scholarly journals Near Infrared Absorption of Ethylene between 8200 cm-1 and 9500 cm-1 to High Pressures and Temperatures

1976 ◽  
Vol 31 (12) ◽  
pp. 1690-1695 ◽  
Author(s):  
F. W. Nees ◽  
M. Buback
Keyword(s):  
Infrared Absorption ◽  
High Frequency ◽  
Near Infrared ◽  
High Pressures ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Experimental Conditions ◽  
High Pressure High Temperature ◽  
Wide Range ◽  
Integrated Intensity

AbstractThe near infrared absorption of pure ethylene in the region of the second overtone of the C-H stretching fundamentals (8200 cm-1 to 9500 cm-1) was measured at supercritical temperatures (Tc = 9.5 °C) between 22 °C and 200 °C from 0.7 bar to 3000 bar. The density and temperature dependence of bandshape, maximum frequency and absorption intensity are reported and discussed. The bands observed within a wide range of experimental conditions are assigned to combination and overtone modes. The molar integrated intensity B̅λ determined between the wavelength of maximum absorption and the high frequency absorption boundary was observed to be independent of pressure and temperature. This enables spectroscopic concentration determinations on ethylene in high pressure - high temperature phase equilibria and reactions.

Near Infrared Absorption of Pure n-Heptane between 5000 cm 1 and 6500 cm-1 to High Pressures and Temperatures

1983 ◽  
Vol 38 (5) ◽  
pp. 528-532 ◽  
Author(s):  
M. Buback ◽  
A. A. Harfoush
Keyword(s):  
High Pressure ◽  
Infrared Absorption ◽  
Near Infrared ◽  
High Pressures ◽  
Kinetic Studies ◽  
Molar Absorptivity ◽  
High Pressure High Temperature ◽  
High Pressures And Temperatures ◽  
Combination Mode ◽  
Better Than

The near infrared absorption of pure n-heptane between 5000 cm-1 and 6500 cm-1 was measured up to 250 °C and to pressures of 2000 bar. The procedure for measuring vibrational intensities at high pressures and temperatures with a precision of better than ± 1% is described. The integrated “molar absorptivity of the combination mode va + vs of the methylene stretching fundamentals turns out to be independent of temperature and density. This offers important applications for high-pressure high-temperature thermodynamic and kinetic studies via quanti­tative near infrared spectroscopy.

High pressure–high temperature phase diagram of InSe

2004 ◽  
Vol 24 (1) ◽  
pp. 111-116 ◽  
Author(s):  
G. Ferlat ◽  
D. Martínez-García ◽  
A. San Miguel ◽  
A. Aouizerat ◽  
V. Muñoz-Sanjosé
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
High Pressure High Temperature ◽  
Temperature Phase Diagram

Notizen: Einkristall-Daten der Hochdruck-Hochtemperaturphase von CaSi2 / Structural Refinement of the High Pressure-High Temperature Phase of CaSi2

1982 ◽  
Vol 37 (11) ◽  
pp. 1487-1488 ◽  
Author(s):  
Jürgen Evers ◽  
Gilbert Oehlinger ◽  
Armin Weiss
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystals ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Structural Refinement ◽  
Interatomic Distances ◽  
High Pressure High Temperature

The high pressure-high temperature phase of CaSi2 is a representative of the α-ThSi2 type of structure. Single crystals grown at 40 kbar and 1000 °C enabled a structural refinement which leads to interatomic distances Si-Si: 229.9(1) pm (1 × ) and 240.0(1) pm (2 × ), Ca-Si: 309.4(4) pm (4 x ) and 323.9(4) pm (8 × ), Ca-Ca: 400.3(3) pm (4 × ) and 428.3(3) pm (4 × ).

scholarly journals Dielectric investigations of La-doped barium titanate

2010 ◽  
Vol 4 (3) ◽  
pp. 193-198 ◽  
Author(s):  
Tadas Ramoska ◽  
Juras Banys ◽  
Ricardas Sobiestianskas ◽  
Mirjana Vijatovic-Petrovic ◽  
Jelena Bobic ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Barium Titanate ◽  
High Frequency ◽  
Low Frequency ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Relaxational Process ◽  
Pechini Process ◽  
La Doped ◽  
Curie Temperature Tc

In the present paper results of the dielectric investigation of barium titanate (BaTiO3) doped with different concentrations of lanthanum are presented. Ceramic samples were prepared by the Pechini process. With increased doping the grain size of ceramics decreases from 2.5 ?m in pure samples down to 0.2 ?m in 0.5 mol% La - doped BaTiO3. Ceramics showed maximally enhanced dielectric permittivity around low-, room and high temperature phase transitions, which are the phase transitions of the pure BaTiO3. The Curie temperature, TC, is lowered by 30 K with increase of doping concentration to 0.5 mol% La. Dielectric spectra revealed three parts: low frequency part which is caused by conductivity process, middle frequency relaxational process part and high frequency relaxational/polar modes contribution.

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