Raman Characterization of Composition and Strain in Si1−xGex/Si Heterostructures

1999 ◽  
Vol 591 ◽  
Author(s):  
Ran Liu ◽  
B. Tillack ◽  
P. Zaumseil
Keyword(s):  
Lattice Mismatch ◽  
Uniaxial Stress ◽  
Longitudinal Optical ◽  
Biaxial Stress ◽  
Optical Phonon Mode ◽  
Polarized Raman ◽  
First Time ◽  
Strain Frequency ◽  
Raman Characterization

ABSTRACTHigh quality epitaxial Sil−xGex/Si (x = 0.09 to 0.27) samples were studied with polarized Raman scattering technique. The LO (longitudinal optical) -TO (transversal optical) phonon mode splitting due to the tetragonal strain imposed by the lattice mismatch between Sil−xGex and Si was observed for the first time in such structures. In contrast to the case of uniaxial stress, the biaxial stress induces a larger strain frequency shift for the LO mode than for the TO mode. The phonon strain shift coefficient for the LO mode was found to be 1010 cm−1, which is larger than most of the values reported in the literatures, and almost composition independent throughout the range of x≤0.27. We argue that the smaller LO strain shift coefficients indicate that the Sil−xGex films used in previous work were partially relaxed.

Raman Characterization of InSb/GaAs Grown by Metalorganic Magnetron Sputtering

1989 ◽  
Vol 160 ◽  
Author(s):  
Z. C. Feng ◽  
S. Perkowitz ◽  
T. S. Rao ◽  
J. B. Webb
Keyword(s):  
Magnetron Sputtering ◽  
Lattice Mismatch ◽  
Longitudinal Optical ◽  
Biaxial Stress ◽  
High Quality ◽  
Gaas Substrates ◽  
Phonon Peak ◽  
Raman Characterization

AbstractThe new technique of metalorganic magnetron sputtering (MOMS) produces high-quality (100) epitaxial InSb films on (100) GaAs substrates, despite the large 14.6% lattice mismatch between InSb and GaAs. We have used Raman scattering to examine MOMS-grown InSb films of thicknesses 0.17 - 2.67 µm, and commercial bulk InSb. We observe the longitudinal optical (LO) phonon peak, and the second order 2LO peak, which is enhanced by outgoing resonance with the E1 + Δ1, gap of InSb. The half-widths and intensities of these bands are related to sample quality as a function of film thickness and to the role of biaxial stress in the InSb film.

Raman characterization of Li(Al1-xCox)O2

2000 ◽  
Vol 15 (3) ◽  
pp. 583-585 ◽  
Author(s):  
G. Chen ◽  
W. Hao ◽  
Y. Shi ◽  
Y. Wu ◽  
S. Perkowitz
Keyword(s):  
Cathode Material ◽  
Raman Spectra ◽  
Lithium Batteries ◽  
Spinel Structure ◽  
Raman Band ◽  
Impurity Phase ◽  
First Time ◽  
Peak Widths ◽  
Raman Characterization

For the first time, we measured Raman spectra from Li(Al1-xCox)O2 (x = 0.5 to 0.9), a new cathode material for lithium batteries. Whereas LiCoO2 sintered at 400 °C develops a spinel structure, Li(Al1-xCox)O2 sintered at 380 °C is amorphous, as shown by its single broad Raman band. Li(Al1-xCox)O2 sintered at 700 or 900 °C shows Raman peaks independent of x that coincide with those from LiCoO2, indicating that Li(Al1-xCox)O2 has the α–NaFeO2 structure (space group R3m). Traces of the impurity phase Co3O4 appear in samples treated at 900 °C but not at 700 °C. The Raman peak widths exceed those in LiCoO2, suggesting that replacement of Co by Al increases disorder among the Li ions.

