Original title: Theoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metals
Translated title: Theoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metals
Authors: Heczko, Martin ; Friák, Martin (referee) ; Veis, Martin (referee) ; Zelený, Martin (advisor)
Document type: Doctoral theses
Year: 2025
Language: eng
Publisher: Vysoké učení technické v Brně. Fakulta strojního inženýrství
Abstract: In this Doctoral thesis, ab initio calculations of electronic structure within the projector augmented wave method are employed to study physical properties of several compounds containing transition metals and manifesting magnetic ordering. In particular, three material problems were studied, namely the magnetic properties of complex A2BBO6 oxides in dependence of various A, B and B metallic elements; the mechanism twinning on atomic level and its application on NM martensite of Mn-rich Ni-Mn-Ga alloys and the phase transformation and stability in Fe2C. The results of first part show that to achieve the highest Curie temperature in A2BBO6 oxides, A element must have ionic radius as small as possible while the magnetic moments of B and B must be maximized. For deformation twinning of Ni-Mn-Ga alloys it is demonstrated that Mn excess leads to more difficult twinning due to increased phase stability of non-modulated martensite and magnetic ordering of excess Mn atoms. At last but not least, the formation of orthorhombic Fe2C from tetragonal rutile structure is explained from thermodynamical, mechanical and kinetic perspectives as a stabilization due to pseudo-Jahn-Teller effect.
Keywords: Ab initio methods; ferromagnetic shape memory alloys; multiferroic oxides; phase stability; twinning; Ab initio methods; ferromagnetic shape memory alloys; multiferroic oxides; phase stability; twinning

Institution: Brno University of Technology (web)
Document availability information: Fulltext is available in the Brno University of Technology Digital Library.
Original record: https://hdl.handle.net/11012/250894

Permalink: http://www.nusl.cz/ntk/nusl-678850


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Universities and colleges > Public universities > Brno University of Technology
Academic theses (ETDs) > Doctoral theses