- Petr Cejpek: Study of the structure of Heusler alloys by x-ray scattering
- 1. 4. 2015, 14:50
- lecture room F2, first floor Ke Karlovu 5
- more information
Abstract:
Recently, Heusler alloys are studied for their interesting magnetic and electronic properties. These properties are strongly dependent on the crystallographic structure. The study was focused on the powder samples and the single-crystalline samples of the composition 2:1:1. The object of interest was the description of crystallographic structure of samples, site occupation numbers of each type of atoms and their possible occupation disorder. Powder diffraction and EXAFS have been measured on powder samples Mn2Co1-xRhxSn. The series undergo tetragonal distortion at approx. x=0.3. The comparison of the measured and simulated EXAFS spectra demonstrated that the occupational disorder is a necessary feature, which must be considered in the analysis of EXAFS data, otherwise the fitting results are not physically feasible.
Classical single-crystal diffractions have been measured on the single-crystal Ni2MnGa by high-resolution reciprocal space mapping. The structure of Ni-Mn-Ga compounds is strongly sensitive to composition. This compound belongs to a family of shape memory alloys, which can show interesting properties such as twinning and a modulation in a structure. We can observe these features in the single-crystal diffraction, because of extra diffraction spots in our measured reciprocal space maps.