Infield magnetic measurement of K & Rb doped Cu0.5Tl0.5Ba2Ca2Cu3-xRbxO10- δ (x= 0, 1) samples

Abstract

The potassium and rubidium doped sample with a concentration of x=0, 1in CuTl=1223 have been prepared by a two-steps solid-state reaction method. These prepared samples have shown orthorhombic crystal structure in which c-axes length decreases with the doping of K and Rb. A metallic variation of resistivity being dependent on temperature is a typical feature of such samples. The potassium and rubidium doped sample with a concentration of x=0, 1in CuTl=1223 samples have shown the onset of superconductivity around 111.3K, 109.3K, 118.6K, and zero resistivity critical temperature at 99.4K, 98.5K, 103.8K, respectively. In FTIR absorption measurements the apical oxygen mode of type Tl-OA-Cu(2) is softened whereas the apical oxygen mode of type Cu(1)-OA-Cu(2) hardened in potassium and rubidium doped sample with a concentration of x=0, 1in CuTl=1223 samples. The planer oxygen mode is also softened in K and Rb-doped samples showing intrinsic characteristics of K and Rb in the ultimate compound. The SEM analysis have shown that Rb-doped sample is demonstration decrease in voids in the lattice and strong pinning sites. The coherence length in the mixed state of doped CuTl-1223 samples is increasing with the increase in temperature due to enhancement in the density of the vortex line. It is also witnessed in the form of increased London penetration depth = (mc2/4nse2)1/2 in such samples. Despite the decrease in the density of carriers, values of Tc, magnitude diamagnetism and Jc are higher in Rb-doped CuTl-1223 samples demonstrating the importance of soft phonons for superior superconducting properties in such samples. A decrease in the magnitudes of the Hc1 (T), irreversibility field Hirr (T), London penetration depth (), Ginzburg Landau parameter (), and pinning energy per unit length have shown that the population of inadvertent pinning centers is decreased in doped samples.