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Silver catalysed nanoscale silicon etching in water vapour
Křížek, Filip ; Pikna, Peter ; Fejfar, Antonín
N+-doped silicon substrates were etched by water vapour under the silver nanoparticles acting as a catalyst. Thin silver layer was deposited on two silicon wafers, where one of them was thermally annealed in nitrogen to create silver nanoparticles. Subsequently, both samples were annealed in water vapour and afterwards analysed by Scanning Electron Microscope. The images have shown that the annealed silver nanoparticles burrowed into the silicon substrate in the case of both samples. This new method of silicon etching introduces an alternative way of manufacturing nanohole arrays in silicon substrates.\n
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IR Laser CVD OF Nanodisperse Ge-Si-Sn Alloys Obtained by Dielectric Breakdown of GeH4/SiH4/SnH4 Mixtures
Křenek, Tomáš ; Bezdička, Petr ; Murafa, Nataliya ; Šubrt, Jan ; Pola, Josef
Nowadays, great attention is devoted to Ge-Si-Sn ternary system, because Si1-x-yGexSny provides the potential of band gap engineering and tuning of the optical properties. IR laser irradiation of equimolar gaseous GeH4 + SiH4 + SnH4 + Ar mixture results in simultaneous decomposition of all three compounds and it allows deposition of nanostructured solid film. Analysis of the films by FTIR and Raman spectroscopy, X-ray diffraction analysis and electron microscopy revealed crystalline nanobodies of pure beta-Sn and crystalline nanoobjects of Ge1-x-ySixSny embedded in an amorphous metastable Ge-Si-Sn alloy. This process allows co-decomposition of all silicon, germanium and tin hydrides which is caused by combination of infrared multiple photon dissociation of absorbing silane and currently proceeding LIDB. This is followed by intermixing/clustering of extruded metal atoms in the gas phase.
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Influence of inhaled manganese oxides nanoparticles on mass of internal organs in mice
Zeman, T. ; Dočekal, Bohumil ; Mikuška, Pavel ; Buchtová, Marcela ; Míšek, Ivan ; Šerý, Omar ; Večeřa, Zbyněk
Results of the statistical analysis of a long-term inhalation experiment on laboratory mice are presented. During 17 weeks of the experiment, the experimental group was exposed to inhaled manganese oxides nanoparticles. Manganese oxides (MnO center dot Mn2O3) nanoparticles (MnONPs) were synthesized continuously via aerosol route in a hot wall tube flow reactor using a thermal decomposition of metal organic precursor manganese(II) acetylacetonate in the flow tube reactor (in vertical position) at temperature 750 degrees C in the presence of 30 vol% of oxygen. The concentration of produced MnONPs at the reactor output was in the range 1-3 x 10(7) particles/cm(3) and the size of generated nanoparticles MnO center dot Mn2O3 was in the range 7-50 nm. Before entering the inhalation chamber, MnONPs in the mixture of N-2, O-2 and air (at total flow rate of 3 L/min) were further diluted using filtrated humidified air (20 L/min) at temperature 21 degrees C resulting in the MnONPs concentration 2 x 10(6) particles/cm(3). At regular time intervals the mass of selected internal organs of mice from both experimental and control group was assessed. It has been proven that inhaled nanoparticles are able to influence the mass of internal organs of mice. Statistically significantly lower mass of kidneys, liver and spleen and higher mass of pancreas have been found in the experimental group compared to the control group.
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Generation of TiO2 Nanoparticles for Follow-Up Inhalation Experiments with Laboratory Animals
Moravec, Pavel ; Schwarz, Jaroslav ; Vodička, Petr ; Koštejn, Martin
A method of TiO2 nanoparticle generation appropriate for follow-up long lasting inhalation experiments with laboratory animals was tested. Nanoparticles were synthesized in an externally heated tube reactor using titanium tetraisopropoxide as a precursor. Total 264 hours of particle generation in four experimental campaigns was performed with one batch of precursor without observable decrease of precursor volatility. Particle production was studied in wide range of experimental conditions such as reactor temperature, reactor flow rate and precursor vapor pressure by pyrolysis, using nitrogen as a carrier gas, and also in oxidizing atmosphere (10 vol. % of oxygen in the reaction mixture). Particle characteristics were investigated by scanning/transmission electron microscopy, energy dispersive spectroscopy, inductively coupled plasma optical emission spectrometry, elemental and organic carbon analyzer, X-ray diffraction and X-ray photoelectron spectrometry. As a result, particle production with number concentration high above 1.0 x 10(7) #/cm(3) and with primary particle size well below 50 nm can be easily achieved in most of investigated experimental conditions. Particles are free of elemental carbon, content of organic carbon is less than 10 weight %, detected crystalline phase is typically anatase, Ti is present in bonds Ti-O (TiO2) and total Ti concentration recalculated on TiO2 is approximately 80 mass %.
Plný tet: SKMBT_C22015041615090 -  PDF
Plný text: content.csg - PDF
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