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| 2. |
- de Leeuw, N.H., et al.
(författare)
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Modeling the competitive adsorption of water and methanoic acid on calcite and fluorite surfaces
- 1998
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 14:20, s. 5900-5906
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Tidskriftsartikel (refereegranskat)abstract
- Atomistic simulation techniques were used to investigate the interaction between the minerals calcite and fluorite with water and methanoic acid. The relative adsorption energies suggest that methanoic acid preferentially adsorbs onto fluorite surfaces, while adsorption of water is energetically preferred over methanoic acid on the calcite cleavage plane in agreement with experiment. The coverage and configuration of adsorbed methanoic acid on the surfaces depends largely on lattice spacing between the cations, and bridging between surface calcium atoms is highly favored. These findings have given an insight into interactions at the atomic level which indicate that modeling techniques should be capable of predicting adsorption behavior and designing collector molecules, which is of central importance to the mineral processing technique of flotation
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| 3. |
- Jonsson, B J, et al.
(författare)
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Method to extract the critical current density and the flux-creep exponent in high-T-c thin films using ac susceptibility measurements
- 1998
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 58:9, s. 5862-5867
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Tidskriftsartikel (refereegranskat)abstract
- High-precision ac susceptibility measurements have been made on high-quality Hg-1212 thin films. A method to analyze chi(1)'(T,H-0,f) and chi(1)" (T,H-0,f) and extract the temperature dependence of the critical current density J(c)(T), as well as the temperature and field-dependent flux-creep exponent n(T,H-0), is presented. With specific measurements at external ac fields Ho in the range 7-100 Oe(rms) we determine the temperature dependence of the critical current density from a single temperature scan. The obtained temperature dependence, J(c)(T), is found to be in good agreement with data obtained from measurements using the traditional "loss-maximum" approach. In addition we present a method to extract the temperature and ac field-dependent flux-creep exponent n(T,H-0) from a set of temperature scans taken at different cc fields and driving frequencies. The observed power law describing the frequency dependence of chi' is consistent with a current-dependent effective activation energy of the form U(J)= U(0)ln(J(c)/J). Furthermore, the flux creep is found to increase with ac field and with temperature except at about 20-30 K below T-c, where our data suggest a slowing down of the flux creep.
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| 9. |
- Rao, Q.H., et al.
(författare)
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Mode II fracture toughness testing of rock
- 1999
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Ingår i: Comptes-rendus / 9 Congrès international de mécanique de roches, Paris, France 1999. - Rotterdam : Balkema Publishers, A.A. / Taylor & Francis The Netherlands. - 905809071X ; , s. 731-734
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Konferensbidrag (refereegranskat)
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| 10. |
- Yun, S H, et al.
(författare)
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Growth of a-axis-oriented HgBa2CaCu2Ox thin films by rapid quenching
- 1999
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Ingår i: Journal of Materials Research. - 0884-2914 .- 2044-5326. ; 14:8, s. 3181-3184
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Tidskriftsartikel (refereegranskat)abstract
- High-quality a-axis-oriented HgBa2CaCu2Ox superconducting thin films have been grown on (100) LaAlO3 substrates using a modified conventional method that contains a short annealing time of 5 min, rapid-quenching process, and an alternative encapsulated approach. We found that the preferred orientations of HgBa2CaCu2Ox thin films can be controlled by rapid quenching at specific temperatures: 800, 700, 600, and 500 degrees C. The films rapidly quenched in water from 700 degrees C during a cooling cycle showed predominantly a-axis orientation perpendicular to the film surface. Phase was confirmed by x-ray diffraction pole figures. The a-axis films exhibited a zero-resistance transition temperature >120 K, which is comparable to epitaxial c-axis-oriented films.
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