The Sintering Effect on the Phase Formation and Transport Current Properties of SmBa2Cu3O7−δ Ceramic Prepared from Nano-Coprecipitated Precursors (original) (raw)
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Journal of Superconductivity and Novel Magnetism, 2011
The effect of heat treatment on the superconducting properties of ErBa2Cu3O7−δ (ErBCO) ceramic materials has been studied. The nano-metal oxalate precursor was prepared using coprecipitation (COP) method. The prepared materials were subjected to calcination process at 900 °C for 12 h and then sintered under oxygen environment for 15 h at 920 °C, 930 °C, 940 °C, and 950 °C, respectively. All samples showed a metallic behavior and single-step transition in the R–T curves. The best zero critical current, T C(R=0)=91.4 K, was for the sample sintered at 920 °C. XRD data showed single phase of an orthorhombic structure. As the sintering temperature increases, the formation of nonsuperconducting phases (impurities) was observed when the samples sintered above 920 °C. The formation of nano-oxalate powders via COP method is a very efficient procedure to produce high-quality superconductors with less processing temperature required.
Sinter-forged YBa2Cu3O7?x superconducting ceramics from the spray-roasted powders
Journal of Materials Science, 1991
The effect of applying a uniaxial stress, while varying the temperature and the time of sinter-forging, on the microstructure and critical current density of the sinter-forged YBa2Cu307_x ceramics has been investigated. Spray-roasted powders from a nitrate-based feed solution were prepared as the starting materials. By applying a relatively low uniaxial stress (2 MPa), the sintered density increased up to 95% of the maximum value. Critical current densities of between 360 and 420 Acm-2 were obtained for the sinter-forged samples which are significantly higher than values reported for pressureless-sintered samples prepared from solid-state reacted powders (typically 70 Acm-=). This increase in the density of the material and the critical current density can be explained by the alignment of the elongated YBa2Cu307_ X grains under applied uniaxial stress during sintering. The elongated YBa2Cu307_ X grains have been characterized by transmission electron microscopy.
Journal of Materials Science, 2006
The Bi(Pb)-2223 superconductor has been prepared via coprecipitation (COP) method from solutions of metal acetates and 2-propanol solution of oxalic acid at low temperature (0-2°C). The metal oxalates powder was subjected to precalcination of 12 h at 730°C, followed by 24 h calcination at 845°C. The pelletized powder was sintered for 24, 48 and 100 h at 850°C. The dominance of high-T C phase was observed for all samples as evidenced in the single step transition of (R-T) curves. The T C(R = 0) for samples sintered at 24, 48 and 100 h were 102, 102 and 104 K, respectively. XRD data showed the tetragonal structure for all samples followed by the enhancement of the 2223 phase as sintering time increased. Ac magnetic susceptibility measurements showed the improvement of the grain connectivity as sintering time increased. SEM micrographs showed large flaky grains of~7 lm in size and randomly distributed, which belong to 2223 phase. The degree of grains alignment increased as the sintering time increased.
Sintering time and properties of YBa2Cu3O?7 superconducting ceramics
Journal of Superconductivity, 1995
The effect of annealing duration in oxygen flow on the superconducting characieristics of YBa2Cu30_7 bulk ceramics was investigated by structural, electrical, magnetic, and electronic microscopy investigations. The long-time annealing is deleterious for the superconductivity in YBa2Cu30_7 ceramics. The optimum time interval for annealing is from 20 to 70 h at 950~ and within this range the maximum value of Tc is obtained.
Sinter-forged YBa 2 Cu 3 O 7-x superconducting ceramics from the spray-r
J Mater Sci, 1991
The effect of applying a uniaxial stress, while varying the temperature and the time of sinter-forging, on the microstructure and critical current density of the sinter-forged YBa2Cu307_x ceramics has been investigated. Spray-roasted powders from a nitrate-based feed solution were prepared as the starting materials. By applying a relatively low uniaxial stress (2 MPa), the sintered density increased up to 95% of the maximum value. Critical current densities of between 360 and 420 Acm-2 were obtained for the sinter-forged samples which are significantly higher than values reported for pressureless-sintered samples prepared from solid-state reacted powders (typically 70 Acm-=). This increase in the density of the material and the critical current density can be explained by the alignment of the elongated YBa2Cu307_ X grains under applied uniaxial stress during sintering. The elongated YBa2Cu307_ X grains have been characterized by transmission electron microscopy.
