Mechanical grinding of precursor powder and its effect on the microstructure and critical current density of Ag/Bi-2223 tapes

Kim, Weon-Ju; Kwon, Sun-Chil; Lee, Ho Jin; Lee, Hee-Gyoun; Hong, Guang; Kuk, Il-Hyun

doi:10.1016/s0921-4534(97)01741-3

Cited by 26 publications

(20 citation statements)

References 15 publications

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“…With an increase in the grinding time from 17 min to 1 h, the PXRD spectrum showed a fast decrease in intensity from 3 to 15 followed by a broad hump at 30 , exactly like our observations. Similar observations were also made by Kim et al (1998) and Luo et al (1994), who measured the effect of mechanical grinding on the superconducting properties of Ag/Bi-2223 tapes and Bi-2212 powders, respectively. The measured PXRD spectrum up to 2 ' 60 showed a similar hump feature at 30 .…”

Section: Background Correctionsupporting

confidence: 83%

“…The average structure of the Bi-2212 phase described in the previous section cannot describe all the features of the X-ray diffractograms of Bi-2212. Unindexed peaks occur which could arise from 'satellite' reflections resulting from modulations in the structure of Bi-2212 (Gao et al, 1988;Kim et al, 1998;Petříček et al, 1990;Miles et al, 1998;Patterson et al, 1990). A mismatch between the perovskite block and rock-salt block in Fig.…”

Section: Profile Refinementmentioning

confidence: 99%

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Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

2021

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The Rietveld refinement technique has been used to determine the extent of intergrowth of the Bi2Sr2CuO6+x phase and co-crystallization of competing phases in the high-temperature superconductor Bi2Sr2CaCu2O8+x (Bi-2212). The refinement was done on powder diffractograms obtained on powders made by grinding single crystals of Bi2Sr2CaCu2O8+x grown using two different self-flux techniques, namely the pressure technique and the regrowth technique, and ground for either 2 min or 2 h. The Rietveld programs JANA and FULLPROF were used for the refinement and both gave consistent results. The Bi and Sr atom positions were refined in the average structure of centrosymmetric space group Bbmb. To incorporate Bi-atom modulation and extract information about the modulation vector, refinement was done in the centrosymmetric space group N^{Bbmb}_{1\overline 11}(Bbmb(0γ1)). The b* component of the modulation vector decreases with a decrease in the superconducting transition temperature in the pressure-technique sample compared with the regrowth sample, suggesting a better alignment of the CuO2 planes with respect to the Bi–O planes in the pressure-technique sample. All the samples exhibit a strong preferred orientation effect. Values of the March–Dollase parameters corresponding to the preferred orientation function were obtained. Brindley absorption contrast factors t ϕ were also calculated, together with the effect of microabsorption on the number of phases present in each sample. Rietveld refinements incorporating all the factors resulted in excellent values for the goodness-of-fit parameters for all the samples, with the lowest value of 2.08 for the pressure-technique sample ground for 2 min. Additionally, the powders corresponding to the pressure-technique crystals have no co-crystallizing phase and ∼94% of the Bi-2212 phase, suggesting that crystals grown by the pressure technique are of extremely good quality, much better than those grown by the regrowth flux technique.

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Section: Background Correctionsupporting

confidence: 83%

Section: Profile Refinementmentioning

confidence: 99%

Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

2021

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“…A comparison of our results to other hybrid PSF membranes in literature is listed in Table 1. 16,[21][22][23][24]50,51 We find that, first, by using the designed dual-channel, molecular-sieving core/shell ZIF@MOF as fillers, the gas permeability and selectivity of asprepared hybrid PSF membrane can be positively improved simultaneously. Second, without sacrificing CO 2 /N 2 selectivity our hybrid PSF membrane provides the largest increases in CO 2 permeability.…”

Section: Nano Lettersmentioning

confidence: 99%

Dual-Channel, Molecular-Sieving Core/Shell ZIF@MOF Architectures as Engineered Fillers in Hybrid Membranes for Highly Selective CO₂ Separation

