Atom Probe Microanalysis of Superconducting YBa2Cu3O7−x

1987 ◽  
Vol 99 ◽  
Author(s):  
S. S. Brenner ◽  
G. L. Kellogg
Keyword(s):  
Oxygen Concentration ◽  
Concentration Profile ◽  
Drift Tube ◽  
Atom Probe ◽  
Oxide Powders ◽  
Tube Type ◽  
Oxygen Concentration Profile

ABSTRACTSuperconducting YBa2Cu3O7−x needles prepared from hot-pressed discs of oxide powders were analyzed in a long drift-tube type atom probe. An analyses was made from a randomly located area about 2 nm in diameter. Most of the oxygen field-evaporated as O2+ ions. The measured composition agreed well with that of YBa2Cu3O6.5 except for yttrium which was found to be too high. The oxygen concentration profile showed fluctuations about 2.5 nm apart which must still be clarified.

Simulation of turbulence and dissolved oxygen concentration profiles over biofilm using k–ɛ turbulence model

2005 ◽  
Vol 52 (7) ◽  
pp. 181-186 ◽  
Author(s):  
H. Nagaoka ◽  
K. Sanda
Keyword(s):  
Mass Transfer ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Turbulence Model ◽  
Laser Doppler Velocimetry ◽  
Concentration Profiles ◽  
Doppler Velocimetry ◽  
Turbulent Model ◽  
Dissolved Oxygen Concentration ◽  
Oxygen Concentration Profile

The objective of this study is to investigate the flow structure over biofilm experimentally and theoretically. Velocity and turbulence profiles over biofilm measured by a laser Doppler velocimetry were compared to simulated profiles using the k–ɛ turbulent model. Also, dissolved oxygen concentration profiles over biofilm are measured using a micro DO sensor. The k–ɛ turbulence model was proved to be a useful tool for the understanding of mass transfer inside and outside biofilm. Dissolved oxygen concentration profile inside and outside biofilm showed the existence of turbulent diffusion inside biofilm.

OXYGEN CONCENTRATION OF Eu1 Ba2 Cu3 O7-x IN VACUUM : AN ATOM PROBE STUDY II

1989 ◽  
Vol 50 (C8) ◽  
pp. C8-477-C8-480 ◽  
Author(s):  
P. P. CAMUS ◽  
H. B. ELSWIJK ◽  
A. J. MELMED
Keyword(s):  
Oxygen Concentration ◽  
Atom Probe

Oxygen concentration of Eu1Ba2Cu3O7−xin vacuum: An atom probe study

1989 ◽  
Vol 55 (25) ◽  
pp. 2667-2669 ◽  
Author(s):  
H. B. Elswijk ◽  
A. J. Melmed ◽  
P. P. Camus
Keyword(s):  
Oxygen Concentration ◽  
Atom Probe

The Atom Probe and Its Application to Steels

1981 ◽  
Vol 39 ◽  
pp. 6-9 ◽  
Author(s):  
S. S. Brenner ◽  
M. K. Miller
Keyword(s):  
Spatial Resolution ◽  
High Voltage ◽  
Drift Tube ◽  
Atom Probe ◽  
Power Supplies ◽  
Dc Potential ◽  
Solute Atoms ◽  
Focusing Lens ◽  
Field Ion Microscope ◽  
Ancillary Equipment

Solute atoms, even in minute quantities, often markedly influence the processing and properties of solids. To understand these effects requires the analysis of highly localized regions. Many techniques have been developed to make such measurements. Among these is the atom probe (AP) which is unique in its atomic-dimensioned spatial resolution and its mass-independent sensitivity.The AP consists of a field-ion microscope (FIM) and a time-of-flight mass spectrometer, Fig. 1. The needle-shaped specimen is mounted on a cryogenically-cooled goniometer stage facing a CEMA and phosphor screen. A central hole in the imaging assembly serves as the entrance aperture to the spectrometer flight tube which is typically 1-2 mm in length. The only focusing lens is an Einzel lens which converges the trajectories of the ions entering the drift tube. Ancillary equipment includes power supplies to provide the specimen with short (20 ns) high voltage pulses superimposed on a DC potential of up to 30 kV.

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