scholarly journals Temperature-Dependent Raman Spectroscopic Study of the Double Molybdate KBi(MoO4)2

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5453
Author(s):  
Min Wang ◽  
Changhao Wang ◽  
Jian Wang ◽  
Liming Lu ◽  
Xiaoye Gong ◽  
...  
Keyword(s):  
High Temperature ◽  
Raman Spectra ◽  
Monoclinic Phase ◽  
Raman Band ◽  
Vibrational Modes ◽  
Temperature Dependent ◽  
Raman Spectroscopic ◽  
Thermal Stability Of ◽  
Good Agreement

In situ high-temperature Raman spectra of polycrystalline KBi(MoO4)2 were recorded from room temperature to 1073 K. Thermal stability of the monoclinic KBi(MoO4)2 was examined by temperature-dependent XRD. The monoclinic phase transformed into the scheelite tetragonal structure at 833 K, and then to the monoclinic phase at 773 K. Quantum chemistry ab initio calculation was performed to simulate the Raman spectra of the structure of KBi(MoO4)2 high-temperature melt. The experimental Raman band at 1023 K was deconvoluted into seven Gaussian peaks, and the calculated results were in good agreement with the experimental data. Therefore, the vibrational modes of Raman peaks of molten KBi(MoO4)2 were assigned. It was confirmed that the isolated structure of [Bi(MoO4)2]− monomer, consisting of Mo6+ centers and Bi3+ sub-centers connected by edge-sharing, mainly exists in the melt of KBi(MoO4)2.

Ultraviolet 363.8-nm Raman Spectroscopic System for in Situ Measurements at High Temperatures

1997 ◽  
Vol 51 (8) ◽  
pp. 1224-1228 ◽  
Author(s):  
Masatomo Yashima ◽  
Masato Kakihana ◽  
Ryosuke Shimidzu ◽  
Hirotaka Fujimori ◽  
Masahiro Yoshimura
Keyword(s):  
Raman Scattering ◽  
Raman Spectra ◽  
High Temperatures ◽  
Continuous Wave ◽  
Thermal Emission ◽  
Tetragonal Zirconia ◽  
Raman Signal ◽  
Raman Spectroscopic ◽  
Uv Excitation

A new ultraviolet (UV) Raman spectroscopic system to measure the Raman scattering from materials at high temperatures up to 1500 °C has been designed. This system is based on a CW (continuous-wave) ultraviolet argon-ion laser (363.8 nm), a spatial filter, a single monochromator coupled to a double-grating rejection filter, and a two-dimensional charge-coupled device (CCD) detector. The plasma lines from the laser are almost completely rejected by a Pellin—Broca prism combined with apertures. In situ Raman measurements for a zirconia (ZrO2) specimen at various high temperatures have been performed by using the UV excitation as well as the conventional visible 488.0-nm excitation for comparison. In the case of visible excitation, thermal emission obstructs the observation of the Raman scattering from zirconia even at 900 °C; it becomes rapidly pronounced between 900 and 1100 °C, and finally it is impossible to observe Raman spectra at temperatures higher than 1200 °C. In sharp contrast to the visible excitation, the UV excitation provides good-quality Raman spectra with practically flat backgrounds for the Raman signal of tetragonal zirconia in the spectral region of 20–1100 cm−1 even at 1500 °C, and it enables clear observation of the monoclinic-tetragonal phase transformation of zirconia occurring between 1100 and 1200 °C.

Raman spectra during the electropolymerization of polypyrrole

1988 ◽  
Vol 3 (5) ◽  
pp. 984-988 ◽  
Author(s):  
C. H. Olk ◽  
C. P. Beetz ◽  
J. Heremans
Keyword(s):  
Raman Spectra ◽  
Quantitative Model ◽  
Reduction Reaction ◽  
Chloride Ions ◽  
Iron Chloride ◽  
Vibrational Modes ◽  
Electrochemical Growth ◽  
Polypyrrole Films ◽  
Normal Mode Calculations

In situ Raman spectra were taken, between 800 and 1200 cm−1, on films of polypyrrole during both the electrochemical growth and the reduction reactions. During the reduction reaction we observed a frequency shift of approximately 10 cm−1 of two in-plane vibrational modes. We attribute these shifts to the bond conjugational defects induced by doping and undoping of the polypyrrole films. A quantitative model for this phenomenon based on normal mode calculations is presented. The electrical conductivity and thermopower of polypyrrole doped with tetrafluoroborate and iron chloride ions is also reported for temperatures between 10 and 350K.

