In-situ TEM studies of magnetization reversal processes in magnetic nanostructures

2005 ◽  
Vol 907 ◽  
Author(s):  
Amanda K Petford-Long ◽  
Thomas Bromwich ◽  
Amit Kohn ◽  
Victoria Jackson ◽  
Takeshi Kasama ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetization Reversal ◽  
Giant Magnetoresistance ◽  
Magnetic Nanostructures ◽  
Magnetic Domain ◽  
Ferromagnetic Material ◽  
In Situ Tem ◽  
Transmission Electron

AbstractOne of the most widely studied types of magnetic nanostructure is that used in devices based on the giant magnetoresistance (GMR) or tunnel magnetoresistance (TMR) phenomena. In order to understand the behaviour of these materials it is important to be able to follow their magnetisation reversal mechanism, and one of the techniques enabling micromagnetic studies at the sub-micron scale is transmission electron microscopy. Two techniques can be used: Lorentz transmission electron microscopy and off-axis electron holography, both of which allow the magnetic domain structure of a ferromagnetic material to be investigated dynamically in real-time with a resolution of a few nanometres. These techniques have been used in combination with in situ magnetizing experiments, to carry out qualitative and quantitative studies of magnetization reversal in a range of materials including spin-tunnel junctions, patterned thin film elements and magnetic antidot arrays. Quantitative analysis of the Lorentz TEM data has been carried out using the transport of intensity equation (TIE) approach.

Clarifying the Role of Mg2Si and Si in Localized Corrosion of Aluminum Alloys by Quasi In Situ Transmission Electron Microscopy

CORROSION ◽  
10.5006/3457 ◽  
2020 ◽  
Vol 76 (5) ◽  
pp. 464-475 ◽  
Author(s):  
Shravan K. Kairy ◽  
Nick Birbilis
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnesium Silicide ◽  
Localized Corrosion ◽  
In Situ Tem ◽  
Al Alloy ◽  
Transmission Electron ◽  
Al Matrix

The role of magnesium silicide (Mg2Si) and silicon (Si) particles in the localized corrosion of aluminum (Al) alloys was investigated herein. Sub-micrometer-sized Mg2Si and Si particles were grown in the Al matrix of Al-Mg-Si and Al-Si alloys, respectively, and characterized by transmission electron microscopy (TEM). A quasi in situ TEM technique was used to study an identical location containing Mg2Si or Si particle in the Al matrix, prior to and following a period of immersion in 0.1 M NaCl at pH 6, 2, and 12. At pH 6 and 2, Mg2Si was initially “anodic,” preferentially dealloying via selective dissolution of Mg, resulting in the development of SiO-rich remnants that are electrochemically inert. The SiO-rich remnants at pH 2 physically detached from the Al matrix. Silicon particles were electrochemically inert at pH 6, while “cathodic” at pH 2, dissolving the Al matrix at their periphery. It was observed that copper (Cu) was redeposited on Si particles at pH 2. At pH 12, Mg2Si and Si were “cathodic” to the Al matrix. This study clarifies, and provides new insights into, the characteristics of Al alloy physical manifestation of corrosion associated with Mg2Si and Si at the nanoscale.

NANOMECHANICS OF INDIVIDUAL ZINC OXIDE NANOBELTS MEASURED BY IN SITU TRANSMISSION ELECTRON MICROSCOPY

2006 ◽  
Vol 05 (06) ◽  
pp. 951-958 ◽  
Author(s):  
XUEDONG BAI ◽  
EN GE WANG ◽  
ZHONG LIN WANG
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Zinc Oxide ◽  
Rectangular Cross Section ◽  
In Situ Tem ◽  
Resonance Modes ◽  
Bending Modulus ◽  
Transmission Electron ◽  
Potential Applications

Zinc oxide nanobelts, grown by a solid–vapor phase thermal sublimation process, are stimulating extensive interest because of their semiconducting and piezoelectric properties, diverse functionalities and chemical stability. For nanomanipulation and nanomeasurement of an individual ZnO nanobelts, in situ transmission electron microscopy (TEM) technique is a unique approach. In this paper, mechanical resonance of a single ZnO nanobelt, induced by an alternative electric field, was studied by in situ TEM. Due to the rectangular cross-section of the nanobelt, two fundamental resonance modes have been observed in corresponding to two orthogonal transverse vibration directions, showing the versatile applications of nanobelts as nanocantilevers and nanoresonators. The bending modulus of the ZnO nanobelts was measured to be ~ 52 GPa and the damping time constant of the resonance in vacuum of 10–8 Torr was ~ 1.2 ms. The ZnO nanobelts are promising in potential applications as nanocantilevers, nanoresonators and nanoactuators.

In-Situ Transmission Electron Microscopy of the Solid-Phase Epitaxial Growth of GaAs: Sample Preparation and Artifact Characterization

1997 ◽  
Vol 480 ◽  
Author(s):  
K. B. Belay ◽  
M. C. Ridgway ◽  
D. J. Llewellyn
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Sample Preparation ◽  
Epitaxial Growth ◽  
Solid Phase ◽  
Ion Beam ◽  
Ex Situ ◽  
In Situ Tem ◽  
Transmission Electron

