Oxygen content, microstructure, and superconductivity of YBa2Cu3O7−x

1987 ◽  
Vol 2 (6) ◽  
pp. 743-749 ◽  
Author(s):  
M. P. A. Viegers ◽  
D. M. de Leeuw ◽  
C. A. H. A. Mutsaers ◽  
H. A. M. van Hal ◽  
H. C. A. Smoorenburg ◽  
...  
Keyword(s):  
Single Phase ◽  
Inner Core ◽  
X Ray ◽  
Cell Parameters ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Quench Temperature ◽  
Orthorhombic Cell ◽  
The Difference ◽  
Individual Grains

The influence of preparation conditions and microstructure on the superconductive properties of single-phase poly-crystalline YBa2Cu3O7−x was investigated by electron probe microanalysis, transmission electron microscopy (TEM), and x-ray powder diffraction as a function of temperature in various ambients supplemented by resistivity and susceptibility measurements. Leaching of Ba was observed when samples were brought in contact with water. The TEM imaging revealed that individual grains have an extremely defect-rich outer shell and an inner core with a domain structure with a and b axes interchanged. The transition temperature Tc was found to decrease with increasing quench temperature in the range 400–900°C. The Tc was observed to be linearly proportional to the difference in the orthorhombic cell parameters (b-a). Further implications are discussed.

Transmission electron microscopy and x-ray structural investigation of La0.7Ca0.3MnO3 thin films

1998 ◽  
Vol 13 (8) ◽  
pp. 2161-2169 ◽  
Author(s):  
Y. H. Li ◽  
K. A. Thomas ◽  
P. S. I. P. N. de Silva ◽  
L. F. Cohen ◽  
A. Goyal ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Changes ◽  
Lattice Mismatch ◽  
X Ray ◽  
Cell Parameters ◽  
Transmission Electron ◽  
The Difference ◽  
Face Centered ◽  
A Minor

The structural changes and magnetoresistance (MR) properties of as-grown and post-annealed La0.7Ca0.3MnO3 films were investigated by transmission electron microscopy (TEM) and x-ray diffraction (XRD). The data for the films were compared to that for bulk La0.7Ca0.3MnO3 post-annealed under the same conditions. The main structure of the as-grown films was face-centered pseudo-cubic with a doubled perovskite unit cell, of size ∼2ap × ∼2ap × 2ap, where ap is the single perovskite parameter. The phase showed a cube-on-cube epitaxy with the underlying LaAlO3 substrate. Upon annealing to a saturation point, a minor primitive pseudo-tetragonal structure evolved, of cell parameters . A total of four possible orientations of the two structures was observed by TEM, comprised of one orientation of the ∼ 2ap × ∼ 2ap × ∼ 2ap cell, i.e., the cube-on-cube epitaxy, giving rise to (00l) peaks in x-ray, and three orientations of the cell, giving rise to a single (00l)/(hk0) peak in x-ray. The bulk La0.7Ca0.3MnO3 sample also contains the × structure. The difference between the bulk and the film and the effects of annealing on films can be ascribed to the influence of strain between the film and substate, induced by lattice mismatch.

scholarly journals Electrochemical hydrogenation, lithiation and sodiation of the GdFe2–xMx and GdMn2–xMx intermetallics

2021 ◽  
pp. 139-149
Keyword(s):  
Electrode Materials ◽  
Electrochemical Impedance ◽  
Diffraction Method ◽  
Electrochemical Characteristics ◽  
Electrochemical Hydrogenation ◽  
Hydrogen Atoms ◽  
X Ray ◽  
Cell Parameters ◽  
The Difference ◽  
Better Than

Electrochemical hydrogenation, lithiation and sodiation of the phases GdFe2–xMx and GdMn2–xMx (M=Mn, Co, Ni, Zn, and Mg) and the influence of doping components on electrochemical characteristics of electrode materials on their basis were studied using X-ray powder diffraction method, scanning electron microscopy, energy dispersive X-ray analysis, X-ray fluorescent spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. Phase analysis showed a simple correspondence between unit cell parameters of the phases and atomic radii of doping elements. Electrode materials based on GdFe2 and GdMn2 doped with 2 at.% of Co, Ni and Mg demonstrated better hydrogen sorption properties than those doped with Mn and Zn. Corrosion resistance of the doped electrodes was also better than of the binary analogues (e.g. corrosion potential of the GdFe2-based electrode was –0.162 V whereas that of GdFe1.96Ni0.04 was –0.695 V). The capacity parameters were increased in the following ranges: Zn<Mn<Mg<Co<Ni and Zn<Fe<Mg<Co<Ni for GdFe2–xMx and GdMn2–xMx, respectively. After fifty cycles of charge/discharge, we observed the changes in surface morphology and composition of the electrode samples. In the structure of studied Laves type phases with MgCu2-type structure, the most suitable sites for hydrogen atoms are tetrahedral voids 8a. During lithiation and sodiation of the phases, the atoms of the M-component of the structure are replaced by the atoms of lithium, and the atoms of gadolinium are replaced by the atoms of sodium. This difference in interaction is due to the difference in atomic sizes of the atoms. No insertion of lithium or sodium into the structural voids of the phases was observed.

