An investigation of the crystalline and electronic structures of a 4:3:3:4 layered Bi–Ca–Sr–Cu oxide

1991 ◽  
Vol 6 (9) ◽  
pp. 1838-1842
Author(s):  
M.D. Giardin ◽  
R. Feduzi ◽  
A. Manara ◽  
J.C. Spirlet ◽  
M. Zocchi ◽  
...  
Keyword(s):  
Electronic Structures ◽  
Onset Temperature ◽  
Appreciable Amount ◽  
Nominal Composition ◽  
Second Phase ◽  
X Ray ◽  
Space Groups ◽  
Resistivity Measurements ◽  
Superconducting Compound ◽  
Diffraction Patterns

Semiconducting samples of a Bi–Ca–Sr–Cu oxide, having a nominal composition 4:3:3:4, were prepared by melting high purity oxides of the various elements. Superconducting samples were obtained by annealing the semiconducting samples at a temperature close to the melting temperature. Electrical resistivity measurements indicated the presence of two superconducting phases, one with the onset temperature at about 110 K, the other with a significantly lower onset temperature. The presence of this second phase is proven by the x-ray powder diffraction patterns. The crystalline structures of both the semiconductor and superconductor samples have almost equal lattice parameters and are orthorhombic, but belong to different space groups: Fmmm and Bbmm, respectively. No significant amount of the 110 K superconducting phase was present in the diffraction pattern of the superconducting compound. XPS and XANES data on the Ca atom indicate that a different electronic state of Ca is present in the superconducting compound, which still contains an appreciable amount of the semiconducting phase.

scholarly journals Synthesis and Characterization of Thermally Stable Hydroxyapatite

2021 ◽  
Vol 45 (1) ◽  
pp. 43-50
Author(s):  
Meriem Harkat ◽  
Safia Alleg ◽  
Rafik Chemam ◽  
Sonia Azzaza ◽  
Majda Mokhtari ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Ammonium Phosphate ◽  
Nominal Composition ◽  
Thermally Stable ◽  
Chemical Route ◽  
X Ray ◽  
Eds Analysis ◽  
Ft Ir ◽  
Diffraction Patterns ◽  
Xrd Patterns

Nanocrystalline and thermally stable hydroxyapatite (HA) powder with nominal composition of Ca10(PO4)6(OH)2 was prepared by wet chemical route from calcium hydroxide Ca(OH)6 and mono ammonium phosphate NH4H2PO4 as calcium and phosphate sources, respectively. The effect of calcination temperature on the structure, microstructure, molecular bonding, thermal behavior and morphology was investigated by X-ray diffraction patterns (XRD), Fourier Transform Infra-Red (FT-IR), Raman spectroscopy, thermogravimetry (TGA), differential thermal analysis (DTA) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) analysis. The XRD patterns of the as-prepared and calcined powders exhibit a single phase of hydroxyapatite. The crystallite size of as-prepared and calcined HA is in the range of 44-182 nm. FT-IR and Raman spectroscopy results are in good agreement with XRD ones. The EDS analysis reveals the presence of all elements. The thermal stability of the synthesized powders is evidenced by TGA/DTA scans which show a weight loss smaller than 2%.

scholarly journals THE ICOSAHEDRAL PHASE OF Al63Cu25Fe12 SYSTEM

2019 ◽  
Vol 28 (1) ◽  
pp. 51-56
Author(s):  
Anastazia Melnik ◽  
Luciano Nascimento
Keyword(s):  
Chemical Elements ◽  
Stoichiometric Composition ◽  
Icosahedral Phase ◽  
Quasicrystalline Phase ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ideal Composition ◽  
Diffraction Patterns