Polarized Raman Characterization of (2,2) Carbon Nanotubes Formed inside the Channels of AEL Crystals

2010 ◽  
Vol 160-162 ◽  
pp. 1596-1600
Author(s):  
Jian Pang Zhai ◽  
Irene Ling Li ◽  
Shuang Chen Ruan
Keyword(s):  
Carbon Nanotubes ◽  
Visible Region ◽  
Polarization Angle ◽  
Zeolite Crystal ◽  
Angle Dependence ◽  
Polarized Raman ◽  
Walled Carbon Nanotubes ◽  
Raman Characterization ◽  
Dipole Transition Moment

A pure AlPO4-11 (AEL) zeolite crystal is optically transparent in visible region and a good insulator with thermal stability up to 1173 K. These excellent physical properties, plus their unique elliptical pore structures, make them an excellent template to fabricate ultra-thin single-walled carbon nanotubes (SWNTs).We studied the polarization dependence Raman spectra for (2,2) SWNTs formed inside the channels of AEL crystals. These (2,2) SWNTs acts as a dipolar antenna, polarized along the crystal channels axis. The polarization angle dependence of the Raman intensity indicates that the enclosed (2,2) SWNTs are highly oriented in the channels with their dipole transition moment mostly along the channels.

Polarized Raman spectra of an oriented single crystal of barium nitrite monohydrate

1983 ◽  
Vol 61 (3) ◽  
pp. 608-612 ◽  
Author(s):  
O. P. Lamba ◽  
H. D. Bist ◽  
Y. S. Jain
Keyword(s):  
Single Crystal ◽  
Raman Spectra ◽  
Longitudinal Optical ◽  
Transverse Optical ◽  
Polarized Raman ◽  
First Time ◽  
Barium Nitrite ◽  
Lattice Modes ◽  
Oriented Single Crystal

The symmetries of the observed Raman lines in the 4000–30 cm−1 region in different orientations of a single crystal of Ba(NO2)2•H2O have been determined and the spectra have been analysed in terms of the phonons originating from the internal modes of the NO2− and H2O groups and the external lattice modes. The longitudinal-optical and transverse-optical (LO–TO) splittings arising from the Coulomb forces in the crystal arc reported for the first time.

Micro-Raman Characterization of 4H-SiC Stacking Faults

2014 ◽  
Vol 778-780 ◽  
pp. 378-381 ◽  
Author(s):  
Nicolo’ Piluso ◽  
Massimo Camarda ◽  
Ruggero Anzalone ◽  
Francesco La Via
Keyword(s):  
Stacking Faults ◽  
Longitudinal Optical ◽  
Raman Mode ◽  
Plasmon Coupling ◽  
Stacking Sequence ◽  
Strongly Correlated ◽  
Phonon Modes ◽  
Spatial Morphology ◽  
Raman Characterization

Micro-Raman characterization has been used as alternative technique to the photoluminescence in order to detect and study 4H-SiC stacking faults. The alteration of the crystalline stacking sequence perturbs the phonon-plasmon coupling which acts between the crystalline phonon modes and the electronic plasma, due to the doping element (N). The shape and the symmetry of the Longitudinal optical Raman mode is strongly correlated to the doping level of the material thus, through the monitoring of the Raman mode, the spatial morphology of the defect can be completely recovered and compared to the results provided by photoluminescence technique. The results show that such a technique allows a very fast inspection on large wafer, because it is totally independent of the stacking fault photoluminescence signals, which cover a large energy range, up to 0.7 eV.

Structural analysis of a Σ5 grain boundary in YBa2Cu3O7δ

1993 ◽  
Vol 51 ◽  
pp. 942-943
Author(s):  
J.-Y. Wang ◽  
Y. Zhu ◽  
A.H. King ◽  
M. Suenaga
Keyword(s):  
Grain Boundary ◽  
Lattice Mismatch ◽  
Weak Link ◽  
Coincidence Site Lattice ◽  
Large Angle ◽  
Dislocation Core ◽  
Superconducting Order Parameter ◽  
Outstanding Problem ◽  
Transmission Electron

One outstanding problem in YBa2Cu3O7−δ superconductors is the weak link behavior of grain boundaries, especially boundaries with a large-angle misorientation. Increasing evidence shows that lattice mismatch at the boundaries contributes to variations in oxygen and cation concentrations at the boundaries, while the strain field surrounding a dislocation core at the boundary suppresses the superconducting order parameter. Thus, understanding the structure of the grain boundary and the grain boundary dislocations (which describe the topology of the boundary) is essential in elucidating the superconducting characteristics of boundaries. Here, we discuss our study of the structure of a Σ5 grain boundary by transmission electron microscopy. The characterization of the structure of the boundary was based on the coincidence site lattice (CSL) model.Fig.l shows two-beam images of the grain boundary near the projection. An array of grain boundary dislocations, with spacings of about 30nm, is clearly visible in Fig. 1(a), but invisible in Fig. 1(b).

