scholarly journals Nanoscale deformation mechanics reveal resilience in nacre of Pinna nobilis shell

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiseok Gim ◽  
Noah Schnitzer ◽  
Laura M. Otter ◽  
Yuchi Cui ◽  
Sébastien Motreuil ◽  
...  
Keyword(s):  
Mechanical Energy ◽  
Pinna Nobilis ◽  
Organic Interfaces ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Deformation Mechanics ◽  
External Stimuli ◽  
Continuous Material ◽  
Non Destructive

Abstract The combination of soft nanoscale organic components with inorganic nanograins hierarchically designed by natural organisms results in highly ductile structural materials that can withstand mechanical impact and exhibit high resilience on the macro- and nano-scale. Our investigation of nacre deformation reveals the underlying nanomechanics that govern the structural resilience and absorption of mechanical energy. Using high-resolution scanning/transmission electron microscopy (S/TEM) combined with in situ indentation, we observe nanoscale recovery of heavily deformed nacre that restores its mechanical strength on external stimuli up to 80% of its yield strength. Under compression, nacre undergoes deformation of nanograins and non-destructive locking across organic interfaces such that adjacent inorganic tablets structurally join. The locked tablets respond to strain as a continuous material, yet the organic boundaries between them still restrict crack propagation. Remarkably, the completely locked interface recovers its original morphology without any noticeable deformation after compressive contact stresses as large as 1.2 GPa.

scholarly journals Atomic-scale observations of electrical and mechanical manipulation of topological polar flux closure

2020 ◽  
Vol 117 (32) ◽  
pp. 18954-18961 ◽  
Author(s):  
Xiaomei Li ◽  
Congbing Tan ◽  
Chang Liu ◽  
Peng Gao ◽  
Yuanwei Sun ◽  
...  
Keyword(s):  
Electric Field ◽  
Domain Wall Motion ◽  
Atomic Scale ◽  
Nanoelectronic Devices ◽  
The Core ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
External Stimuli ◽  
Closure Structure

The ability to controllably manipulate complex topological polar configurations such as polar flux-closures via external stimuli may allow the construction of new electromechanical and nanoelectronic devices. Here, using atomically resolved in situ scanning transmission electron microscopy, we find that the polar flux-closures in PbTiO3/SrTiO3superlattice films are mobile and can be reversibly switched to ordinary single ferroelectriccoradomains under an applied electric field or stress. Specifically, the electric field initially drives movement of a flux-closure via domain wall motion and then breaks it to form intermediatea/cstriped domains, whereas mechanical stress first squeezes the core of a flux-closure toward the interface and then forma/cdomains with disappearance of the core. After removal of the external stimulus, the flux-closure structure spontaneously recovers. These observations can be precisely reproduced by phase field simulations, which also reveal the evolutions of the competing energies during phase transitions. Such reversible switching between flux-closures and ordinary ferroelectric states provides a foundation for potential electromechanical and nanoelectronic applications.

Atomic-resolution Studies of Ca3Co4O9 using in-situ Scanning Transmission Electron Microscopy

2008 ◽  
Vol 14 (S2) ◽  
pp. 436-437 ◽  
Author(s):  
G Yang ◽  
Y Zhao ◽  
K Sader ◽  
A Bleloch ◽  
RF Klie
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
New Mexico ◽  
Scanning Transmission Electron Microscopy ◽  
Atomic Resolution ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

scholarly journals High-Resolution Microstructure Characterization of Additively Manufactured X5CrNiCuNb17-4 Maraging Steel during Ex and in Situ Thermal Treatment

2021 ◽  
Author(s):  
Mihaela Albu ◽  
Bernd Panzirsch ◽  
Hartmuth Schröttner ◽  
Stefan Mitsche ◽  
Klaus Reichmann ◽  
...  
Keyword(s):  
Maraging Steel ◽  
Elevated Temperatures ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Matrix ◽  
Powder Particles ◽  
In Situ Heating ◽  
Heating Up

Powder and SLM additively manufactured parts of X5CrNiCuNb17-4 maraging steel were systematically investigated by electron microscopy to understand the relationship between the properties of the powder grains and the microstructure of the printed parts. We prove that satellites, irregularities and superficial oxidation of powder particles can be transformed into an advantage through the formation of nanoscale (AlMnSiTiCr)-oxides in the matrix during the printing process. The nano-oxides showed extensive stability in terms of size, spherical morphology, chemical composition and crystallographic disorder upon in situ heating up to 950°C in the scanning transmission electron microscope. Their presence thus indicates a potential for oxide-dispersive strengthening of this steel, which may be beneficial for creep resistance at elevated temperatures. The nucleation of copper clusters and their evolution into nanoparticles as well as the precipitation of Ni and Cr particles upon in situ heating have as well been systematically documented.

Reversal Mechanisms in Lithographically Defined Magnetic Thin Film Elements Imaged by Scanning Transmission Electron Microscopy

1997 ◽  
Vol 3 (2) ◽  
pp. 146-153 ◽  
Author(s):  
Stephen McVitie ◽  
John N. Chapman
Keyword(s):  
Thin Film ◽  
Scanning Transmission Electron Microscopy ◽  
Magnetic Behavior ◽  
Hysteresis Cycle ◽  
Magnetic Thin Film ◽  
Lorentz Microscopy ◽  
Magnetic Imaging ◽  
Transmission Electron ◽  
Scanning Transmission

Abstract: The magnetic behavior of lithographically defined thin film elements of permalloy imaged by Lorentz microscopy is described. Elements of thickness <100 nm, with in-plane dimensions in the micron and sub-micron range and of varying shape, have been subjected to in situ fields using an electron microscope that has been optimized for magnetic imaging. The information provided from the imaging modes has identified the details of the magnetization reversal mechanisms in the elements during the course of a hysteresis cycle. In particular, domain wall clusters which form at the edges of the elements are observed prior to switching of the magnetization. Results are described from elements with near single and multidomain structures with different geometry.

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