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| 2. |
- 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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| 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 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Lundin, Anders, et al.
(författare)
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Compressibility, specific heat capacity, and Grüneisen parameter for C60/C70
- 1992
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Ingår i: Solid State Communications. - : Elsevier Science Ltd. - 0038-1098 .- 1879-2766. ; 84:9, s. 879-883
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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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| 7. |
- Sundqvist, Bertil
(författare)
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Resistivity saturation in fcc La under high pressure
- 1992
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 69:18, s. 2693-2696
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Tidskriftsartikel (refereegranskat)abstract
- Data are presented for the electrical resistivity ρ of fcc La as a function of T and p in the range 70 to 700 K and 0 to 1.25 GPa. The data are analyzed using the phenomenological ‘‘parallel resistivity’’ formula for resistivity saturation, which describes very well the T dependences of both ρ and its pressure coefficient. The pressure coefficients of the electron-phonon interaction parameter and Tc are calculated from the p dependence of the electron-phonon component, and the p dependence of the parallel saturation resistivity is obtained from band-structure calculations using a simple Bloch-Boltzmann model. In both cases excellent agreement with experiment is found.
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| 8. |
- Sundqvist, Bertil
(författare)
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Thermal diffusivity and thermal conductivity of Chromel, Alumel, and Constantan in the range 100-450 K
- 1992
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 72:2, s. 539-545
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Tidskriftsartikel (refereegranskat)abstract
- Data are presented for the thermal diffusivity and the thermal conductivity of commercially available Chromel, Alumel, and Constantan alloys, and the specific heat capacity of Alumel, over the temperature range 100 to 450 K. Over this range, the thermal conductivity of all materials increases by more than 50%; room-temperature values are 17, 29, and 23 W m−1 K−1, respectively. The thermal conductivity data are discussed in terms of simple theory.
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