Microwave power loss and XPS measurements on high Tc NdBaCuOxide superconducting system

Abstract In the paper, presented is a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened moulding sands prepared of three kinds of high-silica base and a selected grade of sodium silicate. Measurements of power loss of microwave radiation (Pin) expressed by a total of absorbed power (Pabs), output power (Pout) and reflected power (Pref) were carried-out on a stand of semiautomatic microwave slot line. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological and economical importance for manufacture of high-quality casting moulds and cores of various shapes and sizes. It was found that relative density influences parameters of power output and power reflected from samples of moulding sand placed in a waveguide. Absorption expressed by the parameter Pabs is not related to granularity of high-silica base: fine, medium and coarse. It was found that the semiautomatic microwave slot line supports evaluation of effectiveness of microwave absorption on the grounds of power loss measurements and enables statistic description of influence of relative density of the sandmix on penetration of electromagnetic waves in unhardened moulding sands.

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AC Power Loss Characteristics of Ag-Sheathed High-Tc Superconducting Tapes

Advances in Superconductivity III ◽

10.1007/978-4-431-68141-0_151 ◽

1991 ◽

pp. 679-682 ◽

Cited By ~ 2

Author(s):

T. Sasaoka ◽

M. Kanaoka ◽

Y. Sekii ◽

S. Hosono ◽

M. Seido

Keyword(s):

Power Loss ◽

Superconducting Tapes ◽

High Tc ◽

Ac Power

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Low-Field Microwave Absorption in High-TC Superconducting Oxides

MRS Proceedings ◽

10.1557/proc-99-455 ◽

1987 ◽

Vol 99 ◽

Cited By ~ 1

Author(s):

B. L. Ramakrishna ◽

E. W. Ong ◽

Z. Iqbal

Keyword(s):

Magnetic Field ◽

Particle Size ◽

Composite Material ◽

Microwave Absorption ◽

Superconducting State ◽

Microwave Power ◽

Modulation Amplitude ◽

High Tc ◽

Low Field ◽

Superconducting Oxides

ABSTRACTLow-field non-resonant microwave absorption in an EPR spectrometer has been observed in the superconducting state of different samples of the new high-T oxides, YBa2Cu3O7-δ and La1.8Sr0.2CuO4. It has been attributed to flux slippage occurring at the Josephson junctions existing in the granular composite material. The dependence on particle size, temperature, microwave power, DC modulation amplitude and magnetic field has been studied.

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High resolution STEM imaging study on high Tc superconductor YBa2CuaO7-x

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100106478 ◽

1988 ◽

Vol 46 ◽

pp. 882-883

Author(s):

H.-J. Ou ◽

J. M. Cowley

Keyword(s):

Crystal Structure ◽

High Resolution ◽

Grain Boundary ◽

Strong Field ◽

Imaging Study ◽

Structure Defects ◽

High Tc ◽

High Tc Superconductor ◽

Diffraction Patterns ◽

Lattice Planes

Using the dedicate VG-HB5 STEM microscope, the crystal structure of high Tc superconductor of YBa2Cu3O7-x has been studied via high resolution STEM (HRSTEM) imaging and nanobeam (∽3A) diffraction patterns. Figure 1(a) and 2(a) illustrate the HRSTEM image taken at 10' times magnification along [001] direction and [100] direction, respectively. In figure 1(a), a grain boundary with strong field contrast is seen between two crystal regions A and B. The grain boundary appears to be parallel to a (110) plane, although it is not possible to determine [100] and [001] axes as it is in other regions which contain twin planes [3]. Following the horizontal lattice lines, from left to right across the grain boundary, a lattice bending of ∽4° is noticed. Three extra lattice planes, indicated by arrows, were found to terminate at the grain boundary and form dislocations. It is believed that due to different chemical composition, such structure defects occur during crystal growth. No bending is observed along the vertical lattice lines.

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The many faces of STEM in materials science

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086507 ◽

1991 ◽

Vol 49 ◽

pp. 440-441

Author(s):

John Silcox

Keyword(s):

Materials Science ◽

Auger Spectroscopy ◽

Dark Field ◽

High Tc Superconductors ◽

High Tc ◽

Acoustic Environment ◽

Electromagnetic Vibration ◽

The Many ◽

Serial Mode

Determination of the microstructure and microchemistry of small features often provides the insight needed for the understanding of processes in real materials. In many cases, it is not adequate to use microscopy alone. Microdiffraction and microspectroscopic information such as EELS, X-ray microprobe analysis and Auger spectroscopy can all contribute vital parts of the picture. For a number of reasons, dedicated STEM offers considerable promise as a quantitative instrument. In this paper, we review progress towards effective quantitative use of STEM with illustrations drawn from studies of high Tc superconductors, compound semiconductors and metallization of H-terminated silicon.Intrinsically, STEM is a quantitative instrument. Images are acquired directly by detectors in serial mode which is particularly convenient for digital image acquisition, control and display. The VG HB501A at Cornell has been installed in a particularly stable electromagnetic, vibration and acoustic environment. Care has been paid to achieving UHV conditions (i.e., 10-10 Torr). Finally, it has been interfaced with a VAX 3200 work station by Kirkland. This permits, for example, the acquisition of bright field (or energy loss) images and dark field images simultaneously as quantitative arrays in perfect registration.

