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We investigated the effect of different sintering processes on Ag-added FeSe 0.94 superconducting wires. After applying different sintering procedures, we successfully obtained zero resistivity, at 350 • C for 100 h and at 700 • C for 1 h, in Ag-added FeSe 0.94 superconducting wire produced using the ex-situ powder-in-tube method. The crystal structure of both wires is mainly composed of the tetragonal β-FeSe phase. Ag does not react with selenium, and it can be incorporated into the crystal structure. The transport J c value of these wires is calculated to be 24.4, and 38 A cm −2 at 4.2 K in a self-field, respectively. The low current densities of the wires are attributed to the low core-density and the presence of porosity. The upper critical field is estimated to be 16.2 and 14.6 T from Werthamer-Helfand-Hohenberg theory, respectively.

In this work, FeTe 0.7 Se 0.3 single crystals have been synthesized by using the self-flux method, in order to understand effect of Te doping in the Fe-chalcogenides. For this purpose, the physical properties of sample have been investigated by Scanning Electron Microscopy (SEM), Energy dispersive x-ray (EDX) spectroscopy, X-ray diffraction (XRD) and magnetic techniques. The XRD results show that the sample has tetragonal structure, with some impurity peaks. SEM results demonstrate that the sample is distributed in a terrace-like formation. EDX results indicate that the distribution of Fe, Te and Se on the surface of the sample is homogenous. According to χ -1 -T measurement, antiferromagnetic interaction is observed. In addition, M-H curves show nearly paramagnetic behavior for the sample measured.

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