| 1. |
- Andersson, Britt M., et al.
(author)
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Electrical resistivity and critical temperature of Bi-based high-Tc superconductors to 1 GPa
- 1990
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In: High Pressure Research, volumes 3 to 5. - London : Gordon and Breach. - 2881247466 ; 3:1-6, s. 120-122
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Conference paper (peer-reviewed)abstract
- We have measured the electrical resistance R of a sintered, two-phase, high-TC superconductor with the nominal composition BiSrCaCu2Ox, as a function of T and p. We find d(lnR)/dp ≃ -0.06 GPa-1 at 295 K, while dTC/dp is 2.5 K/GPa for the phase with Tc ≃ 76 and 2 K/GPa for that with TC ≃ 106 K.
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| 2. |
- Andersson, Odd E., et al.
(author)
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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
-
In: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2989-3000
-
Journal article (peer-reviewed)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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| 3. |
- Andersson, Odd E., et al.
(author)
-
Pressure-induced modifications of structural and transport properties in SbCl5 intercalated graphite
- 1992
-
In: Materials Science Forum volumes 91-93, Part I. - Zürich : Trans Tech Publications. - 0878496394 ; , s. 301-306
-
Conference paper (peer-reviewed)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. |
- Diederichs, J., et al.
(author)
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Critical currents in Tl-2122 and Y-124 sinters under high hydrostatic pressure
- 1991
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In: Superconductor Science and Technology, volume 4, Special Issue 1S. - Bristol : Adam Hilger. - 0750301082 ; , s. S97-S99
-
Conference paper (peer-reviewed)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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| 5. |
- Lelaurain, Michelle, et al.
(author)
-
A study of temperature and pressure induced structural and electronic changes in SbCl5 intercalated graphite : Part I: Structural aspects
- 1992
-
In: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 7:11, s. 2978-2988
-
Journal article (peer-reviewed)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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| 6. |
- McRae, Edward, et al.
(author)
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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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In: Molecular Crystals and Liquid Crystals Section A, volumes 244-245. - Yverdon : Gordon and Breach. ; , s. 61--66
-
Conference paper (peer-reviewed)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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| 7. |
- Sundqvist, Bertil, et al.
(author)
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Constant-pressure versus constant-volume resistivities of some high transition temperature superconductors
- 1994
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In: Physica C, volume 235-240. - : Elsevier Science B.V.. ; , s. 1407-1408
-
Conference paper (peer-reviewed)abstract
- The resistivity varrho is always measured at constant p, while theory assumes constant V. For high temperature superconductors there are large differences between constant-p and constant-V resistivities. We have previously shown constant-V results for YBa2Cu3O7−δ and show here similar data for La2−xSrxCuO4. Constant-V data for varrho agree with the behaviour expected for a normal metal, with low-T linearity in T and saturation at high T. We speculate that similar effects will be observed in doped fullerenes (M3C60, M = Li, K, Rb, …).
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