HIGH-FIELD AND MICROSTRUCTURE STUDIES OF SUPERCONDUCTING nYBa2Cu3Oy:AgO COMPOSITES

1989 ◽  
Vol 03 (06) ◽  
pp. 525-535 ◽  
Author(s):  
C.Y. HUANG ◽  
H.H. TAI ◽  
M.K. WU
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Field ◽  
Polarized Light ◽  
Critical Fields ◽  
Strong Pinning ◽  
Current Densities ◽  
Very High ◽  
Scanning Electron

We have measured the resistance of superconducting n YBa 2 Cu 3 O y: AgO (n=2,3,4, and 5) composites above 77 K for magnetic field up to 20 T. The data reveal that the resistance is zero even at 80 K and 20 T. The temperature dependence of the critical field near T c (91.6 K) is very strong, and critical fields at 0 K are thus expected to be very high. Our results of scanning electron microscopy and polarized light microscopy have shown that the presence of silver results in the growth of very large grains (~0.5 mm) with silver dispersed in the grains, giving rise to strong pinning and, hence, large superconducting critical current densities.

Some Physical Properties of Suspendable Superconducting 123-Ag Composites

1989 ◽  
Vol 169 ◽  
Author(s):  
C. Y. Huang ◽  
H. H. Tai ◽  
Y. D. Yao ◽  
T. J. Li ◽  
M. K. Wu
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Field Dependence ◽  
High Field ◽  
Polarized Light ◽  
Hysteresis Loops ◽  
Residual Magnetization ◽  
Superconducting Transition ◽  
Phase Slippage ◽  
Scanning Electron

AbstractWe have measured the M-H hysteresis loops of n YBa2Cu3Oy: Ag (n = 3,5, and 7), and 3RBa2Cu3Oy:Ag (R = rare earth) as a function of temperature. We have found that the residual magnetization and, hence, pinning, is strong and is independent of n and R, but dependent on the metallurgy. The giant creep rates have been measured and are greater than those of pure 123 samples. Scanning electron microscopy and polarized light microscopy have shown that the presence of silver gives rise to the growth of large grains (~1 mm) in the 123-Ag samples. The field dependence of the critical current density is not strong at high field. We have also measured the resistance in field up to 200 kOe. The resistance remains zero even at 80 K and 200 kOe. The field dependence of the superconducting transition is discussed in terms of phase slippage.

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.

Identification of Nd163 phase in melt-textured NdBa2Cu3O7−δ bulk samples

2003 ◽  
Vol 18 (9) ◽  
pp. 2050-2054 ◽  
Author(s):  
Marcello Gombos ◽  
Vicente Gomis ◽  
Anna Esther Carrillo ◽  
Antonio Vecchione ◽  
Sandro Pace ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Optical Microscopy ◽  
Room Temperature ◽  
Polarized Light ◽  
Energy Dispersive ◽  
X Ray ◽  
Spontaneous Formation ◽  
The Stability ◽  
Scanning Electron

In this work, we report on the observation of Nd1Ba6Cu3O10,5 (Nd163) phase of the NdBaCuO system in melt-textured Nd123 bulk samples grown from a mixture of Nd123 and Nd210 phase powders. The observation was performed with polarized light optical microscopy and scanning electron microscopy–energy dispersive x-ray analyses. Images of the identified phase crystals show an aspect quite different from Nd422 crystals. Unexpectedly, Nd163 was individuated, even in “pure” Nd123 samples. Moreover, after long exposure to air, Nd163 disappeared completely in samples synthesized from powders containing Nd210. Thermogravimetry analyses of powders show that the stability of this phase in air is limited to temperatures higher than 900 °C, so Nd163 is unstable and highly reactive at room temperature. Moreover, an explanation of the observation of Nd163 in Nd210 free samples, based on the spontaneous formation of Nd163 phase in a Nd123 melt, is proposed.

scholarly journals Some aspects of nickel electrodeposition in the presence of a magnetic field

2005 ◽  
Vol 70 (10) ◽  
pp. 1213-1217 ◽  
Author(s):  
Nebojsa Nikolic
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnetic Properties ◽  
Dendritic Structure ◽  
Nickel Deposit ◽  
Nickel Electrodeposition ◽  
Nickel Deposits ◽  
Scanning Electron

Nickel deposits obtained from a Watt solution both without and with a perpendicularly oriented magnetic field were examined by scanning electron microscopy (SEM). The nickel deposit obtained without an imposed magnetic field was very rough, with a clearly visible clustered structure. The nickel deposit obtained under a perpendicularly oriented magnetic field has a very developed dendritic structure, which can be denoted as arboreous ? bead dendritic structure. The ob- served difference is essentially ascribed to the effect of a magnetic field on the magnetic properties of nickel.

