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.

Characterization of SrBi2Nb2O9 Thin Films Prepared by Sol Gel Technique

1996 ◽  
Vol 459 ◽  
Author(s):  
E. Ching-Prado ◽  
W. Pérez ◽  
A. Reynés-Figueroa ◽  
R. S. Katiyar ◽  
D. Ravichandran ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Band ◽  
Sol Gel ◽  
Orthorhombic Symmetry ◽  
X Ray Diffraction ◽  
Ft Ir ◽  
Gel Technique ◽  
High Degree ◽  
First Time

ABSTRACTThin films of SrBi2Nb2O9 (SBN) with thicknesses of 0.1, 0.2, and 0.4 μ were grown by Sol-gel technique on silicon, and annealed at 650°C. The SBN films were investigated by Raman scatering for the first time. Raman spectra in some of the samples present bands around 60, 167, 196, 222, 302, 451, 560, 771, 837, and 863 cm−1, which correspond to the SBN formation. The study indicates that the films are inhomogeneous, and only in samples with thicknesses 0.4 μ the SBN material was found in some places. The prominent Raman band around 870 cm−1, which is the A1g mode of the orthorhombic symmetry, is assigned to the symmetric stretching of the NbO6 octahedrals. The frequency of this band is found to shift in different places in the same sample, as well as from sample to sample. The frequency shifts and the width of the Raman bands are discussed in term of ions in non-equilibrium positions. FT-IR spectra reveal a sharp peak at 1260 cm−1, and two broad bands around 995 and 772 cm−1. The bandwidths of the latter two bands are believed to be associated with the presence of a high degree of defects in the films. The experimental results of the SBN films are compared with those obtained in SBT (T=Ta) films. X-ray diffraction and SEM techniques are also used for the structural characterization.

Quantification of Raman Spectra for the Primary Atmospheric Corrosion Products of Lead

1995 ◽  
Vol 49 (9) ◽  
pp. 1299-1304 ◽  
Author(s):  
Leon Black ◽  
Geoffrey C. Allen ◽  
Paul C. Frost
Keyword(s):  
Raman Spectra ◽  
Atmospheric Corrosion ◽  
Raman Band ◽  
Corrosion Products ◽  
Band Intensity ◽  
Laser Raman ◽  
Lead Compounds ◽  
Sample Composition ◽  
Laser Raman Spectra

In this study laser Raman spectra were recorded for eight lead compounds commonly reported as products from the atmospheric corrosion of lead. The spectra obtained demonstrated that this technique is well suited for the characterization of lead compounds. Moreover, when mixtures of these compounds are being studied, a good correlation can be obtained between sample composition and a characteristic Raman band intensity. This correlation should permit an estimate of the quantity of various compounds present in corrosion products.

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.

Darstellung und Charakterisierung der Tetrabutylammoniumsalze von [Tc2Cl8]2-, [Tc2Cl8]3- und [Tc2Br8]2- Preparation and Characterization of the Tetrabutylammonium Salts of [Tc2Cl8]2-, [Tc2Cl8]3- und [Tc2Br8]2-

1980 ◽  
Vol 35 (7) ◽  
pp. 797-801 ◽  
Author(s):  
W. Preetz ◽  
G. Peters
Keyword(s):  
Electronic Spectrum ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
High Extent ◽  
First Time

The reduction of [TcCl6]2- with Zn in conc. HCl after evaporation and extraction of ZnCl2 by diethylether yields a red-brown product from which after dissolving in dilute HCl by a solution of (TBA)Cl in CH2Cl2 (TBA)2[Tc2Cl8] and (TBA)3[Tc2Cl8] can be extracted. The separation is achieved by the much better solubility of the green (TBA)2[Tc2Cl8] in acetone compared with that of the grey-blue (TBA)3[Tc2Cl8]. On treatment of (TBA)2[Tc2Cl8] dissolved in acetone with bromine-free conc. HBr carmine red (TBA)2[Tc2Br8] is obtained for the first time. The vibrational spectra are similar and can be assigned according to the assumed D4h-symmetry. In the Raman spectra of both octachloroditechnetates the intensive Tc-Tc-vibration (A1g) is observed at 307 cm-1, for (TBA)2[Tc2Br8] it is found at 323 cm-1 . The electronic spectrum of (TBA)2[Tc2Cl8] agrees to a high extent with that of the corresponding Re compound

Sign in / Sign up

Export Citation Format

Share Document