Quantifying Dispersion of Nanoparticles in Polymer Nanocomposites Through Transmission Electron Microscopy Micrographs

2014 ◽  
Vol 2 (2) ◽  
Author(s):  
Xiaodong Li ◽  
Hui Zhang ◽  
Jionghua Jin ◽  
Dawei Huang ◽  
Xiaoying Qi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Poisson Process ◽  
Specimen Thickness ◽  
Nanoparticle Dispersion ◽  
Complete Spatial Randomness ◽  
Thin Specimen ◽  
Transmission Electron Microscopy Micrographs ◽  
Transmission Electron ◽  
K Function

The property of nanocomposites is crucially affected by nanoparticle dispersion. Transmission electron microscopy (TEM) is the “golden standard” in nanoparticle dispersion characterization. A TEM Micrograph is a two-dimensional (2D) projection of a three-dimensional (3D) ultra-thin specimen (50–100 nm thick) along the optic axis. Existing dispersion quantification methods assume complete spatial randomness (CSR) or equivalently the homogeneous Poisson process as the distribution of the centroids of nanoparticles under which nanoparticles are randomly distributed. Under the CSR assumption, absolute magnitudes of dispersion quantification metrics are used to compare the dispersion quality across samples. However, as hard nanoparticles do not overlap in 3D, centroids of nanoparticles cannot be completely randomly distributed. In this paper, we propose to use the projection of the exact 3D hardcore process, instead of assuming CSR in 2D, to firstly account for the projection effect of a hardcore process in TEM micrographs. By employing the exact 3D hardcore process, the thickness of the ultra-thin specimen, overlooked in previous research, is identified as an important factor that quantifies how far the assumption of Poisson process in 2D deviates from the projection of a hardcore process. The paper shows that the Poisson process can only be seen as the limit of the hardcore process as the specimen thickness tends to infinity. As a result, blindly using the Poisson process with limited specimen thickness may generate misleading results. Moreover, because the specimen thickness is difficult to be accurately measured, the paper also provides robust analysis of various dispersion metrics to the error of the claimed specimen thickness. It is found that the quadrat skewness and the K-function are relatively more robust to the misspecification of the specimen thickness than other metrics. Furthermore, analysis of detection power against various clustering degrees is also conducted for these two selected robust dispersion metrics. We find that dispersion metrics based on the K-function is relatively more powerful than the quadrat skewness. Finally, an application to real TEM micrographs is used to illustrate the implementation procedures and the effectiveness of the method.

Transmission Electron Microscopy of Semiconductor Based Products

1998 ◽  
Vol 523 ◽  
Author(s):  
John Mardinly ◽  
David W. Susnitzky
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ion Beam ◽  
Semiconductor Industry ◽  
Size Reduction ◽  
Specimen Preparation ◽  
Specimen Thickness ◽  
Ion Milling ◽  
Feature Size ◽  
Transmission Electron

AbstractThe demand for increasingly higher performance semiconductor products has stimulated the semiconductor industry to respond by producing devices with increasingly complex circuitry, more transistors in less space, more layers of metal, dielectric and interconnects, more interfaces, and a manufacturing process with nearly 1,000 steps. As all device features are shrunk in the quest for higher performance, the role of Transmission Electron Microscopy as a characterization tool takes on a continually increasing importance over older, lower-resolution characterization tools, such as SEM. The Ångstrom scale imaging resolution and nanometer scale chemical analysis and diffraction resolution provided by modem TEM's are particularly well suited for solving materials problems encountered during research, development, production engineering, reliability testing, and failure analysis. A critical enabling technology for the application of TEM to semiconductor based products as the feature size shrinks below a quarter micron is advances in specimen preparation. The traditional 1,000Å thick specimen will be unsatisfactory in a growing number of applications. It can be shown using a simple geometrical model, that the thickness of TEM specimens must shrink as the square root of the feature size reduction. Moreover, the center-targeting of these specimens must improve so that the centertargeting error shrinks linearly with the feature size reduction. To meet these challenges, control of the specimen preparation process will require a new generation of polishing and ion milling tools that make use of high resolution imaging to control the ion milling process. In addition, as the TEM specimen thickness shrinks, the thickness of surface amorphization produced must also be reduced. Gallium focused ion beam systems can produce hundreds of Ångstroms of amorphised surface silicon, an amount which can consume an entire thin specimen. This limitation to FIB milling requires a method of removal of amorphised material that leaves no artifact in the remaining material.