Wood identification of charcoal with 3D-reflected light microscopy

IAWA Journal ◽  
2020 ◽  
Vol 41 (4) ◽  
pp. 478-489 ◽  
Author(s):  
Valentina Zemke ◽  
Volker Haag ◽  
Gerald Koch
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Field Emission ◽  
Polarized Light ◽  
Structural Features ◽  
Light Illumination ◽  
Reflected Light ◽  
Carbonized Wood ◽  
Scanning Electron

Abstract The present study focusses on the application of 3D-reflected light microscopy (3D-RLM) for the wood anatomical identification of charcoal specimens produced from domestic and tropical timbers. This special microscopic technique offers a detailed investigation of anatomical features in charcoal directly compared with the quality of field emission scanning electron microscopy (FESEM). The advantages of using the 3D-RLM technology are that fresh fracture planes of charcoal can be directly observed under the microscope without further preparation or surface treatment. Furthermore, the 3D-technique with integrated polarized light illumination creates high-contrast images of uneven and black charcoal surfaces. Important diagnostic structural features such as septate fibres and intercellular canals can be clearly detected and intervessel pits are directly measured. The comparison of the microscopic analyses reveals that 3D-reflected light microscopy (3D-RLM) provides an effective alternative technique to conventional field emission scanning electron microscopy for the identification of carbonized wood.

Predation on copepods by an Alaskan cladorhizid sponge

2007 ◽  
Vol 87 (6) ◽  
pp. 1721-1726 ◽  
Author(s):  
Les Watling
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lipid Content ◽  
Deep Sea ◽  
Prey Capture ◽  
Primary Process ◽  
High Lipid ◽  
Very High ◽  
Prey Items ◽  
Scanning Electron

Deep water cladorhizids are now generally thought to be carnivorous. While the methods of prey capture have been established for species of Asbestopluma, and perhaps Chondrocladia, information is sparse for species of Cladorhiza. The external morphology of the deep-sea Alaskan species, Cladorhiza corona, was examined immediately after collection, and then again later using scanning electron microscopy (SEM). All sponges examined had captured, and in most cases, fully encased, prey items which for the most part consisted of planktonic copepods. The hypothesis of this paper is that the primary process of prey capture is by means of a sticky substance and that prey stick to the sponge on contact. The abundant cladorhizid anisochelae do not seem to be arranged in a manner such that they can be used for prey capture as has been seen in Asbestopluma. Digestion of the prey occurs in a temporary cavity created by migrating sponge cells. Within this cavity lipid from the copepod is liberated, then absorbed and transported to the central part of the sponge. It is not known how much of the remaining tissue of the copepod is digested. Copepods have very high lipid content so their capture would provide the sponge with abundant energy from each prey item. The sponges seem to have their highest density in areas where bottom flow and migrating copepod numbers are both high.

scholarly journals Porosity in Polysilsesquioxane Xerogels

1999 ◽  
Vol 576 ◽  
Author(s):  
Brigitta M. Baugher ◽  
Duane A. Schneider ◽  
Douglas A. Loy ◽  
Kamyar Rahimian
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pore Structure ◽  
Convenient Method ◽  
Sol Gel ◽  
Monomer Concentration ◽  
Inorganic Materials ◽  
Sol Gel Process ◽  
Very High ◽  
Scanning Electron

ABSTRACTPolymerization of organotrialkoxysilanes is a convenient method for introducing organic functionality into hybrid organic-inorganic materials. However, not much is known about the effects of the organic substituent on the porosity of the resulting xerogels. In this study, we prepared a series of polysilsesquioxane xerogels from organotrialkoxysilanes, RSi(OR′)3, with different organic groups (R = H, Me, Et, dodecyl, hexadecyl, octadecyl, vinyl, chloromethyl, cyanoethyl). Polymerizations of the monomers were carried out under a variety of conditions, varying monomer concentration, type of catalyst, and alkoxide substituent. The effect of the organic substituent on the sol-gel process was often dramatic. In many cases, gels were formed only at very high monomer concentration and/or with only one type of catalyst. All of the gels were processed as xerogels and characterized by scanning electron microscopy and nitrogen sorption porosimetry to evaluate their pore structure.

Structural and Magnetic Properties of Sintered Materials on the Basis of Zinc Oxide

2013 ◽  
Vol 200 ◽  
pp. 261-266
Author(s):  
Igor Virt ◽  
Igor Rudyi ◽  
Ivan Kurilo ◽  
Ivan Lopatynskyi ◽  
Marian Frugynskyi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Magnetic Properties ◽  
Theoretical Models ◽  
Structural And Magnetic Properties ◽  
Faraday Method ◽  
The Magnetic Field ◽  
Sintered Materials ◽  
Scanning Electron

Structural and magnetic properties of ceramics Zn1-xCoxO and Zn1-xCrxO are studied. Average sizes of grains are determined by scanning electron microscopy. The magnetic field dependences of magnetic susceptibility are investigated by Faraday method. The relevant theoretical models are chosen.

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