Degradation of superconducting properties of the boron-doped FeSe0.5Te0.5 superconductor system

Abstract

In this study, superconducting samples were prepared using the solid-state method by adding 0, 1, 2, 3, 4, and 5 % boron to the FeSe_0.5Te_0.5 superconductor system. The structural, microstructural, electrical, and magnetic properties of the samples are examined, and the results are presented. The findings show that boron doping disrupted both the structural and electrical conduction mechanisms in the material, leading to the loss of superconductivity as the doping level increased. Structural shrinkage and increased dislocations were observed in the crystal structure. As the doping ratio increased, the normal-state resistivity, the critical transition temperature, and the zero resistance temperature all decreased significantly. The T_c^on values decreased from 15.7 K in the undoped sample to 13.9 K in the 5 % boron doped sample, and T_zero decreased from 14.8 K in the undoped sample to 10.8 K in the 5 % boron doped sample. Additionally, it was found that the diamagnetic properties deteriorated with increased boron doping and shifted toward ferromagnetic properties, negatively affecting the critical current density.