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Firm Analysis by Different Methods
Bohatá, Jolana ; Kaňa, Tomáš (referee) ; Hanušová, Helena (advisor)
The subject of my thesis is an analysis of the selected enterprise. Subsequently, ways of improving its situation will be proposed. In my work, I will gradually address all aspects of the company analysis. Working on my thesis, I will use theoretical knowledge gained while studying at the Faculty of Business at VUT in Brno, as well as practical experience that I have accrued working for the company.
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QUANTUM MECHANICAL STUDY OF PHASE STABILITY IN METALLIC SYSTEMS
Káňa, Tomáš ; Vřešťál, Jan (referee) ; Paidar,, Václav (referee) ; Černý, Miroslav (referee) ; Šob, Mojmír (advisor)
This work presents a theoretical study of stability of phases in selected metallic systems. We propose a model of structural transformations in transition metal disilicides MoSi2, CrSi2, VSi2 and TiSi2 and in Pd thin films grown on cubic substrates W(001) and Nb(001). The obtained results yield the total energy proles for the structural transformations studied, the activation energies needed for each individual transformation and an estimate of the temperature at which the structure can transform. The total energies are calculated by full-potential linearized augmented plane waves (FLAPW) method incorporated in the WIEN2k code. Both generalized gradient approximation (GGA) and local density approximation (LDA) are employed for the exchange-correlation term. It turns out that temperatures corresponding to the activation energies of structural transformations in transition metal disilicides exceed their melting temperatures. Comparing the resulting total energy proles to those obtained by the semiempirical Bond Order interatomic potentials (BOP) substantially helps to adjust the fitting parameters of the BOPs. The estimated temperature of 168 K needed to transform the hcp structure of an innite Pd crystal into the dhcp structure explains the behavior of the Pd thin lm on W(001) and Nb(001) substrates. Pd lms deposited on W(001) substrate and thicker than about 100 monolayers undergo this transformation already at room temperature. Thinner lms need to be annealed at 400 K rst, due to their stronger interaction with the substrate. The difference between the computed result and a real temperature at which the hcp Pd lm transforms its structure to the dhcp can be explained by both the interaction between the lm and the substrate and by the inuence of the domain topology of the lm. Analyzing different models of transformation of the initial hcp Pd structure to the ground state fcc structure, we identied the optimum model that respects the domain topology of the Pd lm.
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Ab initio study of {101-2} twinning transition in magnesium
Káňa, Tomáš ; Ostapovets, Andriy
Twinning is an important deformation mode in materials with the hexagonal close-packed (hcp) structures. The shear deformation combined with shuffling of atomic planes can lead to a transition between the Mg hcp structure and a twinned hcp structure. Studying such a transition by means of ab initio methods should bring more insight into the twinning mechanism in magnesium where the {1012} planes are the twinning planes. Comparison of ab initio results with those obtained using the semi-empirical embedded atom method is provided. It can help improve the fitted parameters of the embedded atom method.
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QUANTUM MECHANICAL STUDY OF PHASE STABILITY IN METALLIC SYSTEMS
Káňa, Tomáš ; Vřešťál, Jan (referee) ; Paidar,, Václav (referee) ; Černý, Miroslav (referee) ; Šob, Mojmír (advisor)
This work presents a theoretical study of stability of phases in selected metallic systems. We propose a model of structural transformations in transition metal disilicides MoSi2, CrSi2, VSi2 and TiSi2 and in Pd thin films grown on cubic substrates W(001) and Nb(001). The obtained results yield the total energy proles for the structural transformations studied, the activation energies needed for each individual transformation and an estimate of the temperature at which the structure can transform. The total energies are calculated by full-potential linearized augmented plane waves (FLAPW) method incorporated in the WIEN2k code. Both generalized gradient approximation (GGA) and local density approximation (LDA) are employed for the exchange-correlation term. It turns out that temperatures corresponding to the activation energies of structural transformations in transition metal disilicides exceed their melting temperatures. Comparing the resulting total energy proles to those obtained by the semiempirical Bond Order interatomic potentials (BOP) substantially helps to adjust the fitting parameters of the BOPs. The estimated temperature of 168 K needed to transform the hcp structure of an innite Pd crystal into the dhcp structure explains the behavior of the Pd thin lm on W(001) and Nb(001) substrates. Pd lms deposited on W(001) substrate and thicker than about 100 monolayers undergo this transformation already at room temperature. Thinner lms need to be annealed at 400 K rst, due to their stronger interaction with the substrate. The difference between the computed result and a real temperature at which the hcp Pd lm transforms its structure to the dhcp can be explained by both the interaction between the lm and the substrate and by the inuence of the domain topology of the lm. Analyzing different models of transformation of the initial hcp Pd structure to the ground state fcc structure, we identied the optimum model that respects the domain topology of the Pd lm.
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Firm Analysis by Different Methods
Bohatá, Jolana ; Kaňa, Tomáš (referee) ; Hanušová, Helena (advisor)
The subject of my thesis is an analysis of the selected enterprise. Subsequently, ways of improving its situation will be proposed. In my work, I will gradually address all aspects of the company analysis. Working on my thesis, I will use theoretical knowledge gained while studying at the Faculty of Business at VUT in Brno, as well as practical experience that I have accrued working for the company.
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Strength and magnetism of Mn-Pt nanocomposites
Káňa, Tomáš ; Šob, Mojmír
Using ab initio electronic structure calculations, we have analysed Mn atoms dissolved in a platinum matrix, forming thus intermetallics MnPt3, MnPt7 and MnPt15 that can be considered as prototypes of natural Mn–Pt nanocomposites. On the whole, manganese addition makes the resulting Mn–Pt compound softer but increases its resistance to shape deformation. With increasing Mn content, both tensile and compressive theoretical strength is enhanced. In agreement with experiment, our calculations confirm the antiferromagnetic (AFM) ground state of the MnPt7 structure with spins directions altering along the [100] crystallographic direction (AFM [100]). In addition, we have proposed and studied three prototypes of linear MnPt15 nanocomposites consisting of Mn nanochains in the Pt matrix. Again, AFM [100] ordering was found in the ground state of MnPt15.
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