scholarly journals Observation of Localized Corrosion of Ni-Based Alloys Using Coupled Orientation Imaging Microscopy and Atomic Force Microscopy

1999 ◽  
Vol 586 ◽  
Author(s):  
Peter J. Bedrossian ◽  
Adam J. Schwartz ◽  
Mukul Kumar ◽  
Wayne E. King
Keyword(s):  
Grain Boundaries ◽  
Orientation Imaging Microscopy ◽  
Sample Surface ◽  
Localized Corrosion ◽  
Corrosive Environment ◽  
Force Microscopy ◽  
Special Boundaries ◽  
Orientation Imaging ◽  
Atomic Force ◽  
Topographic Measurement

ABSTRACTWe present a method for assessing the relative vulnerabilites of distinct classes of grain boundaries to localized corrosion. Orientation imaging microscopy provides a spatial map which identifies and classifies grain boundaries at a metal surface. Once the microstructure of a region of a sample surface has been characterized, a sample can be exposed to repeated cycles of exposure to a corrosive environment alternating with topographic measurement by an atomic force microscope in the same region in which the microstructure had been mapped. When this procedure is applied to Ni and Ni-based alloys, we observe enhanced attack at random grain boundaries relative to special boundaries and twins in a variety of environments.

Indentation Techniques for the Study of Deformation Across Grain Boundaries

2003 ◽  
Vol 778 ◽  
Author(s):  
K. A. Nibur ◽  
D. F. Bahr
Keyword(s):  
Grain Boundaries ◽  
Nanocrystalline Materials ◽  
Orientation Imaging Microscopy ◽  
Slip Systems ◽  
Slip Direction ◽  
Force Microscopy ◽  
Orientation Imaging ◽  
Atomic Force ◽  
Slip Planes ◽  
Active Slip

AbstractThe mechanism by which deformation is transferred across grain boundaries and ways in which boundaries of different misorientations impact this process has been studied using indentation testing. This information could be useful in designing texture of nanocrystalline materials to maximize their mechanical properties for specific applications. Atomic force microscopy (AFM) and orientation imaging microscopy (OIM) has been combined to identify slip systems activated around indentations. When indentations are placed near grain boundaries, slip steps can be imaged on both sides of the boundary and the associated slip systems of each grain can be determined. Dislocation pile ups have been observed around indentations near boundaries which do not share a common slip direction with the active slip planes of either grain, and slip steps have been seen to traverse boundaries when these shared slip directions are present.

Imaging Electron Transport across Grain Boundaries in an Integrated Electron and Atomic Force Microscopy Platform: Application to Polycrystalline Silicon Solar Cells

2009 ◽  
Vol 1153 ◽  
Author(s):  
Manuel J Romero ◽  
Fude Liu ◽  
Oliver Kunz ◽  
Johnson Wong ◽  
Chun-Sheng Jiang ◽  
...  
Keyword(s):  
Thin Films ◽  
Atomic Force Microscopy ◽  
Solar Cells ◽  
Electron Transport ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
High Energy ◽  
Dominant Factor ◽  
Force Microscopy ◽  
Atomic Force

AbstractWe have investigated the local electron transport in polycrystalline silicon (pc-Si) thin-films by atomic force microscopy (AFM)-based measurements of the electron-beam-induced current (EBIC). EVA solar cells are produced at UNSW by <i>EVAporation</i> of a-Si and subsequent <i>solid-phase crystallization</i>–a potentially cost-effective approach to the production of pc-Si photovoltaics. A fundamental understanding of the electron transport in these pc-Si thin films is of prime importance to address the factors limiting the efficiency of EVA solar cells. EBIC measurements performed in combination with an AFM integrated inside an electron microscope can resolve the electron transport across individual grain boundaries. AFM-EBIC reveals that most grain boundaries present a high energy barrier to the transport of electrons for both p-type and n-type EVA thin-films. Furthermore, for p-type EVA pc-Si, in contrast with n-type, charged grain boundaries are seen. Recombination at grain boundaries seems to be the dominant factor limiting the efficiency of these pc-Si solar cells.

