Superlattice Interface and Lattice Strain Study by Ion Channeling

1983 ◽  
Vol 25 ◽  
Author(s):  
C. K. Pan ◽  
D. C. Zheng ◽  
W. K. Chu ◽  
C.-A. Chang
Keyword(s):  
Lattice Strain ◽  
Ion Beam ◽  
Compressive Strain ◽  
Angular Position ◽  
Angle Measurement ◽  
Strain Effect ◽  
Individual Layer ◽  
Ion Channeling ◽  
Kink Angle ◽  
Good Agreement

EXTENDED ABSTRACTWe have studied the interface and the lattice strain of superlattices by ion channeling technique. The objective in this work is to verify the existence of alternating tensile and compressive strain in the superlattice and to develop a method for measuring the lattice strain directly. Alternating layers of GaSb/Al Sb were grown epitaxially by MBE with 10 periods. The thickness of each individual layer is 30 nm. Channeling measurements and analysis were made using a 1.76 MeV 4He ion beam. The measurements reveal higher dechanneling along the [110] axis than along the [100] axis. This is consistent with the dechanneling results published earlier. The high dechanneling along the [110] axis has been considered due to the lattice strain that occurs in the layers caused by the slight mismatch between the lattice constants of the two materials. The strain effect make [110] axis slightly bent from layer to layer (“zigzag”), but it does not occur in [100] axis. The axial angular scan analyses were made around the [110] direction at the different depths using a movable energy window setting. We have found that the angular position of the best alignment shifts from layer to layer. The oscillation of those angular positions with depth is of a direct evidence of the existence of alternating tension and compression strain layers in the superlattice. The “kink” angle at the interface is given by the difference of the angular position between the first and second layer. This is found to be 0.17° ± 0.03 %. This is in a good agreement with the result calculated from elasticity. Preliminary result of this experiment is recently published.3We are also investigating the interface and lattice strain by planar angular scan across the (110) plane at a position three degrees from [110] axis.The similar oscillatory results have been found for {110} planar channeling and the “kink” angle measurement is in a good agreement with the results from axial angular scan.We believe that the method of ion beam channeling and angular scan is very effective in strain measurements in multi-layered heteroexpitaxy system.3. W. K. Chu, C. K. Pan and C.-A. Chang, Phys. Rev. Rapid Communication B28, 4033 (1983).

scholarly journals Constitutive Modeling of the Densification Behavior in Open-Porous Cellular Solids

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2731
Author(s):  
Ameya Rege
Keyword(s):  
Constitutive Model ◽  
Cell Walls ◽  
Compressive Strain ◽  
Pore Collapse ◽  
Compressive Response ◽  
Linear Elastic ◽  
Nonlinear Springs ◽  
Different Types ◽  
Point Of Intersection ◽  
Good Agreement

The macroscopic mechanical behavior of open-porous cellular materials is dictated by the geometric and material properties of their microscopic cell walls. The overall compressive response of such materials is divided into three regimes, namely, the linear elastic, plateau and densification. In this paper, a constitutive model is presented, which captures not only the linear elastic regime and the subsequent pore-collapse, but is also shown to be capable of capturing the hardening upon the densification of the network. Here, the network is considered to be made up of idealized square-shaped cells, whose cell walls undergo bending and buckling under compression. Depending on the choice of damage criterion, viz. elastic buckling or irreversible bending, the cell walls collapse. These collapsed cells are then assumed to behave as nonlinear springs, acting as a foundation to the elastic network of active open cells. To this end, the network is decomposed into an active network and a collapsed one. The compressive strain at the onset of densification is then shown to be quantified by the point of intersection of the two network stress-strain curves. A parameter sensitivity analysis is presented to demonstrate the range of different material characteristics that the model is capable of capturing. The proposed constitutive model is further validated against two different types of nanoporous materials and shows good agreement.

Annealing effects on phase transformation and powder microstructure of nanocrystalline zirconia polymorphs

1999 ◽  
Vol 14 (1) ◽  
pp. 90-96 ◽  
Author(s):  
R. Ramamoorthy ◽  
S. Ramasamy ◽  
D. Sundararaman
Keyword(s):  
Monoclinic Phase ◽  
Lattice Strain ◽  
Dopant Concentration ◽  
Precipitation Method ◽  
Strain Effect ◽  
Volume Percentage ◽  
Annealing Temperatures ◽  
Annealing Effects ◽  
Nanocrystalline Zirconia ◽  
Average Size

Nanocrystalline zirconia powders in pure form and doped with yttria and calcia were prepared by the precipitation method. In the as-prepared condition, all the doped samples show only monoclinic phase, independent of the dopants and dopant concentration. On annealing the powders at 400 °C and above, in the case of 3 and 6 mol% Y2O3 stabilized ZrO2 (3YSZ and 6YSZ), the monoclinic phase transforms to tetragonal and cubic phases, respectively, whereas in 3 and 6 mol% CaO stabilized ZrO2 (3CSZ and 6CSZ), the volume percentage of the monoclinic phase gradually decreases up to the annealing temperature of about 1000 °C and then increases for higher annealing temperatures. The presence of monoclinic phase in the as-prepared samples of doped zirconia has been attributed to the lattice strain effect which results in the less symmetric lattice. For the annealing temperatures below 1000 °C, the phenomenon of partial stabilization of the tetragonal phase in 3CSZ and 6CSZ can be explained in terms of the grain size effect. High resolution transmission electron microscopy (HRTEM) observations reveal the lattice strain structure in the as-prepared materials. The particles are found to be a tightly bound aggregate of small crystallites with average size of 10 nm. The morphology of the particles is observed to be dependent on the dopants and dopant concentration.

