ELECTRICAL NONLINEAR PHENOMENA IN ROCKS

Geophysics ◽  
1973 ◽  
Vol 38 (1) ◽  
pp. 106-124 ◽  
Author(s):  
T. J. Katsube ◽  
R. H. Ahrens ◽  
L. S. Collett
Keyword(s):  
Critical Current Density ◽  
Charge Density ◽  
Critical Current ◽  
Current Density ◽  
Nonlinear Phenomena ◽  
Critical Charge ◽  
Charge Densities ◽  
Dry Electrode ◽  
Electrode Contact ◽  
Geophysical Technique

Evidence is presented in this paper on the electrical nonlinear phenomena occurring above a certain charge density at the electrode plates (critical charge density, [Formula: see text]) for a serpentinite sample with dry electrode contact and a galena sample using moist electrode contact. The critical charge density for the serpentinite sample is [Formula: see text] [Formula: see text]. In terms of critical current density, it is [Formula: see text] at [Formula: see text] hz, or [Formula: see text] at 10 hz. The galena sample shows two critical charge densities, where one is [Formula: see text] and the other is [Formula: see text]. In terms of critical current density, it is [Formula: see text] at [Formula: see text] hz, or [Formula: see text] at 10 hz for the first critical charge. The concept of “critical charge and nonlinearity” is similar to that of “decomposition voltage” of electrodes immersed in an electrolyte. The decomposition voltage is a characteristic of conductors immersed in liquids, and it varies according to the type of conductor. It is thus possible that the nonlinear study of minerals could form a basis of a new geophysical technique, especially in borehole logging, for detecting not only the existence, but also the type, of minerals in the ground.

Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD

1991 ◽  
Vol 49 ◽  
pp. 1080-1081
Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Film Growth ◽  
Chemical Vapor ◽  
Microstructural Characterization ◽  
Ion Milling ◽  
Conventional Grinding

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.

Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

1996 ◽  
Vol 54 ◽  
pp. 338-339
Author(s):  
I-Fei Tsu ◽  
D.L. Kaiser ◽  
S.E. Babcock
Keyword(s):  
Grain Boundary ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Electromagnetic Properties ◽  
Length Scale ◽  
Density Values ◽  
Current Densities ◽  
Applied Fields ◽  
A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

Effects of surface damage on critical current density in MgB2 thin films

2021 ◽  
Vol 22 ◽  
pp. 14-19
Author(s):  
Soon-Gil Jung ◽  
Duong Pham ◽  
Jung Min Lee ◽  
Yoonseok Han ◽  
Won Nam Kang ◽  
...  
Keyword(s):  
Thin Films ◽  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Surface Damage ◽  
Mgb2 Thin Films

Dependence of critical current density on grain morphology in BiCaSrCu2Ox ceramic

Cryogenics ◽  
1991 ◽  
Vol 31 (2) ◽  
pp. 105-109 ◽  
Author(s):  
D.A. Cardwell ◽  
J.W. Cockburn ◽  
L. Cowey ◽  
H. Jones
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Grain Morphology

Temperature dependence of the intragrain critical current density in polycrystalline Ag-sheathed Bi(2223) tapes

1999 ◽  
Vol 9 (2) ◽  
pp. 2659-2662 ◽  
Author(s):  
G. Grasso ◽  
M.R. Cimberle ◽  
C. Ferdeghini ◽  
A.S. Siri ◽  
F. Marti ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Temperature Dependence ◽  
Critical Current ◽  
Current Density
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