et al. 2017

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A novel core/shell porous crystalline structure was prepared using a large pore metal organic framework (MOF, UiO-66-NH, pore size, ∼ 0.6 nm) as core surrounded by a small pore zeolitic imidazolate framework (ZIF, ZIF-8, pore size, ∼ 0.4 nm) through a layer-by-layer deposition method and subsequently used as an engineered filler to construct hybrid polysulfone (PSF) membranes for CO capture. Compared to traditional fillers utilizing only one type of porous material with rigid channels (either large or small), our custom designed core/shell fillers possess clear advantages via pore engineering: the large internal channels of the UiO-66-NH MOFs create molecular highways to accelerate molecular transport through the membrane, while the thin shells with small pores (ZIF-8) or even smaller pores generated at the interface by the imperfect registry between the overlapping pores of ZIF and MOF enhance molecular sieving thus serving to distinguish slightly larger N molecules (kinetic diameter, 0.364 nm) from smaller CO molecules (kinetic diameter, 0.33 nm). The resultant core/shell ZIF@MOF and as-prepared hybrid PSF membranes were characterized by transmission electron microscopy, X-ray diffraction, wide-angle X-ray scattering, scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis, differential scanning calorimetry, and contact angle tests. The dependence of the separation performance of the membranes on the MOF/ZIF ratio was also studied by varying the number of layers of ZIF coatings. The integrated PSF-ZIF@MOF hybrid membrane (40 wt % loading) with optimized ZIF coating cycles showed improved hydrophobicity and excellent CO separation performance by simultaneously increasing CO permeability (CO permeability of 45.2 barrer, 710% higher than PSF membrane) and CO/N selectivity (CO/N selectivity of 39, 50% higher than PSF membrane), which is superior to most reported hybrid PSF membranes. The strategy of using dual-channel molecular sieving core/shell porous crystals in hybrid membranes thus provides a promising means for CO capture from flue gas.

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“…There are different ways to produce nanotube bundles, for example, electric arc, laser ablation, and HiPco. , Nanotubes grown by the electric arc method tend to have capped ends, while it has been suggested that as-produced HiPco nanotubes have a percentage of open nanotubes present. − It is therefore reasonable to think that nanotubes produced by different methods might exhibit somewhat different sorption properties. Recently some groups have measured low coverage isosteric heats of adsorption ( q st ) for Xe on nanotubes prepared from the arc and the HiPco methods, and found that q st for Xe on the nanotubes produced by the electric arc method have considerably higher values than those for Xe on the HiPco nanotubes.…”

Section: Introductionmentioning

confidence: 99%

“…Recent experiments and computer simulations results suggest that as-produced HiPco nanotubes are best modeled because they contain an open fraction of nanotubes. ,,, From the experiments, it is not clear if models need to account for adsorption in interstitial channels in order to accurately describe the experimental data for HiPco SWNTs.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of Methane Adsorption on Single-Walled Carbon Nanotubes

2009

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We present the combined results of ab initio and molecular mechanical calculations, computer simulations, and adsorption isotherms investigations of CH(4) adsorbed on HiPco single-walled carbon nanotubes. Isotherms and adsorption energies obtained in our model and simulations are in good agreement with ours and others experimental results. The theoretical analysis conducted for various homogeneous bundles of close-ended and open-ended tubes confirm not only the adsorption in at least two different stages but also the role played by each of the different adsorption sites on the nanotube bundles. The study of different site and nanotube sizes allows us to establish the presence of open tubes in the as-produced HiPco bundles, without regarding the role that adsorption in large interstitial channels may play. Our results also show that predicted scenarios, for the mechanism and the preferential adsorption sites depend on the size of the nanotubes and those of the bundles.

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Mechanical grinding of precursor powder and its effect on the microstructure and critical current density of Ag/Bi-2223 tapes

Cited by 26 publications

References 15 publications

Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Dual-Channel, Molecular-Sieving Core/Shell ZIF@MOF Architectures as Engineered Fillers in Hybrid Membranes for Highly Selective CO₂ Separation

Comparative Study of Methane Adsorption on Single-Walled Carbon Nanotubes

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Mechanical grinding of precursor powder and its effect on the microstructure and critical current density of Ag/Bi-2223 tapes

Cited by 26 publications

References 15 publications

Quantitative phase analysis of Bi2Sr2CaCu2O8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Quantitative phase analysis of Bi2Sr2CaCu2O8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Dual-Channel, Molecular-Sieving Core/Shell ZIF@MOF Architectures as Engineered Fillers in Hybrid Membranes for Highly Selective CO2 Separation

Comparative Study of Methane Adsorption on Single-Walled Carbon Nanotubes

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Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Quantitative phase analysis of Bi₂Sr₂CaCu₂O_8+x and competing intergrowth and co-crystallizing phases via a Rietveld refinement study

Dual-Channel, Molecular-Sieving Core/Shell ZIF@MOF Architectures as Engineered Fillers in Hybrid Membranes for Highly Selective CO₂ Separation