Superconducting and microstructural properties of Mg1−xAgxB2

A systematic study on the effect of silver (Ag) doping in magnesium diboride (MgB2) superconductor has been undertaken. A series of polycrystalline samples with composition Mg1−xAgxB2 (0 ≤ x ≤ 0.20) were synthesized by using the “in situ” solid state reaction method. All the samples were sintered at 850 °C for 2 h under the high purity argon flow. The room temperature X‐ray diffraction (XRD), low temperature resistivity (ρ‐T) measurements and field emission scanning electron microscopy (FE‐SEM) were performed to explore the phase purity, superconducting transition temperature, and microstructural properties, respectively. The XRD patterns show that Ag doping leads to the formation of MgAg phase. The relative intensity of MgAg phase increases with increasing Ag content. The ρ–T measurement shows that superconducting transition temperature (Tc) decreases slightly with Ag doping. All the samples have Tc between 38.5 K (x = 0.00) and 37 K (x = 0.20). The FE‐SEM images have revealed hexagonal shaped grains with an average grain size between 0.20 and 0.50 µm.