| 1. |
- Feuerbacher, M., et al.
(författare)
-
The Samson phase, β-Mg2Al3, Revisited
- 2007
-
Ingår i: Zeitschrift für Kristallographie. - 0044-2968. ; 222:6, s. 259-288
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
- Andersson, Magnus, et al.
(författare)
-
Electronic and structural properties of Laves-phase MgZn(2) of varying chemical disorder
- 2010
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:2, s. 024202-
-
Tidskriftsartikel (refereegranskat)abstract
- The C14 Laves-phase MgZn(2) has been investigated from 30 to 36 at. % Mg. In this way chemical disorder can be monitored over a limited concentration range and the influence on electron properties can be investigated. Our studies include thermodynamic calculations of atomic configurations of Mg and Zn at off-stoichiometric compositions, electronic-transport measurements, and electronic band-structure calculations of MgZn(2). The disorder introduced by alloying was found to be substitutional for all C14 alloys, and to have a markedly stronger effect on resistivity and magnetoresistance, Delta rho(B)/rho(0), on the Mg-rich side due to strain introduced when Mg substitutes for Zn. rho(T) and Hall constant were characteristic for weakly disordered binary alloys. Delta rho/rho of MgZn(2) was large, reached 6 at 4.2 K and 8 T, and decreased strongly at off-stoichiometric compositions. The results are discussed in view of the band-structure results and in terms of relations between atomic order and electronic properties. Several properties were found to resemble pure Zn. An empirical correlation over more than six orders of magnitude in Delta rho/rho was found for Zn and Zn-based alloys.
|
|
| 3. |
- Euchner, H., et al.
(författare)
-
Anomalous vibrational dynamics in the Mg(2)Zn(11) phase
- 2011
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 83:14, s. 144202-
-
Tidskriftsartikel (refereegranskat)abstract
- We present a combined experimental and theoretical study of the structure and the lattice dynamics in the complex metallic alloy Mg(2)Zn(11), by means of neutron and x-ray scattering, as well as ab initio and empirical potential calculations. Mg(2)Zn(11) can be seen as an intermediate step in structural complexity between the simple Laves-phase MgZn(2) on one side, and the complex 1/1 approximants and quasicrystals ZnMgAl and Zn(Mg)Sc on the other. The structure can be described as a cubic packing of a triacontahedron whose center is partially occupied by a Zn atom. This partially occupied site turned out to play a major role in understanding the lattice dynamics. Data from inelastic neutron scattering evidence a Van Hove singularity in the vibrational spectrum of Mg(2)Zn(11) for an energy as low as 4.5 meV, which is a unique feature for a nearly-close-packed metallic alloy. This corresponds to a gap opening at the Brillouin zone boundary and an interaction between a low-lying optical branch and an acoustic one, as could be deduced from the dispersion relation measured by inelastic x-ray scattering. Second, the measured phonon density of states exhibits many maxima, indicating strong mode interactions across the whole energy range. The origin of the low-energy modes in Mg(2)Zn(11) and other features of the vibrational spectra are studied, using both ab initio and empirical potential calculations. A detailed analysis of vibrational eigenmodes is presented, linking features in the vibrational spectrum to atomic motions within structural building blocks.
|
|
