Lattice-distortion-induced amorphization in indented [110] silicon

1999 ◽  
Vol 14 (3) ◽  
pp. 682-687 ◽  
Author(s):  
Y. Q. Wu ◽  
Y. B. Xu
Keyword(s):  
Amorphous Silicon ◽  
Lattice Distortion ◽  
Lattice Structure ◽  
Amorphous Structure ◽  
Vickers Indentation ◽  
Continuous Transition ◽  
Silicon Matrix ◽  
Transmission Electron ◽  
Matrix Deformation ◽  
Fine Structures

High-resolution transmission electron microscopy (HRTEM) is used to reveal fine structures of amorphous silicon induced by Vickers indentation and its interface with unindented silicon matrix. Deformation microtwins at the interface and continuous transition from lattice structure of crystal into amorphous structure at the interface are observed. Within the amorphous silicon near the periphery of the indented region, there are many clusters characterized by distorted silicon lattice. A possible mechanism of lattice-distortion-induced amorphization at the periphery of indented silicon is suggested. All the indentations are performed at ambient temperature.

Cross-sectional observation on the indentation of [001] silicon

1999 ◽  
Vol 14 (6) ◽  
pp. 2399-2401 ◽  
Author(s):  
Y. Q. Wu ◽  
G. Y. Shi ◽  
Y. B. Xu
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Amorphous Silicon ◽  
Transmission Electron Microscope ◽  
Indentation Depth ◽  
Hydrostatic Stress ◽  
Surface Shape ◽  
Vickers Indentation ◽  
Cross Sectional ◽  
Transmission Electron

A transmission electron microscope (TEM) micrograph of cross-sectionally viewed Vickers indentation made on the surface of (001) silicon at ambient temperature was obtained. The picture clearly reveals a triangle area, pointing downward and having nondiffraction-contrast, left after unloading, which further confirms the amorphized range induced by indentation in silicon. Analysis of the picture directly manifests a significant recovery of indentation depth. Surface shape and range of the amorphous silicon region do not coincide with that of the indenter and the corresponding distribution pattern of hydrostatic stress beneath indentation predicted by elastoplastic theory, respectively. It seems that the amorphization could not be attributed to the result of hydrostatic stress alone.

Size Distribution Of Embedded Nano-Crystallites In Polymorphous Silicon Studied By Raman Spectroscopy And Photoluminescence

2003 ◽  
Vol 762 ◽  
Author(s):  
V. Tripathi ◽  
Y. N. Mohapatra ◽  
V. Suendo ◽  
P. Roca i Cabarrocas
Keyword(s):  
Amorphous Silicon ◽  
Size Distribution ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Photoluminescence Spectra ◽  
Silicon Matrix ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Alternative Material ◽  
Degree Of Order

AbstractPolymorphous Silicon (pm-Si:H) deposited by Plasma Enhanced Chemical Vapour Deposition (PECVD) has emerged as an alternative material to amorphous silicon (a-Si:H). Deposition parameters of pm-Si:H are such that small crystallites get embedded in a relaxed amorphous silicon matrix, thus improving the optical and electrical properties. We study the size of crystallites and degree of order in pm-Si:H using Raman and photoluminescence (PL) spectra of pm-Si:H and a-Si:H. Raman Spectra of a variety of hydrogenated nanostructured silicon (pmSi:H) and amorphous Silicon (a-Si:H) samples grown at different pressures were analyzed. Deconvolution of observed multiple peaks in photoluminescence spectra and fitting to Gaussian size distribution also yields particle size to be in the range of 2.3 to 3.5nm in agreement with Transmission Electron Microscopy and Raman results.

