| 1. |
- Arvanitidis, J., et al.
(författare)
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High pressure study of the 2D polymeric phase of C60 by means of Raman spectroscopy
- 2001
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Ingår i: High Pressure Research. - : Informa UK Limited. - 0895-7959 .- 1477-2299. ; 18:1-6, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- The effect of high hydrostatic pressure, up to 12GPa, on the intramolecular phonon frequencies and the material stability of the two-dimensional tetragonal Cm polymer has been studied by means of Raman spectroscopy in the spectral range of the radial intramolecular modes (200-800cm-1). A number of new Raman modes appear in the spectrum for pressures ≈ 1.4 and ≈ 5.0 GPa. The pressure coefficients for the majority of the phonon modes exhibit changes to lower values at P=4.0 GPa, which may be related to a structural modification of the 2D polymer to a more isotropic phase. The peculiarities observed in the Raman spectra are reversible and the material is stable in the pressure region investigated.
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| 2. |
- Arvanitidis, J., et al.
(författare)
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High pressure study of the 2D polymeric phase of C60by means of raman spectroscopy
- 2000
-
Ingår i: High Pressure Research. - : Taylor & Francis. - 0895-7959 .- 1477-2299. ; 18:1-6, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- The effect of high hydrostatic pressure, up to 12 GPa, on the intramolecular phonon frequencies and the material stability of the two-dimensional tetragonal C-60 polymer has been studied by means of Raman spectroscopy in the spectral range of the radial intramolecular modes (200-800 cm(-1)). A number of new Raman modes appear in the spectrum for pressures similar to 1.4 and similar to 5.0 GPa. The pressure coefficients for the majority of the phonon modes exhibit changes to lower values at P=4.0 GPa, which may be related to a structural modification of the 2D polymer to a more isotropic phase. The peculiarities observed in the Raman spectra are reversible and the material is stable in the pressure region investigated.
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| 3. |
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| 4. |
- Li, S., et al.
(författare)
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Crystallographic structures of PbWO4
- 2003
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Ingår i: High Pressure Research. - : Informa UK Limited. - 0895-7959 .- 1477-2299. ; 23:3, s. 343-347
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Ohlin, C André, et al.
(författare)
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Carbon dioxide reduction in biphasic aqueous-ionic liquid systems by pressurized hydrogen
- 2003
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Ingår i: High Pressure Research. - : Informa UK Limited. - 0895-7959 .- 1477-2299. ; 23:3, s. 239-242
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Tidskriftsartikel (refereegranskat)abstract
- This work reports the hydrogenation of carbon dioxide/inorganic carbonate salts to formic acid/formate in two phase systems comprising an ionic phase, in which the catalyst is immobilized, and an aqueous phase in which the carbonates and formate are confined, is reported. The reactions were followed in situ by multinuclear NMR. Pressurized H-2 gas was used for the reduction.
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| 6. |
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| 7. |
- Wunschel, M, et al.
(författare)
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High-pressure phase transitions in tetrakis(trimethylsilyl)silane Si[Si(CH3)(3)](4)
- 2003
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Ingår i: High Pressure Research. - : Informa UK Limited. - 1477-2299 .- 0895-7959. ; 23:4, s. 425-437
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Tidskriftsartikel (refereegranskat)abstract
- The compound tetrakis(trimethylsilyl)silane S-i[Si(CH3,)(3)](4) (TSi) has been studied at room temperature for pressures up to 2 1.5(1) GPa, using X-ray powder diffraction with synchrotron radiation. Three different phases are reported in the investigated pressure range. The c.c.p.-type structure is stable up to a pressure of 0.19(1) GPa (Fm (3) over barm, a = 13.52110)Angstrom, V = 2471.95(1)Angstrom(3), Z = 4 at 0.02(1)GPa). It shows a severe orientational disorder of the molecules. At pressures 0.19(1)-0.71(1)GPa a monoclinic phase (HP1) is found with space group P2(1)/n and Z=8 (a = 17.746(1)Angstrom, b = 16.098(1)Angstrom, c= 16.871(1)Angstrom, gamma = 111.437(5)degrees and V = 4486.3(8) Angstrom(3) at 0.24(1)GPa). Another monoclinic phase (HP2) exists at pressures 0.52(1)-8.67(5)GPa. This phase has a smaller unit cell than the HP1 phase with Z(.)=2 (a =8.3778(8)Angstrom, b=9.1050(7)Angstrom, c= 13.3024(8)Angstrom, gamma= 111.63(1)degrees and V = 943.22(6) Angstrom(3) at 1.73(2)GPa). The pressure dependencies of the unit-cell volumes are successfully described by Mumaghan or Vinet-type equations of state. The structures at different pressures and temperatures of TSi and related compounds are described as distorted superstructures of the c.c.p. arrangement. The occurrence of different superstructures is rationalized as the result of an optimized packing of ordered molecules of various shapes.
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| 8. |
- Wågberg, Thomas, et al.
(författare)
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2D polymerization and doping of fullerenes under pressure
- 2000
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Ingår i: High Pressure Research vol. 18. - : Gordon & Breach. ; 18:1-6, s. 139-143
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Konferensbidrag (refereegranskat)abstract
- Tetragonal polymeric C60 has been studied by Raman spectroscopy and other methods. Attempts have been made to transform samples from the tetragonal to the orthorhom-bic phase and vice versa. The results suggest that the transformation is direct with no intermediate stage with free molecules. Tetragonal C60 has also been intercalated by potassium metal.
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| 9. |
- Ahuja, R
(författare)
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High pressure studies of sodium and silver halides
- 2000
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Ingår i: HIGH PRESSURE RESEARCH. - : GORDON BREACH SCI PUBL LTD. - 0895-7959. ; 18:1-6, s. 131-138
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the structural phase transitions in sodium and silver halides theoretically under high compressions by means of first-principles self-consistent total-energy calculations within the local-density approximation using the full-potential
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