Investigation of the change of boron and thalium additivesin ybco superconductors with various sinteringtemperatures

In this thesis, the pure YBa2Cu3O7-δ superconductor at temperatures of 900 °C, 920 °C, 1000 °C and 1020 °C ( ±2 °C/min, ±5 °C/min and ±10 °C/min), (YBa2Cu3O7-δ)1-x(B2O3)x (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) superconductor at temperatures of 1000 °C and 1020 °C ( ±2 °C/min, ±5 °C/min and ±10 °C/min) and (YBa2Cu3O7-δ)1-x(Tl2O3)x (x= 0.05, 0.1, 0.2, 0.3) superconductor at temperatures of 1000 °C and 1020 °C ( ±2 °C/min and ±10 °C/min) have been produced using the solid state reaction method. The temperatures of the preparation of the samples and boron and thallium additive have been investigated on effect of the structural, electrical and magnetic properties of the compound. Superconducting phase formation was investigated By examining the structural properties of the samples (XRD and SEM / EDS). Critical values of superconductivity were found by electrical (MR-T) and magnetic (M-T, M-H) measurements and the effects of boron and thallium doping and production temperatures on superconductivity quality were investigated. In addition, the upper critical area, the lower critical area, the activation energy and the pinning forces are calculated and whether the materials produced are suitable for engineering applications. It has been found that the better homogeneous phase in the pure YBa2Cu3O7-δ compound and hence the better superconductivity structure is at a temperature of 1000 °C ±2 °C/min. The value of the best structure in the boron-doped YBa2Cu3O7-δ compound was found to be at a temperature of 1000 °C ±2 °C/min with boron doping of 0.05. The value of the best structuring in the thallium-doped YBa2Cu3O7-δ compound was found to be at a temperature of 1000 °C ± 10 °C/min with 0.3 thallium addition. As the boron doping ratio increased, the homogeneity deteriorated and the superconductivity property decreased. In cases where the boron doping is after 0.2, the diamagnetic-paramagnetic phase transition is seen in the examples. If the boron doping is after 0.3, the normal conduction from superconductivity has occurred. In the case of thallium-added samples, the diamagnetic-paramagnetic phase transition was observed at 1020 °C ±10 °C/min.