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First-principles studies of the electronic and structural properties of Lead Zirconate Titanate (PZT)
Planer, Jakub ; Friák, Martin (referee) ; Bartošík, Miroslav (advisor)
This work is focused on Density Functional Theory (DFT) calculations of oxygen vacancy diffusion barriers in mixed perovskite lead zirconate titanate and its pure counterparts. We found out that barrier heights are different in lead titanate and lead zirconate caused by the different localization of the excess electrons due to the oxygen vacancy formation. Diffusion barriers were also determined for titanium-rich mixed phases and compared to experimental values. This work contributes to clarify unusually low experimentally measured diffusion coefficients in PZT. We found out that the induced vacancy states are forming localized bonds to the lead atoms which causes the oxygen vacancies to become immobile due to the increase of the activation energy of the diffusion process.
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Dynamic viscosity of electroinsulating liquids
Míka, Petr ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
This work deals with persepective environmentally friendly electroinsulating liquids. Important properties of currently used electroinsulating liquids are listed. Physical nature of viscosity of liquids and its temperature dependance are described and methods of its measuring are listed. Also temperature dependance of density is described from physical point of view. Measurement of density and of temperature dependance of viscosity of chosen vegetable and mineral oils was performed. On the basis of this measurement was calulated the activation energy of these samples. Two methods of dynamic viscosity measurement were used for some samples.
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determination of kinetic parameter of reactions using DSC
Kopecký, Jan ; Kouřil, Miloslav (referee) ; Jan, Vít (advisor)
The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.
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Phase transformation in magnesium MgZnAl-based alloys
Kodetová, Veronika ; Vlach, Martin (advisor) ; Mathis, Kristián (referee)
In the present work, there was analyzed thermal evolution of the phase transformation in the MgZnAl and MgZnAlCa alloys with different concentration of the Zn and Ca. The grains were occupied by the phase with quasicrystaline icosaedral structure in the as-cast alloys and after isochronal annealing up to 240 řC. The thermal measurements revealed two exothermic effects in the MgZnAl alloy and three exothermic effects in the MgZnAlCa alloy during linear heat treatment in the temperature range of 100 - 250 řC. In agreement to the thermal response, two and three stages of electrical resistivity decrease were observed in the same temperature range. The lower thermal changes, absolute resistivity changes and microhardness were observed in the alloy with Ca-addition and lower concentration of Zn.
