| 1. |
- Andersson, Per, et al.
(author)
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Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of some polymers
- 1975
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In: Journal of Polymer Science Polymer Physics Edition. - : Wiley. - 1542-9385 .- 0098-1273. ; 13:2, s. 243-251
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Journal article (peer-reviewed)abstract
- The pressure dependence of the specific heat of poly(methyl methacrylate), polystyrene, and atactic and isotactic polypropylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300°K and in the pressure range 0-37 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, while the specific heat decreases. The pressure dependencies are most pronounced at low pressures. The results are compared with other experimental results and with theoretical calculations.
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| 2. |
- Sundqvist, Bertil, et al.
(author)
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The thermal properties of an epoxy resin at high pressure and temperature
- 1977
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In: Journal of Physics D. - Bristol : Institute of Physics. - 0022-3727 .- 1361-6463. ; 10:10, s. 1397-1403
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Journal article (peer-reviewed)abstract
- The thermal conductivity lambda , thermal diffusivity and heat capacity per unit volume has been measured for an epoxy resin, Araldite AW 106, with hardener HV 953 U. Measurements have been carried out at room temperature up to 2.5 GPa and between 300 and 430K at 0.11 and 0.27 GPa. The glass transition temperature and its pressure (P) dependence have been determined. The quantity delta lambda / delta P was found to change abruptly in the temperature region of the glass transition.
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| 3. |
- Sundqvist, Bertil, et al.
(author)
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Thermal conduction of metals under pressure
- 1976
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In: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 47:2, s. 177-182
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Journal article (peer-reviewed)abstract
- It is shown that the original Ångström method of determining the thermal diffusivity of metals is not valid in the case of a specimen surrounded by a solid medium, and an appropriate modification is described. Several simplifications of this method are also presented and criteria for their validity given. An electronic system has been developed for automatic sampling and analysis of the temperature data. The new method has been applied to Cu under pressure, and the results show that the thermal conductivity rises by 6.4% up to 2.5 GPa (25 kilobar).
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| 4. |
- Sundqvist, Bertil, et al.
(author)
-
Thermal conductivity of copper under high pressure
- 1977
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In: High Temperatures-High Pressures. - London : Pion Ltd. - 0018-1544 .- 1472-3441. ; 9:1, s. 41-48
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Journal article (peer-reviewed)abstract
- The thermal diffusivity, a, of copper has been measured at room temperature up to a pressure of 2.5 GPa (25 kbar) by means of a method recently developed. In this pressure range the diffusivity increases linearly with a slope of (1/a)da/dp = 2.7x10-2 GPa-1. As the density and specific heat of copper are known as functions of pressure, this result can be used to obtain the pressure dependence of the thermal conductivity, lambda, with the result (1/lambda)d(lambda)/dp = 3.1x10-2 GPa-1. This value is shown to agree well with theoretical calculations of this slope. However, a comparison between this result and the pressure dependence of the electrical conductivity shows deviations from the Wiedemann-Franz law.
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| 5. |
- Sundqvist, Bertil, et al.
(author)
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Thermal conductivity of gold and silver at high pressures
- 1978
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In: Journal of Physics and Chemistry of Solids. - : Elsevier B.V.. - 0022-3697 .- 1879-2553. ; 39:10, s. 1133-1137
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Journal article (peer-reviewed)abstract
- The thermal diffusivities of gold and silver have been measured under pressure up to 2.5 GPa at room temperature. From the measured data the pressure dependence of the thermal conductivity, λ, has been calculated. The values found for the pressure coefficient λ−1 δλ/δP were 3.9 × 10−2GPa−1 for gold and 4.0 × 10−2 GP silver at atmospheric pressure. The results are compared to theoretical predictions of the pressure dependence and also to previous experimental results for copper and aluminium. For the noble metals, small angle or “vertical” scattering of electrons is shown to have a stronger volume dependence than “horizontal” scattering.
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| 6. |
- Sundqvist, Bertil, et al.
(author)
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Measurement of the pressure dependence of the electron-phonon interaction in aluminium
- 1979
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In: Journal of Physics F: Metal Physics. - Bristol : Institute of Physics. - 0305-4608. ; 9:9, s. L161-L166
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Journal article (peer-reviewed)abstract
- The authors report measurements of the electrical resistance of aluminium in the temperature range 30-40 degrees C and the pressure range 0.2-1.0 GPa. From these experiments the pressure dependence of the electron-photon interaction lambda is evaluated. With p in GPa the result is lambda (p)= lambda 0 exp(-0.0467p+4.7*10-4 p2). This expression for lambda describes accurately the observed pressure dependence of the superconducting Tc for pressures up to about 4 GPa.
