| 11. |
- 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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| 12. |
- Andersson, Odd E., et al.
(författare)
-
A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part II. Experimental data for c-axis resistivity
- 1992
-
Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2989-3000
-
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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| 13. |
- Andersson, Odd E., et al.
(författare)
-
Pressure-induced modifications of structural and transport properties in SbCl5 intercalated graphite
- 1992
-
Ingår i: Materials Science Forum volumes 91-93, Part I. - Zürich : Trans Tech Publications. - 0878496394 ; , s. 301-306
-
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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| 14. |
- Diederichs, J., et al.
(författare)
-
Critical currents in Tl-2122 and Y-124 sinters under high hydrostatic pressure
- 1991
-
Ingår i: Superconductor Science and Technology, volume 4, Special Issue 1S. - Bristol : Adam Hilger. - 0750301082 ; , s. S97-S99
-
Konferensbidrag (refereegranskat)abstract
- Utilizing AC susceptibility measurements the authors have investigated the inter and intragranular properties of selected bulk materials under hydrostatic pressures to 3.5 GPa. A single phase Tl2CaBa2Cu2O8 sample with superconducting transition temperature Tc approximately=107 K shows a clear maximum in Tc(P) at approximately 2.2 GPa coupled with a nearly twofold increase to 3 GPa of the intergranular critical current density JcJ near Tc. The second sample, a YBa2Cu4O8 sinter, shows a large linear increase in Tc with pressure (+5.5 K/GPa) as well as a fivefold increase JcJ to 3 GPa. Applying a critical state model, the authors find that Tc(P) varies as lambda g-2(P), where lambda g is the intragranular (London) penetration depth.
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| 15. |
- Lelaurain, Michelle, et al.
(författare)
-
A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part I: Structural aspects
- 1992
-
Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2978-2988
-
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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| 16. |
- Lundin, Anders, et al.
(författare)
-
A piston-and-cylinder device for compressibility studies on polymers and other "soft" materials
- 1994
-
Ingår i: High Pressure Research volume 13, issue 1-3. - Yverdon : Gordon and Breach. ; , s. 141-145
-
Konferensbidrag (refereegranskat)abstract
- We describe an all-steel piston-and-cylinder device for pVT studies on “soft” materials, including liquids, in the range 100-450 K and 0-1.5 GPa. The internal diameter is 15 mm with sample lengths between 10 and 50 mm. Piston displacements are measured to within 0.1 μm using differential transformer transducers. Pressure is calculated from force per unit area and the deformation of pistons and cylinder under pressure are taken into account. The inaccuracy in ΔV/V is less than 0.5%. Experimental data are shown for indium and urea.
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| 17. |
- Lundin, Anders, et al.
(författare)
-
Compressibility of C60 between 150 and 335 K and up to 1 GPa
- 1994
-
Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 27:6, s. 463-466
-
Tidskriftsartikel (refereegranskat)abstract
- The bulk modulus B of C60 has been measured in the range 150-335 K and up to 1 GPa, for the first time in the f.c.c. rotationally disordered phase, through the f.c.c. → s.c. transition, and in the s.c. phase. At 298 K we find B values of 8.8 (s.c.) and 6.8 GPa (f.c.c.), significantly lower than those found in previous studies. At the transition B decreases with decreasing V, which is probably an effect of orientational ordering on intermolecular interactions.
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| 18. |
- Lundin, Anders, et al.
(författare)
-
Compressibility, specific heat capacity, and Grüneisen parameter for C60/C70
- 1992
-
Ingår i: Solid State Communications. - : Elsevier Science Ltd. - 0038-1098 .- 1879-2766. ; 84:9, s. 879-883
-
Tidskriftsartikel (refereegranskat)abstract
- We have measured the specific heat capacity cp of C60/C70 between 110 and 310 K and its compressibility κ up to 1.1 GPa (11 kbar) at 293 K, a range in t and p which overlaps reported ranges of stability of both the rotationally disordered high T, low p fcc phase and the low T high p orientationally ordered sc phase. No sharp anomaly is observed in cp at the transition. The bulk modulus B near p = 0 was 8.4 GPa, rapidly increasing to about 16 GPa near 1 GPa. For our data, the intermolecular forces could be modeled by either a Lennard-Jones or a Born-Mayer potential, but this was not the case if literature data for compression vs. p were used.
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| 19. |
- McRae, Edward, et al.
(författare)
-
On the relevance of certain transport-structure correlations in SbCl5-intercalated graphite to our overall understanding of GIC c axis conductivity
- 1994
-
Ingår i: Molecular Crystals and Liquid Crystals Section A, volumes 244-245. - Yverdon : Gordon and Breach. ; , s. 61--66
-
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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| 20. |
- Staun Olsen, J., et al.
(författare)
-
High pressure studies up to 50 GPa of Bi-based high-Tc superconductors
- 1991
-
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 44:2, s. 211-213
-
Tidskriftsartikel (refereegranskat)abstract
- The high-Tc superconductor with nominal composition BiSrCaCu2Ox has been studied at high pressure, i.e. up to 50 GPa. A tetragonal structure was compatible with the measurements at all pressures, and no phase change was observed. The bulk modulus, B0 = 62.5 GPa, obtained has a somewhat smaller value than the one estimated earlier.
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