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The influence of the CO concentration in the gas phase on the distribution of carbon in Bridgman-grown, multicrystalline silicon is studied. The growth experiments were conducted in a high-vacuum induction furnace either under a CO enriched atmosphere or under CO free conditions. Furthermore, thermodynamic calculations in the system silicon/oxygen/carbon were done. In crystal growth under a CO enriched atmosphere a SiC-containing layer is formed on the top surface of the melt in agreement with the calculated phase diagram. In this case, the level of substitutional carbon in the cystal was found to be almost constant, whereas the axial carbon concentration in crystals grown under CO free conditions increases monotonously according to Scheil's law.

Verbrauchte nickelhaltige Nichtedelmetallkatalysatoren aus der chemischen Industrie, der Erdölraffination, der Lebensmittel-und Pharmaindustrie sind potenzielle Sekundärrohstoffe für das Recycling von Nickel. Im Rahmen der Forschungsarbeit wurde ein Badschmelzverfahren für nickelhaltige Katalysatoren entwickelt, die organische Reste der Fetthärtung sowie Erdölraffination enthalten. Bei diesem Verfahren wird Nickelstein gebildet und weitere Wertmetalle wie Molybdän und Wolfram werden in eine verwertbare Schlacke überführt. Der Energiegehalt der organischen Verbindungen wird für den Schmelzprozess genutzt. Damit wird eine erhebliche Energieeinsparung und Verringerung von CO 2 -Emissionen erreicht.Spent nickel-containing base metal catalysts from chemical industry, crude oil refining, food and pharmaceutical industry are potential secondary raw materials for the recycling of nickel. Therefore, a bath smelting technology was developed for nickel-containing catalysts with organic residues of fat hardening and crude oil refining. With this process nickel matte is produced and further valuable metals like molybdenum and tungsten are enriched in a recyclable slag. The high energy content of the organic components is used for the smelting process. Consequently a considerable saving of energy and reduction of CO 2 emissions would be reached.