Methodology;
1) sample synthesis using the solid-state method, co-precipitation method;
The Bi1.6Pb0.4Sr2Ca2Cu3Oδ sample preparation was done using solid state co-precipitation method (Pb is not doped but as booster); sample A (Bi-2223+acetic acid, blue solution, 60°C at 300 RPM) mixed with sample B (oxalic acid+isopropanol (480 ml)+deionized H2O (320), clear solution, 60°C at 300 rpm) in ice bath (ice to momentarily stop the reaction, 2°C-5°C. deep-blue). Next the solvent from the mixed samples were filtered using vacuum filum and dried at 80°C for 24 hours then grinding, calcined, sintering to form a pellet. The precursor powder was subjected to pre-calcination of 12 h at 840°C, followed by 24 h calcination at 845°C. The pelletized powder was sintered for 24, 48 and 100 h at 845°C.The pellet then exposed to thermal neutron irradiation for one, 1-hour.
2) Determine the critical current temperature, Tc and critical current density, Jc using four-probe point;
Tc, Jc measurement using four-probe point – run for 3 hours | AC susceptibility (AC machine) – run for 6 hours
3) Identify the structural and phase formation between using the SEM graphics and XRD formation;
XRD analysis- the sample are grind until turns powder, refer to EVA software | SEM – determine the phase and structural formation.
Results (based on the objectives no.):
2) neutron irradiation → introduce defect → result in high Tc → enhance flux pinning
3) > Tc formula (obtained Tc = 106 K nearly to dominance Bi-2223 Tc = 110K) at R = 0 ohm in superconducting state
> Jc formula (Jc=Ic/A, area=bar), function – transport (*Ic = Jc); Ic -transport current which the flow voltage clearly appear; in superconducting state (at 77K, current set to 10 mA→20 mA the voltage maintain at 0.35mV but once start to change, when increase at 220 mA that’s the Ic used | 70K, current set to 220 mA | 30K, 400 mA | test from 77K until 30K 400 mA the maximum current can be applied)
*based on calculation using formula, expected the peak output (double peak/phases) for Jc from Tc.
*difference transport current density and critical current density
> AC susceptibility (normalized, diamagnet); only to observe the peak and determine the phases; also to validate Tc and Jc in magnetic field, can find Jc as well
4) > XRD – increase purity Bi-2223, determine phases which dominance (Bi-2122/Bi-2223), pattern should be sharp not broad as need to be single, high purity> SEM – flaky
3(a) The critical current temperature, Tc is the temperature reached zero resistance (zero current); compare the critical temperature, Tc between the non-irradiated sample and one-hour irradiation
3(b) The critical current density, Jc of the one-hour irradiated Bi-2223 calculated using the current measured at a temperature range within 77K-30K and the area of the sample (measured current divided by area); discuss on the properties of the current density at each temperature and the highest Jc calculated is the critical current density.
3(c) Relating the critical current temperature in determining the AC susceptibility
4(a) The structural and phase formation between the pure sample and one-hour irradiated Bi-2223; analyse the morphological structure for both conditions, based on SEM images and discuss the effect of one-hour irradiation on the characterization of the sample.
4(b) Discuss on the XRD formation obtained with the purity of the superconductor.
