|
|
Inverse-Heusler Mn2FeSi alloy prepared by powder metallurgy route
Životský, O. ; Skotnicová, K. ; Čegan, T. ; Juřica, J. ; Gembalová, L. ; Zažímal, František ; Jirásková, Yvonna ; Szurman, I.
The Mn2FeSi inverse-Heusler alloy was prepared by solid-state reactions using ball milling for 168 h in n hexane. Two milling procedures varying in the ball-to-powder ratio, namely 4:1 and 10:1, were used to follow \ntheir influence on alloy formation and its physical properties. In both cases no Heusler structure was obtained \ndirectly and therefore the subsequent annealing at 1223 K for 1.5 h in pure Ar was applied. The energy dispersive X-ray analysis resulted in the chemical composition about 49.0-49.9 at% Mn, 25.3-25.6 at% Fe, and \n24.8-25.4 at% Si, in a good agreement with nominal one. X-ray diffraction of both powders confirmed inverse Heusler XA structure of lattice parameters 0.5675 nm (4:1) and 0.5677 nm (10:1), only slightly higher as \ntheoretically obtained 0.560 nm. The presence of minor oxidation phases was also observed in the particle \nstructure of powders. Magnetic properties were analysed at low and room temperatures. Both alloys exhibit \nparamagnetic behaviour at room temperature confirmed by transmission Mössbauer spectroscopy \nmeasurements. Different magnetic behaviour of alloys is observed below 65 K.
|
|
|
Dielectric layers fabricated by material printing
Olejníková, Marie ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
This master‘s thesis deals with the use of the material printing method for fabrication of dielectric films. Final high- dielectric composite film consisted of BaTiO3 based inkjet-printed layer and spin-coated polyvinylpyrrolidone (PVP) layer. The effect of ball-milling on BaTiO3 suspension was studied by DLS a XRD methods. Printing formulation and parameters of inkjet printing were optimized with respect to the surface morphology of printed BaTiO3 films using contact profilometry method. Impedance analysis was used to determine the value of effective dielectric constant of the final dielectric composite film using thin film capacitor structure. Effective dielectric constant of composite dielectric film was 4,9 ± 0,4.
|
|
|
Photocatalytic layers of tungsten trioxide fabricated by material printing
Saňák, Tomáš ; Krystyník,, Pavel (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with milling of dispersed particles of WO3 using low-cost wet ball milling. Thin layers of WO3 were formed from them. These layers were characterized by profilometry, turbidity measurements, XRD and SEM. The photocatalytic activity was studied by the electrocatalytic properties of these layers. Profilometric measurements showed declining trends with milling time. XRD measurements confirmed the milling process and revealed a change in the crystalline phase during this process. Electrophotocatalytic measurements confirmed the photocatalytic activity of these layers and revealed its trends.
|
|
|
Dielectric layers fabricated by material printing
Olejníková, Marie ; Pekárková, Jana (referee) ; Dzik, Petr (advisor)
This master‘s thesis deals with the use of the material printing method for fabrication of dielectric films. Final high- dielectric composite film consisted of BaTiO3 based inkjet-printed layer and spin-coated polyvinylpyrrolidone (PVP) layer. The effect of ball-milling on BaTiO3 suspension was studied by DLS a XRD methods. Printing formulation and parameters of inkjet printing were optimized with respect to the surface morphology of printed BaTiO3 films using contact profilometry method. Impedance analysis was used to determine the value of effective dielectric constant of the final dielectric composite film using thin film capacitor structure. Effective dielectric constant of composite dielectric film was 4,9 ± 0,4.
|
|
|
Photocatalytic layers of tungsten trioxide fabricated by material printing
Saňák, Tomáš ; Krystyník,, Pavel (referee) ; Dzik, Petr (advisor)
This diploma thesis deals with milling of dispersed particles of WO3 using low-cost wet ball milling. Thin layers of WO3 were formed from them. These layers were characterized by profilometry, turbidity measurements, XRD and SEM. The photocatalytic activity was studied by the electrocatalytic properties of these layers. Profilometric measurements showed declining trends with milling time. XRD measurements confirmed the milling process and revealed a change in the crystalline phase during this process. Electrophotocatalytic measurements confirmed the photocatalytic activity of these layers and revealed its trends.
|
|
| |
|
|
Příprava a charakterizace struktur ZnO malých rozměrů
Grym, Jan ; Fernández, P. ; Piqueras, J.
ZnO low dimensional structures were prepared in order to study their unique electronic and optical properties. ZnO nanocrystals were obtained by ball milling of commercially available powders. This process was found to produce particles with sizes of tens to hundreds nanometers being composed of nanocrystals down to a few nanometers. ZnO micro and nanorods mainly of hexagonal shape as well as nanotubes and nanocombs were grown by vapor-solid method in a muffle furnace under the flow of high purity argon.
|
guest ::
