840 and 850 °C). Bi2Sr2CaCu2(KMnO4)xO8+δ compounds with x = 0, 0.01, 0.03, 0.05 and 0.07 were prepared by the conventional solid-state reaction method. The phase composition and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and Raman Spectroscopy. The XRD phase study showed that the optimum sintering temperature was 850 °C with a KMnO4 doping concentration of 0.05. With increased doping (x), the texture of Bi2212 became more crystalline, with a grain growth preference along the (00l) direction. It is clear that the rate of formation of the Bi2212 phase is favored by high sintering temperature and addition of KMnO4. The line intensities of the Bi-2212 phase were found to increase significantly with KMnO4 addition up to the critical value of x = 0.01 and the cell structure volume is seen to decrease with increasing doping rate. This may be attributed to inhomogeneities in oxygen concentration This indicates that the sintering temperature has a strong influence on the structural and morphological properties. As reported in the literature, the Raman modes at 489.76 cm-1 and 630 cm-1 are associated with the vibrations of O(3)BiA1g and O(2)SrA1g along the c axis for the Bi-2212 phase. The A1g modes are symmetric for vibrations of Bi, Sr, Ca, Cu, OBi, OSr and OCu along the c axis.