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Phase transformation in bio-compatible Mg-based alloys
Hornát, Bohumil ; Vlach, Martin (advisor) ; Mathis, Kristián (referee)
ÙÖÖ ÒØ Ñ Ø Ö Ð Ö × Ö × Ó Ò Ò ÑÔÖÓÚ Ò Ú ÓÖ Ó Ð ØÛ Ø Ñ ¹ Ò × ÙÑ ÐÐÓÝ Û Ú Û Ù× ×Ô ÐÐÝ Ò ØÖ Ò×ÔÓÖØ Ò Ù×ØÖÝ Ò Ñ ¹ Ò ž Å ¹Ê ¹Ë ¹ÅÒ × ÐÐÓÝ× Ò ÓÒ× Ö × ÔÖÓÑ × Ò Ñ Ø Ö Ð ÓÖ Ø × ÔÔÐ Ø ÓÒמ ÁÒ Ø ÔÖ × ÒØ ÛÓÖ ¸ Ø Ö Û × ×ØÙ Ø ÖÑ Ð ÚÓÐÙØ ÓÒ Ó Ø Ô × ØÖ Ò× ÓÖÑ Ø ÓÒ× Ò Å ¹Ê ¹Ë ¹ÅÒ × ÐÐÓÝ× Ý Ö ÒØ Ð × ÒÒ Ò ÐÓ¹ Ö Ñ ØÖÝ Ò Ñ ×ÙÖ Ò Ñ ÖÓ Ö Ò ×מ Ì Ø ÖÑ Ð Ö ×ÔÓÒ× × Ø Ö ÒØ Ø Ò Ö Ø × Û Ö Ó × ÖÚ Ò Ø Ø Ú Ø ÓÒ Ò Ö × Ó Ø ÔÖÓ ×× × Û Ö Ð ÙÐ Ø ž Ì Ø ÖÑ Ð Ö ×ÔÓÒ× × Û Ö ××Ó Ø Û Ø Ò Ú Ù Ð ÔÖ Ô Ø Ø ÓÒ ÓÖ ×ÓÐÚ ÒØ ÔÖÓ ×× × × ÓÒ ÓÑÔ Ö ×ÓÒ Û Ø Ð Ø Ö ØÙÖ ž ÈÖ Ô Ø Ø ÓÒ × ÕÙ Ò Ó ×Ý×Ø Ñ Å ¹ Û Ö Ó × ÖÚ Ò Ñ Ø Ö Ð× Å ½Ë ½ÅÒ Ò Å ½¼ ½Ë ½ÅÒž ÈÖ ¹ Ô Ø Ø ÓÒ × ÕÙ Ò Ó ×Ý×Ø Ñ Å ¹ Û Ö Ó × ÖÚ Ò Ø Ñ Ø Ö Ð Å ½Ë ½ÅÒž ÈÖ Ô Ø Ø ÓÒ Ó Ô ÖØ Ð × ÅÒ¾Ë Ò Ô ÖØ Ð × ÓÒØ Ò Ò ÅÒ Ò Ê Û Ö Ø ¹ Ø Ò ×ØÙ ÐÐÓÝמ À Ö Ò Ò Û Ö ÒÓØ Ó × ÖÚ Ò Ú ÖØ Ð ×× Ø Ö Û Ö ÒÓØ × Ò ÒØ Ö × × Ó Ö Ò ×× Ò Ø ÙÖ Ò ÒÒ Ð Ò ÙÔ ØÓ ½¼ ž
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Phase transformation in magnesium MgZnAl-based alloys
Kodetová, Veronika ; Vlach, Martin (advisor)
In the present work, there was analyzed thermal evolution of the phase transformation in the MgZnAl and MgZnAlCa alloys with different concentration of the Zn and Ca. The grains were occupied by the phase with quasicrystaline icosaedral structure in the as-cast alloys and after isochronal annealing up to 240 řC. The thermal measurements revealed two exothermic effects in the MgZnAl alloy and three exothermic effects in the MgZnAlCa alloy during linear heat treatment in the temperature range of 100 - 250 řC. In agreement to the thermal response, two and three stages of electrical resistivity decrease were observed in the same temperature range. The lower thermal changes, absolute resistivity changes and microhardness were observed in the alloy with Ca-addition and lower concentration of Zn.
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Phase transformation in magnesium MgZnAl-based alloys
Kodetová, Veronika ; Vlach, Martin (advisor)
In the present work, there was analyzed thermal evolution of the phase transformation in the MgZnAl and MgZnAlCa alloys with different concentration of the Zn and Ca. The grains were occupied by the phase with quasicrystaline icosaedral structure in the as-cast alloys and after isochronal annealing up to 240 řC. The thermal measurements revealed two exothermic effects in the MgZnAl alloy and three exothermic effects in the MgZnAlCa alloy during linear heat treatment in the temperature range of 100 - 250 řC. In agreement to the thermal response, two and three stages of electrical resistivity decrease were observed in the same temperature range. The lower thermal changes, absolute resistivity changes and microhardness were observed in the alloy with Ca-addition and lower concentration of Zn.
