Large Jc Enhancement of Bi-2212 Ceramics by Triple Doping of Li, K, and Na in Bi1.8-x(Li,Na,K)xSr2Ca1.1Cu2.1Oy (x=0.05, 0.1, and 0.25) Composition

The samples with compositions of Bi1.8-x(Li,Na,K)(x)Sr2Ca1.1Cu2.1Oy (x = 0.05, 0.1, 0.25) were prepared by the solid-state reaction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and DC magnetization measurements. XRD data indicates that all samples have an ideal ratio of Bi-2212 phase; moreover, some impurity phases such as Bi2CaO4 and Bi4Sr4CaCu3O4 are observed to disappear in the maximum alkaline-doped sample (x = 0.25). SEM observations have shown that, with the increase in the amount of alkaline-doped elements, the grain sizes grow significantly. The highest onset superconducting transition temperature obtained from M-T data belongs to the alkaline-doped (Na, K, and Li) samples at high contents (x > 0.05). It has been found that the sample with x = 0.25 (Na, K, Li) has the largest magnetic hysteresis loop, indicating that high level of triple alkaline element doping positively affects the superconductivity properties of the Bi-2212 phase due to the better intergranular coupling. In addition, Bean's critical model has been used for determining the critical current density. It has been found that maximum J(c) of 141.42 x 10(4) A/cm(2) at H = 1 kOe and T = 15 K is achieved in the x = 0.25 alkaline-doped sample, which is higher than the pure samples obtained by the same initial conditions in literature.

Automated summary

By preparing samples with different contents of alkaline-doped elements in the Bi-2212 phase, it was observed that high levels of alkaline element doping can improve the superconducting properties of the samples and affect the intergranular coupling. Analysis through XRD and SEM revealed that with an increase in the content of alkaline-doped elements, the grain sizes of the samples significantly increased.