Analytical Transmission Electron Microscopy and Scanning Transmission Electron Microscopy Techniques for the Characterization of Nanomaterial Composition, Phase and Crystallinity

Kim, Bojeong; Hochella, Michael F.

doi:10.1016/b978-0-08-099948-7.00004-x

Cited by 8 publications

(7 citation statements)

References 52 publications

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“…Individual clay platelets are only a few nanometers thick. However, once they form stacks and patches, clay platelets produce thicker sample regions for TEM analysis, which result in relatively dark contrast on those images [ 57 ]. It is also worth mentioning that dehydration of hydrated structures of clay minerals in the TEM vacuum or electron beam damage may occur during the TEM analysis, producing artifacts in the results [ 57 ].…”

Section: Resultsmentioning

confidence: 99%

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

2016

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The aggregation and colloidal stability of three, commercially-available, gamma-aluminum oxide nanoparticles (γ-Al2O3 NPs) (nominally 5, 10, and 20–30 nm) were systematically examined as a function of pH, ionic strength, humic acid (HA) or clay minerals (e.g., montmorillonite) concentration using dynamic light scattering and transmission electron microscopy techniques. NPs possess pH-dependent surface charges, with a point of zero charge (PZC) of pH 7.5 to 8. When pH < PZC, γ-Al2O3 NPs are colloidally stable up to 100 mM NaCl and 30 mM CaCl2. However, significant aggregation of NPs is pronounced in both electrolytes at high ionic strength. In mixed systems, both HA and montmorillonite enhance NP colloidal stability through electrostatic interactions and steric hindrance when pH ≤ PZC, whereas their surface interactions are quite limited when pH > PZC. Even when pH approximates PZC, NPs became stable at a HA concentration of 1 mg·L−1. The magnitude of interactions and dominant sites of interaction (basal planes versus edge sites) are significantly dependent on pH because both NPs and montmorillonite have pH-dependent (conditional) surface charges. Thus, solution pH, ionic strength, and the presence of natural colloids greatly modify the surface conditions of commercial γ-Al2O3 NPs, affecting aggregation and colloidal stability significantly in the aqueous environment.

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Section: Resultsmentioning

confidence: 99%

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

2016

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“…Radiolysis involves the ionization of sample atoms during inelastic scattering and breaks chemical bonds, resulting in the formation of defects, including amorphization, sputtering atoms from the surfaces. 22 However, compared to conventional oxide perovskites, halide perovskites are less stable under electron beam irradiation. Their nanostructures are intractable to be characterized using TEM due to the instability to high-energy electron beams.…”

Section: Introductionmentioning

confidence: 99%

“…As illustrated in Figure a, knock-on displacement involves the transfer of momentum from incident electrons to sample atoms during high-angle electron scattering, resulting in the displacement of internal atoms (especially those with low Z ). Radiolysis involves the ionization of sample atoms during inelastic scattering and breaks chemical bonds, resulting in the formation of defects, including amorphization, sputtering atoms from the surfaces …”

Section: Introductionmentioning

confidence: 99%

Orientational Dependence of Electron Beam Irradiation Damage in Lead-Free Halide Double Perovskite Cs₂AgBiBr₆

Zhang

et al. 2021

J. Phys. Chem. C

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Irradiation damage in halide perovskites usually enhances ion migration, decomposition, formation of intermediate phases, etc., which further decrease the working stability of halide perovskite optoelectronic devices. For example, due to the beam-sensitive nature of halide perovskites, the artifact information about local structures and microstructures is difficult to avoid during transmission electron microscopy (TEM) characterization. The interaction mechanism between high-energy electron beams and halide perovskites is still unclear. In this work, the electron-beam irradiation effect on solution-grown halide double perovskite Cs2AgBiBr6 crystals was systematically investigated by TEM. Depending on the different orientations of Cs2AgBiBr6, two kinds of electron beam irradiation damage were observed. When the irradiation on Cs2AgBiBr6 is along the [110]pc zone axis, a new phase Cs2Ag0.5BiBr6 with a vacancy-ordered superstructure forms, which is attributed to the “knock-on displacement” mechanism. In contrast, when the electron beams are along the [111]pc zone axis of Cs2AgBiBr6, an amorphous phase is gradually generated due to the “radiolysis” mechanism. Our finding clearly reveals the characteristics of irradiation damage in representative halide perovskites and further provides a new understanding of the working instability of halide perovskite optoelectronic devices.

