scholarly journals Vertically Aligned Single-Crystalline CoFe2O4 Nanobrush Architectures with High Magnetization and Tailored Magnetic Anisotropy

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 472
Author(s):  
Lisha Fan ◽  
Xiang Gao ◽  
Thomas O. Farmer ◽  
Dongkyu Lee ◽  
Er-Jia Guo ◽  
...  
Keyword(s):  
Self Assembly ◽  
Strain Relaxation ◽  
Critical Role ◽  
Misfit Strain ◽  
Interface Layer ◽  
Single Crystalline ◽  
Precise Control ◽  
Scanning Transmission ◽  
Vertically Aligned ◽  
Non Equilibrium

Micrometer-tall vertically aligned single-crystalline CoFe2O4 nanobrush architectures with extraordinarily large aspect ratio have been achieved by the precise control of a kinetic and thermodynamic non-equilibrium pulsed laser epitaxy process. Direct observations by scanning transmission electron microscopy reveal that the nanobrush crystal is mostly defect-free by nature, and epitaxially connected to the substrate through a continuous 2D interface layer. In contrast, periodic dislocations and lattice defects such as anti-phase boundaries and twin boundaries are frequently observed in the 2D interface layer, suggesting that interface misfit strain relaxation under a non-equilibrium growth condition plays a critical role in the self-assembly of such artificial architectures. Magnetic property measurements have found that the nanobrushes exhibit a saturation magnetization value of 6.16 μB/f.u., which is much higher than the bulk value. The discovery not only enables insights into an effective route for fabricating unconventional high-quality nanostructures, but also demonstrates a novel magnetic architecture with potential applications in nanomagnetic devices.

Block Copolymer Templating for Formation of Quantum Dots and Lattice Mismatched Semiconductor Structures

2010 ◽  
Vol 1258 ◽  
Author(s):  
Smita Jha ◽  
Chi-Chun Liu ◽  
Joo Hyung Park ◽  
Monika K. Wiedmann ◽  
T S Kuan ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Block Copolymer ◽  
Self Assembly ◽  
Strain Relaxation ◽  
Selective Area Growth ◽  
Regular Array ◽  
Defect Reduction ◽  
Precise Control ◽  
Semiconductor Structures ◽  
Selective Area

AbstractTemplated growth for the fabrication of semiconductor nanostructures such as quantum dots and lattice-mismatched structures has been employed in this study. Self assembly of block copolymers (BCP) has been exploited to create a regular array of nanoscale patterns on a substrate to generate the growth template. These patterned templates were used for the selective area growth of pseudomorphic quantum dots, allowing for precise control over the dot size and spatial distribution. Strain relaxation in lattice-mismatched structures grown past the pseudomorphic limit was also studied. Analysis of the grown structures suggests that this approach using block copolymer templating followed by selective growth can be used for defect reduction in lattice-mismatched materials.

Application of analytical electron microscopy to studies of equilibrium and non-equilibrium segregation in materials

1992 ◽  
Vol 50 (2) ◽  
pp. 1214-1215
Author(s):  
Edward A Kenik
Keyword(s):  
Electron Microscopy ◽  
Analytical Electron Microscopy ◽  
Extended Defects ◽  
Probe Diameter ◽  
Specimen Holder ◽  
Analytical Electron ◽  
Scanning Transmission ◽  
Solute Atoms ◽  
Equilibrium Segregation ◽  
Non Equilibrium

Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 666 parallel detection electron energy loss spectrometry (PEELS) systems. A double-tilt, liquid-nitrogen-cooled specimen holder was employed for microanalysis in order to minimize contamination under the focussed spot.

Strain Relaxation and In-Situ Observation of Voiding in Passivated Aluminum Alloy Lines.

1993 ◽  
Vol 308 ◽  
Author(s):  
Paul R. Besser ◽  
Thomas N. Marieb ◽  
John C. Bravman
Keyword(s):  
Strain Relaxation ◽  
Grazing Incidence ◽  
Scanning Transmission Electron Microscope ◽  
In Situ Observation ◽  
X Ray ◽  
Scanning Transmission ◽  
Length Width ◽  
Measured Strain ◽  
Ray Geometry

ABSTRACTStrain relaxation in passivated Al-0.5% Cu lines was measured using X-ray diffraction coupled with in-situ observation of the formation and growth of stress induced voids. Samples of 1 μm thick Al-0.5% Cu lines passivated with Si3N4 were heated to 380ºC, then cooled and held at 150ºC. During the test, principal strains along the length, width, and height of the line were determined using a grazing incidence x-ray geometry. From these measurements the hydrostatic strain in the metal was calculated and strain relaxation was observed. The thermal cycle was duplicated in a high voltage scanning transmission electron microscope equipped with a backscattered electron detector. The 1.25 μm wide lines were seen to have initial stress voids. Upon heating these voids reduced in size until no longer observable. Once the samples were cooled to 150ºC, voids reappeared and grew. The measured strain relaxation is discussed in terms of void and θ-phase (Al2Cu) formation.

scholarly journals Electron-Phonon Coupling Parameter of Ferromagnetic Metal Fe and Co

