Effect of Annealing Temperature Condition on the Phase Formation and Electric Properties of YBa2Cu3O7-Δ Superconductor Synthesised by Thermal Treatment Method

Abstract

The current study reports on the effect of annealing temperature on the phase formation and electrical properties of YBa₂Cu₃O_7-δ superconductor synthesised by thermal treatment technique. The specimens were separated into sets A, B, and C. The sets A and B were sintered at 980 °C for 24 h and then exposed to additional annealing at 650 °C and 500 °C for 12 h, respectively, during the sintering process while being cooled down to room temperature under oxygen flow. The set C was only sintered at 980 °C for 24 h in oxygen flow and without annealing. All prepared samples were analysed by X-ray diffraction (XRD) technique, field-emission scanning electron microscope (FESEM) and four-point probe measurement. The structural examination via the XRD technique showed an orthorhombic crystal structure with the main phase of YBa₂Cu₃O_7-δ for all samples, besides a small amount of YBa₂Cu₃O_7-δ as a secondary phase for samples B and C. According to the findings of the FESEM examination, the annealing of the samples caused an increase in the average grain size of the samples. The temperature-resistivity measurements showed that all samples exhibited metallic behaviour in the normal state with a high critical transition temperature (95.6 K) obtained after annealing at 650 °C for set A. Thus, the experimental results showed that further annealing at 650 °C may be the optimal heat treatment temperature for producing YBa₂Cu₃O_7-δ superconductors with better superconducting properties.