Analysis of the physical properties of MgB₂ superconductor with Zn(NO₃)₂·6H₂O addition

MgB₂ superconductors in the form of tablets doped with Zn(NO₃)₂·6H₂O at different ratios (0–1–2–3% and 4%) by mass were produced in this study. The crystallographic, mechanical, electrical and magnetic properties of the obtained samples were investigated. For this purpose, X-ray diffraction analysis (XRD), microhardness analysis, temperature-dependent electrical resistance measurement (R-T), and magnetic moment change measurement depending on the magnetic field (m-H) were performed on the samples. The critical current densities (J_c) of the samples were calculated using the Bean Method and the J_c-H graph was created. Microhardness analysis was performed using the Vickers Method. Through the Vickers Method, Meyer’s Law, Proportional Sample Resistance (PSR) Model, Elastic/Plastic Deformation (EPD) Model and Indentation-Induced Cracking (IIC) Model were used from microhardness modeling. In the analyses, it was determined that plane peaks belonging to MgB₂ were seen in all samples, the critical transition temperature (T_c) decreased depending on the increase in the doping ratio from 37.55 to 34.27 K, and there were widenings in the m-H curves. An increase in the J_c value at 0.32 T, depending on the doping ratio of Zn(NO₃)₂·6H₂O, was observed from 3.01 × 10¹ to 3.23 × 10³ A/cm². It was also observed that all samples exhibited the reverse indentation size effect (RISE) behavior, and the samples became softer with the doping ratio.