scholarly journals Bi-based high Tc superconducting fibers by melt extraction

1992 ◽  
Vol 7 (9) ◽  
pp. 2365-2372
Author(s):  
J.J. Chang ◽  
G. Rudkowska ◽  
A. Zaluska ◽  
P. Rudkowski ◽  
J.O. Ström-Olsen ◽  
...  
Keyword(s):  
Crystallization Process ◽  
Lattice Parameter ◽  
Squid Magnetometry ◽  
X Ray Diffraction ◽  
Initial Composition ◽  
Scanning Calorimetry ◽  
High Tc ◽  
X Ray ◽  
Melt Extraction ◽  
Bcc Phase

Bismuth-based high Tc superconductors have been prepared as fibers by a technique of melt extraction. As-made, the fibers are amorphous with diameters ranging from 0.7 μm to 100 μm and lengths of up to 5 cm. The fibers were subsequently transformed into high Tc superconductors by heat treatment in air. Superconducting transitions at 105 K and 82 K were measured in annealed fibers of initial composition Bi1.8Pb0.2Sr2Ca3Cu4Ox by SQUID magnetometry. The volume fractions of superconducting phases were estimated to have lower bounds of 30% for 2212 and 5% for 2223. The crystallization process has been studied by differential scanning calorimetry, electron microscopy, and x-ray diffraction. Crystallization involves first the formation of the Bi-2201 phase and a bcc phase with lattice parameter a = 0.425 nm before finally significant fractions of both the Bi-2212 and Bi-2223 phases are formed.

scholarly journals SOLID DOSAGE FORM DEVELOPMENT OF GLIBENCLAMIDE WITH INCREASING THE SOLUBILITY AND DISSOLUTION RATE USING COCRYSTALLIZATION

2018 ◽  
Vol 10 (6) ◽  
pp. 181
Author(s):  
Arif Budiman ◽  
Sandra Megantara ◽  
Putri Raraswati ◽  
Tazyinul Qoriah
Keyword(s):  
Dissolution Rate ◽  
Dosage Form ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Solid Dosage Form ◽  
Solid Dosage ◽  
Infra Red ◽  
Form Development

Objective: The aim of this study was to develop a solid dosage form of glibenclamide with increasing the solubility properties of glibenclamide with cocrystallization method.Methods: Virtual screening was performed to investigate the interaction between glibenclamide and a co-former. Saccharin, the selected co-former, then co-crystallized with glibenclamide with equimolar ratios of 1:1 and 1:2 using the solvent evaporation method. Further characterization was performed using an infra-red (IR) spectrophotometer, differential scanning calorimetry (DSC), and powder x-ray diffraction (PXRD).Results: Co-crystals of 1:2 equimolar ratio were more highly soluble compared to pure glibenclamide (30-fold for 12 h and 24-fold for 24 h). The dissolution rate had also increased from 46.838% of pure glibenclamide to 77.655% of glibenclamide co-crystal in 60 min. There was no chemical reaction observed during the co-crystallization process based on the IR spectrum. However, there was a new peak in the X-Ray diffractogram and a reduction of melting point in the DSC curve, indicating the formation of co-crystals.Conclusion: The optimal co-crystal ratio of glibenclamide-saccharin was found to be 1:2, which was successful in improving the solubility of glibenclamide.

Exploring concomitant/conformational dimorphism in a difluoro-substituted phosphoramidate derivative

2019 ◽  
Vol 75 (4) ◽  
pp. 451-461 ◽  
Author(s):  
Avantika Hasija ◽  
Deepak Chopra
Keyword(s):  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Dispersion Energy ◽  
Torsion Angles ◽  
X Ray ◽  
Electrostatic Contribution ◽  
Distinguished Contribution

The concomitant occurrence of dimorphs of diphenyl (3,4-difluorophenyl)phosphoramidate, C18H14F2NO3P, was observed via a solution-mediated crystallization process with variation in the symmetry-free molecules (Z′). The existence of two forms, i.e. Form I (block, Z′ = 1) and Form II (needle, Z′ = 2), was characterized by single-crystal X-ray diffraction, differential scanning calorimetry and powder X-ray diffraction. Furthermore, a quantitative analysis of the energetics of the different intermolecular interactions was carried out via the energy decomposition method (PIXEL), which corroborates with inputs from the energy framework and looks at the topology of the various intermolecular interactions present in both forms. The unequivocally distinguished contribution of strong N—H...O hydrogen bonds along with other interactions, such as C—H...O, C—H...F, π–π and C—H...π, mapped on the Hirshfeld surface is depicted by two-dimensional fingerprint plots. Apart from the major electrostatic contribution from N—H...O hydrogen bonds, the crystal structures are stabilized by contributions from the dispersion energy. The closely related melting points and opposite trends in the calculated lattice energies are interesting to investigate with respect to the thermodynamic stability of the observed dimorphs. The significant variation in the torsion angles in both forms helps in classifying them in the category of conformational polymorphs.