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| 7. |
- Malmhäll, Roger, et al.
(author)
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Hall effect in Metglas 2826A and 2826 - dependence on temperature and pressure
- 1977
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In: Proceedings of International Conference on Magnetism, ICM 76. - : Elsevier. - 072040732X - 9780720407327 ; 86-88, s. 796-798
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Conference paper (peer-reviewed)abstract
- The Hall resistivity, ρH, of Metglas 2826A is measured for 0.6 ≤ T/Tc ≤ 1.9. Below To (∼255 K), the extraordinary Hall coefficient R1 is constant at +4.24 x x10-8 m3/As. The magnetic susceptibility, derived from our data, exhibits a Curie-Weiss behaviour above 350 K and varies as (T - Tc)-1.75 for (T - Tc) < 90 K. In 2826 at 300 K ρH drops linearly with increasing pressure.
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| 8. |
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| 9. |
- Alm, Ove, et al.
(author)
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A multiple coaxial wire for pressure calibration
- 1974
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In: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 45:4, s. 594-595
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Journal article (peer-reviewed)abstract
- A single wire containing several metals suitable for pressure calibration has been produced by extrusion. Coaxial combinations of Ce-Bi-TI and Ce-Bi-Ba have been prepared by the procedure described.
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| 10. |
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| 11. |
- Alm, Ove, et al.
(author)
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Thermal conductivity of KCl up to 19 kbar
- 1974
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In: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 35:3, s. 421-424
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Journal article (peer-reviewed)abstract
- The pressure dependency of the thermal conductivity of KCl has been measured at room temperature up to 19 kbar. The high pressure tool was of the “belt” type and a solid medium was used. The specimen was cylindrical and was heated along its axis. The conductivity was found to increase linearly at a rate of (3·3 ± 0·3) per cent/kbar.
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| 12. |
- Alm, Ove, et al.
(author)
-
Thermal conductivity of NaCl up to 40 kbar and 240-400 K
- 1975
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In: High Temperatures-High Pressures. - 0018-1544 .- 1472-3441. ; 7:2, s. 235-239
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Journal article (peer-reviewed)abstract
- The thermal conductivity, λ, of NaCl has been measured at pressures up to 40 kbar and temperatures between 240 K and 400 K in a solid medium in a 'belt' type of high-pressure apparatus. A steady state method with axial heating of a cylindrical specimen was employed. The increase of lambda with pressure was almost linear and the ratio of the thermal conductivity at 25 kbar to that at atmospheric pressure, λ(25)/λ(0), was found to be 1.72, and independent of temperature within the experimental error.
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| 13. |
- Alm, Ove, et al.
(author)
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Thermal conductivity of NaF at high pressures
- 1979
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In: High Temperatures-High Pressures. - 0018-1544 .- 1472-3441. ; 11, s. 339-341
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Journal article (peer-reviewed)abstract
- The thermal conductivity, λ, of NaF was measured over the pressure range 0-3 GPa at room temperature. An approximately linear variation of λ with P was observed in this range, and the ratio λ(P)/λ(0) was found to be 1.12 for P = 1 GPa.
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| 14. |
- Almbladh, Carl-Olof, et al.
(author)
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Comments on core-hole lifetime effects in deep-level spectroscopies
- 1978
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In: Physical Review B. - 1550-235X. ; 17:2, s. 929-939
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Journal article (peer-reviewed)abstract
- he effects of a finite core-hole lifetime on deep-level spectra in solids have recently attracted much interest. We here present a solvable model which enables a detailed analysis of lifetime effects. For x-ray photoemission and x-ray absorption, our analysis gives support for the usual convolution approach where the infinite lifetime spectrum is convoluted with a Lorentzian lifetime broadening. In particular, we demonstrate the inadequacy of a recent intuitive approach which predicts a suppression of the phonon broadening for short core-hole lifetimes. This is done by testing the different theories on our model. We also show that a straightforward diagrammatic analysis leads to the same conclusion. Finally, we discuss the phonon response to the total process of core-hole creation and subsequent annihilation in an x-ray or Auger emission event. It is explained in some detail that the lifetime independence of the shake-up connected with the first step in this process is in no contradiction with the fact that the phonon system is uneffected by the total deep-level process in the limit of short core-hole lifetimes. We also analyze the process of 1s hole creation and subsequent Auger K-LL emission and give explicit expressions for this process.
