Role of silver addition on mechanical and superconducting properties of high-Tc superconductors

Nano-platinum additives ball milled with hollow carbon spheres for mechanical tensile promotion of 2212- Pb1+x(HCNs/Pt)xBiSr2CaCu2O8 superconductor

In the present investigations platinum nano-particles in range of ≤ 20 nm were carefully ball milled with nominal composition of hollow carbon nano-spheres to apply as a softener ductile mechanical tensile promoter for 2212-PBSCCO superconductor. The samples with general formula Pb1+x(HCNs/Pt)xBiSr2CaCu2O8 where (x = 0.1,0.2 and 0.4 mol) were carefully synthesized via solid state reaction route with a certain thermal treatment cycle involving, annealing step at 865 °C for 20 h. The mechanical tensile strength measurements for the sample with x = 0.4 mol from CNs/Pt achieved maximum mechanical tensile strength value of 45.77 MPa., with promotion ratio ~ 21.08% in contrast with pure-sample x = 0 with mechanical tensile of 37.8 MPa. Furthermore, the additions of (HCNs/Pt) does not damage the whole superconductivity on the investigated range (0 ≤ x ≤ 0.4 mol). Results indicated that, the additions of (HCNs/Pt) had a remarkable, suppressing the Tc-values to Tc-offset = 62.2 K for the sample with maximum additive ratio x = 0.4 mol.

Influence of Ag on the Properties of Ca0.9Yb0.1MnO₃ Sintered Ceramics

In this study, Ca_0.9Yb_0.1MnO₃ + x wt.% Ag (with x = 0, 1, 3, 5, and 10) thermoelectric materials were prepared via the classical ceramic method. In spite of the very high sintering temperature (1300 °C), no significant Ag losses were observed following this process. Moreover, Ag addition enhanced cation mobility during sintering due to the formation of a liquid phase. Microstructurally, it was found that Ag decreases porosity; this was confirmed by density measurements. Ag was also found to promote the formation of a Ca₂Mn₂O₅ secondary phase. Despite the presence of this secondary phase, samples with Ag displayed lower electrical resistivity than Ag-free ones, without a drastic decrease in the absolute Seebeck coefficient. The highest thermoelectric performances, which were determined by power factor, were obtained in 1 wt.% Ag samples. These maximum values are slightly higher than the best of those reported in the literature for sintered materials with similar compositions, with the additional advantage of their being obtained using a much shorter sintering procedure.