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High Resolution Electron Microscopy of internal interfaces in layered materials

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174734 ◽

1990 ◽

Vol 48 (4) ◽

pp. 320-321

Author(s):

Yoichi Ishida ◽

Hideki Ichinose ◽

Yutaka Takahashi ◽

Jin-yeh Wang

Keyword(s):

Grain Boundaries ◽

Mirror Symmetry ◽

Functional Materials ◽

High Resolution Electron Microscopy ◽

Layered Materials ◽

Plane Boundary ◽

Chemical Information ◽

Layer Plane ◽

High Tc ◽

Cubic Metals

Layered materials draw attention in recent years in response to the world-wide drive to discover new functional materials. High-Tc superconducting oxide is one example. Internal interfaces in such layered materials differ significantly from those of cubic metals. They are often parallel to the layer of the neighboring crystals in sintered samples(layer plane boundary), while periodically ordered interfaces with the two neighboring crystals in mirror symmetry to each other are relatively rare. Consequently, the atomistic features of the interface differ significantly from those of cubic metals. In this paper grain boundaries in sintered high-Tc superconducting oxides, joined interfaces between engineering ceramics with metals, and polytype interfaces in vapor-deposited bicrystal are examined to collect atomic information of the interfaces in layered materials. The analysis proved that they are not neccessarily more complicated than that of simple grain boundaries in cubic metals. The interfaces are majorly layer plane type which is parallel to the compound layer. Secondly, chemical information is often available, which helps the interpretation of the interface atomic structure.

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Intergrowth of modulated structures in high Tc Bi-Sr-Ca-Cu-O superconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173510 ◽

1990 ◽

Vol 48 (4) ◽

pp. 76-77

Author(s):

A.Q. He ◽

G.W. Qiao ◽

J. Zhu ◽

H.Q. Ye

Keyword(s):

Twin Structure ◽

Modulated Structure ◽

High Tc ◽

One Dimensional ◽

Lattice Constants ◽

Superconducting Phases ◽

Modulated Structures ◽

Layer Structures

Since the first discovery of high Tc Bi-Sr-Ca-Cu-O superconductor by Maeda et al, many EM works have been done on it. The results show that the superconducting phases have a type of ordered layer structures similar to that in Y-Ba-Cu-O system formulated in Bi2Sr2Can−1CunO2n+4 (n=1,2,3) (simply called 22(n-1) phase) with lattice constants of a=0.358, b=0.382nm but the length of c being different according to the different value of n in the formulate. Unlike the twin structure observed in the Y-Ba-Cu-O system, there is an incommensurate modulated structure in the superconducting phases of Bi system superconductors. Modulated wavelengths of both 1.3 and 2.7 nm have been observed in the 2212 phase. This communication mainly presents the intergrowth of these two kinds of one-dimensional modulated structures in 2212 phase.

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Modulated structures in (Bi,Pb)-Sr-Ca-Cu-O films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173443 ◽

1990 ◽

Vol 48 (4) ◽

pp. 62-63

Author(s):

Shozo Ikeda ◽

Hirotoshi Hayakawa ◽

Daniel R. Dietderich

Keyword(s):

Rf Magnetron Sputtering ◽

Potential Method ◽

High Tc ◽

Bscco System ◽

Heat Treated ◽

Modulated Structures ◽

High Tc Phase ◽

Deposited Films ◽

Sputtering System

Pb addition makes easier to form the high Tc phase in the BSCCO system. However, Pb easily vaporized at high temperature. A controlled Pb potential method has been applied to grow the high Tc phase in films. Initially, films are deposited on cleaved MgO substrates using an rf magnetron sputtering system. These amorphous as-deposited films are heat treated in a sealed gold capsule along with a large pellet of Pb-added BSCCO. Details of the process and characterization of the films have been reported elsewhere (1). Films trated for 0.5h at 850° C contain mainly the low Tc phase with a small amount of the high Tc phase. Hawever, films treated for 3h at 850°C consist mainly of the high Tc phase. This film is superconductive with a Tc(zero) of 106K. The Pb/Bi ratio of the films, analysed by SEM- EDS, are 0.12 and 0.18 for heat tratment times of 0.5 and 3h, respectively. The present study investigates the modulated structures of these films using HREM.

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