Weakened Lattice-Strain Effect in MoOx@NPC-Supported Ruthenium Dots toward High-Efficiency Hydrogen Generation

2021 ◽  
Author(s):  
Min Song ◽  
Haeseong Jang ◽  
Chuang Li ◽  
Min Gyu Kim ◽  
Xuqiang Ji ◽  
...  
Keyword(s):  
Buffer Layer ◽  
Lattice Strain ◽  
High Efficiency ◽  
Hydrogen Generation ◽  
Crystalline Substance ◽  
Strain Effect

Designing conductive amorphous buffer layer between crystals (or lowering the crystallinity of one component) to minimize lattice-strain influence between highly crystalline substance and nearby constitute, alleviating the lattice strain thus...

Search for Ion Induced Mixing in Ceramic-Ceramic Systems

1995 ◽  
Vol 396 ◽  
Author(s):  
K.R. Padmanabhan
Keyword(s):  
Auger Electron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Ion Beam ◽  
Epitaxial Films ◽  
Ion Beam Mixing ◽  
Ceramic Substrates ◽  
Ion Channeling ◽  
Ceramic Films ◽  
Dose Dependent

AbstractThin sputtered ceramic films deposited on ceramic substrates were subjected to either Kr+ or Xe+ ion bombardment for ion beam mixing studies in ceramic-ceramic systems. The amount of mixing if any was evaluated from Rutherford backscattering and Auger electron spectroscopy. In some instances ceramic films were deposited on epitaxial films or single crystal substrates for ion channeling analysis. No significant mixing was observed in any of the systems with ZrC. However, analysis of the interface in Si3N4/ SiC system indicates appreciable mixing and ion beam induced damage to the substrate. The mixing appears to be dose dependent for heavier ions.

The Complementary Nature of Electron Microscopy and ION Channeling for the Assessment of Radiation Damage Evolution in Ceramics

1998 ◽  
Vol 4 (S2) ◽  
pp. 558-559
Author(s):  
K. E. Sickafus
Keyword(s):  
Damage Evolution ◽  
Ion Irradiation ◽  
Ion Beam ◽  
Quantitative Measure ◽  
Heavy Ion ◽  
Damage Parameter ◽  
Irradiation Damage ◽  
Damage Level ◽  
Ion Channeling ◽  
Typical Experiment

In ion irradiation damage studies on ceramics, damage evolution is often assessed using Rutherford backscattering spectroscopy and ion channeling (RBS/C) techniques. In a typical experiment, a single crystal ceramic sample is irradiated with heavy ions and then the crystal is exposed to He ions along a low-index crystallographic orientation. Simultaneously, the backscattered He ion yield is measured as a function of ion energy loss. For He ions scattered from the heavy ion irradiated volume, the He ion yield increases in proportion to the heavy ion dose. The RBS/C yield rises because the He ion beam is dechanneled by, for instance, interstitial point defects and clusters and their associated strain fields. A quantitative measure of dechanneling is denoted by χmin, defined as the ratio of the He ion yield along a low-index crystal orientation, to the yield obtained in a random (non-channeling) orientation. The damage parameter xmin varies from 0 to 1, where 1 represents the maximum damage level that can be measured by RBS/C.

scholarly journals Lattice strain distribution resolved by X-ray Bragg-surface diffraction in an Si matrix distorted by embedded FeSi2nanoparticles

2013 ◽  
Vol 46 (6) ◽  
pp. 1796-1804 ◽  
Author(s):  
Rossano Lang ◽  
Alan S. de Menezes ◽  
Adenilson O. dos Santos ◽  
Shay Reboh ◽  
Eliermes A. Meneses ◽  
...  
Keyword(s):  
Strain Distribution ◽  
Beam Energy ◽  
Lattice Strain ◽  
Ion Beam ◽  
Silicon Layer ◽  
Semiconductor Substrate ◽  
X Ray ◽  
Out Of Plane ◽  
Diffraction Peaks ◽  
Surface Diffraction

Out-of-plane and primarily in-plane lattice strain distributions, along the two perpendicular crystallographic directions on the subsurface of a silicon layer with embedded FeSi2nanoparticles, were analyzed and resolved as a function of the synchrotron X-ray beam energy by using ω:φ mappings of the ({\overline 1}11) and (111) Bragg-surface diffraction peaks. The nanoparticles, synthesized by ion-beam-induced epitaxial crystallization of Fe+-implanted Si(001), were observed to have different orientations and morphologies (sphere- and plate-like nanoparticles) within the implanted/recrystallized region. The results show that the shape of the synthesized material singularly affects the surrounding Si lattice. The lattice strain distribution elucidated by the nonconventional X-ray Bragg-surface diffraction technique clearly exhibits an anisotropic effect, predominantly caused by plate-shaped nanoparticles. This type of refined detection reflects a key application of the method, which could be used to allow discrimination of strains in distorted semiconductor substrate layers.

