Berlin 2018 – wissenschaftliches Programm
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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 27: Postersession KFM
KFM 27.31: Poster
Donnerstag, 15. März 2018, 15:00–17:00, Poster E
Crystallisation of Bismuth in an Inert Atmosphere and Electrical Characterization of these Crystals — •Christian Düputell, Arne Ludwig, and Andreas D. Wieck — Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, D-44780 Bochum
The aim of this work is to validate diverse melting processes for the growing of bismuth crystals in different gas atmospheres (purity of used Bi: 99,99%). Therefore, melting in two different atmospheres has been performed; in air and in an inert atmosphere (argon). The methods were assessed in terms of characterisation of the grown crystals; for this purpose, the crystals were examined visually as well as electrically.
A particular advantage of an inert atmosphere is the prevention of oxidation of the growing crystals. This leads to the formation of purer, larger as well as more distinct bismuth crystals. The observation has been proven in two different ways: first by a visual characterisation of the crystals using a light microscope and second by Hall-Effect measurements of selected crystal samples. The results of the Hall-Effect measurements demonstrate the particular electrical and magnetic properties of the half-metal bismuth. At room temperature, the measured Hall-coefficient of crystals formed in the air is about −9,64(30) · 10−9 m3 C−1 in comparison to −9,42(16) · 10−7 m3 C−1 of crystals formed in an inert atmosphere.
Furthermore, a modification of the so called "Czochralski process" has been examined. So in future works it may be possible to improve the forming of bismuth single crystals without manual intervention.