Malaysian Journal of Fundamental and Applied Sciences, 2017
Superconductor YBa2-xAgxCu3O7δ in a bulk form has been developed through modified sol-gel processing. The preparation involved dissolving metal organic precursor in a mixture of propanoic acid and propylamine which then undergo for annealing at 900 °C for 5 hours and sintering at 950 °C for 5 hours. The bulk samples were characterized using X-ray diffractogrameter (XRD), resistivity measurement technique and Scanning Electron Microscope (SEM). The highest critical current temperature (TC) value was found at 84 K for x=0.05. The value decrease as the silver (Ag) concentration increase. The highest critical current density (JC) value measured for x =0.05 were 5.977 A/cm 2 at 50 K and 4.748 A/cm 2 at 60 K. YBa2Cu3O7δ (Y123) phase remains as orthorhombic for all samples. SEM micrograph showed the clear grains for the pure samples and it became not visible as the Ag concentration increase.
Sintering and Microstructure - Property Relations for YBa2Cu3Ox
MRS Proceedings, 1987
The recent discovery of high temperature superconductivity in YBa2Cu3O7 has led to intense activity in the processing of these oxides. The earliest attempts to synthesize these materials were based on solid state routes. These routes do not produce highly sinterable powders. Solution routes can potentially produce much more sinterable powders. We have investigated several synthesis routes - both solid state and solution. The details of these will be presented elsewhere(1). Here, we contrast the physical properties and the densification behavior of powders made via solid state and solution routes. We also present preliminary results on the microstructural characterization and electrical properties of the sintered samples.
High temperature superconductors (HTSC) of microcrystalline ceramic material ErBa2Cu3O7-δ (ErBCO) have been successfully synthesized via chemical co-precipitation (COP) using metal acetate precursors, and physical mixtures of oxides and carbonates, by conventional solid state route (SSR). The COP sample requires 27 hours for the heat treatment while the SSR sample needs 72 hours. We compare the superconducting properties of ErBCO produced from both methods. Resistivity versus temperature measurements (R-T) showed that all samples exhibit very good metallic behaviour. The transition temperature, TC(R=0) for the COP samples were was found to be at 91.4 K while it occurs at 90.9 K for the SSR sample sintered at 920°C. X-ray diffraction (XRD) data showed a single phase of an orthorhombic structure for all the samples. Scanning electron micrographs (SEM) showed grains of sizes ≤ 40μm were randomly distributed in all the highly compacted samples. However, the sample prepared via COP exhib...
Central European Journal of Chemistry, 2006
We have investigated the influence of Ca-substitution and different rare earths on the microstructure of RE 1−x Ca x Ba 2 Cu 3 O 7−δ (RE= Y, Eu, Er; x=0, 0.2, 0.3) superconducting ceramics. Scanning electron microscopy, X-ray microanalysis and energy dispersive spectroscopy have been used to study the microstructure and the chemical composition of the samples. A correlation was established between the polycrystalline microstructure and phase formation depending on the additive content. We observed that calcium is distributed uniformly in the crystals. The formation of minor impurity phases improved the sintering conditions.
Thin Solid Films, 2013
YBa 2 Cu 3 O 7 − δ films were produced on (00l) SrTiO 3 single crystal substrates by a sustainable fluorine-free chemical solution deposition method. Using water as the primary solvent and low-cost precursors, a direct sintering process without calcination could be obtained. Variation of the heating rate towards the sintering temperature showed a strong effect on texture, surface morphology, phase purity and concurrent superconducting properties. Using an optimized heating rate of 5°C min −1 , superconducting films were produced with an onset critical temperature of 92 K, a difference in critical temperature during transition of 1.8 K, a critical current density of 1.1 MA cm −2 and a critical current of 50 A cm −1 width at 77 K and self-field.