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| 3. |
- Andersson, Odd E., et al.
(författare)
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A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part IV: Basal plane resistivity
- 1995
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 10:7, s. 1653-1660
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Tidskriftsartikel (refereegranskat)abstract
- Using an inductive technique, we have measured the in-plane resistivity rhoa of stages 2, 4, 5, and 8 SbCl5-GIC's versus temperature T and pressure p in the ranges 130–300 K and 0–0.85 GPa. The room temperature values of rhoa range from 4.0 µOcm for the stages 5 sample to 7.7 µOcm for the stage 8 sample. At all pressures, rhoa shows a metallic temperature dependence rhoa ~ Ta, with 1 < a < 2, but in contrast to the c-axis resistivity rhoc, it depends only very weakly on pressure and/or intercalate structural order. We show that the behavior observed is consistent with a band conduction model.
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- Andersson, Odd E., et al.
(författare)
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Low temperature calibration of Manganin pressure gauges
- 1997
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 68:2, s. 1344-1345
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Tidskriftsartikel (refereegranskat)abstract
- High pressures are often measured using the resistance of Manganin wires. However, the pressure coefficient of resistance is known to depend on temperature. We have measured this temperature dependence by comparing the output from a Manganin gauge with that of a well calibrated Zeranin gauge and determined a correction factor which enables us to measure the pressure at any temperature between 150 and 300 K with a temperature dependent error well below 0.5%.
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- Andersson, Odd E., et al.
(författare)
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The c-axis resistivity for two HOPG-based, first stage CuAl2Cl8 and second stage CuCl2 - graphite intercalation compounds as a function of both pressure and temperature
- 1996
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Ingår i: Journal of Physics and Chemistry of Solids, volume 57, issues 6-8. - : Elsevier Ltd.. ; , s. 719-723
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Konferensbidrag (refereegranskat)abstract
- In this paper we present data for the c-axis resistivity of first stage CuAl2Cl8 GIC and second stage CuCl2 GIC as functions of pressure, p, (0.0 < p < 1.5 GPa) and of temperature, T, (4 < T < 300 K). We show evidence of a possible new high-pressure phase above 1.0 GPa for the CuAl2Cl8 GIC and we show that the CuCl2 GIC is very stable at all pressures and temperature investigated. We make a comparison with previous results on SbCl5 GICs and other chloride intercalation compounds and with theories treating the temperature and pressure coefficients of transport parameters in layered solids.
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- Edman, Ludvig, et al.
(författare)
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Electrical resistivity of single crystal graphite under pressure: an anisotropic 3-D semimetal
- 1998
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 57:11, s. 6227-6230
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Tidskriftsartikel (refereegranskat)abstract
- The in-plane (ρa) and c-axis (ρc) resistivities of natural single-crystal graphite have been measured from 4 to 450 K at zero pressure and from 77 to 450 K under pressures up to 500 MPa. Data for ρc differ strongly from earlier results obtained on synthetic graphite in showing a strong T dependence of the pressure coefficient, while data for ρa agree well with those from previous studies. Our results can be analyzed quantitatively in a simple free-electron model, and we conclude that in contrast to quasi-two-dimensional synthetic graphite, natural single-crystal graphite is an anisotropic three-dimensional semimetal.
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| 8. |
- Lundin, Anders, et al.
(författare)
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Compressibility of C61D2 up to 1 GPa in the temperature range 175 - 345 K
- 1996
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Ingår i: Carbon. - : Elsevier Science Ltd.. - 0008-6223 .- 1873-3891. ; 34:9, s. 1119-1121
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the bulk modulus K for C61D2 up to 1 GPa in the temperature range 175–343 K. For face-centered cubic C61D2 above 290 K, we find an anomalously low value for K below about 0.15 GPa, possibly indicating pressure-induced changes in the structure. The (extrapolated) zero-p bulk modulus K(0) decreases with increasing T from 6.7 GPa at 175 K to 5.2 GPa at 343 K. A comparison with hypothetical expanded f.c.c. C60 with the same lattice constant shows that K(0) values are similar, indicating that the main intermolecular interactions are still between molecular bellies, not the sidegroups.
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- McRae, Edward, et al.
(författare)
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Transport study of (T,p) phase diagram in PdAl2Cl8 intercalated graphite
- 1996
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Ingår i: Journal of Physics and Chemistry of Solids, volume 57, issues 6-8. - : Elsevier Ltd.. ; , s. 827-831
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Konferensbidrag (refereegranskat)abstract
- We have examined the c-direction variations of resistance, Rc (or resistivity, varrhoc) over the 4.2–295 K. temperature range at ambient pressure, and over the 160–295 K range for pressures up to 1.5 GPa on first stage PdAl2Cl8 graphite intercalation compounds. All samples examined manifest a rapid, nonlinear decrease in Rc with pressure (maximum ¦dln Rc/dp¦ > 300 % GPa−1 at 0.4 GPa. The overall Rc decrease is around 90% by 1GPa, a value greater than that observed in any other GIC to date. Upon slow pressure release, the resistance increases linearly but to only about 20–25% of its initial (1 bar) value for HOPG-based materials: on the contrary, it returns along its initial R-p trajectory for GICs based on single crystal graphite. We discuss these data with reference to the X-ray diffraction results, to the significance of the residual resistivity and to studies on other similar lamellar solids.
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| 13. |
- Sundqvist, Bertil, et al.
(författare)
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A study of temperature and pressure-induced structural and electronic changes in SbCl5 intercalated graphite : Part III. Analysis of the T and p dependence of the c-axis resistivity
- 1995
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 10:2, s. 436-446
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental data for the c-axis electrical resistivity of SbCl5 intercalated graphite between 20 and 300 K. The data are analyzed together with our previous results for these and other samples [O. E. Andersson et al., J. Mater. Res. 7, 2989 (1992)]. Before the analysis, we correct the experimental data to constant volume, as assumed by theorists. We show that the correction factor is much larger for these materials than for normal metals. Although the original data showed significant nonlinearities with T, the corrected data are linear in T to within the experimental accuracy for low-stage compounds below the intercalate crystallization temperature. We compare our results with several models and conclude that both the temperature dependence, the pressure dependence, and the relative changes in the in-plane and c-axis resistivities associated with intercalate crystallization can be best described by a band conduction model.
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| 14. |
- Sundqvist, Bertil, et al.
(författare)
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In-plane electrical resistivity of La2-xSrxCuO4 at constant volume
- 1995
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 51:9, s. 6111-6114
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Tidskriftsartikel (refereegranskat)abstract
- Literature data for the in-plane electrical resistivity ρ of single-crystal La2-xSrxCuO4 with 0.07 ≤x≤0.34 have been corrected to constant crystal volume V using literature data for the pVT properties and for the resistivity vs pressure p. The original data at constant p show the usual anomalies observed for ceramic high-transition-temperature superconductors, such as linearity of ρ to extremely high T at optimum doping and an upwards curvature (ρ∝T1.5) for overdoped material. After correction, the data for ρ at constant volume are linear in T for overdoped material only. We show that phonons cannot be ruled out as the major carrier scattering agent.
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