The present work aimed to characterize the microstructure of the icosahedral phase (quasicrystalline phase-ϕ) of the system with stoichiometric composition of the quasicrystal Al63Cu25Fe12. The ternary alloy with nominal composition of Al63Cu25Fe12 was processed by mechanical alloying (MA) as a viable solid state processing method for producing various metastable and stable quasicrystalline phases. The structural characterization of the obtained samples was performed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), while the elemental composition of the chemical elements Al, Fe and Cu were determined by X-ray spectroscopy technique of dispersive energy (EDS). According to the results of XRD, the diffraction patterns of Al63Cu25Fe12 showed the presence of β-Al(Fe, Cu) and λ-Al13Fe4 phases coexist with the thermodynamic ϕ-phase quasicrystalline. Finally, elemental analysis indicates that during alloy synthesis there is little variation of the ideal composition. The results indicate that alloys with high percentage of icosahedral phase can be obtained by casting in the air.

Effect of Lanthanum Substitution on Structure and Modulation in Bi2Sr2-xLaxCaCu2O8+d (0≤x≤0.3) Superconducting Compound

2021 ◽  
Vol 406 ◽  
pp. 240-249
Author(s):  
Mourad Mimouni ◽  
Mohammed Sadok Mahboub ◽  
Mohammed Fayçal Mosbah ◽  
Ghani Rihia ◽  
Soria Zeroual ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Element Concentration ◽  
Superconducting Phase ◽  
Nominal Composition ◽  
X Ray ◽  
Orthorhombic Cell ◽  
Superconducting Compound ◽  
La Substitution ◽  
Modulation Vector ◽  
Scanning Electron

The effect of La substitution on the structure and its modulation in samples with a nominal composition of Bi2Sr2-xLaxCaCu2O8+d where 0≤x≤0.3 superconducting phase was investigated. The X-ray powder diffraction (XRPD) results showed an almost pure Bi-2212 phase, confirmed by the estimated amount of element concentration using dispersive energy X-ray spectroscopy (EDX). Scanning electron microscopy (SEM) micrographs showed a decrease of both crystallite size and connectivity when Lanthanum concentration increases. Le Bail refinement using the Jana2006 program gives a very good value of goodness of fit (GOF) factor. Also, the refinement reveals that for x=0.3 the orthorhombic cell transforms to the tetragonal one and the modulation vector q increases when increasing La concentration.

X-ray powder diffraction studies of fibrillar zinc trimolybdates ZnMo3O10·nH2O (n=3.75,5,10)

1999 ◽  
Vol 14 (4) ◽  
pp. 276-279
Author(s):  
Wiesław Łasocha ◽  
Wiesław Surga ◽  
Alicja Rafalska-Łasocha
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Lattice Parameters ◽  
Fiber Axis ◽  
Powder Diffraction Data ◽  
Parallel Fibers ◽  
X Ray ◽  
Space Groups ◽  
Diffraction Patterns

The X-ray powder diffraction data of polycrystalline fibrillar zinc trimolybdates ZnMo3O10·3.75H2O, ZnMo3O10·5H2O, and ZnMo3O10·10H2O, are reported. An uncommon diffraction pattern was recorded in the case of the “wet fibers” of ZnMo3O10·10H2O, which could be indexed assuming a model of parallel fibers with translation disorder along the fiber axis. The powder diffraction patterns, lattice parameters, space groups, and other data describing these compounds are presented in this paper.© 1999 International Centre for Diffraction Data.

Effects of lithium oxide on the electrical properties of CuO at low temperatures

1990 ◽  
Vol 5 (8) ◽  
pp. 1739-1744 ◽  
Author(s):  
F. Lanza ◽  
R. Feduzi ◽  
J. Fuger
Keyword(s):  
Electrical Properties ◽  
Single Phase ◽  
Lithium Oxide ◽  
Antiferromagnetic Order ◽  
Second Phase ◽  
Strong Decrease ◽  
X Ray ◽  
Resistivity Measurements ◽  
Calorimetric Measurements ◽  
Straight Lines

We present an investigation of the influence of four dopant lithium concentrations on the electrical properties of CuO. X-ray measurements have revealed a single phase formed up to 4.2 at. % of Li, and a second phase formed, Li2CuO2, in the case of 10.5 at. % of Li concentration. The log(ρ/T) vs 1/T data are better represented by two straight lines than by one and show an initial strong decrease of the conduction activation energies for small contents of Li (<1.7 at. %), which becomes weak for larger contents. The change in slope observed in the resistivity measurements as a function of temperature has also been investigated by calorimetric measurements, revealing a specific heat anomaly which can be associated with the antiferromagnetic order transition.