Quantitative Measurements of Segregation In Co-Cr-X Magnetic Recording Media by Energy-Filtered Transmission Electron Microscopy

1998 ◽  
Vol 517 ◽  
Author(s):  
J. Bentley ◽  
J.E. Wittig ◽  
T.P. Nolan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Recording ◽  
Core Loss ◽  
Specimen Thickness ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Quantitative Measurements ◽  
Transmission Electron ◽  
Random Angle

AbstractReliable core-loss spectroscopic methods have been developed for mapping elemental segregation in Co-Cr-X magnetic recording media by energy-filtered transmission electron microscopy. Extraction of quantitative compositions at a spatial resolution approaching 1 nm involves sophisticated treatments for diffraction contrast, variations in specimen thickness, and closely-spaced oxygen K and chromium L23 ionization edges. These methods reveal that intergranular chromium levels are ∼25 at.% for random-angle boundaries and ∼15 at.% for 90° boundaries in films of Co84Cr12Ta4 d.c. magnetron sputtered at 250°C.

A temperature-jump technique for time-resolved cryo-transmission Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 742-743
Author(s):  
H. Chestnut ◽  
D. P. Siegel ◽  
J. L. Burns ◽  
Y. Talmon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Liquid Crystalline ◽  
Temperature Jump ◽  
Specimen Preparation ◽  
Thin Specimen ◽  
Time Resolved ◽  
Sequence Of Events ◽  
Transmission Electron ◽  
Focused Beam

Transmission electron microscopy of rapidly-frozen, hydrated specimens (cryo-TEM) is a powerful way of examining labile microstructures. This technique avoids some artifacts associated with conventional preparative methods. Use of a controlled environment vitrification system (CEVS) for specimen preparation reduces the risk of unwanted sample changes due to evaporation, and permits the examination of specimens vitrified from a defined temperature. Studies of dynamic processes with time resolution on the order of seconds, in which the process was initiated by changes in sample pH, have been conducted. We now report the development of an optical method for increasing specimen temperature immediately before vitrification. Using our method, processes that are regulated by temperature can be initiated in less than 500 msec on the specimen grid. The ensuing events can then be captured by plunge-freezing within an additional 200 msec.Dimyristoylphosphatidylcholine (DMPC) liposomes, produced by extrusion, were used as test specimens. DMPC undergoes a gel/liquid crystalline transition at 24°C, inducing a change in liposome morphology from polyhedral to spherical. Five-μl aliquots of DMPC dispersions were placed on holey-carbon-filmed copper grids mounted in the CEVS environmental chamber, and maintained at 6-8°C and 80% relative humidity. Immediately before the temperature jump most of the sample was blotted away with filter paper, leaving a thin specimen film on the grid. Upon pressing the trigger, an electronic control circuit generated this timed sequence of events. First, a solenoid-activated shutter was opened to heat the specimen by exposing it for a variable time to the focused beam of a 75W Xenon arc lamp. Simultaneously, a solenoid-activated cryogen shutter in the bottom of the CEVS was opened. Next, the lamp shutter was closed after the desired heating interval. Finally, a solenoid-activated cable release was used to trigger a spring-loaded plunger in the CEVS, propelling the sample into a reservoir of liquid ethane. Vitrified samples were subsequently transferred to a Zeiss EM902 TEM, operated in zero-loss brightfield mode, for examination at −163°C.