scholarly journals Nonvolatile modulation of electronic structure and correlative magnetism of L10-FePt films using significant strain induced by shape memory substrates

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Chun Feng ◽  
Jiancheng Zhao ◽  
Feng Yang ◽  
Kui Gong ◽  
Shijie Hao ◽  
...  
Keyword(s):  
Shape Memory ◽  
Elastic Strain ◽  
Lattice Strain ◽  
Physical Nature ◽  
Strain Engineering ◽  
Strain Effect ◽  
Pure Strain ◽  
Electronic Density ◽  
Fept Film ◽  
Novel Approach

Abstract Tuning the lattice strain (εL) is a novel approach to manipulate the magnetic, electronic and transport properties of spintronic materials. Achievable εL in thin film samples induced by traditional ferroelectric or flexible substrates is usually volatile and well below 1%. Such limits in the tuning capability cannot meet the requirements for nonvolatile applications of spintronic materials. This study answers to the challenge of introducing significant amount of elastic strain in deposited thin films so that noticeable tuning of the spintronic characteristics can be realized. Based on subtle elastic strain engineering of depositing L10-FePt films on pre-stretched NiTi(Nb) shape memory alloy substrates, steerable and nonvolatile lattice strain up to 2.18% has been achieved in the L10-FePt films by thermally controlling the shape memory effect of the substrates. Introduced strains at this level significantly modify the electronic density of state, orbital overlap and spin-orbit coupling (SOC) strength in the FePt film, leading to nonvolatile modulation of magnetic anisotropy and magnetization reversal characteristics. This finding not only opens an efficient avenue for the nonvolatile tuning of SOC based magnetism and spintronic effects, but also helps to clarify the physical nature of pure strain effect.

Results of geoelectrical soundings for mapping of a marine clay along the Tangkak-Pagoh highway Johor, Malaysia

1989 ◽  
Vol 20 (2) ◽  
pp. 117
Author(s):  
A.G. Rafek ◽  
A.R. Samsudin
Keyword(s):  
Apparent Resistivity ◽  
Fine Sand ◽  
Convex Curve ◽  
Marine Clay ◽  
Borehole Data ◽  
Individual Layer ◽  
The North ◽  
Geoelectrical Resistivity ◽  
Good Agreement ◽  
Clay Horizon

Geoelectrical resistivity soundings conducted along the north-south expressway in the Tangkak-Pagoh area during its construction enabled the mapping of a marine clay which was present in alluvium. The apparent resistivity curves of the marine clay area, were characterised by low apparent resistivity values falling to almost zero, and a characteristic shape which was different from areas of weathered metasediments and weathered granite adjacent to this area. Apparent resistivities for both metasediments and granite were intermediate to high, with a distinct upward convex curve for metasediments and a flat upward convex curve for granite. Quantitative interpretation was able to distinguish between an upper and a lower clay horizon, which have differentconsistency and fine sand content. The thickness of the upper clay horizon, which varies between 8.0 m to 9.0 m according to borehole data showed good agreement with that obtained by resistivity soundings. The base of the lower clay horizon remained undetected by the resistivity soundings because of its very low specific resistivity. Using the thickness of weathered layers as observed along the road cuttings as a guide, good agreement between field data and calculated values was obtained in determining the specific resistivities and individual layer thicknesses for the granite and metasediment weathering profiles.

scholarly journals Lattice Strain Analysis of a Mn-Doped CdSe QD System Using Crystallography Techniques

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 639 ◽  
Author(s):  
Hamizi ◽  
Johan ◽  
Ghazali ◽  
Wahab ◽  
Chowdhury ◽  
...  
Keyword(s):  
Lattice Strain ◽  
Reaction Times ◽  
Strain Analysis ◽  
Xrd Analysis ◽  
Lattice Parameter ◽  
Strain Effect ◽  
Similar Reaction ◽  
Cdse Qds ◽  
Particle Size Reduction ◽  
Mn Doped

In this work, we report on the different sizes of manganese-doped cadmium selenide quantum dots (Mn-doped CdSe QDs) synthesized for 0 to 90 min using a reverse micelle organic solvent method and surfactant having a zinc blende structure, with physical size varying from 3 to 14 nm and crystallite size from 2.46 to 5.46 nm and with a narrow size distribution. At similar reaction times, Mn-doped CdSe QDs displayed the growth of larger QDs compared with the pure CdSe QDs. Due to the implementation of lattice strain owing to the inclusion of Mn atoms in the CdSe QD lattice, the lattice parameter was compressed as the QD size increased. Strain was induced by the particle size reduction, as observed from X-ray diffractometer (XRD) analysis. The analyses of the strain effect on the QD reduction are discussed relative to each of the XRD characteristics.

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