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| 15. |
- Almbladh, Carl-Olof
(author)
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Incomplete phonon relaxation in X-ray emission
- 1976
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In: Solid State Communications. - 1879-2766. ; 22:6, s. 339-342
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Journal article (peer-reviewed)abstract
- We calculate the phonon broadening in x-ray emission for Li, Na, Al, and K, treating the excitation and the subsequent emission as one quantum process. When the core-hole lifetime width is of the same order as the Debye energy, incomplete phonon relaxation gives a partial quenching of the Stokes shift and an additional width. This effect has previously not been seriously investigated; we find here that it gives a likely explanation of the broad Li emission edge.
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| 16. |
- Almbladh, Carl-Olof, et al.
(author)
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Interpretation of high-energy X-ray satellites of L2,3 emission bands of Na, Mg, Al and Si
- 1975
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In: Journal of Physics C: Solid State Physics. - 0022-3719. ; 8:23, s. 4117-4123
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Journal article (peer-reviewed)abstract
- The high-energy satellite of the L2,3 X-ray emission band in Na, Mg, Al and Si has for a long time been attributed to the decay of an initial state with two holes in the 2p shell. In particular, the satellite threshold has been assigned to an initial (2p2)1D state. It has recently been found that X-ray and Auger data give two different values for the energy of this doubly-ionized state, and attempts have been made to interpret this difference in terms of localized valence states. The authors have re-examined the interpretation of the L2,3, satellite using data on K and L2,3 satellites, Auger and radiative Auger KLL spectra. It is concluded that the L2,3 satellite originates from an initial (2p2)3P state, contrary to previous assumptions.
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| 17. |
- Almbladh, Carl-Olof, et al.
(author)
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On the thermal broadening of core levels in metals due to many‐electron effects
- 1978
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In: Physica Status Solidi (B). ; 85:1, s. 135-143
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Journal article (peer-reviewed)abstract
- Ferrell's expression for the XPS lineshape is derived in a formalism which explicitly takes the electron—electron interaction into account. Also the corresponding expression for X-ray absorption is given. In the presence of other broadenings, which are comparable or larger than kT, the electronic part of the core-level broadening in XPS is indistinguishable from a Gaussian. This Gaussian broadening is of the same order as the expected phonon broadening for Al at room temperature and above, but it is of little importance for Li and Na. In X-ray absorption, the effect seems in some cases to be important when extracting phonon broadenings from experimental data.
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| 18. |
- Almbladh, Carl-Olof, et al.
(author)
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Screening of a proton in an electron gas
- 1976
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In: Physical Review B. - 1550-235X. ; 14:6, s. 2250-2254
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Journal article (peer-reviewed)abstract
- Calculations are reported of the nonlinear screening of a proton in an electron gas of densities corresponding to rs=1-6. Results for charge densities and total energies are presented from self-consistent Kohn-Sham ground-state calculations. The results differ markedly from the case of linear screening, particularly at low densities. The occurrence of a bound state around the proton for rs>1.9 indicates that hydrogen in jellium is in the form of a screened H- ion. It is also found that at metallic densities the induced polarization around the proton is insensitive to rs, and the screening length is almost constant (0.65) for 2
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| 19. |
- Almbladh, Carl-Olof, et al.
(author)
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The spherical-solid model: An application to x-ray edges in Li, Na, and Al
- 1976
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In: Physical Review B. - 1550-235X. ; 13:8, s. 3307-3319
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Journal article (peer-reviewed)abstract
- In order to treat highly localized excitations in a solid a simple spherical model has been developed. The Coulomb potential from the nucleus at the site of the excitation is treated exactly, while the potentials from the surrounding sites are turned into pseudoion pontentials. Only the spherical average of these potentials is retained and separate self-consistent calculations for the ground state and for the excited state are made. These states are mistreated by the model but the difference accurately describes the large effects of polarization involved. The positions of the x-ray edges are obtained with an accuracy of 0.5 eV for singly ionized levels and 1 eV for doubly ionized levels. The phase shifts relevant to the Nozières-De Dominicis theory of x-ray absorption and emission edges and x-ray photoemission line shapes are also calculated. We obtain a noticeable many-body enhancement of the L2,3 edge in Na while the many-body effect in Li and Al is negligible. Our exponents agree with those extracted from recent x-ray photoemission experiments, but they do not agree with those extracted from x-ray emission or absorption spectra. We argue that the exponents taken from the photoemission experiment are more reliable but no definite conclusion concerning the validity of the present many-body theory should be drawn until the experimental situation has become more clear.
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| 20. |
- Andersson, Per, et al.
