Diamagnetic and structural characterization of orthorhombic high-temperature superconductors in the system Y–Ba–Cu–O

1987 ◽  
Vol 65 (9) ◽  
pp. 1145-1148 ◽  
Author(s):  
M. Raudsepp ◽  
F. C. Hawthorne ◽  
X. Z. Zhou ◽  
I. Maartense ◽  
A. H. Morrish ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Structure Refinement ◽  
High Temperature Superconductors ◽  
Meissner Effect ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Preparation Conditions ◽  
Square Planar

Ceramic samples of the 90 K superconductor with nominal composition YBa2Cu3O7−x were made under varying preparation conditions. Some samples have a narrow transition-temperature range of about 1.5 K and a 100% "ac Meissner effect" near 77 K. The magnetic losses below 85 K were much reduced in these samples. Rietveld structure refinement in space group Pmmm using powder X-ray diffraction data showed significant oxygen vacancies in the square-planar CuO2 chains parallel to the y axis in the y–z plane, and Cu disorder about the origin along the x axis. The sample with the superior superconducting properties has the formula YBa2Cu3O6.92.

scholarly journals Characterization of ferrite nanoparticles for preparation of biocomposites

2017 ◽  
Vol 8 ◽  
pp. 1257-1265 ◽  
Author(s):  
Urszula Klekotka ◽  
Magdalena Rogowska ◽  
Dariusz Satuła ◽  
Beata Kalska-Szostko
Keyword(s):  
Chemical Method ◽  
Ferrite Nanoparticles ◽  
Chemical Activity ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

Ferrite nanoparticles with nominal composition Me0.5Fe2.5O4 (Me = Co, Fe, Ni or Mn) have been successfully prepared by the wet chemical method. The obtained particles have a mean diameter of 11–16 ± 2 nm and were modified to improve their magnetic properties and chemical activity. The surface of the pristine nanoparticles was functionalized afterwards with –COOH and –NH2 groups to obtain a bioactive layer. To achieve our goal, two different modification approaches were realized. In the first one, glutaraldehyde was attached to the nanoparticles as a linker. In the second one, direct bonding of such nanoparticles with a bioparticle was studied. In subsequent steps, the nanoparticles were immobilized with enzymes such as albumin, glucose oxidase, lipase and trypsin as a test bioparticles. The characterization of the nanoparticles was acheived by transmission electron microscopy, X-ray diffraction, energy dispersive X-ray and Mössbauer spectroscopy. The effect of the obtained biocomposites was monitored by Fourier transform infrared spectroscopy. The obtained results show that in some cases the use of glutaraldehyde was crucial (albumin).

scholarly journals Synthesis and Characterization of Ni2+-doped SnO2 Powders

2019 ◽  
Vol 35 (4) ◽  
Author(s):  
Trinh Thi Loan ◽  
Nguyen Ngoc Long
Keyword(s):  
Oxygen Vacancies ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Near Band Edge ◽  
X Ray Diffraction ◽  
Violet Emission ◽  
Dopant Content ◽  
X Ray ◽  
Undoped Sno2

The SnO2:Ni2+ powders with dopant contents ranging from 0.0 to 12 mol% have been synthesized by sol-gel method. The samples were characterized by X-ray diffraction (XRD) Raman spectroscopy, energy-dispersive X-ray spectrometer (EDS) and photoluminescense (PL) spectra. XRD analysis showed that samples doped with low Ni- concentrations exhibited single SnO2 crystalline phase, whereas the samples with high Ni- concentrations exhibited a mixture of SnO2 and NiO phases. The lattice parameters of the SnO2 host were independent on Ni2+ dopant content, while Raman mode positions were dependenton Ni2+ dopant content. The PL spectrum of the undoped SnO2 was characterized by the emission peaks due to near band edge (NBE) emission and the violet emission peaks associated with surface dangling bonds or oxygen vacancies and Sn interstitials.

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.

Mechanical Spectroscopy Study on Cu53.5Zr42Al4.5 Alloy

2011 ◽  
Vol 312-315 ◽  
pp. 1233-1237
Author(s):  
Odila Florêncio ◽  
Paulo Sergio Silva ◽  
Fernando Henrique De Sá ◽  
Paulo Wilmar Barbosa Marques ◽  
Javier Andres Muñoz Chaves ◽  
...  
Keyword(s):  
Internal Friction ◽  
Amorphous Structure ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Mechanical Spectroscopy ◽  
Temperature Function ◽  
X Ray ◽  
Casting Technique ◽  
Dsc Curves

