STATISTICAL ANALYSIS OF ATOM-PROBE DATA (I) : DERIVATION OF SOME FINE-SCALE FEATURES FROM FREQUENCY DISTRIBUTIONS FOR FINELY DISPERSED SYSTEMS

AbstractThe pulsed laser atom probe has been used to characterise the fine scale chemistry of a range of III-V ternary and quaternary compound semiconductors (GaInAs, AlInAs, GaAlInAs) grown, using MOCVD techniques, on indium phosphide substrates. It has been observed that there are fine scale chemical fluctuations in some specimens on a scale of typically 10–20 nm. The fluctuations appear to be a result of localized clustering of the group III components in the epilayer. In quaternary material there is evidence for different degrees of clustering for different components. It is suggested that this compositional fluctuation is a consequence of clustering occuring above a miscibility gap. The existence of a TEM contrast mechanism inherent to the material has the effect of making TEM an unreliable indicator of fine scale compositional variations in these systems.

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The Measurement of Composition During the Early Stages of the Spinodal Decomposition of Fe-Cr Alloys

MRS Proceedings ◽

10.1557/proc-186-209 ◽

1990 ◽

Vol 186 ◽

Cited By ~ 1

Author(s):

M.G. Hetherington ◽

J.M. Hyde ◽

M.K. Miller

Keyword(s):

Monte Carlo ◽

Phase Separation ◽

Spinodal Decomposition ◽

Atom Probe ◽

Statistical Techniques ◽

Fine Scale ◽

Monte Carlo Calculations ◽

Early Stages ◽

Non Linear

AbstractThe properties of many advanced alloys are derived from extremely fine-scale microstructures. This poses interesting questions about the measurement of composition on this scale. The phase separation of model Fe-Cr alloys has been been studied with the atom-probe. Statistical techniques have been used to estimate the composition and compare the results with the predictions of linear and non-linear theories of spinodal decomposition and the distributions obtained from Monte-Carlo calculations.

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Species frequency distribution as a function of the surface area

Acta Societatis Botanicorum Poloniae ◽

10.5586/asbp.1984.010 ◽

2014 ◽

Vol 53 (1) ◽

pp. 87-98

Author(s):

Anna J. Kwiatkowska

Keyword(s):

Statistical Analysis ◽

Surface Area ◽

Frequency Distribution ◽

Point Of View ◽

Sample Plot ◽

Statistical Point ◽

Frequency Distributions ◽

Species Frequency

Paper deals with the results of statistical analysis of the type of frequency distribution of species occuring in the field layers of two forest phytocoenoses. In the both cases frequency distributions were ranged out for the surface area of 1, 2, 4, 8, 16, 32 and 64 m<sup>2</sup>. The types of frequency distributions were determined on the grounds of the values of Fisher's and Pearson's K coefficients. Analysed distributions were classified into Pearson's system. Also the size of the sample plot at which the empirical frequency distributions were symetrical, from the statistical point of view, nad where they were U-shaped was determined.

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Specimen preparation of irradiated materials for examination in the atom probe field ion microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100172140 ◽

1994 ◽

Vol 52 ◽

pp. 882-883

Author(s):

K. F. Russell ◽

M. K. Miller

Keyword(s):

Neutron Irradiation ◽

Atom Probe ◽

Specimen Preparation ◽

Fine Scale ◽

Probe Field ◽

Taper Angle ◽

Ion Microscopy ◽

Remote Operations ◽

Field Ion Microscope

The atom probe field ion microscope (APFIM) is well suited to the characterization of the fine scale features and defects that are formed in materials due to exposure to neutron irradiation. However, in order for the technique to be effective, suitable specimens are required. Atom probe field ion microscopy specimens are in the form of ultrasharp needles that are usually produced by a series of mechanical and chemical or electrochemical methods. These needles have a typical end radius of approximately 10 to 50 nm and a taper angle of between 1 and 5. The small dimensions mean that the specimens are extremely fragile and difficult to handle and do not easily lend themselves to remote operations in a hot cell. The small size and mass of the APFIM specimen has the advantage that the amount of material required is minimal.A concept in working with irradiated materials is to keep exposure to the operator "as low as reasonably achievable" (ALARA).

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