Theoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metals

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but.committeeprof. Ing. Ivo Dlouhý, CSc. (předseda) Mgr. Martin Friák, Ph.D. (člen) RNDr. Martin Veis, Ph.D. (člen) prof. Mgr. Miroslav Černý, Ph.D. (člen) doc. RNDr. Ilja Turek, DrSc. (člen)cs
but.defenceTeoretická predikce nových magnetických materiálů a jejich fyzikálních vlastností patří k vysoce aktuálním tématům. Dizertat získal původní výsledky s jednoznačným vědeckým potenciálem, což bylo potvrzeno i recensovanými publikacemi. Poznatky sjou významné v oblasti (i) vlivu složení na vlastnosti oxidů A2BBo6, (ii) popisu nanodvojčatění v nestochiomatických magnetických materiálech s tvarovou pamětí a (iii) transformaci mezi nestochiometrickými složeními Fe2C. Výsledky prokázaly značnou erudici a předpoklady k tvůrčí vědecké práci.cs
but.jazykangličtina (English)
but.programMateriálové vědycs
but.resultpráce byla úspěšně obhájenacs
dc.contributor.advisorZelený, Martinen
dc.contributor.authorHeczko, Martinen
dc.contributor.refereeFriák, Martinen
dc.contributor.refereeVeis, Martinen
dc.date.accessioned2025-04-25T03:57:11Z
dc.date.available2025-04-25T03:57:11Z
dc.date.created2025cs
dc.description.abstractIn 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.en
dc.description.abstractIn 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.cs
dc.description.markPcs
dc.identifier.citationHECZKO, M. Theoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metals [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2025.cs
dc.identifier.other163099cs
dc.identifier.urihttps://hdl.handle.net/11012/250894
dc.language.isoencs
dc.publisherVysoké učení technické v Brně. Fakulta strojního inženýrstvícs
dc.rightsStandardní licenční smlouva - přístup k plnému textu bez omezenícs
dc.subjectAb initio methodsen
dc.subjectmultiferroic oxidesen
dc.subjecttwinningen
dc.subjectferromagnetic shape memory alloysen
dc.subjectphase stabilityen
dc.subjectAb initio methodscs
dc.subjectmultiferroic oxidescs
dc.subjecttwinningcs
dc.subjectferromagnetic shape memory alloyscs
dc.subjectphase stabilitycs
dc.titleTheoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metalsen
dc.title.alternativeTheoretical modelling of phase stability, magnetic and mechanical properties of compounds based on transition metalscs
dc.typeTextcs
dc.type.driverdoctoralThesisen
dc.type.evskpdizertační prácecs
dcterms.dateAccepted2025-04-22cs
dcterms.modified2025-04-24-11:47:56cs
eprints.affiliatedInstitution.facultyFakulta strojního inženýrstvícs
sync.item.dbid163099en
sync.item.dbtypeZPen
sync.item.insts2025.04.25 05:57:11en
sync.item.modts2025.04.25 05:33:11en
thesis.disciplinebez specializacecs
thesis.grantorVysoké učení technické v Brně. Fakulta strojního inženýrství. Ústav materiálových věd a inženýrstvícs
thesis.levelDoktorskýcs
thesis.namePh.D.cs
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