(author)
-
Electrical resistance of Evanohm under pressure
- 1975
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In: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 46:9, s. 1292-1293
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Journal article (peer-reviewed)abstract
- The electrical resistance of Evanohm wire has been determined as a function of hydrostatic pressure. A Teflon cell with a novel type of electrical feedthrough was used to contain the fluid medium. The resistance was found to decrease approximately linearly by 0.3% up to 27 kilobar. The remarkably small variation of its resistance with temperature and pressure makes Evanohm a suitable material for strain measurements under pressure.
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| 21. |
- Andersson, Per, et al.
(author)
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Pressure dependence of the thermal conductivity of an epoxy resin
- 1973
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In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 44:2, s. 705-707
-
Journal article (peer-reviewed)abstract
- The pressure dependence of the thermal conductivity of Araldite has been determined in a cylindrical geometry at 300 K. The pressure coefficient was found to be independent of the percentage of hardener, the conductivity at 25 kbar being higher by the factor 1.75 ± 0.05 than at atmospheric pressure.
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| 22. |
- Andersson, Per
(author)
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Pressure dependence of the thermal conductivity of some polyamides
- 1976
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In: Macromolecular Chemistry and Physics. - Basel : Wiley. - 1022-1352 .- 1521-3935. ; 177, s. 271-277
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Journal article (peer-reviewed)abstract
- The pressure dependence of the thermal conductivities of five polyamides (nylons) have been determined ina cylindrical geometry at 300 K and in the pressure range 0-25 kbar. The conductivities increase strongly with pressure, the values at 25 kbar being higher by the factors 1,83, 1,90, 2,07, and 2,03 for, respectively, nylon 66, nylon 610, nylon 6, nylon 11, and nylon 12, than those at atmospheric pressure. The results are compared with other exerimental results and with theoretical calculations. The difference in conductivity response to pressure between the different varieties is discussed.
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| 23. |
- Andersson, Per, et al.
(author)
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Pressure dependence of the thermal conductivity, thermal diffusivity, and specific heat of polyethylene
- 1973
-
In: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 44:6, s. 2601-2605
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Journal article (peer-reviewed)abstract
- The pressure dependence of the specific heat of high‐density polyethylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300 K and in the pressure range 0–25 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, the values at 25 kbar being higher by factors of 2.75 and 2.77, respectively, than those at atmospheric pressure. The specific heat decreases, most strongly so at low pressures, and its value at 25 kbar is 0.80 times that at atmospheric pressure. The thermal conductivity of low‐density polyethylene was determined as a function of pressure. Its value at 25 kbar was found to be 2.19 times that at atmospheric pressure. The difference in conductivity response to pressure between the two varieties is given a simple theoretical interpretation.
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| 24. |
- Andersson, Per, et al.
(author)
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Specific heat of solids at high pressures from simultaneous measurements of thermal conductivity and diffusivity
- 1972
-
In: High Temperatures-High Pressures. - 0018-1544 .- 1472-3441. ; 4:1, s. 101-109
-
Journal article (peer-reviewed)abstract
- A method of determining the specific heat of solids at high pressures, from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry, is described. Results are reported for polytetrafluoroethylene (Teflon) in the range 0-30 kbar at 300 K. With increasing pressure both the thermal conductivity and diffusivity increase strongly and approximately linearly, while the specific heat decreases, most strongly at low pressures.
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| 25. |
- Andersson, Per
(author)
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Thermal conductivity and heat capacity of cyclohexane under pressure
- 1978
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In: Journal of Physics and Chemistry of Solids. - : Elsevier. - 0022-3697 .- 1879-2553. ; 39:1, s. 65-68
-
Journal article (peer-reviewed)abstract
- The transient hot-wire technique was used to determine the thermal conductivity, λ, and the specific heat capacity per unit volume, ρcp, of cyclohexane up to 1.5 GPa in the range 120–340 K. The measurements were carried out in a piston-cylinder apparatus, 45 mm in internal diameter, cooled by liquid nitrogen. There is only a small (6%) increase in λ on freezing, while there is an increase by a factor of two corresponding to the plastic→ normal crystal transition. The variation of λ with temperature (T) at P = 0.03 GPa is d(lnλ)/dT = −2.2×10−3K−1 for the liquid and d(ln λ)/dT = −0.9×10−3K−1 for the plastic crystalline phase. In the normal crystal phase an approximate T−1 dependence is observed. Within each of the phases λ increases linearly with pressure, and the slope of λ (P) is smallest in the plastic crystal phase. The existence of a recently reported new high pressure phase is evident from conductivity data. Qualitative ρcp -results are reported.
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