Interrogation of Alumina Grain Boundaries using Atomic Force Microscopy

1999 ◽  
Vol 580 ◽  
Author(s):  
P.A. Tibble ◽  
B.R. Heywood ◽  
R. Richardson ◽  
P. Barnes
Keyword(s):  
Particle Size ◽  
Atomic Force Microscopy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Preferential Growth ◽  
Polycrystalline Alumina ◽  
Present Evidence ◽  
Force Microscopy ◽  
Atomic Force ◽  
Uniform Growth

AbstractA number of MgO doped (3wt%) polycrystalline alumina samples were prepared. The preparation of these samples varied; different regimes for annealing (1500 – 1600°C) and a range of dwell times were examined. Atomic force microscopy (AFM) was used to study surface features. Information on grain boundary dimensions (depth, width) is presented along with a study of grain particle size. The growth of the grain boundaries was found to contradict Mullins' theory of uniform growth with time. We also present evidence for Ostwalds' ripening and the preferential growth of [001] oriented grains.

scholarly journals Generalized Hertz model for bimodal nanomechanical mapping

2016 ◽  
Vol 7 ◽  
pp. 970-982 ◽  
Author(s):  
Aleksander Labuda ◽  
Marta Kocuń ◽  
Waiman Meinhold ◽  
Deron Walters ◽  
Roger Proksch
Keyword(s):  
Contact Mechanics ◽  
Small Amplitude ◽  
Sample Surface ◽  
Hertzian Contact ◽  
Modes Of Operation ◽  
Hertz Model ◽  
Force Microscopy ◽  
Atomic Force ◽  
Resonant Modes ◽  
Shape And Size

Bimodal atomic force microscopy uses a cantilever that is simultaneously driven at two of its eigenmodes (resonant modes). Parameters associated with both resonances can be measured and used to extract quantitative nanomechanical information about the sample surface. Driving the first eigenmode at a large amplitude and a higher eigenmode at a small amplitude simultaneously provides four independent observables that are sensitive to the tip–sample nanomechanical interaction parameters. To demonstrate this, a generalized theoretical framework for extracting nanomechanical sample properties from bimodal experiments is presented based on Hertzian contact mechanics. Three modes of operation for measuring cantilever parameters are considered: amplitude, phase, and frequency modulation. The experimental equivalence of all three modes is demonstrated on measurements of the second eigenmode parameters. The contact mechanics theory is then extended to power-law tip shape geometries, which is applied to analyze the experimental data and extract a shape and size of the tip interacting with a polystyrene surface.

Investigation of Surface Grooves from Migrating Grain Boundaries

2002 ◽  
Vol 750 ◽  
Author(s):  
Nicole E. Munoz ◽  
Shelley R. Gilliss ◽  
N. Ravishankar ◽  
C. Barry Carter
Keyword(s):  
Atomic Force Microscopy ◽  
Grain Boundary ◽  
Light Microscopy ◽  
Grain Boundaries ◽  
High Purity ◽  
Moving Boundary ◽  
Migration Process ◽  
Force Microscopy ◽  
Atomic Force ◽  
And Migration

ABSTRACTVisible-light microscopy (VLM) and atomic-force microscopy (AFM) were used to study the progression of grain-boundary grooving and migration in high-purity alumina (Lucalox™). Groove profiles from the same grain boundaries were revisited using AFM following successive heat-treatments. The grooves measured from migrating grain boundaries were found to have asymmetric partial-angles compared to those measured from boundaries that did not migrate during the experiment. For a moving boundary, the grain with the larger partial-angle was consistently found to grow into the grain with the smaller partial-angle. Migrating boundaries were observed to leave behind remnant thermal grooves. The observations indicate that the boundary may be bowing out during the migration process.

Sufficient condition for reliability measurement of sample geometry by atomic force microscopy

2020 ◽  
pp. 11-15
Author(s):  
Alexander S. Kravchuk ◽  
Anzhelika I. Kravchuk
Keyword(s):  
Atomic Force Microscopy ◽  
Preliminary Investigation ◽  
Sample Surface ◽  
Sufficient Condition ◽  
Surface Geometry ◽  
Force Microscopy ◽  
Atomic Force ◽  
Geometric Deviations ◽  
Reliability Measurement ◽  
Microscope Stage

