Structural and Electrical Properties of Nanosized Sm2O3 Doped Bi(1.6)Pb(0.4)Sr(2)Ca(2)Cu(3)Oy Superconductors

Bi(1.6)Pb(0.4)Sr(2)Ca(2)Cu(3)Oy superconductor samples doped with nanosized samarium oxide (Sm2O3) in different amounts (0, 0.05, 0.08, 0.10, and 0.20) were synthesized by a solid-state reaction method and then characterized. The structure and morphology of the samples were characterized by using X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Element composition analysis was deployed by energy dispersive X-ray (EDX) spectroscopy measurement. Superconducting transition temperatures of the samples were estimated from dc resistivity (R-T) measurement. XRD showed that both Bi-2223 and Bi-2212 phases coexist in the samples having orthorhombic crystal structure. The volume fraction of Bi-2223 phase showed the highest percentage (77%) for the sample with x = 0.05 addition. It was observed that the volume fraction of Bi-2223 phase decreases and Bi-2212 phase increases with further increasing Sm content. SEM revealed that grain size decreases when the addition content was increased from 0.08 to 0.20 with less inter-coupling between superconducting grains. EDX showed that there are no extra peaks observed except for Sm peaks, confirming that all elements used in the samples were introduced into the Bi-2223 structure. The superconducting transition temperatures T-c,T-onset and T-c,T-offset increased for Sm content x = 0.05, but decreased with further addition amount

The characterization of bi-based ceramic superconductors by magnetic susceptibility measurements

Bi1,7-xPb0,3GdxSr2Ca2Cu3Oy ve Bi1,7-xPb0,3NbxSr2Ca2Cu3Oy süperiletken örneklere Niyobyum ve Gadolinyum eklenmesinin yapısal, manyetik ve süperiletken özellikler üzerindeki etkileri incelenmiştir. Süperiletken örnekler geleneksel katıhal reaksiyon yöntemi ile hazırlanmıştır. Niyobyum ve Gadolinyum katkılı süperiletken örneklerin geçiş sıcaklığını, kritik akım yoğunluğunu ve boşluk konsantrasyonunu belirlemek için ac alınganlık ölçümleri ve örneklerin yapısal karakterizasyonu, yüzey morfolojisi ve faz analizi için X-ışını kırınımı (XRD), taramalı elektron mikroskobu (SEM) ve yoğunluk ölçümleri yapılmıştır. AC alınganlık ölçümlerinden Niyobyum katkısı ile kritik başlangıç sıcaklıklarının Nb0, Nb1, Nb2, Nb3, Nb4 örnekleri için sırasıyla 108, 105, 104, 105, 100 K ve Gadolinyum katkısı ile kritik başlangıç sıcaklıklarının Gd0, Gd1, Gd2, Gd3, Gd4 örnekleri için sırasıyla 108, 77, 77, 72, 70 K olduğu gözlenmiştir. XRD ölçümleri, Niyobyum katkısı ile yüksek-Tc fazının hacim kesri artarken düşük-Tc fazının hacim kesrinin azaldığını ve Gd katkısının artmasıyla ise yüksek-Tc fazının hacim kesrinin azaldığını ve düşük-Tc fazının hacim kesrinin sisteme hakim olduğunu göstermektedir. SEM fotoğraflarından Niyobyum katkı miktarı arttıkça porozitenin azaldığı ve tanecikler arası bağlantıların iyileştiği, Gd katkı oranı arttırıldığında ise, örneklerin yüzey morfolojisinin ve tanecik bağlılığının bozulduğu gözlenmiştir. Yoğunluk ölçümleri de SEM sonuçlarını desteklemektedir. The effects of addition of Niobium and Gadolinium on structural, magnetic and superconducting properties in Bi1,7-xPb0,3GdxSr2Ca2Cu3Oy and Bi1,7-xPb0,3NbxSr2Ca2Cu3Oy superconducting samples were investigated. The superconducting samples were prepared by conventional solid state reaction method. The investigation consisted of X-ray diffraction (XRD), scanning electron microscope (SEM), density measurements for structural characterization, surface morphology and phase analysis and ac susceptibility to determine the critical current density and hole concentration of the samples. In ac susceptibility measurements with Niobium addition, the critical onset temperatures were observed to be about 108, 105, 104, 105 and 100 K for samples Nb0, Nb1, Nb2, Nb3 and Nb4, and with Gadolinium addition, the critical onset temperatures were observed to be about 108, 77, 77, 72, and 70 K for samples Gd0, Gd1, Gd2, Gd3 and Gd4, respectively. XRD measurements show that high-Tc phase increases and low-Tc phase decreases with the Niobium substitution whereas high-Tc phase volume fraction decreases and low-Tc phase volume fraction dominates the system with increasing Gd addition. When Niobium addition was increased, the porosity decreases and grain connectivity of the samples were observed to improve and when Gd addition ratio was increased, surface morphology and grain connectivity of the samples were observed to degrade from SEM investigations. Density measurements are in line with SEM results

