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Recovery of Waste Semiconductors for CVD Precursors.
Bumba, Jakub ; Dytrych, Pavel ; Fajgar, Radek ; Dřínek, Vladislav
The newly patented method for regeneration of ultrapure silicon and germanium via magnesium silicide and magnesium germanide from waste photovoltaic (PV) cells, broken germanium lenses and waste magnesium chips was utilized to obtain chemical vapour deposition (CVD) precursors for application in electronics, optics or nanoparticles synthesis. Magnesium silicide and germanide were prepared directly by thermal synthesis from waste materials in optimized tube reactor at 400°C and 5 Pa. X-Ray Diffraction (XRD) confirmed 97.9% respective 95% purity of products. The presence of silicon and germanium hydrides (CVD precursors) prepared by acid hydrolysis in the second step of the process was verified by Gas Chromatography–Mass Spectroscopy (GC/MS) and Fourier Transform Infrared Spectroscopy (FTIR). The crude, unrefined mixture of silicon hydrides served as raw material for CVD experiment at different substrates. SEM images confirmed occurrence of various micro and nano particles which could be used in electronics, optics and catalysis.
Plný tet: SKMBT_C22019011614381 -  PDF
Plný text: content.csg - PDF
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Non-Thermal Crystallization of TiO2 Thin Films using Supercritical Carbon Dioxide Modified by Ethanol-Water Mixture.
Sajfrtová, Marie ; Cerhová, Marie ; Jandová, Věra ; Dřínek, Vladislav ; Matějová, L. ; Daniš, S.
In this work, the scCO2 modified by mixture of water and ethanol was used for a preparation of crystalline and pure nanostructured TiO2 thin films in one step processing. All the experiments were performed over precursor titania thin films prepared by reverse micelles assisted sol-gel method, using hardly removable nonionic surfactant Triton X-114, however, forming uniform nano-domains. The effect of temperature (40-150 °C), pressure (10-30 MPa), modifier composition \n(20, 50 and 80 % w/w of water in ethanol) and concentration inscCO2 (5-15 wt. %) and consumed amount of solvent (50-200 g) on microstructure and purity\nof TiO2 thin films was thoroughly studied by means of Raman spectroscopy, X-ray diffraction, and contact angle measurements.
Plný tet: SKMBT_C22018100509361 - PDF
Plný text: content.csg - PDF
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