Influence of rare earth (Nd,Er) doping on electrical and structural properties of low density Bi₁.₆Pbₒ.₄Sr₂Ca₂₋ₓREₓCu₃08 superconductors prepared via coprecipitation technique / Noor Syuhaida Ibrahim

The influence on electrical and structural properties of rare earth elements (Nd and Er) doped on low density Bii.6Pbo.4Sr2Ca2-xRExCu5 where x = 0.000, 0.025, 0.050, 0.100 and 0.200 is investigated. In determining the best level of sucrose, the samples were prepared via co-precipitation method with mixing of C12H22O11 (O.OOg, 0.05g, 0.10g and 0.015g) with standard Bii.6Pbo.4Sr2Ca2Cus. For all series of standard samples, the best Tc zer0 obtained was at 98 K which belongs to low density sample (S3) with addition of 0.10 g sucrose. Comparing to standard high density sample SI (O.OOg), the low density sample S3 (0.1 Og) exhibited higher critical current density Jc, by three folds. The XRD results confirmed that low density sample represented by S3 remains in tetragonal structure which indicate that adding sucrose into the samples did not change its crystal structure. For all Nd-doped and Er-doped samples, the curves of normalized resistance displayed normal metallic behavior above Tc onset. However, Tc Zero decreased for all doped samples due to increase in dopant concentration. Substitution smaller size of Nd3+ (1.123A) and Er2+ (1.03A) on Ca2+ (1.14A) has distorted the lattice structure which leads to the decrease of Tc zer0. Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-ray (EDX) were performed to determine the surface morphology and the composition of elements of the samples respectively. FESEM results showed that the grains are compacted and randomly distributed and as the concentration of dopant is increased. The misorientation at grain boundaries have formed weak links and hence limit the values of Jc.