Crystalline Phases and Electronic Structures in Superconducting Bi – Sr – Ca – Cu Oxides

1997 ◽  
Vol 12 (8) ◽  
pp. 2009-2013
Author(s):  
M. D. Giardina ◽  
R. Feduzi ◽  
D. Inzaghi ◽  
A. Manara ◽  
C. Giori ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Photoelectron Spectroscopy ◽  
Electronic Structures ◽  
Theoretical Interpretation ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Edge Structure ◽  
X Ray ◽  
Quantum Percolation ◽  
X Ray Absorption

Two classes of samples, designated A and B, of layered Bi–Sr–Ca–Cu oxides having the same nominal composition 4 : 3 : 3 : 4, but different thermal histories, were investigated by using field modulated microwave absorption (ESR), powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and x-ray absorption near the edge structure (XANES). Previous electrical resistivity measurements showed that the B samples presented only two superconducting phases with midpoints of the transition temperatures at ∼80 K and ∼105 K. The microwave absorption technique indicated instead the presence of islands which became superconducting at the above-mentioned temperatures also in the A samples. The crystalline and electronic structures of the two types of samples are illustrated and discussed. A plausible theoretical interpretation of the experimental results, based on a quantum percolation model with Coulomb interaction, is also given.

X-ray powder diffraction data for three red azo pigments: sodium, barium, and ammonium lithol salts

2017 ◽  
Vol 32 (3) ◽  
pp. 187-192 ◽  
Author(s):  
Alicja Rafalska-Łasocha ◽  
Marta Grzesiak-Nowak ◽  
Piotr Goszczycki ◽  
Katarzyna Ostrowska ◽  
Wiesław Łasocha
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Space Groups ◽  
Cell Parameters ◽  
Synthesis Procedure ◽  
Diffraction Patterns

Lithol reds belong to the group of azo pigments, which were popular artists’ colouring materials in the first half of the twentieth century. These pigments were also used in many branches of industry. Here, we report X-ray powder diffraction data, unit-cell parameters, and space groups for three compounds from this group: sodium (E)-2-((2-hydroxynaphthalen-1-yl)diazenyl)naphthalene-1-sulphonate monohydrate (Na lithol red), monoclinic, space group C2/c, with cell parameters a = 33.343(7), b = 6.667(2), c = 16.397(4) Å, β = 90.83°, V = 3644.51 Å3, Z = 8; barium (E)-2-[(2-hydroxynaphthalen-1-yl)diazenyl]naphthalene-1-sulphonate trihydrate (Ba lithol red), monoclinic, space group P21/m, with cell parameters a = 17.758(9), b = 6.209(4), c = 16.857(8) Å, β = 92.07°, V = 1857.39 Å3, Z = 2; and ammonium (E)-2-[(2-hydroxynaphthalen-1-yl)diazenyl]naphthalene-1-sulphonate monohydrate (NH4 lithol red), monoclinic, space group P2/c, with cell parameters a = 17.721(5), b = 6.428(3), c = 16.911(5) Å, β = 100.31(3)°, V = 1895.31 Å3, and Z = 4. In the first and third cases we synthesised the pigments in their monohydrate form, performed X-ray powder diffraction measurements, and indexed all of the obtained diffraction maxima. In the case of the barium compound, despite many efforts in the course of the synthesis procedure, the powder diffraction patterns of the obtained samples were not of the best quality. Nevertheless, we indexed the best one and found a reliable space group and cell parameters.

scholarly journals Charge Order and Suppression of Superconductivity in HgBa2CuO4+d at High Pressures