This study consists of the characterization of the anelastic properties of a Bulk Metallic Glasses (BMG) by mechanical spectroscopy, which can be defined as an energy absorption technique. The equipment used was the acoustic elastometer system, the anelastic relaxation spectra were carried out with a heating rate of 1 K/min and vacuum better than 10-5 torr, in the temperature range of 300 K to 640 K. The amorphous sample studied, with nominal composition of Cu53.5Zr42Al4.5, was processed by skull push-pull casting technique in a rectangular cavity cooper mould. Differential scanning calorimeter (DSC) curves have evidenced the amorphous structure although the X-ray diffraction (XDR) pattern has indicated a heterogeneous microstructure with amorphous matrix and some metaestable nanocrystalline phases which have not been identified yet. The dynamical elastic modulus of this alloy (between 54 GPa and 58 GPa at room temperature) and internal friction patterns as temperature function implied an increase of the crystalline phase during the measurements. This effect was confirmed with new X-ray diffraction measurements after the internal friction experiments.

E/Z Isomerization of 3-Hydrazonocamphor Promoted by Coordination to Palladium or Platinum

2007 ◽  
Vol 72 (5-6) ◽  
pp. 649-665 ◽  
Author(s):  
M. Fernanda N. N. Carvalho ◽  
Ana S. D. Ferreira ◽  
João L. Ferreira da Silva ◽  
Luís F. Veiros
Keyword(s):  
Free Ligand ◽  
Intramolecular Hydrogen Bonding ◽  
Planar Geometry ◽  
Spectroscopic Techniques ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Intramolecular Hydrogen ◽  
C Nmr

3-Hydrazonocamphor, 3-(RR1NN)C10H14O (R = Me, R1 = H), undergoes intramolecular hydrogen bridging by coordination to platinum or palladium. This effect is evidenced by considerable decrease in the ν(C=O) frequency (compared to the free ligand) in the IR spectra of the complexes [MCl2L2] (M = Pd, Pt; L = 3-(RR1NN)C10H14O) as well as by the magnetic non- equivalence of the two ligands, as revealed by 13C NMR. DFT calculations indicate that coordination of 3-(Me(H)NN)C10H14O promotes E/Z isomerization of the hydrazono group of the ligand, inducing formation of intramolecular hydrogen bonding and corresponding stabilization of the complex. Characterization of the complexes [MCl2L2] (M = Pt; L: R, R1 = Me (1), R = Me, R1 = H (2) and M = Pd; L: R = Me, R1 = H (3)) was performed by analytical and spectroscopic techniques. Redox properties of the 3-hydazonocamphors and their complexes were studied by cyclic voltammetry. The structure of trans-[PtCl2{3-(Me2NN)C10H14O}2] was determined by single-crystal X-ray diffraction analysis. The complex has square-planar geometry and crystallizes in the tetragonal P43 space group.

Preparation and Characterization of Sr, Ba Filled Type-I Ge Clathrate Single Crystals

2007 ◽  
Vol 336-338 ◽  
pp. 896-899 ◽  
Author(s):  
Ke Feng Cai ◽  
L.C. Zhang ◽  
Q. Lei
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Nominal Composition ◽  
Type I ◽  
Vibrational Modes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Optimum Synthesis ◽  
Good Agreement

Sr or Ba filled type-I Ge clathrate single crystals were prepared using high pure elemental Ga, Ge, and Sr or Ba as the starting materials, and Ga as a flux. Powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), differential scanning calorimeter (DSC) were used to characterize the crystals, respectively. The results show that large and well-crystallized single crystals can be prepared under optimum synthesis condition. The composition of the crystals is in good agreement with the nominal composition (M8Ga16Ge30, M=Sr, Ba). Raman spectra of the single crystals were studied at room temperature and several of the Raman active vibrational modes in the crystals have been identified.

Synthesis and Characterization of Copper(II) and Zinc(II) Complexes Containing 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone

2003 ◽  
Vol 58 (10) ◽  
pp. 1009-1014 ◽  
Author(s):  
Subrata Kumar Dey ◽  
Bappaditya Bag ◽  
Dilip Kumar Dey ◽  
V. Gramlich ◽  
Yadong Li ◽  
...  
Keyword(s):  
Room Temperature ◽  
Magnetic Measurements ◽  
Electronic Spectroscopy ◽  
Coordination Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Square Planar ◽  
Distorted Octahedral

The synthesis, structure, and physical properties of a series of mononuclear complexes viz. [Cu(L)2] 1, [CuL2(CH3O)2] 2 and [Zn(L)2] 3 (where L = 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP)) are presented. The complexes were characterized by elemental analysis, IR and electronic spectroscopy (1 and 2), magnetic measurements at room temperature (1 and 2) and thermogravimetric analysis. The structures of all the three complexes were determined by single crystal X-ray diffraction studies. The coordination geometry around complexes CuL2 (1) and ZnL2 (3) is slightly distorted square planar while the geometry around Cu(II) of [Cu(L)2(CH3O)2] (2) is distorted octahedral with four oxygen atoms of two PMBP ligand occupying the equatorial positions and two methanol molecules occupying the two axial positions.