In-situ high-temperature Raman spectroscopic studies of aluminosilicate liquids

1995 ◽  
Vol 22 (2) ◽  
Author(s):  
Isabelle Daniel ◽  
Philippe Gillet ◽  
BrentT. Poe ◽  
PaulF. McMillan
Keyword(s):  
High Temperature ◽  
Spectroscopic Studies ◽  
Raman Spectroscopic

FTIR, FTR Spectral Analysis and DFT Calculations of 1, 8-Dimethyl Naphthalene

2012 ◽  
Vol 584 ◽  
pp. 371-375
Author(s):  
V. Pouchaname ◽  
R. Madivanane ◽  
A. Tinabaye
Keyword(s):  
Spectral Analysis ◽  
Dft Calculations ◽  
Raman Spectra ◽  
Solid Phase ◽  
Computational Method ◽  
Basis Sets ◽  
Vibrational Modes ◽  
Normal Coordinate ◽  
Good Agreement ◽  
Ft Raman

ABSTRACT. Solid phase FTIR and FT-Raman spectra of 1, 8-dimethylnaphthalene have been recorded in the region 3700-50 cm-1. The spectra were interpreted with aid of normal coordinate analysis based on DFT using standard B3LYP/6-31G basis sets. After scaling there is good agreement between observed and calculated frequencies. Comparison of the simulated spectra with the experimental spectra provides important information about the ability of the computational method to describe the vibrational modes.

Behavior of phengite at high temperature and high pressure: In situ IR and Raman spectroscopic studies

2019 ◽  
Author(s):  
WENDI Liu ◽  
Yan Yang ◽  
Zeming Qi ◽  
Zhongping Wang ◽  
Weihua Huang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Spectroscopic Studies ◽  
Raman Spectroscopic ◽  
In Situ Ir ◽  
Ir And Raman

Thermodynamic Analysis of Reaction Equilibria in Ionic and Molecular Liquid Systems by High-Temperature Raman Spectroscopy

2009 ◽  
Vol 63 (9) ◽  
pp. 1050-1056
Author(s):  
Angelos G. Kalampounias ◽  
Soghomon Boghosian
Keyword(s):  
Raman Spectroscopy ◽  
High Temperature ◽  
Complex Formation ◽  
Equilibrium Constant ◽  
Thermodynamic Analysis ◽  
Raman Band ◽  
Thermal Dissociation ◽  
Temperature Dependent ◽  
Liquid Systems ◽  
Molten Phase

A formalism for correlating relative Raman band intensities with the stoichiometric coefficients, the equilibrium constant, and the thermodynamics of reaction equilibria in solution is derived. The proposed method is used for studying: (1) the thermal dissociation of molten KHSO4 in the temperature range 240–450 °C; (2) the dinuclear complex formation in molten TaCl5–AlCl3 mixtures at temperatures between 125 and 235 °C. The experimental and calculational procedures for exploiting the temperature-dependent Raman band intensities in the molten phase as well as (if applicable) in the vapors thereof are described and used for determining the enthalpy of the equilibria: (1) 2HSO4−( l) ↔ S2O72–( l) + H2O( g), Δ H0 = 64.9 ± 2.9 kJ mol−1; and (2) 1/2Ta2Cl10( l) + 1/2Al2Cl6( l) ↔ TaAlCl8( l), Δ H0 = −12.1 £ 1.5 kJ mol−1.

scholarly journals Raman Spectroscopic Study of Coal Samples during Heating

2019 ◽  
Vol 9 (21) ◽  
pp. 4699 ◽  
Author(s):  
Yingfang Xie ◽  
Jinglin You ◽  
Liming Lu ◽  
Min Wang ◽  
Jian Wang
Keyword(s):  
High Temperature ◽  
Spectroscopic Study ◽  
Spectral Characteristics ◽  
Blue Shift ◽  
Carbonaceous Materials ◽  
Temperature Dependent ◽  
Spectral Parameters ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Raman Spectral

Raman spectroscopy can be used to record the characteristic spectra of carbonaceous materials. The D and G bands are the most popular and most important spectral characteristics when discussing carbonaceous materials. In this paper, a Raman spectroscopic study of different coals was first carried out using a 355 nm wavelength laser beam as an excitation source. The spectral parameters of the resultant spectra were evaluated and analyzed. Raman spectral characteristics of different kinds of coals were explored. The high temperature-dependent Raman spectra of the coals were further collected in a temperature range from 298 to 1473 K in order to investigate the transformations of the internal structure of the coals during the pyrolysis process. An abnormal blue shift of the G band occurred at moderate temperature (600–900 K), and the intensity of the G band became weaker at high temperatures, indicating pyrolysis and graphitization of the sample at moderate and high temperature, respectively.

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