Synthesis, Characterization and Activation energy of Nano-(GO)x/(Cu,Tl)-1234 Superconducting Composites

Comparative investigation of low and high pelletize pressure for (Ag)x/CuTl-1223 nanoparticles-superconductor composites

“…The resistivity verses temperature T ( ) rdata of nano-composites were measured via four-probe system at temperature ranging from 30 K to 300 K. Figure 10 and figure 11 shown the temperature dependent electricalresistivity T ( ) rin the T T o £ £300 K, for (Ag) x /CuTl-1223 nano-Ag-composites, with nanoparticles contents (x = 0.0, 1.0, 1.5, and 2.0 wt%) prepared at low as well as high pelletize pressure, respectively. All synthesized nano-Ag-composites indicates metallic-like nature at high temperature above T c in the normal state, and a superconducting transition state as the temperature decreased below T c [14]. The transition regions are shown in large scale in the inset of figures 10 and 11 to clarify the T 0 , c ( ) and to show how the T c onset was )) = was reported to be approximately 91-98 K, at low-pressure synthesis.…”

“…Figure 5 presents the variation in the percent phase fraction of CuTl-1223 superconductor verses Ag NPs concentration (x = 0, 1.0, and 2.0 wt%) in (Ag) x /CuTl-1223 nano-composites at both low and pelletization high-pressure. The inclusion of silver (Ag) nano-particles along with pelletization high-pressure, restricted the formation of additional phases, and maintained the crystal structure of main CuTl-1223 matrix [14]. It was noticeable from figure 5 that volume fraction determined for (Ag) x /CuTl-1223; x = 2.0 wt% is the optimum level at both low and high pressure, implying the distinct improvement in the superconductivity.…”

“…The mechanism for the increase of U o at ambient pressure synthesis is defined by the presence of Ag NPs between the grains, which can serve as intergrain connectivity [23,24]. Additional argument, the rise in activation energy could explain the interaction of mobile carriers with nano-(Ag)-particles at inter-grain sites [14].…”

“…The activation energy U o ( )of (Ag) x /CuTl-1223 nano-composites with contents (x = 0.0, 1.0, 1.5, and 2.0 wt%), processed under high-pressure observed from 0.023 eV to 0.038 eV, as displayed in the (inset) of figure 15, respectively. The reason for the increase in 'U o ' under high pressure synthesis is due to the metallic Ag NPs present in the inter-grain sites by filling voids, reduced pores, and strengthened inter-grains weak-links by compressing the grains together, resulting further increasing the activation energy of nano-(Ag) x /CuTl-1223 composites [14,29]. Table 5 indicates the calculated values of activation energy for the (Ag) x /CuTl-1223 samples prepared at low and high-pressure of 0.202 GPa.…”

“…The table 5 clearly demonstrates that the activation energy increases at high pressure over low pressure, which is verified by SEM, XRD, and resistivity verses temperature T ( ) rdata. Therefore, the addition of metallic nano-(Ag)-particles and a high pelletize pressure can reduced defects density and improve weak-links which promote better superconducting properties of various HTSCs [5,6,14,18,22,29].…”