Papers by Keyword: Superconductor

Abstract: In this study, we investigate the sensitive photonic crystal sensor formed by the coupling between two photonic crystals containing a superconducting layer. We consider TE polarization and normal incidence for the analysis presented in this work. Our study shows that the cavity mode resulting from this coupling is strongly dependent on the temperature of the superconductor layer. The effect of the temperature of the superconducting layer and thicknesses on the quality factor is examined. The results show that the sensor superconducting structure gives a high quality factor. This structure can be used to realize a highly sensitive photonic crystal sensor.

Abstract: In this study, effort was made to develop novel, cutting-edge composite materials consisting of conducting Al-CNTs and green synthesis silver nanoparticles (AgNPs). Spark plasma sintering (SPS) and very intense ball milling were used to develop the composites. The nanocomposites' microstructure, thermal and electrical conductivity were determined. Al-4%CNTs was refined into finer grains when AgNPs are present. The Al-4%CNTs+2%Ag.NPs composite produces a higher dislocation density because of the production of sub-grain. Al-AgNPs + CNTs can be used to make conductors with a high aspect ratio and lower contact resistance at the CNT junctions. It was established that enhanced electrical and thermal conductivity can be obtained using the developed AgNPs from sustainable materials to increase the dispersion of CNTs in Al for the production of high tensile conductors.

Abstract: The challenge in this research is the producing of nanoparticle superconductor compound. The benefit of nanoparticle is making the improving of the superconductor compound. The Bi₂Sr₂Ca₂Cu₃O₁₀ (Bi-2223) compound prepared by Co-precipitation method at different sintering temperatures (600, 700, 850 °C) (20 hrs) with pH value (7). The electric resistivity of samples measured under liquid helium closed cycle cryogenic system. The TEM estimation of sample prepared by Co-precipitation recognized the range of particles size is about (22 - 48nm) at sintering temperature (600 °C). The range of nanoparticles size is in about (65-112 nm) at sintering temperature (700 °C) and (80-124) nm at sintering temperatures (850°C). The critical temperature of sample at sintering temperatures (700, 850 °C) was about (109 ,112) K respectively The crystal structure confirmed by using X-ray diffraction, these peaks were found to be well indexed by the tetragonal phase of Bi-2223. It was defined the successful of this method is a function to presence of full properties for superconductor compound like Bi-2223 system. .

Abstract: The major problems that facing sustainability is the heat production with electricity transmission. The research and engineering communities hope that superconductive materials will be employed in the power transmission, without any losses along the way. Solid-state reaction is a one of the methods for preparing compound samples. This method was used to prepare the nominal chemical formula Y₂Ba₄Cu₇O₁₅. The calcining of the mixed powder at constant temperature of 800C0, followed by compressing the mixed, under (7, 8, 9) tons/cm2 pressures, as pallets shape with diameter 1.5 cm and thickness (0.2-0.3) cm inducing. The prepared samples were encounter many sintering processes through constant temperature. The sintering processes were done in the furnace by rising and cooling temperature with Oxygen rate 0.5 L/min. The samples were measured electrically to determine the resistivity changes in different temperatures (77–300) K, using four-probe technique. The results for the samples A, B and C shows the onset superconducting transition temperatures (Tc (onset)) at 88 K, 93 K, and 99 K respectively. The XRD data illustrated a polycrystalline structure for all samples. The transition temperature, oxygen content (δ) and the lattice parameter increase with increasing the pressure.

Abstract: Bi-Pb-Sr-Ca-Cu-O (BPSCCO) superconductors are recognized as a projectable high-temperature superconductor for high-efficiency electrical applications. The addition of Ti enhances the formation of the Bi-2223 phase from the BPSCCO superconductor. The process of producing BPSCCO superconducting materials with TiO₂ dopants is performed by the solid-state process and the production of wire rolling, consisting of bismuth (III) oxide powder (Bi₂O₃ = 99%), Strontium Carbonate powder (SrCO₃ = 99%), Calcium Carbonate powder (CaCO₃ = 99%), Copper Oxide powder (CuO₂ = 99%), Lead Oxide powder (PbO₂ = 98%) Bi: Pb: Sr: Ca: Cu ratio: 1.6: 0.4:2:2:3 doped by 1 %wt Titanium Oxide powder (TiO₂ = 98.5%). The variables used in this study were the comparison of the sintering method at 860°C for 24 hours and 820 °C calcination for 20 hours, and 850°C sintering for 20 hours. The superconductor characterization was tested through the X-Ray Diffraction (XRD) test, Scanning Electron Microscopy (SEM), and Resistivity test. XRD test results showed the formation of Bi₂Sr₂CuO₆ and Bi₂Sr₅Cu₃O₁₆ phase. SEM results showed an increase in grain size. The resistivity test results showed that all samples formed critical temperatures, 9.6 and 9.5K respectively.

Abstract: In this work, comparison of TiO₂ additions on the physical properties of YBa₂Cu₃O_δ superconductor system with nominal starting compositions at x= 0, 1, 2, and 5 wt.% was studied derived via solid state reaction and co-precipitation method. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result from XRD shown that all the samples were polycrystalline for solid state reaction, while single phase appear for co-precipitation methods. The intensity of the peak become higher with increasing amount of TiO₂ addition indicating the presence of increased amount of the unreacted in the samples. The refine lattice parameters indicated that all the samples have an orthorhombic crystal structure without occurrence of orthorhombic-tetragonal phase transformation. Furthermore, from SEM images for solid state reaction and co-precipitation method showed that the grain size of the samples decreased with TiO₂ increased. Small addition of TiO2 derived from co-precipitation method enhanced the YBCO microstructures.

