High temperature superconductors ( BSSCO & YBCO)
People Involved:I. Abdolhosseini Sarsari, H. Salamati, P. Kameli
We have studied the effect of precursor powder size on the microstructure and intergranular behavior of polycrystalline (Bi,Pb)2 Sr2 Ca2 Cu3 Oy (Bi-2223) superconductors. Polycrystalline Bi-2223 superconductors were prepared from the powders with different milling times. The XRD results show that by decreasing precursor powder size, the Bi-2223 phase fraction increases in sintered samples. It was found that the grain size and grain connectivity improved by decreasing precursor powder size. The analysis of temperature dependence of AC susceptibility near the transition temperature (Tc ) indicates that, by decreasing the precursor powder size in the Bi-2223 system, the intergranular critical current density increases. We have estimated the effective volume fraction of the grains in the framework of the Critical State Model based on our experimental results. This estimation shows, the effective volume of the grains increases by decreasing precursor powder size.
Fig. Temperature dependence of the (a) real and
(b) imaginary parts of the AC susceptibility for all samples in AC field
amplitude of 400 A/m at a frequency of 333 Hz.
Fig. Plot of imaginary vs real components of
AC susceptibility in AC field amplitude of 200 A/m at a frequency of at f = 333 Hz for all samples.
A systematic study of the magnetoresistance of Bi1.66Pb0.34Sr2Ca2ÀxMgxCu3Oy (x = 0, 0.2 and 0.4) samples has been studied within the thermally activated flux creep model. Under lower applied magnetic field, the calculated flux pinning energies, U(H) and intergranular upper critical field, Hc2 decreases by increasing the amount of Mg. The higher electronegativity of Mg in the unit cell promotes more intake of oxygen in the material, and the grain boundaries are in more over-doped regime. These over-doped regions reduce the intergranular coupling and increases weak link behavior of Mg doped samples.
Fig: The Arrhenius plot of the resistivity of sample B in the range 0–1T.
To learn more:
The Effect of Precursor Powder Size on the Microstructure and Intergranular Properties of (Bi,Pb)2 Sr2 Ca2 Cu3 Oy Superconductors
Ismaeil Abdolhosseini, Parviz kameli, and Hadi Salamati
Japanese Journal of Applied Physics Vol. 47, No. 6, 2008, pp. 4505–4510
Thermally activated flux creep in the Bi1.66Pb0.34Sr2Ca2ÀxMgxCu3Oy superconductors
P. Kameli, H. Salamati, I. Abdolhosseini, D. Sohrabi
AC susceptibility study of Bi1.66Pb0.34Sr2Ca2−xMgxCu3Oy (x = 0, 0.2 and 0.4) superconductor systems
P. Kameli, H. Salamati, I. Abdolhosseini