Browsing by Author "Stull, John Leete"
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Item Magnetostriction of Magnetite(Alfred University. Faculty of Ceramic Engineering. Kazuo Inamori School of Engineering, 1954-02-01) Stull, John LeeteThe magnetostriction of Fe3O4 was measured, using the strain gauge technique. Two methods were used to measure the magnetostrictive behavior of single crystals and polycrystalline samples as a function of orientation and temperature. The measurements show that magnetostriction does not play an important part in causing a peak in initial permeability in magnetite near its low-temperature transition. Another conclusion is that magnetostriction measurements can be used for this type of material as a tool to detect changes in the direction of easy magnetization.Item Semiconductivity in Cadmium Telluride(Alfred University. Faculty of Ceramic Engineering. Kazuo Inamori School of Engineering, 1958-06) Stull, John LeeteConventional Hall coefficient and resistivity measurements were carried out in single crystals of CdTe, both "pure" and with added impurities, and in hot-pressed polycrystalline specimens. In most cases, the sign of the current carriers was consistent with the valence of the added impurity. Discrepancies in certain trivalent impurity crystals are explained on the basis of an excess of Cd vacancies. The mobilities for electrons averaged about 200 cm2/v sec, and those of holes about 40 cm2/v sec, both at room temperature. Anomalous changes in resistivity as a function of applied electric field and heat treatment in crystals containing both donors and acceptors were found and investigated. A rough model is developed which accounts for most of the effects observed.