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“…Atomic-resolution scanning transmission electron microscopy (STEM) uses a scanning beam mode that can be focused to a diameter as small as 0.1 nm by condenser lenses, which means that STEM can achieve the finest possible probe size of 0.5 Å with the maximum current available. 161 This merit allows for atomic scale resolution in imaging and chemical analysis of heteroatom-doped carbons. The STEM images are formed by filtering the scattered electrons over a certain angular range of the diffracted beam, which usually allows differentiation between bright-field (BF) and dark-field (DF) imaging modes.…”

Section: Characterization Of Heteroatom-doped Porous Carbonsmentioning

confidence: 99%

Polymer-Derived Heteroatom-Doped Porous Carbon Materials

et al. 2020

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Heteroatom-doped porous carbon materials (HPCMs) have found extensive applications in adsorption/separation, organic catalysis, sensing, and energy conversion/storage. The judicious choice of carbon precursors is crucial for the manufacture of HPCMs with specific usages and maximization of their functions. In this regard, polymers as precursors have demonstrated great promise because of their versatile molecular and nanoscale structures, modulatable chemical composition, and rich processing techniques to generate textures that, in combination with proper solid-state chemistry, can be maintained throughout carbonization. This Review comprehensively surveys the progress in polymer-derived functional HPCMs in terms of how to produce and control their porosities, heteroatom doping effects, and morphologies and their related use. First, we summarize and discuss synthetic approaches, including hard and soft templating methods as well as direct synthesis strategies employing polymers to control the pores and/or heteroatoms in HPCMs. Second, we summarize the heteroatom doping effects on the thermal stability, electronic and optical properties, and surface chemistry of HPCMs. Specifically, the heteroatom doping effect, which involves both single-type heteroatom doping and codoping of two or more types of heteroatoms into the carbon network, is discussed. Considering the significance of the morphologies of HPCMs in their application spectrum, potential choices of suitable polymeric precursors and strategies to precisely regulate the morphologies of HPCMs are presented. Finally, we provide our perspective on how to predefine the structures of HPCMs by using polymers to realize their potential applications in the current fields of energy generation/conversion and environmental remediation. We believe that these analyses and deductions are valuable for a systematic understanding of polymer-derived carbon materials and will serve as a source of inspiration for the design of future HPCMs.

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Analytical Transmission Electron Microscopy and Scanning Transmission Electron Microscopy Techniques for the Characterization of Nanomaterial Composition, Phase and Crystallinity

Cited by 8 publications

References 52 publications

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

Orientational Dependence of Electron Beam Irradiation Damage in Lead-Free Halide Double Perovskite Cs₂AgBiBr₆

Polymer-Derived Heteroatom-Doped Porous Carbon Materials

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Analytical Transmission Electron Microscopy and Scanning Transmission Electron Microscopy Techniques for the Characterization of Nanomaterial Composition, Phase and Crystallinity

Cited by 8 publications

References 52 publications

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

Aggregation and Colloidal Stability of Commercially Available Al2O3 Nanoparticles in Aqueous Environments

Orientational Dependence of Electron Beam Irradiation Damage in Lead-Free Halide Double Perovskite Cs2AgBiBr6

Polymer-Derived Heteroatom-Doped Porous Carbon Materials

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Orientational Dependence of Electron Beam Irradiation Damage in Lead-Free Halide Double Perovskite Cs₂AgBiBr₆