Analysis of the Intermetallic Compound Formed in Hot Dip Aluminized Steel

2006 ◽  
Vol 15-17 ◽  
pp. 159-163 ◽  
Author(s):  
Kee Hyun Kim ◽  
Benny van Daele ◽  
Gustaaf Van Tendeloo ◽  
Yong Sug Chung ◽  
Jong Kyu Yoon
Keyword(s):  
Intermetallic Compound ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Liquid Aluminium ◽  
Thin Specimen ◽  
Tem Analysis ◽  
X Ray ◽  
Cell Parameters ◽  
Transmission Electron ◽  
Aluminized Steel

A hot dip aluminising process was carried out with a 1mm steel sheet dipped into the Al-10at.% Si melt in an automatic hot-dip simulator. When steel and liquid aluminium are in contact with each other, a thin intermetallic compound (IMC) is formed between the steel and the aluminium. The analysis and identification of the formation mechanism of the IMC is needed to manufacture the application products. Energy dispersive X-ray spectroscopy (EDX) and electron probe microanalysis (EPMA) are normally used to identify the phases of IMC. In the Al-Fe-Si system, numerous compounds with only slight differences in composition are formed. Consequently, EDX and EPMA are insufficient to confirm exactly the thin IMC with multiphases. In this study, transmission electron microscopy (TEM) analysis combined with EDX was used. The TEM sample was prepared with focused ion beam (FIB) sampling. The FIB lift-out technology is used to slice a very thin specimen with minimum contamination for TEM analysis. It is clearly shown that the IMC consists of Al-27 at. % Fe-10 at. % Si and is identified as Al8Fe2Si with a hexagonal unit cell (space group P63/mmc). The cell parameters are a= 1.2404nm and c= 2.6234nm.

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

2011 ◽  
Vol 412 ◽  
pp. 263-266
Author(s):  
Hong Wei Zhang ◽  
Li Li Zhang ◽  
Feng Rui Zhai ◽  
Jia Jin Tian ◽  
Can Bang Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Phase ◽  
Volume Fraction ◽  
Material Structure ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

Synthesis and Characterization of T12Ba2CaCu2O8 and T12Ba2Ca2Cu3O10

1989 ◽  
Vol 169 ◽  
Author(s):  
Lauren E. H. McMills ◽  
Shu Li ◽  
Zhen Zhang ◽  
Martha Greenblatt
Keyword(s):  
Magnetic Susceptibility ◽  
Powder Diffraction ◽  
Single Phase ◽  
Synthesis And Characterization ◽  
Synthetic Method ◽  
Superconducting Properties ◽  
X Ray ◽  
Preparation Conditions ◽  
The Relationship

AbstractSingle-phase samples of T12Ba2CaCu2O8 and T12Ba2Ca2Cu3O10 have been prepared using a reliable and simple synthetic method. Samples were characterized by x-ray powder diffraction, magnetic susceptibility and four probe resistivity methods. The TcR=0 values for T12Ba2CaCu2O8 ranged from 100 to 105K, whereas those for T12Ba2Ca2Cu3O10 ranged from 96 to 107K. The relationship between the superconducting properties and the various preparation conditions are discussed.

Characterization of Zn0.96Al0.02Ga0.02O Thermoelectric Material

2013 ◽  
Vol 802 ◽  
pp. 227-231
Author(s):  
Panida Pilasuta ◽  
Pennapa Muthitamongkol ◽  
Chanchana Thanachayanont ◽  
Tosawat Seetawan
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Single Phase ◽  
Hexagonal Structure ◽  
Hexagonal Crystal Structure ◽  
X Ray Diffraction ◽  
Hexagonal Crystal ◽  
X Ray ◽  
Transmission Electron

Crystal structure of Zn0.96Al0.02Ga0.02O was analyzed by X-Ray diffraction (XRD) technique and the microstructure was observed by scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD results showed single phase and hexagonal structure a = b = 3.24982 Å, and c = 5.20661 Å. The SEM and TEM results showed the grain size of material arrangement changed after sintering and TEM diffraction pattern confirmed hexagonal crystal structure of Zn0.96Al0.02Ga0.02O after sintering.

