CHARACTERIZATION AND MICRO-RAMAN STUDIES OF Bi2−xPbxSr2Ca2Cu3O10+δ (0 ≤ x ≤ 0.6) SUPERCONDUCTOR

1994 ◽  
Vol 08 (10) ◽  
pp. 591-603
Author(s):  
U. SINHA ◽  
S. SATHAIAH ◽  
R. N. SONI ◽  
H. D. BIST ◽  
S. C. MATHUR ◽  
...  
Keyword(s):  
Ac Susceptibility ◽  
Solubility Limit ◽  
Dc Resistivity ◽  
Apical Oxygen ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
X Ray ◽  
Percentage Volume ◽  
Pb Substitution ◽  
Scanning Electron

The X-ray diffraction (XRD), ac susceptibility, dc resistivity, and scanning electron microscopy (SEM) measurements on Bi 2−x Pb x Sr 2 Ca 2 Cu 3 O 10+δ (x = 0.0, 0.2, 0.4, and 0.6) superconductors have been correlated with the Raman scattering studies. Remarkable increases in the transition temperature and percentage volume of high T c phase are found till x = 0.4. Raman spectra also reveal dramatic changes at x = 0.4 in the phonon modes at 625 and 460 cm −1 associated with oxygen vibrations in BiO plane and apical oxygen of CuO 5 pyramid, respectively. The observed changes have been attributed to the phenomenon of oxygen redistribution among various layers. Optimum solubility limit of Pb substitution is found to be x = 0.4.

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.

A STUDY OF LOW TEMPERATURE SINTERED Mg–Mn NANO-FERRITES

2009 ◽  
Vol 23 (01) ◽  
pp. 125-132 ◽  
Author(s):  
V. SHARMA ◽  
P. MATHUR ◽  
N. SHARMA ◽  
A. SHARMA ◽  
A. THAKUR ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cation Distribution ◽  
Hot Pressing ◽  
The Other ◽  
Dc Resistivity ◽  
Microstructural Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Citrate Precursor ◽  
Scanning Electron

In the present study, Mg x Mn 1–x Fe 2 O 4 series of ferrites with x = 0.1, 0.3, 0.5, 0.7 and 0.9 were prepared by the citrate precursor technique. One set of samples was subjected to normal and the other to hot-pressed technique. Microstructural properties were studied with the help of X-ray diffraction (XRD) and scanning electron microscopy (SEM) for both sets of samples. Hot pressing of Mg – Mn ferrites results in an improvement of their magnetic and micro-structural properties, as it simultaneously controls grain growth and porosity. Hot pressing of Mg – Mn ferrites, however, results in deterioration of their dc resistivity. The cation distribution has been studied by X-ray analysis and magnetization. The variation of saturation magnetization and Curie temperature with increasing concentration of Mg 2+ ions can be explained on the basis of cation distribution and Neel two sublattice models. Possible mechanisms, models and theories contributing to these results have been discussed.

scholarly journals Solubility of Cu, Ni, Mn in Boron-Rich Fe-B-C Alloys

2021 ◽  
Vol 22 (1) ◽  
pp. 110-116
Author(s):  
O.V. Sukhova
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Solubility Limit ◽  
Alloying Elements ◽  
Residual Liquid ◽  
Quantitative Metallography ◽  
Microstructure Development ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

In the present study, the microstructure development and mechanical properties of the cast boron-rich Fe–B–C alloys cooled at 10 and 103 K/s were investigated as functions of alloying elements additions. These alloys were prepared in the following compositional ranges: B (10–14 wt.%), C (0.1–1.2 wt.%), M (5 wt.%), where M – Cu, Ni or Mn, balance Fe. Structural properties were characterized by quantitative metallography, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Mechanical properties of the structural constituents, such as microhardness and fracture toughness, were measured by a Vickers indenter. Copper becomes negligibly incorporated into the phases Fe(B,C) and Fe2(B,C) of the Fe–B–C alloys, but solubility limit forces the remaining solute into the residual liquid. As a result, the globular Cu inclusions are seen in the structure. As compared with copper, nickel has higher solubility in the constituent phases, with preferential solubility observed in the Fe2(B,C) crystals, where Ni occupies Fe positions. Having limited solubility, nickel also forms secondary Ni4B3 phase at the Fe2(B,C) boundaries. Manganese was found to dissolve completely in the Fe–B–C alloys forming substitutional solid solutions preferentially with Fe(B,C) dendrites. By entering into the iron borides structure, Mn and Ni improve their ductility but lower microhardness. The peculiarities in the structure formation and properties of the doped boron-rich Fe–B–C alloys were explained with electronic structure of the alloying elements considered.

scholarly journals Influence of Bi2O3 on microstructure and electrical properties of ZnO-SnO2 ceramics

2007 ◽  
Vol 39 (3) ◽  
pp. 229-240 ◽  
Author(s):  
T. Ivetic ◽  
M.V. Nikolic ◽  
M. Slankamenac ◽  
M. Zivanov ◽  
D. Minic ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Ball Mill ◽  
Energy Dispersive Spectrometer ◽  
Molar Ratio ◽  
Dc Resistivity ◽  
Impedance Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Scanning Electron

The effects of small amounts (0.5; 1.0 and 1.5 mol. %) of bismuth oxide on the microstructure and electrical properties of ZnO-SnO2 ceramics have been studied. Starting powders of ZnO and SnO2 were mixed in the molar ratio 2:1. After adding Bi2O3 this mixture was mechanically activated for 10 minutes in a planetary ball mill, uniaxially pressed and sintered at 1300?C for 2h. The phase composition of the sintered samples was analyzed by X-Ray Diffraction (XRD) and by Energy Dispersive Spectrometer (EDS). Morphologies were examined by Scanning Electron Microscopy (SEM). An Impedance/Gain Phase Analyzer (HP 4194A) was used to measure the impedance spectra (100Hz - 10MHz) at different temperatures. The electrical DC resistivity/conductivity at different temperatures was measured using a High Resistance Meter (HP 4329A).

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3141-3152
Author(s):  
Alma C. Chávez-Mejía ◽  
Génesis Villegas-Suárez ◽  
Paloma I. Zaragoza-Sánchez ◽  
Rafael Magaña-López ◽  
Julio C. Morales-Mejía ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Surface Characteristics ◽  
Amorphous Solids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Activities ◽  
Anodic Spark Oxidation ◽  
Porous Surfaces ◽  
Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

The Effect of the Microstructure of Diffusion Barriers on the Palladium Activation for Electroless Copper Deposition

2002 ◽  
Vol 716 ◽  
Author(s):  
Seok Woo Hong ◽  
Yong Sun Lee ◽  
Ki-Chul Park ◽  
Jong-Wan Park
Keyword(s):  
Electron Microscopy ◽  
Diffusion Barriers ◽  
Copper Deposition ◽  
X Ray Diffraction ◽  
Plan View ◽  
X Ray ◽  
Transmission Electron ◽  
Electroless Copper ◽  
Sheet Resistance Measurement ◽  
Scanning Electron

AbstractThe effect of microstructure of dc magnetron sputtered TiN and TaN diffusion barriers on the palladium activation for autocatalytic electroless copper deposition has been investigated by using X-ray diffraction, sheet resistance measurement, field emission scanning electron microscopy (FE-SEM) and plan view transmission electron microscopy (TEM). The density of palladium nuclei on TaN diffusion barrier increases as the grain size of TaN films decreases, which was caused by increasing nitrogen content in TaN films. Plan view TEM results of TiN and TaN diffusiton barriers showed that palladium nuclei formed mainly on the grain boundaries of the diffusion barriers.

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