The mechanism of nanoparticle precipitation induced by electron irradiation in transmission electron microscopy

Jiang, Nan

doi:10.1016/j.ultramic.2018.09.009

Cited by 4 publications

(7 citation statements)

References 28 publications

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“…As for TEM images, it has been reported that the electron beams in TEM would reduce Pd(II) to Pd(0) effectively during analysis, 40,41 which also led to the invention of an electron-beam-induced synthetic approach of Pd(0) NPs. [42][43][44] In periodic structures, this phenomenon has been often observed in MOFs. 45,46 Recently, Wang's group 14 also noticed this in their Pd(II)-containing two-dimensional (2D)-COF system.…”

Section: Resultsmentioning

confidence: 99%

Spirobifluorene-Based Three-Dimensional Covalent Organic Frameworks with Rigid Topological Channels as Efficient Heterogeneous Catalyst

Sun

et al. 2021

CCS Chem

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Although the past decade has witnessed tremendous progress in the development of covalent organic frameworks (COFs), three-dimensional (3D) COFs fabrications and characterizations are still much less studied compared with two-dimensional (2D) COFs, due to their complicated topology structures caused by interpenetration and limited choices of node-building blocks. In this work, we constructed a novel 3D COF (SP-3D-COF-BPY) successfully using orthogonal dual-planar spirobifluorene and bipyridine as building blocks. Also, we demonstrated the application of 3D COF-supported Pd(II) catalyst in heterogeneous catalysis. A sevenfold interpenetrated dia structure was revealed for SP-3D-COF-BPY by powder X-ray diffraction (PXRD) in conjunction with structural simulation and Pawley refinement. The bipyridine-linked frameworks bear one-dimensional (1D) unobstructed rigid channels and offer a high density of discrete coordination sites for chelating Pd(II) species. Very high loading of Pd(II) (∼15 wt %) was achieved in the asymmetric (as)-prepared Pd(II)@3D-COF-BYP. The generated highly ordered porous channels and easily accessible catalytic sites, such as COF-supported Pd(II) complex, serves as a highly active and stable microporous heterogeneous catalyst in Suzuki-Miyaura coupling reactions. The observed catalytic efficiency was high and the catalyst could be conveniently reused multiple times without any noticeable decay in catalytic performance.

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Section: Resultsmentioning

confidence: 99%

Spirobifluorene-Based Three-Dimensional Covalent Organic Frameworks with Rigid Topological Channels as Efficient Heterogeneous Catalyst

Sun

et al. 2021

CCS Chem

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“…In addition, some of these excited electrons may be ejected out of the TEM sample as the secondary electrons [72]. For a non-conductive material, this leads to charging, which subsequently generates static electric field in the sample, and induces another type of sample damage process, called damage by induced electric field (DIEF) [72,79]. Depending on the nature of irradiated material, the damage may raise the resistivity of the material, and thus the DIEF effect is increasing in the process, resulting in composition segregation or phase separation.…”

Section: Damage By Induced Electric Fieldmentioning

confidence: 99%

“…For some composite materials, such as an oxide glass doped with metal atoms, DIEF effect directly results in the nucleation and precipitation of metal NPs [79]. With electron beam irradiation, the knock-on collisions activate diffusion of the embedded metal atoms.…”

Section: Damage By Induced Electric Fieldmentioning

confidence: 99%

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Transformation and degradation of metal halide perovskites induced by energetic electrons and their practical implications

Dang¹,

Luo²,

Xu³

et al. 2021

Nano Futures

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Transmission electron microscopy (TEM) has been used in the characterizations of the lattice and defect structures as well as electronic and chemical properties of various materials. When TEM analyses were performed on lead halide perovskites (LHPs) and related materials, it has often been found that transformation and damage were easily induced in the specimens by electron beam irradiation. As the structural and chemical instabilities of LHPs and related materials are the main obstacle that must be overcome for their practical large-scale applications in solar cells and other optoelectronic applications, we examine whether and how the TEM-based irradiation and analyses can serve the purpose of rapid evaluation of the instabilities of a LHP to stimuli such as light and electric field which are crucial to its optoelectronic applications. We first provide a brief overview of the basic physical properties of LHPs related to the instability and the current understanding of the general mechanisms of sample damages induced by energetic electrons, followed with an analysis of the distinctive vulnerability and damaging features of LHPs with respect to electron beam irradiation. Based on the analysis of the similarities in the mechanisms of the damages generated by different stimuli, proper conditions are outlined with which the TEM-based investigations can be employed as a speed-up tester for the instabilities of LHPs against photon (including visible, ultraviolet and x-ray) exposure and an applied electric field. Furthermore, the perspectives of employing TEM-based processes in the fabrication of nanostructures and directly carrying out subsequent in situ analysis are elaborated, which is key to acquiring knowledge for improving focused electron beam-based industrial micro- and nanofabrication technologies.

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“…These mechanisms can well interpret amorphization of SiO2. Besides phase separation and phase transformation, the precipitation of metal nanoparticles is also an energetic favorable process under electron beam [8]. The Gibbs free energy barrier for nucleation of metal particles can be largely reduced under electron beam, and the directional drifting of atoms driven by the electric forces accelerates the kinetic process of metal particle precipitation as well.…”

mentioning

confidence: 99%

Damage by Induced Electric Field versus Radiolysis

Jiang

2019

Microsc Microanal

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Radiolysis has been the most referred mechanism to interpret damage phenomena in electron microscopy, especially in semiconductor and insulator materials. This type of damage is initiated from the electronic excitation and ionization by beam electrons. In radiation chemistry, the original concept of radiolytic process results in the cleavage of chemical bond(s) due to exposure to ionizing radiation, and forms radicals. These radicals are highly reactive. The main difference between radiolysis and ionization is that in the former the radical has at least one unpaired electron and this molecule or atom does not carry a charge, while in the latter the ion is either positively or negatively charged due to the loss or gain of an electron [1]. Obviously the radiolytic process in radiation chemistry is not the same as what we meant in TEM, in which beam damage is not caused by chemical reaction (with nearest rigid atoms) but by displacement of atom. In rigid solids, the mechanism should be able to provide explicitly how the atom acquires momentum to displace, rather than how the chemical bond breaks. Unfortunately, only a few have addressed this in details among a vast number of publications.

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The mechanism of nanoparticle precipitation induced by electron irradiation in transmission electron microscopy

Cited by 4 publications

References 28 publications

Spirobifluorene-Based Three-Dimensional Covalent Organic Frameworks with Rigid Topological Channels as Efficient Heterogeneous Catalyst

Spirobifluorene-Based Three-Dimensional Covalent Organic Frameworks with Rigid Topological Channels as Efficient Heterogeneous Catalyst

Transformation and degradation of metal halide perovskites induced by energetic electrons and their practical implications

Damage by Induced Electric Field versus Radiolysis

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