Abstract: Compound Hg₂Sr_2-xBa_xCa₂Cu₃O₁₀ high temperature superconductor looks like (HTSC) has been prepared as a pellet by two step solid state reaction with a certain substitution percentages (0.5, 1,1.5,2) of Ba compensation rate of Sr respectively using appropriate weight of pure material Hg₂O₃, Sr(NO₃)₂, Ba(NO₃)₂, CaCO₃, and Cu(NO₃)₂ proportional to their molecular weight. XRD used for study structure properties, a computer program was used to calculation of spike dimensions the lattice parameters a, b and c shows Tetragonal, Electrical resistivity at x= 1.5 of Ba are obtained when the best value of Tc= 142 K.

Abstract: In this study, pulsed laser deposition technique was used to deposit bismuth plumbum strontium calcium copper oxide {Bi (Pb)SrCaCu0} thin films on MgO single crystal substrate. Solid state procedure which is inexpensive technique used in the production process of the Bi (Pb)SrCaCu0 superconductor bulk sample. In this work, Handy YAG Lasers (model: HYL 101 E) has been used. It is a high power class 4 solid state (ND: YAG) Q-switched pulsed laser and 532 nm (visible green: second harmonic) has been used to ablate the films. The substrate used in this work was single crystal MgO with the (100) orientation. Scanning Electron Microscopy (SEM) was used to observe the microstructure of fracture surface and cross section of thin film materials. Variable Pressure Scanning Electron Microscope (LEO-VPSEM) was used to study the correlation between the microstructure features. SEM studies have shown that the surface morphology of the bulk sample comprises platelets of average size ≈10μm with uniform and homogenous microstructure. The typical morphology of the as deposited films showed a continuous phase, granular structure, which spherical particles up to 5μm in diameter. The most prominent types of particulates BPSCCO films on MgO substrate are droplets with smooth surface, bigger droplets with granular surface, spherically-shaped features confined by randomly oriented facets, submicron rod-like features, Cu-enriched needles, platelets, irregularly-shaped Cu-rich outgrowths, strongly Cu-enriched tabular outgrowths, big target fragments, island growth structure, cubic and rectangular cubic structures. SEM analysis also showed that the deposition time have a pronounced influence on the particle size. The target morphology, which develops under laser-irradiation, depends on the laser fluence and the technique, by which the laser beam is moved relatively to the target during ablation. Laser-irradiated surfaces normally become altered both physically and chemically and morphological changes take the form of periodic structures such as ripples and ridges.

Abstract: MgB₂ superconductor is a superconductor with a critical temperature of around 39K and has the potential to replace Nb₃Sn and NbTi as superconducting coils to produce high magnetic fields. In this study, monofilament wires have been made to analyze the doping effect of SiC and Carbon Nanotubes (CNT) in its manufacture using Powder-In-Tube (PIT) method. Stainless Steel (SS-316) tube was used as a tube filled with powders of starting materials of Mg, B, SiC and CNT. A total of 8 samples were prepared with variations in the addition of SiC, and CNT as much as 5, 10, and 15 wt %, and also the variations in the addition of Mg composition by 0 and 10 mol % from normal stoichiometric values. The samples were rolled and sintered at 800°C for 3 hours. The samples then were analyzed using SEM (Scanning Electron Microscopy) to analyze the surface morphology, XRD (X-Ray Diffractometer) to analyze the formed phases and crystal structures, and then resistivity versus temperature using cryogenic systems to analyze their superconductivity properties. Based on the results of the XRD analysis, the MgB₂ phase is the major phase in the samples and the SiC doping causes the formation of minor phases of Mg₂Si and Fe₃C. The addition of SiC causes a decrease in crystalline properties of the MgB₂ phase due to reaction with SiC, while the addition of CNT does not cause the formation of a new phase. Based on the results of the analysis of resistance versus temperature, it is seen that the addition of SiC causes a decrease in T_C value. While the addition of CNT causes the improvement in the nature of superconductivity, but it also causes the decrease of its T_C values.

Abstract: The (Tl_1-xCr_x)Sr₂CaCu₂O₇ (Tl-1212) sample with nominal starting composition for x = 0.0, 0.2 and 0.3 were prepared by the solid-state reaction method. The samples were studied by powder x-ray diffraction method and electrical resistance versus temperature measurement. Excess conductivity analysis was carried out using the Aslamazov–Larkin (AL) theory, and the dimension of fluctuation-induced conductivity (λ) was determined. The Lawrence–Donaich (LD) theory was used to calculate the coherence length (ξ_c(0)), Josephson coupling (J), and γ = (ξ_ab(0)/ξ_c(0)) of the superconductive samples. Excess conductivity analysis showed that Cr substitution induced 2D-to-3D conductivity transition at the highest transition temperature (T_2D-3D) observed at x = 0.3. The calculations based on the Lawrence–Doniach model revealed that the shortest coherence length and weakest inter-plane coupling (J) occurred when x = 0.2. The sample with x = 0.2 and 0.3 showed the Tl-1212 as the major phase. The highest onset temperature of 110 K was observed in the x = 0.2 sample. Our result showed that the formal value of 2.3+ is more important than the Josephson interlayer coupling J in optimizing the transition temperature.