Microstructural Study of Diamond Deformed Under High Pressure and Temperature

1985 ◽  
Vol 43 ◽  
pp. 230-231
Author(s):  
E. F. Koch
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Lattice Structure ◽  
Diamond Particle ◽  
Polycrystalline Diamond ◽  
Sintering Process ◽  
Ion Milling ◽  
Sintered Compact ◽  
Transmission Electron ◽  
High Pressure Sintering

Because of the extremely rigid lattice structure of diamond, generating new dislocations or moving existing dislocations in diamond by applying mechanical stress at ambient temperature is very difficult. Analysis of portions of diamonds deformed under bending stress at elevated temperature has shown that diamond deforms plastically under suitable conditions and that its primary slip systems are on the ﹛111﹜ planes. Plastic deformation in diamond is more commonly observed during the high temperature - high pressure sintering process used to make diamond compacts. The pressure and temperature conditions in the sintering presses are sufficiently high that many diamond grains in the sintered compact show deformed microtructures.In this report commercially available polycrystalline diamond discs for rock cutting applications were analyzed to study the deformation substructures in the diamond grains using transmission electron microscopy. An individual diamond particle can be plastically deformed in a high pressure apparatus at high temperature, but it is nearly impossible to prepare such a particle for TEM observation, since any medium in which the diamond is mounted wears away faster than the diamond during ion milling and the diamond is lost.

Structure of stacking faults in pyrite using TEM techniques

1992 ◽  
Vol 50 (1) ◽  
pp. 358-359
Author(s):  
Raja Subramanian ◽  
Kenneth S. Vecchio
Keyword(s):  
Lattice Structure ◽  
Stacking Faults ◽  
Covalent Bond ◽  
Group Symmetry ◽  
Iron Pyrite ◽  
Dislocation Glide ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Contrast Analysis ◽  
Chlorine Ions

The structure of stacking faults and partial dislocations in iron pyrite (FeS2) have been studied using transmission electron microscopy. Pyrite has the NaCl structure in which the sodium ions are replaced by iron and chlorine ions by covalently-bonded pairs of sulfur ions. These sulfur pairs are oriented along the <111> direction. This covalent bond between sulfur atoms is the strongest bond in pyrite with Pa3 space group symmetry. These sulfur pairs are believed to move as a whole during dislocation glide. The lattice structure across these stacking faults is of interest as the presence of these stacking faults has been preliminarily linked to a higher sulfur reactivity in pyrite. Conventional TEM contrast analysis and high resolution lattice imaging of the faulted area in the TEM specimen has been carried out.

Devitrification products of rapidly solidified Ni-Nb amorphous alloys.

1990 ◽  
Vol 48 (4) ◽  
pp. 950-951
Author(s):  
G. A. Bertero ◽  
W.H. Hofmeister ◽  
N.D. Evans ◽  
J.E. Wittig ◽  
R.J. Bayuzick
Keyword(s):  
Electron Microscopy ◽  
Amorphous Structure ◽  
Sulphuric Acid Solution ◽  
X Ray Diffraction ◽  
High Fracture ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Rapidly Solidified ◽  
Electromagnetically Levitated

Rapid solidification of Ni-Nb alloys promotes the formation of amorphous structure. Preliminary results indicate promising elastic properties and high fracture strength for the metallic glass. Knowledge of the thermal stability of the amorphus alloy and the changes in properties with temperature is therefore of prime importance. In this work rapidly solidified Ni-Nb alloys were analyzed with transmission electron microscopy (TEM) during in-situ heating experiments and after isothermal annealing of bulk samples. Differential thermal analysis (DTA), scanning electron microscopy (SEM) and x-ray diffraction (XRD) techniques were also used to characterize both the solidification and devitrification sequences.Samples of Ni-44 at.% Nb were electromagnetically levitated, melted, and rapidly solidified by splatquenching between two copper chill plates. The resulting samples were 100 to 200 μm thick discs of 2 to 3 cm diameter. TEM specimens were either ion-milled or alternatively electropolished in a methanol-10% sulphuric acid solution at 20 V and −40°C.

scholarly journals Photoinduced multistage phase transitions in Ta2NiSe5

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Q. M. Liu ◽  
D. Wu ◽  
Z. A. Li ◽  
L. Y. Shi ◽  
Z. X. Wang ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Lattice Structure ◽  
Condensed Matter ◽  
Electronic States ◽  
Excitation Intensity ◽  
Coherent Phonon ◽  
Optical Penetration Depth ◽  
Transmission Electron ◽  
Metal Phase Transition ◽  
Atom Displacement

