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Preparation and Study of a Rare Ternary Insulating Magnet

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Author: Wallin, Thomas J.
Advisor: DeFotis, Gary C.
Committee Members: Orwoll, Robert A.; Lukaszew, R. A. (Rosa Alejandra); Starnes, W.H.
Issued Date: 2010-05-14
Subjects: Magnetism
Antiferromagnetism
Ferromagnetism
Paramagnetism
Magnetic Phase Diagram
Magnetic Susceptibility
URI: http://hdl.handle.net/10288/2027
Description: Just previously in the advisor's laboratory, study of the magnetic properties of Co1-xMnx-yNiyCl2∙2H2O was initiated. Based on that work, it was clear that several additional compositions at least need to be prepared and measured in order to (a) complete the survey of two-dimensional composition space, and (b) accumulate enough information on the global behavior of the material as a function of composition to enable a reliable interpretation of the measured properties to be made. This mixed magnetic system is only the second ternary mixed magnet to be examined from this phase transition perspective. The pure components and binary mixtures of this system (Co/Mn/NiCl2∙2H2O) had been previously studied in this laboratory. However, the theory for ternary systems is far less developed than for the binary systems. As such, there is a very real possibility of uncovering qualitatively new phenomena in our study. Six new compositions, differing significantly from the previous seven, were prepared, characterized, and measured in the present work. The procedure was to measure the magnetic susceptibility as a function of temperature, between 1.5 and 300K; analyze the high temperature paramagnetic properties with appropriate basic theory; examine the data at low temperatures for signs of transitions; measure magnetization isotherms to look for indication of field-induced transitions and hysteresis; and also look for signs of the time dependence and associated fundamental irreversibility in any of the foregoing properties. Analysis of the data yields the beginnings of a magnetic phase diagram, that is a plot of ordering temperature versus the two composition variables, T(x,y). It is the second such plot ever determined and published.
Degree: Bachelors of Science in Chemistry


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