scholarly journals Synthesis, Characterization, and Thermal Decomposition of Pure and Dysprosium Doped Yttrium Phosphate System

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
K. K. Bamzai ◽  
Nidhi Kachroo ◽  
Vishal Singh ◽  
Seema Verma
Keyword(s):  
Thermogravimetric Analysis ◽  
Ammonium Hydroxide ◽  
Xrd Analysis ◽  
Lattice Parameter ◽  
Energy Dispersive ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Structural Investigations ◽  
X Ray

Yttrium phosphate and dysprosium doped yttrium phosphate were synthesized from aqueous solutions using rare earth chloride, phosphoric acid, and traces of ammonium hydroxide. The synthesized material was then characterized for their structural investigations using powder X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) supplemented with energy dispersive X-ray analysis (EDAX). The spectroscopic investigations were carried out using Fourier transform infrared (FTIR) spectroscopy. The thermal stability was studied using differential thermogravimetric analysis (DTA), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. X-ray diffraction analysis reveals that both yttrium phosphate and dysprosium doped yttrium phosphate belong to tetragonal system with lattice parameter  Å,  Å and  Å,  Å, respectively. The stoichiometry of the grown composition was established by energy dispersive X-ray analysis. The EDAX analysis suggests the presence of water molecules. The presence of water molecules along with orthophosphate group and metallic ion group was confirmed by FTIR analysis. Thermogravimetric analysis suggests that decomposition in case of yttrium phosphate takes place in three different stages and the final product stabilizes after 706°C, whereas in case of dysprosium doped yttrium phosphate the decomposition occurs in two different stages, and the final product stabilizes after 519°C.

Synthesis and Investigation of Al2O3/SiO2 /ZrO2 Powders via Selective Laser Sintering

2012 ◽  
Vol 569 ◽  
pp. 297-300 ◽  
Author(s):  
Wei Wang ◽  
Yong Xian Liu ◽  
Xiang Dong Shi ◽  
Jin Hua Li ◽  
J.Y.H. Fuh
Keyword(s):  
Crystallization Process ◽  
Eutectic Temperature ◽  
Selective Laser Sintering ◽  
Ternary Eutectic ◽  
Composite Ceramic ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Scanning Electron Microcopy ◽  
Zro2 System

This research focused on the synthesis and investigation of the thermal properties and microstructure of the Al2O3/SiO2 /ZrO2 system applied to dental field. The composite ceramic was studied by scanning electron microcopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Detailed investigations of the different proportions of materials on the preparation and microstructural phases of ternary eutectic were presented. Furthermore, the crystallization process was investigated by using DSC and XRD. The results indicate that sintering microstructure of the ternary eutectic composite is greatly influenced by the materials proportions. The synthetically thermal analysis shows that the eutectic temperature of ternary Al2O3/SiO2 /ZrO2 composite is 1040°C, is well matching the phase diagram of Al2O3/SiO2 /ZrO2.

The Effect of Sample Substrate on the Structural Properties of Co-Deposited Films of A-Ge:H

1990 ◽  
Vol 192 ◽  
Author(s):  
S.J. Jones ◽  
W.A. Turner ◽  
D. Pang ◽  
W. Paul
Keyword(s):  
Yield Strength ◽  
Crystallization Process ◽  
Exothermic Peak ◽  
High Yield ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Strength Differential ◽  
Substrate Temperatures ◽  
Deposited Films

ABSTRACTResults from structural measurements on r.f. glow discharge produced a-Ge:H films have been found to be substrate dependent. The variations in the results were found to depend on both the substrate temperature, Ts, and the substrate yield strength. Differential scanning calorimetry results were particularly affected by these parameters. For films prepared at Ts = 150°C, the DSC spectra contain two exothermic peaks when the films are deposited on low yield strength substrates while only one exothermic peak is present for films deposited on high yield strength substrates. One exothermic DSC peak is seen in spectra for all films prepared at Ts = 300°C no matter what substrates were used. This DSC spectral dependence is attributed to differences in the microstructure of films deposited at the two substrate temperatures, as seen in TEM micrographs. X-ray diffraction measurements performed on films annealed to various temperatures show that all of the exothermic DSC peaks described above are associated with the crystallization process. Thus, for the films prepared at low Ts, crystallization is either a one or two step process depending on the yield strength of the substrate.