2021 ◽  
Vol 6 (3) ◽  
pp. 25
Author(s):  
Manuel Izquierdo ◽  
Daniele C. Freitas ◽  
Dorothée Colson ◽  
Gastón Garbarino ◽  
Anne Forget ◽  
...  
Keyword(s):  
High Pressures ◽  
Charge Order ◽  
Charge Ordering ◽  
X Ray Diffraction ◽  
Metallic Behavior ◽  
X Ray ◽  
Resistivity Measurements ◽  
Diffraction Patterns ◽  
A Charge ◽  
Insight Into

New insight into the superconducting properties of HgBa2CuO4 (Hg-1201) cuprates is provided by combined measurements of electrical resistivity and single crystal X-ray diffraction under pressure. The changes induced by increasing pressure up to 20 GPa in optimally doped single crystals were investigated. The resistivity measurements as a function of temperature show a metallic behavior up to ~10 GPa that gradually passes into an insulating state, typical of charge ordering, which totally suppresses superconductivity above 13 GPa. The changes in resistivity are accompanied by the apparition of sharp Bragg peaks in the X-ray diffraction patterns, indicating that the charge ordering is accompanied by a 3D oxygen ordering. Considering that pressure induces a charge transfer of about 0.02 at 10 GPa, our results are the first observation of charge order competing with superconductivity developed in the overdoped region of the phase diagram of a Hg-based cuprate.

High Tc Superconducting Y-Ba-Cu-O Thick Fim by Screen Printing

1987 ◽  
Vol 99 ◽  
Author(s):  
H. H. Yen ◽  
J. H. Kung ◽  
Y. C. Chen ◽  
P. T. Wu
Keyword(s):  
Film Thickness ◽  
Screen Printing ◽  
Copper Oxides ◽  
Onset Temperature ◽  
Superconducting Film ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
Zero Resistance ◽  
Diffraction Patterns

ABSTRACTSuperconducting film of ternary copper oxides from the Y-Ba-Cu-O system has been prepared by screen printing on 96% A1203 substrate with onset temperature at 95K and zero resistance at 85K. X-ray diffraction patterns show that film will react with the A1203 substrate. With decreasing film thickness the superconductivity is destroyed and may become a semiconductor.

X-Ray Investigations on Some Salts of Hydrazine and Hydrazine Derivatives

1961 ◽  
Vol 5 ◽  
pp. 133-141 ◽  
Author(s):  
M. Stammler ◽  
D. Orcutt
Keyword(s):  
Unit Cell ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Space Groups ◽  
Inorganic Acids ◽  
Cell Dimensions ◽  
System Cell ◽  
Diffraction Patterns ◽  
Perchlorate Salt

AbstractThe salts of hydrazine or methyl derivatives of hydrazine were prepared by neutralization of the base with inorganic acids, for instance, HBF4, HClO4, H SO4, and HCl. Upon recrystallization of the product from a suitable solvent, X-ray diffraction patterns were obtained. Hydrazine tetrafluoborate H2N-NH2·HBF4 was found to crystallize in the monoclinic system. Cell dimensions and possible space groups were determined. The corresponding perchlorate salt crystallizes in two forms, one of which is isomorphous with hydrazine tetrafluoborate. The second form seems to be stabilized by small amounts of water.The tetrafluoborate salt was prepared from the 1,1-dimethyl hydrazine. It was found to crystallize in the tetragonal system with a primitive unit cell. The perchlorate salt of this base is isomorphous with the fluoborate but with a slightly larger unit cell. Both materials undergo plastic-like deformation. The general appearance and mechanical properties are similar to those of a hydrocarbon wax. The 1,1-dimethyl hydrazine sulfate and the 1,1-dimethyl hydrazine hydrochloride have a lower symmetry than the HBF4 salt and do not show the wax-like properties of the latter. Based on the study of these chemically related compounds an explanation is offered for the properties of 1,1-dimethyl hydrazine tetrafluoborate in terms of crystalline structure.

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