| 1. |
- Andersson, Ove, et al.
(författare)
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A low-temperature high-pressure apparatus with a temperature control system
- 1992
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Ingår i: High Pressure Research. - : Informa UK Limited. - 0895-7959 .- 1477-2299. ; 10:4, s. 599-606
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Tidskriftsartikel (refereegranskat)abstract
- A low-temperature high-pressure apparatus was designed using commercial cryogenic equipment. Pressures up to 1 GPa and temperatures down to 40 K can be obtained in a volume of up to 30 cm3. The apparatus is of the piston-cylinder type with a piston diameter of 45 mm, and the pressure can be varied at all temperatures, An adaptive temperature control system keeps the temperature inside the pressure cylinder constant to within ±0.1 K.
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| 2. |
- Andersson, Ove, et al.
(författare)
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Chirality and the thermophysical properties of molecular solid phases under pressure: (+)- and (±)-camphor
- 1990
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Ingår i: Molecular Physics. - : Taylor & Francis Group. - 0026-8976 .- 1362-3028. ; 70:6, s. 1065-1083
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Tidskriftsartikel (refereegranskat)abstract
- Thermal conductivity λ, heat capacity per unit volume pcP and P-T phase diagrams are investigated for both (+)- and (±)-camphor. The transient hotwire method is used at temperatures in the range 100–430 K and at pressures up to 1·75 GPa. We detect solid phases I-IV for (+)-camphor and I′-V′ for (±)-camphor. We conclude that λ is independent of enantiomeric composition for plastic-crystal phase pairs I-I′, II-II′ and IV-IV′. Phase V′ also appears to be a plastic-crystal phase. Non-plastic phases III and III′ show a variation of λ with T that differ considerably from that expected for a simple crystal, with the greatest such difference being observed for the racemic compound III′. An unannealed specimen of the racemic compound III′ is probably chirally disordered and shows a variation of λ with T for T < 130 K, which may indicate phonon-assisted fracton hopping.
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| 3. |
- Andersson, Ove, et al.
(författare)
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Thermal conductivity, heat capacity and phase diagram of cyclooctanol in liquid, solid and glassy crystal states under high pressure
- 1990
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Ingår i: Molecular Physics. - : Taylor & Francis Group. - 0026-8976 .- 1362-3028. ; 71:3, s. 523-539
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Tidskriftsartikel (refereegranskat)abstract
- Using the transient hot-wire method, thermal conductivity and heat capacity per unit volume are measured for solid and liquid phases and glassy crystal states of cyclooctanol, and information is provided on the phase diagram under high pressure. A new solid phase (III) is detected and characterized as a normal crystal phase, whereas all other solid phases (I, II, IV, V) are characterized as plastic crystal phases. We find evidence that the plastic crystal phases I, II and IV could each be the source for a distinct glassy crystal state. It is argued for phase II that its possession of both a low thermal conductivity and a low dielectric permittivity could be accounted for by assuming restricted reorientational motion of the molecules. The unusual (although small) decrease of thermal conductivity observed through the glassy to plastic crystal transitions may indicate that phonons can couple to reorientational motion in the plastic crystal phases I, II and IV.
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| 4. |
- Forsman, Hans, et al.
(författare)
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Dielectric relaxation and new phase of cyclooctanol at pressures to 1 GPa
- 1991
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Ingår i: Journal of Non-Crystalline Solids. - : Elsevier. - 0022-3093 .- 1873-4812. ; 131-133:Part 2, s. 1145-1148
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Tidskriftsartikel (refereegranskat)abstract
- On the four previously known solid phases of cyclooctanol (I, II, IV and V in our notation), two (IV and V) are stable only at high pressure. In this work, new data on dynamic dielectric properties of cyclooctanol at high pressure are presented. The results are compared with corresponding thermal conductivity data. It is concluded that the dielectric properties of phase II are consistent with the thermal conductivity properties if it is assumed that a substantial fraction of the dipoles interact with each other. The molecular interaction favours reorientation around an axis of negligible dipole moment. The new solid phase, phase III, which was discovered through thermal conductivity measurements, is detected dielectrically in the present study.
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| 5. |
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| 6. |
- Sundqvist, Bertil, et al.
(författare)
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Structure, disorder, and phase diagram of C60 up to 1 GPa and below 300 K
- 1994
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Ingår i: High Pressure in Material Science and Geoscience. - Praha, Czech Republic : Prometheus. - 8085849933 ; , s. 109-112
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Konferensbidrag (refereegranskat)abstract
- We have measured the compressibility and the thermal conductivity of C60 in the range below 300 K and up to 1 GPa (10 kbar). From the data obtained we have deduced the p-T phase diagram of C60. Literature data show that the ratio of pentagon-to-hexagon oriented molecules in the orientationally ordered phase decreases with increasing pressure, and from our data we conclude that C60 forms a new, completely "hexagon oriented" phase above 0.6 GPa at 150 K, or 1.2 GPa at 300 K. The glass transition temperature (90 K at atmospheric pressure) is found to increase by 54 K/GPa.
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