| 1. |
- Andersson, Odd E., et al.
(författare)
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C-axis resistance of HgCl2 intercalated graphite as a function of temperature and pressure
- 1989
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Ingår i: Synthetic Metals volume 34. - Lausanne : Elsevier Sequoia SA. ; , s. 485-490
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Konferensbidrag (refereegranskat)abstract
- The c-axis resistance of stage 3 HgCl2 intercalated graphite has been measured as a function of temperature T and pressure p in the range 40 to 300 K and up to 1 GPa (10 kbar). The absolute resistivity and its T- and p- dependence are all in good agreement with data for other acceptor compounds. The measurements show that a previosly unknown phase transformation occurs above 0.4 GPa. Below 250 K the high pressure phase is metastable down to zero pressure, and an x-ray diffraction analysis of metastable material shows that no stage change occurs. The transition thus probably leads to a different in-plane structure characterized by a more densely packed intercalate layer.
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| 2. |
- 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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| 3. |
- Berg, J, et al.
(författare)
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Crater formation in Langmuir-Blodgett films induced by electronic sputtering with fast heavy ions
- 1987
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Ingår i: Applied Physics Letters. - 0003-6951 .- 1077-3118. ; 51:17, s. 1379-
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Tidskriftsartikel (refereegranskat)abstract
- Secondary ion formation by fast heavy ion impact (electronic sputtering) on Langmuir–Blodgett films of fatty acids has been studied. The results show unambiguously that molecular ions originate from molecules in layers other than the surface layer. Furthermore, the results indicate that craters may be formed in electronic sputtering of such films. The depth of the craters depends on the stopping power of the incident ion and lower limits of the order of 100–200 Å are obtained from the ion data.
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| 4. |
- Roepstorff, P., et al.
(författare)
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Application of Plasma Desorption Mass Spectrometry to Molecular Weight Determination of Structural Protein from Insect Cuticle
- 1986
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Ingår i: Journal of Mass Spectrometry. - : Wiley. - 1076-5174 .- 1096-9888. ; 13:12, s. 689-691
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Tidskriftsartikel (refereegranskat)abstract
- During sequence determination of a structural protein from the cuticle of the migratory locust, Locusta migratoria, a discrepancy was found between the molecular weight calculated from the sequence data (15 323) and that estimated by SDS-gel electrophoresis (21 600). The protein contains several repeated sequences, and the discrepancy might indicate that part of the sequence was missing or that the protein contained a large prosthetic group. The molecular weight of the protein was determined by 127I-plasma desorption mass spectrometry to be 15 329±50 which confirms the sequence data and shows the molecular weight determination based on SDS-electrophoresis to be too high.
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| 5. |
- 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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| 6. |
- Sundqvist, Bertil, et al.
(författare)
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Pressure-temperature phase diagrams of stage-2-4 potassium-graphite intercalation compounds deduced from anomalies in the basal plane resistivity
- 1987
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 35:15, s. 8231-8242
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Tidskriftsartikel (refereegranskat)abstract
- The basal-plane resistivities ρ of stage-2–4 potassium-graphite intercalation compounds (K-GIC’s) have been measured as functions of temperature T and pressure p using a contactless method. The pressure range investigated was 0–1.4 GPa. For stage-2 K-GIC (KC24) measurements were made in the temperature range 90–300 K, while for the higher-stage materials the range was mainly limited to 245–300 K. In all cases ρ increases with p through the anomalous regime near the phase transitions, whereas dρ/dp is always negative in the stable high-p (high-stage) phases. Approximate p-T phase diagrams are deduced from anomalies in ρ corresponding to the staging and in-plane order-disorder transitions, respectively. In all cases the slopes dp/dT of the phase boundaries for the high-pressure staging transitions are such that the transitions extrapolate to positive T at atmospheric p, although no such transitions have been reported. The low-p staging-ordering phase boundary of KC24 is particularly complex, involving segments with both dp/dT→0 (125<200 K) and dp/dT→∞ (T≊125 K). The p-T diagrams are compared with recent structural experiments and models. We suggest that the complexity of the KC24 phase diagram is attributable to the weakly incommensurate in-plane structure at low p and T.
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