AbstractUltrafast control of material physical properties represents a rapidly developing field in condensed matter physics. Yet, accessing the long-lived photoinduced electronic states is still in its early stages, especially with respect to an insulator to metal phase transition. Here, by combining transport measurement with ultrashort photoexcitation and coherent phonon spectroscopy, we report on photoinduced multistage phase transitions in Ta2NiSe5. Upon excitation by weak pulse intensity, the system is triggered to a short-lived state accompanied by a structural change. Further increasing the excitation intensity beyond a threshold, a photoinduced steady new state is achieved where the resistivity drops by more than four orders at temperature 50 K. This new state is thermally stable up to at least 350 K and exhibits a lattice structure different from any of the thermally accessible equilibrium states. Transmission electron microscopy reveals an in-chain Ta atom displacement in the photoinduced new structure phase. We also found that nano-sheet samples with the thickness less than the optical penetration depth are required for attaining a complete transition.

scholarly journals A Study of Thin Film Resistors Prepared Using Ni-Cr-Si-Al-Ta High Entropy Alloy

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Ruei-Cheng Lin ◽  
Tai-Kuang Lee ◽  
Der-Ho Wu ◽  
Ying-Chieh Lee
Keyword(s):  
Annealing Temperature ◽  
Phase Evolution ◽  
Amorphous Structure ◽  
High Entropy Alloy ◽  
X Ray Diffraction ◽  
Temperature Coefficient Of Resistance ◽  
X Ray ◽  
High Entropy ◽  
Transmission Electron ◽  
Thin Film Resistors

Ni-Cr-Si-Al-Ta resistive thin films were prepared on glass and Al2O3substrates by DC magnetron cosputtering from targets of Ni0.35-Cr0.25-Si0.2-Al0.2casting alloy and Ta metal. Electrical properties and microstructures of Ni-Cr-Si-Al-Ta films under different sputtering powers and annealing temperatures were investigated. The phase evolution, microstructure, and composition of Ni-Cr-Si-Al-Ta films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Auger electron spectroscopy (AES). When the annealing temperature was set to 300°C, the Ni-Cr-Si-Al-Ta films with an amorphous structure were observed. When the annealing temperature was at 500°C, the Ni-Cr-Si-Al-Ta films crystallized into Al0.9Ni4.22, Cr2Ta, and Ta5Si3phases. The Ni-Cr-Si-Al-Ta films deposited at 100 W and annealed at 300°C which exhibited the higher resistivity 2215 μΩ-cm with −10 ppm/°C of temperature coefficient of resistance (TCR).

Towards 3D image-based nanocrystallography by means of transmission electron goniometry

2004 ◽  
Vol 839 ◽  
Author(s):  
Peter Moeck ◽  
Wentao Qin ◽  
Philip B. Fraundorf
Keyword(s):  
Lattice Structure ◽  
Three Dimensions ◽  
Structural Defects ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Z Contrast ◽  
Individual Nanoparticles ◽  
Nanocrystal Model ◽  
The Ideal

ABSTRACTIt is well known that the crystallographic phase and morphology of many materials changes with the crystal size in the tens of nanometer range and that many nanocrystals possess structural defects in excess of their equilibrium levels. A need to determine the ideal and real structure of individual nanoparticles, therefore, arises. High-resolution phase-contrast transmission electron microscopy (TEM) and atomic resolution Z-contrast scanning TEM (STEM) when combined with transmission electron goniometry offer the opportunity of develop dedicated methods for the crystallographic characterization of nanoparticles in three dimensions. This paper describes tilt strategies for taking data from individual nanocrystals “as found”, so as to provide information on their lattice structure and orientation, as well as on the structure and orientation of their surfaces and structural defects. Internet based java applets that facilitate the application of this technique for cubic crystals with calibrated tilt-rotation and double-tilt holders are mentioned briefly. The enhanced viability of image-based nanocrystallography in future aberration-corrected TEMs and STEMs is illustrated on a nanocrystal model system.

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