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determination of kinetic parameter of reactions using DSC
Kopecký, Jan ; Kouřil, Miloslav (referee) ; Jan, Vít (advisor)
The master thesis deals with DSC measurments a calculation of kinetic parameters. In the theoretical part, iron alotropy is briefly described, followed by a description of the DSC analysis itself. The thesis also includes division and derivation of isoconversional methods for calculating the activation energy. In the experimental part, a series of measurments is perfomed on pure iron prepared by Cold Spray method. In the paper the influence of deformation on the Curie temperature of the magnetic transformation in -Fe and transformation > is investigated. The activation energy is calculated for transformation > for different degrees of deformation. The degree of deformation is monitored by channeling contrast.
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Phase transformation in bio-compatible Mg-based alloys
Hornát, Bohumil ; Vlach, Martin (advisor) ; Mathis, Kristián (referee)
ÙÖÖ ÒØ Ñ Ø Ö Ð Ö × Ö × Ó Ò Ò ÑÔÖÓÚ Ò Ú ÓÖ Ó Ð ØÛ Ø Ñ ¹ Ò × ÙÑ ÐÐÓÝ Û Ú Û Ù× ×Ô ÐÐÝ Ò ØÖ Ò×ÔÓÖØ Ò Ù×ØÖÝ Ò Ñ ¹ Ò ž Å ¹Ê ¹Ë ¹ÅÒ × ÐÐÓÝ× Ò ÓÒ× Ö × ÔÖÓÑ × Ò Ñ Ø Ö Ð ÓÖ Ø × ÔÔÐ Ø ÓÒמ ÁÒ Ø ÔÖ × ÒØ ÛÓÖ ¸ Ø Ö Û × ×ØÙ Ø ÖÑ Ð ÚÓÐÙØ ÓÒ Ó Ø Ô × ØÖ Ò× ÓÖÑ Ø ÓÒ× Ò Å ¹Ê ¹Ë ¹ÅÒ × ÐÐÓÝ× Ý Ö ÒØ Ð × ÒÒ Ò ÐÓ¹ Ö Ñ ØÖÝ Ò Ñ ×ÙÖ Ò Ñ ÖÓ Ö Ò ×מ Ì Ø ÖÑ Ð Ö ×ÔÓÒ× × Ø Ö ÒØ Ø Ò Ö Ø × Û Ö Ó × ÖÚ Ò Ø Ø Ú Ø ÓÒ Ò Ö × Ó Ø ÔÖÓ ×× × Û Ö Ð ÙÐ Ø ž Ì Ø ÖÑ Ð Ö ×ÔÓÒ× × Û Ö ××Ó Ø Û Ø Ò Ú Ù Ð ÔÖ Ô Ø Ø ÓÒ ÓÖ ×ÓÐÚ ÒØ ÔÖÓ ×× × × ÓÒ ÓÑÔ Ö ×ÓÒ Û Ø Ð Ø Ö ØÙÖ ž ÈÖ Ô Ø Ø ÓÒ × ÕÙ Ò Ó ×Ý×Ø Ñ Å ¹ Û Ö Ó × ÖÚ Ò Ñ Ø Ö Ð× Å ½Ë ½ÅÒ Ò Å ½¼ ½Ë ½ÅÒž ÈÖ ¹ Ô Ø Ø ÓÒ × ÕÙ Ò Ó ×Ý×Ø Ñ Å ¹ Û Ö Ó × ÖÚ Ò Ø Ñ Ø Ö Ð Å ½Ë ½ÅÒž ÈÖ Ô Ø Ø ÓÒ Ó Ô ÖØ Ð × ÅÒ¾Ë Ò Ô ÖØ Ð × ÓÒØ Ò Ò ÅÒ Ò Ê Û Ö Ø ¹ Ø Ò ×ØÙ ÐÐÓÝמ À Ö Ò Ò Û Ö ÒÓØ Ó × ÖÚ Ò Ú ÖØ Ð ×× Ø Ö Û Ö ÒÓØ × Ò ÒØ Ö × × Ó Ö Ò ×× Ò Ø ÙÖ Ò ÒÒ Ð Ò ÙÔ ØÓ ½¼ ž
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