TBE in Sweden

2020 ◽  
Keyword(s):  
Genetic Characterization ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Second Phase ◽  
Serum Samples ◽  
Tick Borne Encephalitis ◽  
Specific Immunoglobulin ◽  
Tick Borne Encephalitis Virus ◽  
First Time

Tick-borne encephalitis virus (TBEV) was isolated for the first time in Sweden in 1958 (from ticks and from 1 tick-borne encephalitis [TBE] patient).1 In 2003, Haglund and colleagues reported the isolation and antigenic and genetic characterization of 14 TBEV strains from Swedish patients (samples collected 1991–1994).2 The first serum sample, from which TBEV was isolated, was obtained 2–10 days after onset of disease and found to be negative for anti-TBEV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA), whereas TBEV-specific IgM (and TBEV-specific immunoglobulin G/cerebrospinal fluid [IgG/CSF] activity) was demonstrated in later serum samples taken during the second phase of the disease.

Chemical Constituents and Antibacterial Activity of Cissus Aralioides.

2020 ◽  
Vol 17 ◽  
Author(s):  
Balogun Olaoye Solomon ◽  
Ajayi Olukayode Solomon ◽  
Owolabi Temitayo Abidemi ◽  
Oladimeji Abdulkarbir Oladele ◽  
Liu Zhiqiang
Keyword(s):  
Plant Extract ◽  
Chemical Constituents ◽  
Ethyl Acetate Fraction ◽  
Antibacterial Activities ◽  
Sub Saharan Africa ◽  
Chromatographic Purification ◽  
Whole Plant ◽  
Sub Saharan ◽  
First Time

: Cissus aralioides is a medicinal plant used in sub-Saharan Africa for treatment of infectious diseases; however the chemical constituents of the plant have not been investigated. Thus, in this study, attempt was made at identifying predominant phytochemical constituents of the plant through chromatographic purification and silylation of the plant extract, and subsequent characterization using spectroscopic and GC-MS techniques. The minimum inhibitory concentration (MICs) for the antibacterial activities of the plant extract, chromatographic fractions and isolated compounds were also examined. Chromatographic purification of the ethyl acetate fraction from the whole plant afforded three compounds: β-sitosterol (1), stigmasterol (2) and friedelin (3). The phytosterols (1 and 2) were obtained together as a mixture. The GC-MS analysis of silylated extract indicated alcohols, fatty acids and sugars as predominant classes, with composition of 24.62, 36.90 and 26.52% respectively. Results of MICs indicated that friedelin and other chromatographic fractions had values (0.0626-1.0 mg/mL) comparable with the standard antibiotics used. Characterization of natural products from C. aralioides is being reported for the first time in this study.

Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

2018 ◽  
Vol 9 (1) ◽  
pp. 101-108 ◽  
Author(s):  
Shubhangi J. Mane-Gavade ◽  
Sandip R. Sabale ◽  
Xiao-Ying Yu ◽  
Gurunath H. Nikam ◽  
Bhaskar V. Tamhankar
Keyword(s):  
Green Synthesis ◽  
Color Change ◽  
Limit Of Detection ◽  
Aqueous Media ◽  
Suitable Condition ◽  
Cost Effective ◽  
Spectroscopic Studies ◽  
Calibration Plot ◽  
First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

scholarly journals Waste-Based One-Part Alkali Activated Materials

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2911
Author(s):  
Margarida Gonçalves ◽  
Inês Silveirinha Vilarinho ◽  
Marinélia Capela ◽  
Ana Caetano ◽  
Rui Miguel Novais ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Microstructural Analysis ◽  
Construction Materials ◽  
Sodium Metasilicate ◽  
High Compressive Strength ◽  
Hardened State ◽  
First Time ◽  
Furnace Slag ◽  
Alkali Activated

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

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