Effects of Heat Treatment Temperature on Phase Formation and Properties of Bi-2212 Spray Pyrolysis Powder

Bi2Sr2CaCu2Ox(Bi-2212) primary powder was prepared by spray pyrolysis method. The effect of heat treatment temperature on powder phase formation and properties was studied. The mass loss and phase transformation of the primary powder were analyzed by TG-DSC, the phase composition of the powder was analyzed by XRD, the microstructure of the powder was observed by SEM, and the superconducting physical properties of the samples were determined by the magnetization method. It is found that at 535-570 degrees C, the nitrate residues in the primary powder of spray pyrolysis gradually decompose; the Bi-2201 phase is formed at 605-640 degrees C; when the temperature reaches 775 degrees C, the Bi-2212 phase begins to form. With the increase in heat treatment temperature, the crystallinity of the powder continues to increase, and the content of Bi-2212 phase first increases and then decreases. The best phase-forming sintering temperature is 860 degrees C. In addition, through the in-depth analysis of the DSC curve and the M-T curve, it is found that the schedule of low-temperature pre-decomposition at 640 degrees C followed by high-temperature phase-forming sintering at 860 degrees C can further improve the quality of the powder.