| 1. |
- Lundberg, Bo, et al.
(författare)
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Basal plane resistivity and phase diagram of HNO3 intercalated graphite in the range 130–320 K and 0–1.6 GPa
- 1986
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Ingår i: Solid State Communications. - : Elsevier Science Ltd.. - 0038-1098 .- 1879-2766. ; 58:10, s. 747-751
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Tidskriftsartikel (refereegranskat)abstract
- The basal plane resistivity varrho of stages 3–5 HNO3 intercalated graphite has been measured as a function of temperature T and pressure p in the range 130–320 K and 0–1.6 GPa (16 kbar). A contactless method was used. The phase boundary of the 250 K ordering transition at zero pressure was traced up to 320 K through the corresponding anomaly in varrho. The pressure dependence of varrho was strongly stage dependent, such that for stages 3, 4 and 5 the observed pressure coefficients (1/varrho)dvarrho/dp were approximately 0.08, −0.08, and −0.22 GPa−1, respectively, near zero pressure.
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| 2. |
- Lundberg, Bo, et al.
(författare)
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Resistivity of a composite conducting polymer as a function of temperature, pressure, and environment: Applications as a pressure and gas concentration transducer
- 1986
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 60:3, s. 1074-1079
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Tidskriftsartikel (refereegranskat)abstract
- The resistivity of a commercial carbon-filled composite conducting polymer (ET-Semicon[large-closed-square]) has been measured as a function of temperature between 80 and 400 K and under pressure up to 1.5 GPa (15 kbar). Large changes in resistivity were observed. The resistivity was also very sensitive to the presence of certain solvents and hydrocarbons. The results are explained as percolation effects caused by changes in volume due to pressure, thermal expansion, or dissolved solvents. The material studied is found to have a wide range of potential applications for pressure measurements and as a transducer for gas or liquid concentration.
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| 3. |
- Sundqvist, Bertil, et al.
(författare)
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Contactless basal plane resistivity measurements under pressure and the pressure/temperature phase diagram of stage 2 SbCl5 intercalated graphite
- 1986
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Ingår i: Journal of Physics C: Solid State Physics. - Bristol : Institute of Physics. - 0022-3719. ; 19:35, s. 6915-6929
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Tidskriftsartikel (refereegranskat)abstract
- The basal plane resistivity rho of stage 2 SbCl5 intercalated graphite has been measured as a function of temperature T and pressure p in the range 195-300K and 0-1.75 GPa, using a contactless method. rho is found to increase with increasing p. New evidence is found for the existence of the high-pressure (>1 GPa) phase suggested by Houser and co-workers (1984). The p/T phase boundaries for the low T(<230K) and intermediate p (>0.35 GPa) ordered phases are outlined. A re-analysis of previous results for stage 1 SbF5 intercalated graphite indicates a similar phase diagram for this material.
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| 4. |
- Sundqvist, Bertil, et al.
(författare)
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Pressure-temperature phase boundaries in KC24: Evidence for a kinetically-hindered low-temperature staging transition
- 1986
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 34:5, s. 3532-3535
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Tidskriftsartikel (refereegranskat)abstract
- The pressure-temperature phase diagram of KC24 was mapped out using in-plane resistivity anomalies to identify phase boundaries. Surprisingly, the 300-K staging transitions at 3.4 and 6.4 kbar are found to connect to the 1-bar ordering-stacking transitions at Tu=123 K and Tl=96 K, respectively, whereas the loci of P, T anomalies cannot be equilibrium phase boundaries since the low-P, low-T transitions do not involve stage transformations. We suggest that this unusual behavior is due to kinetic hindering of the low-T staging transitions, predicted by simple equilibrium models and observed in the analogous Li compound. A possible origin of the slow staging kinetics at low T in KC24 is the pinning of discommensurations at Daumas-Herold boundaries.
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| 5. |
- Sundqvist, Bertil
(författare)
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Transport properties of liquid mercury under high pressure
- 1986
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Ingår i: High Temperatures - High Pressures Volume 18. - London : Pion Ltd. - 0 85086 132 2 ; , s. 655-663
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Konferensbidrag (refereegranskat)abstract
- The thermal diffusivity, electric resistivity, and Seebeck coefficient of liquid mercury have been measured under pressures up to >600 MPa (6 kbar) near room temperature. The thermal diffusivity was measured by a modified two-frequency Ångström method, capable of taking into account radial heat loss by conduction. The pressure dependence of the thermal conductivity was calculated, and the Lorenz ratio was found to be independent of volume. In the same experiment, the compressibilities of two epoxy resins (Araldite) were measured.
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