Relation of starting precursors to the resulting high-Tc phases in the Pb and Sb doped Bi—Sr—Ca—Cu—O system

1994 ◽  
Vol 9 (2) ◽  
pp. 292-296 ◽  
Author(s):  
F. Constantinescu ◽  
R. Holiastou ◽  
D. Niarchos ◽  
G.K. Nicolaides ◽  
F. Vasiliu ◽  
...  
Keyword(s):  
Ac Susceptibility ◽  
Partial Substitution ◽  
Dc Resistivity ◽  
Squid Magnetometry ◽  
Superconducting Properties ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Phase Sample ◽  
Semiconducting Behavior

The introduction of more reactive precursors for Pb and Sr (oxalates), as well as Ca (citrate) and the use of a Bi nitrate decomposition route, has increased the percentage of the high-Tc (2223) phase in the Bi—Sr—Ca—Cu—O (BSCCO) system. Partial substitution of Bi(Pb) with Sb gives an almost single (2223) phase sample. In addition, a single (2212) phase sample is obtained when high purity Bi2O3 is used as a precursor, whereas Bi acetate leads to semiconducting behavior. The morphology of the samples is studied with a scanning electron microscope (SEM), the stoichiometry with energy-dispersive x-ray analysis (EDAX), and the structure with x-ray diffraction (XRD), while the superconducting properties are investigated by dc-resistivity, ac-susceptibility, and SQUID magnetometry techniques.

The Composition Effect on the Nanocrystallization of Finemet Amorphous Alloys

1996 ◽  
Vol 457 ◽  
Author(s):  
J. Zhu ◽  
T. Pradell ◽  
N. Clavaguera ◽  
M. T. Clavaguera-Mora
Keyword(s):  
Amorphous Alloys ◽  
Nucleation And Growth ◽  
Secondary Crystallization ◽  
Composition Effect ◽  
Phase Precipitation ◽  
X Ray Diffraction ◽  
Initial Composition ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffusion Controlled

ABSTRACTDifferential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), Neutron Diffraction (ND) and Mössbauer Spectroscopy (MS) were used to study the nanocrystallization process of Fe73.5Cu1Nb3Si22.5–xBx (x=5, 7, 8, 9 and 12) amorphous alloys. Both the temperature range and the activation energy of Fe(Si) phase precipitation from the amorphous martrix increase with the initial B composition. The initial Si composition influences the mechanism of the nanocrystallization: for the Si rich samples, the beginning of nucleation and growth processes is interface controlled, for the B rich samples it is diffusion controlled. Secondary crystallization from the remaining amorphous is mainly Fe3B and Fe2B, the ratio of Fe3B/Fe2B being dependent on the initial composition too.

Characterization of the Aurivillius Type PbBi4Ti4O15 Piezoelectric Ceramic Doped with Eu3+

2006 ◽  
Vol 45 ◽  
pp. 2483-2488
Author(s):  
L. Pablos ◽  
Maria Elena Villafuerte-Castrejón ◽  
A. Ibarra-Palos ◽  
J. Ocotlán-Flores ◽  
R. Sato ◽  
...  
Keyword(s):  
Piezoelectric Ceramic ◽  
Solubility Limit ◽  
Lattice Parameter ◽  
Layered Oxides ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Density Measurements ◽  
X Ray ◽  
Wide Range

PbBi4Ti4O15 belongs to the bismuth oxide layers family discovered by Aurivillius more than 50 years ago. In the last few years, there has been considerable interest in layered oxides exhibiting ferroelectric, piezoelectric and other related properties due to their wide range of application in technical devices. In the present work the PbBi4Ti4O15 solid solution formed with Eu3+ was synthesized by coprecipitation method and solubility limit was found. All compounds were characterized by scanning electron microscopy, density measurements and X-ray diffraction. The variation of lattice parameter with the Eu3+ concentration was obtained. Raman spectroscopy was carried out in order to determine the Eu3+ site in the lattice. Thermal analysis (thermogravimetry and differencial scanning calorimetry) results are also presented.

Morphological and structural evolutions of nonequilibrium titanium-nitride alloy powders produced by reactive ball milling

1992 ◽  
Vol 7 (4) ◽  
pp. 888-893 ◽  
Author(s):  
M. Sherif El-Eskandarany ◽  
K. Sumiyama ◽  
K. Aoki ◽  
K. Suzuki
Keyword(s):  
Electron Microscopy ◽  
Titanium Nitride ◽  
Gas Flow ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nitrogen Gas ◽  
X Ray ◽  
Grain Sizes ◽  
Transmission Electron

Nonequilibrium titanium-nitride alloy powders have been fabricated by a high energetic ball mill under nitrogen gas flow at room temperature and characterized by means of x-ray diffraction, scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry. Initial hcp titanium is completely transformed to nonequilibrium-fcc Ti–N after 720 ks of the milling time. The fcc Ti–N phase is stable at relatively low temperature and transforms at 855 K to Ti2N and δ phases. At the final stage of milling, the particle- and grain-sizes of alloy powders are 1 mm and 5 nm, respectively, and the lattice parameter is 0.419 nm.

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