SUPERCONDUCTIVITY IN Bi-Sr-Ca-Mg-Cu-OXIDE

1991 ◽  
Vol 05 (11) ◽  
pp. 771-777 ◽  
Author(s):  
A.Y. KHAN ◽  
M. MOHAMMAD ◽  
M. SHAHNAZ ◽  
S.K. HASNAIN
Keyword(s):  
Magnetic Susceptibility ◽  
Electrical Resistance ◽  
Meissner Effect ◽  
Superconducting Phase ◽  
Partial Substitution ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Minor Phase ◽  
X Ray ◽  
A Minor

A Mg -substituted material with nominal composition Bi 2 Sr 2 Ca 3 Mg 2 Cu 6 O x, prepared by partial substitution of Ca by isovalent Mg in the 2256 composition of Bi-Sr-Ca-Cu-O , has been studied by the measurements of electrical resistance, magnetic susceptibility and X-ray diffraction pattern. Results show the existence of a superconducting phase with onset T c at 112.5±1 K along with a minor phase with onset T c =88 K . The material retained superconducting characteristics (Meissner effect and T c onset ) even after a period of six months.

DIELECTRIC PROPERTIES OF Zr-DOPED Ba0.985Bi0.01TiO3 SYNTHESIZED BY INORGANIC DISTILLATION UNDER ATMOSPHERIC PRESSURE

2013 ◽  
Vol 27 (04) ◽  
pp. 1350026 ◽  
Author(s):  
JING WANG ◽  
SHENGLIN JIANG ◽  
LINHUA SONG
Keyword(s):  
Atmospheric Pressure ◽  
Nominal Composition ◽  
X Ray Diffraction ◽  
Multilayer Ceramic Capacitors ◽  
X Ray ◽  
High K ◽  
Diffraction Patterns ◽  
High K Dielectric ◽  
Diffuse Phase

To meet the requirement of next-generation multilayer ceramic capacitors, the synthesis and characterization of Ba 0.985 Bi 0.01 TiO 3-based high-k dielectric compositions are reported. Solid solutions with a nominal composition of 0.4 Ba 0.985 Bi 0.01 TiO 3–0.6 BaTi 1-x Zr x O 3 (x = 0.001, 0.005, 0.01, 0.02, 0.04, 0.06, 0.1) was synthesized by distillation method. Room-temperature X-ray diffraction patterns showed an increase and then a decrease in the tetragonality of Ba 0.985 Bi 0.01 TiO 3 after modifying with BaTi 1-x Zr x O 3. The decrement in tetragonality (c/a ratio) was accompanied by lowering of Curie temperature. 0.4 Ba 0.985 Bi 0.01 TiO 3–0.6 BaTi 0.995 Zr 0.005 O 3 was found to exhibit diffuse phase transition accompanied by an ultrahigh dielectric constant of 77,619, a loss tangent < 1 and a grain size < 1 μm.

scholarly journals Crystallization and preliminary X-ray analysis of a novel type of lipolytic hydrolase fromBacillus licheniformis

2014 ◽  
Vol 70 (4) ◽  
pp. 473-475
Author(s):  
Hansol Ju ◽  
Ramesh Pandian ◽  
Kyungmin Kim ◽  
Kyeong Kyu Kim ◽  
T. Doohun Kim
Keyword(s):  
Structure Refinement ◽  
Molecular Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Peg 4000 ◽  
Replacement Solution ◽  
Increasing Demand ◽  
Identification And Characterization

With increasing demand in biotechnological applications, the identification and characterization of novel lipolytic enzymes are of great importance. The crystallization and preliminary X-ray crystallographic study of a novel type of hydrolase fromBacillus licheniformis(BL28) are described here. Recombinant BL28 protein containing a C-terminal His tag was overproduced inEscherichia coliand purified to homogeneity. BL28 was crystallized using 0.2 Mammonium acetate, 0.1 Msodium citrate tribasic dihydrate pH 5.6, 30%(w/v) PEG 4000 as a crystallizing solution. X-ray diffraction data were collected to a resolution of 1.67 Å with anRmergeof 5.8%. The BL28 crystals belonged to the tetragonal space groupP41212, with unit-cell parametersa=b= 57.89,c= 167.25 Å. A molecular-replacement solution was obtained and structure refinement of BL28 is in progress.

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