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| 2. |
- Mikhaylushkin, A. S., et al.
(författare)
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Mikhaylushkin et al. Reply
- 2008
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 101:4, s. 049602-
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Mikhaylushkin, A. S., et al.
(författare)
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Electron-concentration and pressure-induced structural changes in the alloys In1–xXx (X=Cd,Sn)
- 2005
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Ingår i: Phys. Rev. B. ; 72, s. 134202-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Electron-concentration and pressure-induced structural transitions in solid solutions In1–xCdx (0<=x<=0.1) and In1–xSnx (0<=x<=0.2) have been investigated by means of first principles calculations. At ambient pressure the structural sequence face-centered cubic --> body-centered tetragonal (c/a>sqrt(2)) --> body-centered tetragonal (c/a
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| 4. |
- Mikhaylushkin, A. S., et al.
(författare)
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Fluctuating lattice constants of indium under high pressure
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:19
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Tidskriftsartikel (refereegranskat)abstract
- Recent high-pressure investigations of elemental In have yielded controversial results. We show that the observed high-pressure face-centered orthorhombic (fco) structure can be explained as an intermediate state between two body-centered tetragonal (bct) structures with different c/a ratios (c/a < &RADIC;2 and c/a > root2, respectively). In a pressure range from about 50 to 200 GPa these two bct structures correspond to local minima of the total energy with respect to orthorhombic distortion of the ground-state bct In structure. The fco saddle point represents a tiny barrier and even at low temperatures rapid structural fluctuations should occur. Such a situation has not been identified in any other elemental metal.
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| 5. |
- Mikhaylushkin, A. S., et al.
(författare)
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Structural and magnetic properties of FeHx (x=0.25; 0.50; 0.75)
- 2006
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Ingår i: AIP Conf. Proc.. - : AIP. - 0735403295 - 9780735403291 ; , s. 161-167
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Konferensbidrag (refereegranskat)abstract
- The structural and magnetic properties of the FeHx (x=0.25; 0.50; 0.75) compounds have been studied using the projector augmented wave (PAW) method within the generalized gradient approximation (GGA). We compare the hcp, dhcp and fcc structures and find that for the considered concentrations of hydrogen the hcp structure is most stable in a wide pressure range. The magnetic behavior of iron is crucially influenced by hydrogen. In particular, the local moment on a Fe atom depends on the number of hydrogen atoms in the atom surroundings. Iron atoms, which are crystallographically equivalent in their original structures (hcp, fcc) but have different number of hydrogen neighbors, are shown to have different local magnetic moments. This finding suggests that the experimental observations of two magnetic moments in iron hydride can be explained by nonstoichiometry of the hydride and might not be a direct evidence for the presence of the dhcp phase.
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| 6. |
- Asker Göransson, Christian, et al.
(författare)
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First-principles solution to the problem of Mo lattice stability
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 77:22
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Tidskriftsartikel (refereegranskat)abstract
- The energy differences between the ground state body-centered structure and closed-packed face-centered structure for transition metals in the middle of the series show unusually large disagreements when they are obtained by the thermochemical approach based on the analysis of experimental data or by first-principles electronic structure calculations. Considering a typical example, the lattice stability of Mo, we present a solution to this long-standing problem. We carry out ab initio molecular dynamics simulations for the two phases at high temperature and show that the configurational energy difference approaches the value derived by means of the thermochemical approach. The main contribution to the effect comes from the modification of the canonical band structure due to anharmonic thermal motion at high temperature.
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| 7. |
- Burakovsky, L., et al.
(författare)
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High-Pressure-High-Temperature Polymorphism in Ta : Resolving an Ongoing Experimental Controversy
- 2010
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 104:25, s. 255702-
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Tidskriftsartikel (refereegranskat)abstract
- Phase diagrams of refractory metals remain essentially unknown. Moreover, there is an ongoing controversy over the high-pressure melting temperatures of these metals: results of diamond anvil cell (DAC) and shock wave experiments differ by at least a factor of 2. From an extensive ab initio study on tantalum we discovered that the body-centered cubic phase, its physical phase at ambient conditions, transforms to another solid phase, possibly hexagonal omega phase, at high temperature. Hence the sample motion observed in DAC experiments is very likely not due to melting but internal stresses accompanying a solid-solid transformation, and thermal stresses associated with laser heating.
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| 8. |
- Häussermann, Ulrich, et al.
(författare)
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Alloys Bi1-xSbx under High-Pressure
- 2004
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Ingår i: Physical Review B. - 1098-0121. ; 69, s. 134203-1 - 134203-10
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Tidskriftsartikel (refereegranskat)
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| 9. |
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| 10. |
- Tengå, Andreas, 1976-, et al.
(författare)
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Sphalerite-chalcopyrite polymorphism in semimetallic ZnSnSb2
- 2005
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Ingår i: Chemistry of Materials. - Washington, DC : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 17:24, s. 6080-6085
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the system ZnSnSb2 in the course of our attempts to modify thermoelectric Zn-Sb frameworks. ZnSnSb2 is only accessible when employing Sn as reactive flux in the synthesis. The material shows an order-disorder transition in the temperature interval between 225 and 240 degrees C and decomposes peritectically at about 360 degrees C. The high-temperature form of ZnSnSb2 adopts the Zn/Sn disordered cubic sphalerite-type structure. Electron microscopy investigations reveal that samples quenched from 350 degrees C already contain domains of the low-temperature form, which has the Zn/Sn ordered tetragonal chalcopyrite structure. The c/a ratio of the tetragonal structure is, within experimental errors, identical to the ideal value 2. This gives rise to intricate microtwinning in the low-temperature chalcopyrite form of ZnSnSb2 as obtained in samples quenched from 250 degrees C. First principles electronic structure calculations demonstrate that the tetragonal low-temperature form of ZnSnSb2 has a narrow band gap of about 0.2 eV. This is in agreement with the semimetallic behavior of the material found from resistivity measurement. The shape of the electronic density of states for ZnSnSb2 is similar to thermoelectric binary Zn-Sb frameworks. However, the thermopower of ZnSnSb2 is rather low with room-temperature values ranging from 10 to 30,mu V/K.
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