A sufficient condition for determining the reliability of geometry measurements using atomic force microscopy for relatively small cantilever tilt angles is proposed. A relationship between the basic geometric parameters of surface roughness, geometric deviations of the probe, the angles of the cantilever and the inclination of the side faces of the probe, as well as the dimensions of the nonlocal point of the probable contact of its side faces with protrusions of roughness has been established. As a sufficient condition for the reliability of geometry measurements using atomic force microscopy, an obvious requirement is accepted. It determines the smallness of the ratio of the sizes of a nonlocal point to the distance between neighboring nonlocal points. Publications in which the measurement of surface nano-geometry of the samples does not indicate the roughness of the sample surface and the probe, the angles at the tip of the probe and the tilt of the cantilever, as well as the best resolution (smallest step) at which the study is carried out, cannot be accepted as reliable, because the results obtained in them are probabilistic in nature. The surface images obtained using atomic force microscopy without proper justification for the resolution (value of the measurement step) represent only a qualitative picture, on the basis of which it makes no sense to carry out any computational manipulations. In order to increase the reliability of measurements of surface geometry using atomic force microscopy, it is necessary to radically increase the accuracy of the manufacture of probes, as well as use probes with the smallest possible angle at the apex. In addition, it is necessary to make changes in the design of the atomic force microscopy. In particular, the automatic rotation of the microscope stage should be designed. It should provide closeness the probe axis direction to the normal to the average plane of the sample. This “integral” angle of rotation of the microscope stage is easily iteratively determined at the stage of preliminary investigation of the geometry of the surface of the sample. In this case, it will be necessary to geometrically increase the length of the cantilever so that the base extends beyond the limits of the sample.

Features of the Manufacturing Process of Silicon Tips for Cantilevers

2021 ◽  
Vol 26 (3-4) ◽  
pp. 234-245
Author(s):  
A.V. Novak ◽  
◽  
V.R. Novak ◽  
A.V. Rumyantsev ◽  
◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Silicon Film ◽  
Statistical Parameter ◽  
Sample Surface ◽  
Test Sample ◽  
Oxygen Atmosphere ◽  
Maximum Height ◽  
Force Microscopy ◽  
Atomic Force ◽  
Crystallographic Planes

Sample surface examination in atomic force microscopy is carried out using cantilevers having the form of elastic consoles with sharp needle (tip) at the free end. Quality of images obtained from atomic force microscope (AFM) heavily depends on tip sharpness degree. Silicon cantilevers made based on wet anisotropic etching are widely used in atomic force microscopy. This paper studies the dependence of the shape and size of the resulting tip on the concentration of KOH in the solution, as well as the effect of pyrogenic oxidation and oxidation in a dry oxygen atmosphere on the sharpness of the tip during the sharpening process. It was shown that when 70 % concentration is used, tips with the highest aspect ratio and maximum height are obtained. In this case, the shape of the needle is an octagonal pyramid, the lateral faces of which are formed by eight crystallographic planes from {311} and {131}. It was found that in a two-stage sharpening process, consisting of pyrogenic oxidation and oxidation in a dry oxygen atmosphere, it is possible to form sufficiently sharp probes with a tip radius of 2–5 nm and an apex angle of 14–24°. It has been established that a one-stage sharpening process based on pyrogenic oxidation provides only the production of probes with a radius of about 14 nm. Comparative tests of the manufactured probes in obtaining AFM images of a test sample of a polycrystalline silicon film with hemispherical grains (HSG-Si) were presented. Research study has revealed that such a statistical parameter as the relative increment of the surface area Sdr is the most sensitive to probe sharpness for surfaces of the HSG-Si film type.

Investigation of Epitaxial GaN Films by Conductive Atomic Force Microscopy

2003 ◽  
Vol 764 ◽  
Author(s):  
S. Dogan ◽  
J. Spradlin ◽  
J. Xie ◽  
A. A. Pomarico ◽  
R. Cingolani ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
Sample Surface ◽  
Conductive Atomic Force Microscopy ◽  
Force Microscopy ◽  
Topological Features ◽  
Atomic Force ◽  
Local Current ◽  
Semiconductor Junction ◽  
Surrounding Areas ◽  
Conduction Properties

AbstractThe current conduction in GaN is very topical and is the topic of a vast amount of research. By simultaneously mapping the topography and the current distribution, conductive atomic force microscopy (C-AFM) has the potential to establish a correlation between topological features and localized current paths. In this study, this technique was applied to image the conduction properties of as-grown and post-growth chemically etched samples GaN epitaxial layers on a microscopic scale. Our results show that prismatic planes have a significantly higher conductivity than the surrounding areas of the sample surface. A large and stable local current was mainly observed from the walls of the etched pits, under forward and reverse bias of the metallized AFM tip/semiconductor junction.

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