The Effects of Mn Doping on the Structural and Optical Properties of ZnO

Zn1-xMnxO(x = 0.00, 0.01, and 0.05, respectively) was synthesized by using solid state reaction method. The structural properties were characterized by using X-ray diffraction and scanning electron microscopy. Optical properties were investigated by UV-visible spectroscopy. X-ray diffraction patterns indicate that all samples have hexagonal wurtzite structure without any impurity phases. The diffraction intensity increases and the peak position shifts to a lower 2 theta angle with Mn concentration. The lattice parameters a and c, the volume of unit cell increase with Mn content indicating that Mn2+ ions go to Zn2+ ions in ZnO lattice. The grain size increases with Mn doping while the microstrain and dislocation density decrease. UV-vis spectra of the samples show that undoped ZnO sample has an energy band gap E-g of 3.34 eV. The optical study indicates a red shift in the absorbance spectra and a decrease in the band gap E-g with Mn content. This decrease of band gap may be attributed to the influence of dopant ions. The morphology and grain distribution of ZnO samples were analysed by scanning electron microscopy. The particle sizes are higher in doped samples when compared to the undoped sample and the surface roughness increases with Mn content. The grains are closely, densely packed and pores/voids between the grains increase with Mn content

Effect of Nb addition on magnetic, structural and superconducting properties of (Bi, Pb)-2223 superconductors

In this work, the effects of Nb2O5 addition with different ratios on the structural and magnetic properties of Bi1.7-xPb0.3NbxSr2Ca2Cu3Oy (x = 0.00-0.20) superconducting samples were investigated. (Bi, Pb)-2223 superconducting samples were prepared by conventional solid-state reaction method. The phase formation, phase fraction and lattice parameters were determined from X-ray powder diffraction (XRD) measurements, the microstructure, surface morphology analyses of the samples were carried out using scanning electron microscope (SEM). Additionally, ac susceptibility measurements were done in order to determine the critical current density (J(c)) and hole concentration (p) of the samples. AC susceptibility measurements were done at various ac fields (ranging from 20 to 160 A/m) to understand the effect of Nb addition on magnetic properties of Bi1.7-xPb0.3NbxSr2Ca2Cu3Oy superconductor. Critical onset (T (c) (on) ) and loss peak temperatures (T-p) were estimated from the ac susceptibility curves. It was observed from ac susceptibility measurements that the critical onset temperatures decreased from about 108-98 K with increasing Nb addition (x = 0.00-0.20). The imaginary part of susceptibility was used to calculate the intergranular critical current density (J(c)) by means of the Bean's model. X-ray diffraction analysis revealed that the samples consisted of a mixture of Bi-2223 and Bi-2212 phases as the major constituents and non-superconducting phase Ca2PbO4 as the minor. It was also shown from XRD measurements that volume fraction of high-T-c phase decreases with increasing Nb addition up to x = 0.20. The sample with Nb addition of x = 0.20 showed the highest volume fraction of Bi-2223 phase (86 %). When Nb addition was increased, the surface morphology and grain connectivity are found to degrade, the grain sizes decrease and porosity of the samples were observed to increase from SEM images except the sample with x = 0.20 Nb addition

Effects of Graphene Oxide Doping on Magnetic and Structural Properties of Bi1.6Pb0.4Sr2Ca2Cu3Oy Superconductor

Bi1.6Pb0.4Sr2Ca2Cu3Oy superconductor samples doped with graphene oxide (GO) in different weight percentages (0 wt.%, 0.002 wt.%, 0.004 wt.%, and 0.010 wt.%) were synthesized by a solid-state reaction method and then characterized. The structure and morphology of the samples were characterized by x-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). XRD analysis revealed that all the samples contained Bi-2223 and Bi-2212 phases with a small amount of impurity phase. The results showed that GO doping did not change the lattice parameters or structure of the samples dramatically, indicating that GO remains between the grains, playing a role of weak links. SEM revealed that all the samples had randomly distributed grains with plate-like shape. A decrease of the pore size, and hence enhanced densification and better connections between the grains, was observed for the 0.010 wt.% GO-doped sample when compared with the other samples. Magnetization measurements (M-T) were used to determine the onset critical temperature (T-c) of each sample, revealing that T-c decreased with increasing GO content up to x = 0.004 but increased slightly for the GO content x = 0.010. The results also showed that the highest onset critical temperature, T-c (75 K) and Josephson current, I-0 (5.89 mu A) values were obtained for the 0.010 wt.% GO-doped sample, which thus represents the optimum doping amount to improve the magnetic and structural properties

Effects of Gd substitution on magnetic, structural and superconducting properties of Bi1.7-xPb0.3GdxSr2Ca2Cu3Oy

The effects of Gd addition on the structural and magnetic properties of Bi1.7-xPb0.3GdxSr2Ca2Cu3Oy (x = 0.00-0.20) superconducting samples were investigated. The samples were prepared by conventional solid state reaction method. The phase formation, phase fraction and lattice parameters were determined from X-ray diffraction (XRD) measurements, while the microstructure, surface morphology analyses of the samples were carried out using scanning electron microscope. As Gd addition was increased, surface morphology and grain connectivity of the samples were observed to degrade. XRD results indicated that the lattice parameter c decrease with increasing Gd addition while Bi-2223 phase disappear and Bi-2212 phase become dominant. AC susceptibility measurements were performed at various ac fields (ranging from 20 to 160 A/m) to understand the effect of Gd addition on magnetic properties of Bi1.7-xPb0.3GdxSr2Ca2Cu3Oy superconductors. The results showed that both critical temperature (T-c) and critical current densities (J(c)) were found to decrease with increasing Gd addition. It was found that T-c values decrease from 108 to 70 K with increasing Gd addition