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METALIC NANOPARTICLES AND NANOSTRUCTURES
Nohavica, Dušan
A brief overview of the field of metallic nanoparticles and nanocrystalline materials preparation and their properties is presented. Dependence of the chemical potential on surface curvature is important for particles solubility in the melt, vapour pressure of liquids as a function of droplet radius, Ostwald ripening and sintering of the individual particles. Melting point and lattice constant depends on the radius of nanoparticles as well. The major processing for nanocrystalline materials production includes chemical reaction, vapour condensation, electrodeposition, ball grinding, SPD etc.
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ZnO NANOPARTICLES AND THEIR APPLICATIONS – NEW ACHIEVMENTS
Nohavica, Dušan ; Gladkov, Petar
The advantages of ZnO are a low price, good gas sensing properties, photocatalytic activity, antibacterial activity, possibility to prepare structures with interesting optical properties, like photonic crystals, catalytic materials etc. In our laboratory the special research type of MOCVD apparatus has been developed. In the study we have investigated the influence of the growth rate on the morphology of ZnO deposited on Si (100), GaP (111) as well as nanoporous GaP. The same apparatus has been used for ZnO nanoparticles preparation with the diameter of individual nanoparticles of about 25 nm.
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Respiratory and cardiovascular health effects of nanoparticles
Nohavica, Dušan
Numerous combustion related and natural sources generate airborne ultra fine particulate matter (<100 nm). Several epidemiological studies have found adverse respiratory and cardiovascular health effects in susceptible parts of the population to be associated with these particles. Published clinical studies with 10-50 μg/m3 ultra fine elemental carbon particles as surrogates for ambient particles did induce cardiovascular effects in healthy adults.
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Epitaxní růst z kapalné fáze
Nohavica, Dušan
Poměrně rozsáhlá přednáška shrnuje základní aspekty přípravy epitaxních vrstev z kapalné fáze (LPE), s důrazem ne deposici polovodičů. Jsou uvedeny způsoby dosažení maximální reprodukovatelnosti růstového procesu a účinnosti deposice. Důraz je rovněž kladen na rozbor mechanizmů tvorby dislokací v epitaxních vrstvách.
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Asymetrie krystalografických pórů v polovodičích A.sup.3./sup. B.sup.5./sup
Nohavica, Dušan ; Gladkov, Petar ; Jarchovský, Zdeněk
V příspěvku je dokumentována naprostá neekvivalence rovin (011) z hlediska vytváření porů v InP a některých dalších sloučeninách A.sup.3./sup. B.sup.5./sup. . V rovině (01-1) existují tři druhy krystalograficky orientovaných porů s různou orientací. V rovině kolmé, (011) existují pouze trojúhelnikové průsečíky porů s touto rovinou. Tepelným zpracováním InP destiček jsou pory konvertovány do sférických dutin, jejichž laterálním zárustem se daří snižovat hustotu defektů prorůstajících z podložky.
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Surface to bulk vacancy conversion in GaAs - discussion of the problem
Nohavica, Dušan ; Krier, A.
In the contribution the growth condition influence in MOVPE, MBE and ALE on the surface vacancies conversion to the bulk one was discussed. We adopted Van Vechten's concept supposing comparison of the reconstruction velocity and growth rate as leading parameters of the conversion. We try to consider reaction kinetics in Farrell's et al. surface vacancies fade away mechanisms during MBE growth on the reconstructed surfaces.
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