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2755
Author(s):  
Kyuhwe Kang ◽  
Gyung-Min Choi
Keyword(s):  
Coupling Parameter ◽  
Critical Role ◽  
Circuit Modeling ◽  
Metallic Materials ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Complicated Process ◽  
G Value ◽  
Non Equilibrium

The electron-phonon coupling (g) parameter plays a critical role in the ultrafast transport of heat, charge, and spin in metallic materials. However, the exact determination of the g parameter is challenging because of the complicated process during the non-equilibrium state. In this study, we investigate the g parameters of ferromagnetic 3d transition metal (FM) layers, Fe and Co, using time-domain thermoreflectance. We measure a transient increase in temperature of Au in an FM/Au bilayer; the Au layer efficiently detects the strong heat flow during the non-equilibrium between electrons and phonons in FM. The g parameter of the FM is determined by analyzing the temperature dynamics using thermal circuit modeling. The determined g values are 8.8–9.4 × 1017 W m−3 K−1 for Fe and 9.6–12.2 × 1017 W m−3 K−1 for Co. Our results demonstrate that all 3d transition FMs have a similar g value, in the order of 1018 W m−3 K−1.

Growth of single crystalline Si on graphene using RF-MBE: Orientation control with an AlN interface layer

2021 ◽  
Vol 548 ◽  
pp. 149295
Author(s):  
Ashraful G. Bhuiyan ◽  
Taiji Terai ◽  
Tomohiro Katsuzaki ◽  
Naoki Takeda ◽  
Akihiro Hashimoto
Keyword(s):  
Interface Layer ◽  
Single Crystalline ◽  
Orientation Control

scholarly journals Misfit Strain Relaxation of Ferroelectric PbTiO3/LaAlO3 (111) Thin Film System

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Y. B. Xu ◽  
Y. L. Tang ◽  
Y. L. Zhu ◽  
Y. Liu ◽  
S. Li ◽  
...  
Keyword(s):  
Thin Film ◽  
Strain Relaxation ◽  
Misfit Strain ◽  
Film System ◽  
Thin Film System

Self-assembled three-dimensional hierarchical graphene hybrid hydrogels with ultrathin β-MnO2 nanobelts for high performance supercapacitors

2015 ◽  
Vol 3 (4) ◽  
pp. 1540-1548 ◽  
Author(s):  
Sheng Zhu ◽  
Hui Zhang ◽  
Ping Chen ◽  
Lin-Hui Nie ◽  
Chuan-Hao Li ◽  
...  
Keyword(s):  
Self Assembly ◽  
High Performance ◽  
Three Dimensional ◽  
The Self ◽  
Mass Loading ◽  
Hybrid Hydrogel ◽  
Precise Control ◽  
Ultrafine Structure ◽  
Hybrid Hydrogels ◽  
Self Assembled

A facile protocol for the self-assembly of the rGO/β-MnO2 hybrid hydrogel with ultrafine structure and precise control of mass-loading for high performance supercapacitors is reported.

Hierarchically grown single crystalline RuO2 nanorods on vertically aligned few-walled carbon nanotubes

2012 ◽  
Vol 89 ◽  
pp. 115-117 ◽  
Author(s):  
Yumin Lee ◽  
Byungwoo Kim ◽  
Hyun Jung Jung ◽  
Jun Ho Shim ◽  
Youngmi Lee ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Single Crystalline ◽  
Vertically Aligned ◽  
Walled Carbon Nanotubes

scholarly journals Dissecting the Structure-Function Relationship of a Fungicidal Peptide Derived from the Constant Region of Human Immunoglobulins

2016 ◽  
Vol 60 (4) ◽  
pp. 2435-2442 ◽  
Author(s):  
Tecla Ciociola ◽  
Thelma A. Pertinhez ◽  
Laura Giovati ◽  
Martina Sperindè ◽  
Walter Magliani ◽  
...  
Keyword(s):  
Self Assembly ◽  
Galleria Mellonella ◽  
Critical Role ◽  
Yeast Cells ◽  
Therapeutic Effects ◽  
Constant Region ◽  
Content Type ◽  
Complementarity Determining Regions

ABSTRACTSynthetic peptides encompassing sequences related to the complementarity-determining regions of antibodies or derived from their constant region (Fc peptides) were proven to exert differential antimicrobial, antiviral, antitumor, and/or immunomodulatory activitiesin vitroand/orin vivo, regardless of the specificity and isotype of the parental antibody. Alanine substitution derivatives of these peptides exhibited unaltered, increased, or decreased candidacidal activitiesin vitro. The bioactive IgG-derived Fc N10K peptide (NQVSLTCLVK) spontaneously self-assembles, a feature previously recognized as relevant for the therapeutic activity of another antibody-derived peptide. We evaluated the contribution of each residue to the peptide self-assembling capability by circular-dichroism spectroscopy. The interaction of the N10K peptide and its derivatives withCandida albicanscells was studied by confocal, transmission, and scanning electron microscopy. The apoptosis and autophagy induction profiles in yeast cells treated with the peptides were evaluated by flow cytometry, and the therapeutic efficacy against candidal infection was studied in aGalleria mellonellamodel. Overall, the results indicate a critical role for some residues in the self-assembly process and a correlation of that capability with the candidacidal activities of the peptidesin vitroand their therapeutic effectsin vivo.

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