Experimental verification of the need for either jj or intermediate coupling in the 5f states of plutonium

2003 ◽  
Vol 802 ◽  
Author(s):  
K. T. Moore ◽  
M. A. Wall ◽  
A. J. Schwartz ◽  
B. W. Chung ◽  
J. G. Tobin ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electron Microscope ◽  
Synchrotron Radiation ◽  
Single Phase ◽  
High Spatial Resolution ◽  
Intermediate Coupling ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Energy Loss ◽  
X Ray Absorption

ABSTRACTHere, we demonstrate the power of electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM) to investigate the electronic structure plutonium. Using EELS, TEM, and synchrotron-radiation-based X-ray absorption spectroscopy (XAS), we provide the first experimental evidence that Russell-Saunders (LS) coupling fails for the 5f states of Pu. These results support the assumption that only the use of jj or intermediate coupling is appropriate for the 5f states of Pu. EELS experiments were performed in a TEM and are coupled with image and diffraction data, therefore, the measurements are completely phase specific. It is shown that EELS in a TEM may be used to circumvent the difficulty of producing single-phase or single-crystal samples due to its high spatial resolution.

Nanoporous Ni and Ni-Cu Fabricated by Dealloying

2009 ◽  
Vol 1228 ◽  
Author(s):  
Masataka Hakamada ◽  
Yasumasa Chino ◽  
Mamoru Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Noble Metals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Difference ◽  
20 Nm ◽  
Good Workability ◽  
Scanning Electron

AbstractMetallic nanoporous architecture can be spontaneously attained by dealloying of a binary alloy. The nanoporous architecture can be often fabricated in noble metals such as Au and Pt. In this study, nanoporous Ni, Ni-Cu are fabricated by dealloying rolled Ni-Mn and Cu-Ni-Mn alloys, respectively. Unlike conventional Raney nickel composed of brittle Ni-Al or Cu-Al intermetallic compounds, the initial alloys had good workability probably because of their fcc crystal structures. After the electrolysis of the alloys in (NH4)2SO4 aqueous solution, nanoporous architectures of Ni and Ni-Cu with pore and ligament sizes of 10–20 nm were confirmed by scanning electron microscopy and transmission electron microscopy. X-ray diffraction analyses suggested that Ni and Cu atoms form a homogeneous solid solution in the Ni-Cu nanoporous architecture. The ligament sizes of nanoporous Ni and Ni-Cu were smaller than that of nanoporous Cu, reflecting the difference between diffusivities of Ni and Cu at solid/electrolyte interface. Ni can reduce the pore and ligament sizes of resulting nanoporous architecture when added to initial Cu-Mn alloys.

SYNTHESIS AND PIXE CHARACTERIZATION OF CuInSe2 AND CuIn3Se5

2006 ◽  
Vol 16 (01n02) ◽  
pp. 127-136
Author(s):  
P. MALAR ◽  
TAPASH RANJAN RAUTRAY ◽  
V. VIJAYAN ◽  
S. KASIVISWANATHAN
Keyword(s):  
Electron Microscopy ◽  
Single Phase ◽  
Compositional Analysis ◽  
X Ray Diffraction ◽  
Stoichiometric Mixture ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Studies ◽  
Constituent Elements

Polycrystalline ingots of CuInSe 2 and CuIn 3 Se 5 were synthesized by melt-quench technique starting from the stoichiometric mixture of constituent elements. X-ray Diffraction (XRD) studies confirmed the single-phase nature of the materials. Compositional analysis by Particle Induced X-ray Emission (PIXE) showed that the compounds are near stoichiometric. Thin films of CuInSe 2 and CuIn 3 Se 5 were grown from pre-synthesized CuInSe 2 and CuIn 3 Se 5 powders. The films were polycrystalline, single-phase and near stoichiometric in nature, as indicated by Transmission Electron Microscopy (TEM) and PIXE studies.

Synthesis and characterization of tungsten oxide nanorods

2004 ◽  
Vol 19 (12) ◽  
pp. 3665-3670 ◽  
Author(s):  
D.Z. Guo ◽  
K. Yu-Zhang ◽  
A. Gloter ◽  
G.M. Zhang ◽  
Z.Q. Xue
Keyword(s):  
Electron Microscopy ◽  
Tungsten Oxide ◽  
Electric Heating ◽  
Tungsten Oxides ◽  
X Ray ◽  
Preparation Conditions ◽  
Transmission Electron ◽  
Oxide Nanorods ◽  
Electron Energy Loss

Single crystalline nanorods (15–200 nm in diameter and hundreds nanometers in length) have been formed on the carbon-covered W wires by simple electric heating under a vacuum of 5 × 10−4 Pa. The chemical composition and crystalline structure of the nanorods were carefully investigated by various characterization techniques such as scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. After ruling out any possible existence of carbon nanotubes (CNTs), tungsten carbide, W–Fe alloying, and formation of other types of tungsten oxides, monoclinic W18O49 phase has been well identified. The mechanism of nanorod formation of sub-tungsten oxide (∼WO2.7 compared to WO3) will be discussed in relation to the sample preparation conditions.

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