The influence of WO₃ nano-particle addition on the structural and mechanical properties of Bi_1.8Sr₂Ca_1.1Cu_2.1O_y ceramics

The effect of nano-sized WO₃ (40 nm) addition on the physical and magnetic properties of Bi-2212 superconductors was investigated by X-rays diffraction (XRD), scanning electron microscopy, dc electrical resistivity, magnetic hysteresis loop measurements and Vickers microhardness measurements. XRD observations indicated that the number and type of nonsuperconductor phases changes with increasing nano-sized WO₃ content. With increase in W content the critical temperature decreases and the resistivity value at room temperature for sample W4 significantly increases. In addition, the adding of W into the samples causes a remarkable decrease of the area enclosed hysteresis cycles. The critical current density (J_c) at 10 K of the all W-doped samples was lower than that of the pure sample, indicating that superconductor properties of samples negatively affect when nono-sized W particles enters into the structure. In addition, the obtained microhardness values in this work indicated that the all samples have the typical indentation size effect behavior.