AbstractIn-situ transmission electron microscopy (TEM) has been used to characterize the solidphase epitaxial growth of amorphized GaAs at a temperature of 260°C. To maximize heat transfer from the heated holder to the sample and minimize electron-irradiation induced artifacts, non-conventional methodologies were utilized for the preparation of cross-sectional samples. GaAs (3xI) mm rectangular slabs were cut then glued face-to-face to a size of (6x3) mm stack by maintaining the TEM region at the center. This stack was subsequently polished to a thickness of ~ 200 ýtm. A 3 mm disc was then cut from it using a Gatan ultrasonic cutter. The disc was polished and dimpled on both sides to a thickness of ~15 mimT.h is was ion-beam milled at liquid nitrogen temperature to an electron-transparent layer. From a comparison of in-situ and ex-situ measurements of the recrystallization rate, the actual sample temperature during in-situ characterization was estimated to deviate by ≤ 20°C from that of the heated holder. The influence of electron-irradiated was found to be negligible by comparing the recrystallization rate and microstructure of irradiated and unirradiated regions of comparable thickness. Similarly, the influence of “thin-foil effect” was found to be negligible by comparing the recrystallization rate and microstructure of thick and thin regions, the former determined after the removal of the sample from the microscope and further ion-beam milling of tens of microns of material. In conclusion, the potential influence of artifacts during in-situ TEM can be eliminated by the appropriate choice of sample preparation procedures.

In Situ TEM Heating Study of the γ Lamellae Formation inside the α2 Matrix of a Ti-45Al-7.5Nb Alloy

2010 ◽  
Vol 146-147 ◽  
pp. 1365-1368 ◽  
Author(s):  
Li Mei Cha ◽  
Helmut Clemens ◽  
Gerhard Dehm ◽  
Zao Li Zhang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Ex Situ ◽  
In Situ Tem ◽  
Transmission Electron ◽  
Initial Stage ◽  
Heat Treated ◽  
The Matrix ◽  
In Situ Heating

In-situ heating transmission electron microscopy (TEM) was employed to investigate the initial stage of lamellae formation in a high Nb containing γ-TiAl based alloy. A Ti-45Al-7.5Nb alloy (at %), which was heat treated and quenched in a non-equilibrium state such that the matrix consists of ordered a2 grains, was annealed inside a TEM up to 750 °C. The in-situ TEM study reveals that g laths precipitate in the a2 matrix at ~ 750 °C possessing the classical Blackburn orientation relationship, i.e. (0001)a2 // (111)g and [11-20]a2 // <110]g. The microstructure of the in-situ TEM experiment is compared to results from ex-situ heating and subsequent TEM studies.

Micromagnetic Processes in Steels

1991 ◽  
Vol 232 ◽  
Author(s):  
A. D. Beale ◽  
M. G. Hetherington ◽  
J. P. Jakubovics ◽  
B. A. Lewis ◽  
C. B. Scruby
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Domain Structure ◽  
Magnetic Domain ◽  
Magnetic Domain Structure ◽  
Magnetoacoustic Emission ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTMagnetoacoustic emission (MAE) and Barkhausen emission (BE) measurements have been carried out on steel specimens heat treated to produce various microstructures ranging from martensitic/bainitic to ferritic/pearlitic. The magnetic domain structure of the specimens has been studied using transmission electron microscopy, and micromagnetic processes have been observed using an in-situ magnetizing device. The results are used in the interpretation of the MAE and BE measurements.

scholarly journals In-situ TEM annealing of amorphous Fe-24at.%W coatings and the effect of crystallization on hardness

2020 ◽  
Vol 56 (5) ◽  
pp. 4006-4012
Author(s):  
Antonio Mulone ◽  
Inga Ennen ◽  
Andreas Hütten ◽  
Uta Klement
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amorphous Structure ◽  
In Situ Tem ◽  
Amorphous Coating ◽  
Scanning Calorimetry ◽  
Plating Bath ◽  
Maximum Value ◽  
Transmission Electron

AbstractThis paper describes the crystallization which occurs upon annealing of an amorphous Fe-24at.%W coatings, electrodeposited from a glycolate-citrate plating bath. A combination of Differential Scanning Calorimetry and in-situ Transmission Electron Microscopy annealing is used to study the onset of crystallization of the amorphous coating. The in-situ TEM analyses reveal the formation of first crystallites after annealing at 400 °C for 30 min. Upon a temperature increase to 500–600 °C, the crystallites develop into Fe-rich nanocrystals with ~ 40 nm grain size. The nanocrystals are dispersed in the remaining amorphous Fe-W matrix, which results in the formation of a mixed nanocrystalline-amorphous structure. The observed crystallization can be held responsible for the increase in the hardness obtained upon annealing of Fe-24at.%W coatings. In fact, the hardness of the as-deposited material increases from 11 to 13 GPa after annealing at 400 °C, and it reaches the maximum value of 16.5 GPa after annealing at 600 °C.

scholarly journals In Situ TEM Studies of Catalysts Using Windowed Gas Cells

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 779 ◽  
Author(s):  
Fan Ye ◽  
Mingjie Xu ◽  
Sheng Dai ◽  
Peter Tieu ◽  
Xiaobing Ren ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Structural Evolution ◽  
In Situ Tem ◽  
Gas Cell ◽  
Environmental Transmission ◽  
Transmission Electron ◽  
Wide Range ◽  
Environmental Transmission Electron Microscopy

For decades, differentially pumped environmental transmission electron microscopy has been a powerful tool to study dynamic structural evolution of catalysts under a gaseous environment. With the advancement of micro-electromechanical system-based technologies, windowed gas cell became increasingly popular due to its ability to achieve high pressure and its compatibility to a wide range of microscopes with minimal modification. This enables a series of imaging and analytical technologies such as atomic resolution imaging, spectroscopy, and operando, revealing details that were unprecedented before. By reviewing some of the recent work, we demonstrate that the windowed gas cell has the unique ability to solve complicated catalysis problems. We also discuss what technical difficulties need to be addressed and provide an outlook for the future of in situ environmental transmission electron microscopy (TEM) technologies and their application to the field of catalysis development.

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