Nanostructural characterizations of hydrogen-permselective Si–Co–O membranes by transmission electron microscopy

2009 ◽  
Vol 24 (2) ◽  
pp. 372-378 ◽  
Author(s):  
Shinji Fujisaki ◽  
Koji Hataya ◽  
Tomohiro Saito ◽  
Shigeo Arai ◽  
Yuji Iwamoto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Gas Permeation ◽  
Hydrogen Gas ◽  
Transmission Electron Microscopy Micrographs ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Diffraction Patterns ◽  
Permeation Properties

Nanostructural characterizations of liquid metal–organic precursors-derived cobalt-doped amorphous silica (Si–Co–O) membranes supported on a mesoporous anodic alumina capillary (MAAC) tube were performed to study their unique high-temperature hydrogen gas permeation properties. Cross-sectional scanning transmission electron microscopy images and selected-area electron diffraction patterns indicated that the metal cobalt and the different oxidation states of cobalt oxides (CoO and Co3O4) nanocrystallites having a size range of 5–20 nm were in situ formed in the mesopore channels of the MAAC tube. In addition, high-resolution transmission electron microscopy micrographs and electron energy loss spectroscopy elemental mapping images indicated that the highly dense Co-doped amorphous Si–O formed within the mesopore channels of the MAAC tube. These nanostructural features could contribute to the hydrogen-selective permeation properties observed for the membranes.

scholarly journals Energy Dependence of Amorphization of Ge by Kr Ions

1992 ◽  
Vol 279 ◽  
Author(s):  
R. C. Birtcher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Energy Dependence ◽  
Defect Density ◽  
Thin Specimen ◽  
Ion Energy ◽  
Transmission Electron

ABSTRACTThin Ge specimens have been irradiated with Kr ions of different energies, and the dose required for complete amorphization determined by in situ transmission electron microscopy. Because Ge is directly amorphized by a single energetic Kr ion, onset of amorphization was detected after the lowesi ion doses. The Kr dose required for complete amorphization was found to increase linearly with ion energy over the range 0.5 MeV to 3.5 MeV. With the assumption that the defect density required for amorphization is independent of ion energy, the number of defects produced in a thin specimen by each ion decreases with increasing energy as the reciprocal of the incident ion energy. TRIM calculations indicate that there is a slight decrease in the amount of damage required with increasingion energy.

A Simple Transmission Electron Microscopy Method for Fast Thickness Characterization of Suspended Graphene and Graphite Flakes

2016 ◽  
Vol 22 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Stefano Rubino ◽  
Sultan Akhtar ◽  
Klaus Leifer
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Specimen Thickness ◽  
Fast Method ◽  
Bright Field ◽  
Axis Orientation ◽  
Suspended Graphene ◽  
Transmission Electron ◽  
Low Symmetry

AbstractWe present a simple, fast method for thickness characterization of suspended graphene/graphite flakes that is based on transmission electron microscopy (TEM). We derive an analytical expression for the intensity of the transmitted electron beam I0(t), as a function of the specimen thickness t (t<<λ; where λ is the absorption constant for graphite). We show that in thin graphite crystals the transmitted intensity is a linear function of t. Furthermore, high-resolution (HR) TEM simulations are performed to obtain λ for a 001 zone axis orientation, in a two-beam case and in a low symmetry orientation. Subsequently, HR (used to determine t) and bright-field (to measure I0(0) and I0(t)) images were acquired to experimentally determine λ. The experimental value measured in low symmetry orientation matches the calculated value (i.e., λ=225±9 nm). The simulations also show that the linear approximation is valid up to a sample thickness of 3–4 nm regardless of the orientation and up to several ten nanometers for a low symmetry orientation. When compared with standard techniques for thickness determination of graphene/graphite, the method we propose has the advantage of being simple and fast, requiring only the acquisition of bright-field images.

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