| 1. |
- 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 II. Experimental data for c-axis resistivity
- 1992
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2989-3000
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Tidskriftsartikel (refereegranskat)abstract
- We present experimental data for the c-axis resistivity ?c of stage s = 2, 3, 4, 5, and 8, SbCl5 intercalated graphite, over the temperature range 40 to 300 K and the pressure range 0 to 0.8 GPa (0–8 kbar). For most specimens studied, resistance anomalies are observed below 230 K at atmospheric pressure and at pressures up to 0.5 GPa at 293 K. These anomalies are explained in terms of structural changes from a disordered or partly crystallized in-plane intercalate structure at atmospheric pressure and T > 230 K to an almost completely crystallized structure below this temperature, or at elevated pressures, as discussed in a companion paper. In the crystallized phases ?c is approximately linear in T except for stage 8, for which a nonlinear behavior, with a negative temperature coefficient of resistivity below 200 K, is observed. The results are compared with previously available literature data, and the p-T phase diagram is briefly discussed.
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| 2. |
- 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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| 3. |
- Andersson, Odd E., et al.
(författare)
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Pressure-induced modifications of structural and transport properties in SbCl5 intercalated graphite
- 1992
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Ingår i: Materials Science Forum volumes 91-93, Part I. - Zürich : Trans Tech Publications. - 0878496394 ; , s. 301-306
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Konferensbidrag (refereegranskat)abstract
- The structure and the c-axis resistivity of SbCl5 intercalated graphite have been studied as functions of T and p, over the ranges 40 to 295 K and 0 to 0.7 GPa. Slow cooling or slow application of pressure p > 0.4 GPa lead to states of complete but different crystallization of the intercalate, but after rapid cooling or pressurization any crystallization is incomplete. The resistivity of the high pressure crystallized phase is about 50% lower than that of the low T, low p phase under identical p-T conditions. No significant difference is seen between the behaviour of HOPG-based and single crystal based materials.
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| 4. |
- Andersson, Odd E., et al.
(författare)
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Structure, c-axis resistivity, and p-T phase diagram of SbCl5 intercalated graphite
- 1989
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Ingår i: Synthetic Metals volume 34. - Lausanne : Elsevier Sequoia SA. ; , s. 187-192
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Konferensbidrag (refereegranskat)abstract
- Experimental data are reported for the c-axis resistivity varrhoc of stages n = 3,4,5 and 8 SbCl5 intercalated graphite as a function of T and p, in the range 40 – 300 K and 0-0.5 GPa (5 kbar). varrhoc varied in a systematic way with p, T, and n. Well ordered low-T phases were obtained for all stages; disordering at 200 – 235 K gave rise to well defined multiple anomalies in varrhoc. We also report x-ray diffraction data on the stage 2 compound: evidence was found for large variations in the in-plane structure even for nominally identical samples.
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| 5. |
- Edman, Ludvig, et al.
(författare)
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Sodium-sodium halide co-intercalated graphite: chemistry, structure and electrical transport
- 1999
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Ingår i: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 60:4, s. 475-482
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Tidskriftsartikel (refereegranskat)abstract
- This study deals with the second to fourth stage compounds resulting from the co-intercalation of sodium and sodium halides into graphite. The charge transfer was determined through chemical analyses and X-ray diffraction and the results are compatible with Raman spectroscopy data. We present detailed results on c axis conduction between 4.2 K and 295 K and for hydrostatic pressures as high as 1.6 GPa. Possible mechanisms explaining the c axis conduction are discussed.
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| 6. |
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| 7. |
- Lelaurain, Michelle, et al.
(författare)
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A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part I: Structural aspects
- 1992
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2978-2988
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the effects of temperature (10 = T = 295 K) and pressure (0 = p = 0.8 GPa) on the state of intercalate layer crystallization in SbCl5 graphite intercalation compounds of stages 2, 4, and 8. At room temperature (RT), the intercalate layer may in some second stage compounds be fully crystallized and lowering the temperature creates no further modifications. In all other cases, i.e., those in which the intercalate layer has only partial crystallization at RT, lowering T leads to the formation of new in-plane unit cells, the final state depending on the kinetics. Applying pressure to above 0.3–0.5 GPa results in crystallization in all cases, different from that induced simply by lowering of the temperature. We discuss the unit cells observed and the relationships they bear to each other in the light of other works on similar compounds.
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| 8. |
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| 9. |
- McRae, Edward, et al.
(författare)
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On the relevance of certain transport-structure correlations in SbCl5-intercalated graphite to our overall understanding of GIC c axis conductivity
- 1994
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Ingår i: Molecular Crystals and Liquid Crystals Section A, volumes 244-245. - Yverdon : Gordon and Breach. ; , s. 61--66
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Konferensbidrag (refereegranskat)abstract
- This paper presents some new data on the SbCl5-intercalated graphite family as concerns the relationships between c axis resistivity, ρc(T,p), and intercalate layer structure. Results on the influence of intercalate layer crystallization and the nature of the host graphite are discussed and compared with those on other GIC families. Certain data are examined in the light of available theories and such an analysis raises a number of questions.
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| 10. |
- McRae, Edward, et al.
(författare)
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Raman light scattering and c-axis resistivity evidence for a pressure-induced stage transformation in PdAl2Cl8 intercalated graphite.
- 2000
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 62:20, s. 13757-13766
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Tidskriftsartikel (refereegranskat)abstract
- We have examined several samples of first- to third-stage PdAl2Cl8-intercalated graphite under hydrostatic pressures up to 1 GPa. In stage-1 highly oriented pyrolytic graphite–(HOPG) and single-crystal-graphite-based materials, the c-axis resistivity decreases sharply above a few kilobars; pressure release induces a reversible return to the initial value only in the case of the latter sample. Raman spectra taken in situ under pressure on a HOPG-based material show similarly irreversible effects. Analysis of the spectra taken on higher-stage samples leads to the conclusion that hydrostatic pressure beyond a few kilobars increases the density of the intercalate within the graphitic galleries, transforming the initial sample to a higher-stage material. Since there is no loss of intercalate, the overall intercalate-to-host charge transfer remains constant so that the Raman frequency is approximately the same for both first- and second-stage products. This is an unusual situation in which there is thus an apparent lack of Raman signature in spite of the stage change.
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| 11. |
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| 12. |
- 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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