Controlled Synthesis and Characterization of Magnetic Chalcospinels Nanocrystals

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dc.contributor Szulczewski, Gregory
dc.contributor Allred, Jared
dc.contributor Pan, Shanlin
dc.contributor Mankey, Gary
dc.contributor.advisor Gupta, Arunava Akbari Afkhami, Farhad
dc.contributor.other University of Alabama Tuscaloosa 2022-04-13T20:34:29Z 2022-04-13T20:34:29Z 2020
dc.identifier.other u0015_0000001_0004278
dc.identifier.other AkbariAfkhami_alatus_0004D_14271
dc.description Electronic Thesis or Dissertation en_US
dc.description.abstract Binary and ternary metal chalcogenides have become well-known materials among chemists, physicists, material scientists, and other researchers of the field, and they have attracted significant attention because of their novel chemical, magnetic, electronic, mechanical and optical properties. Among the metal chalcogenides, chromium-based chalcospinels ACr2X4 (A = Cu, Co, Fe, Cd, and Hg; X = S, Se, and Te) have gained significant attention because they are a notable class of magnetic materials such as semiconductors, magnetic metals, and insulators. In this work, a general overview of binary and ternary metal chalcogenides and their nanocrystals has been provided. We have also provided an overview of the wet-chemical colloidal methods as an important approach to size and shape-controlled synthesize of nanocrystals. We have also discussed the importance of metal doping reactions as a pathway to create previously unavailable multielemental materials for high-performance applications. In this set of studies, colloidal nanocrystals of chromium-based chalcospinels of CuCr2S4 and CuCr2Se4 have been synthesized via hot-injection and heat-up methods and were characterized using experimental methodology comprised of different microstructural and structural tests. The magnetic properties of these nanocrystals have also been studied. The next studied system was Cr-doped pyrite CuSe2 nanocrystals, eventually leading to the observation of significant enhancement of ferromagnetic moment by Cr-doping in octahedral sites of the pyrite structure. We performed a unique reaction in which nanocrystals of CrxCu1-xSe2 (x = 0.1-0.5) formed in the pyrite phase, which is not stable in bulk form. The host p-CuSe2 nanocubes did also undergo a degradation influenced by the reaction temperature and the doping of Cr3+ ions in the pyrite crystal structure. The Cr-doped nanocrystals of the pyrite phase were formed during the heat-up procedure and by increasing the reaction temperature transformed to CuCr2Se4 spinel nanocrystals. To the best of our knowledge, no cationic substitution of chromium for copper has been reported on pyrite CuSe2 systems so far, likely due to the significant size difference between chromium and copper. Therefore, the results of this work are a powerful approach for the design and fabrication of new multielemental materials that may not be stable in the bulk form. en_US
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated. en_US
dc.subject Chalcospinels
dc.subject Colloidal Synthesis
dc.subject Magnetic Materials
dc.subject Nanocrystals
dc.title Controlled Synthesis and Characterization of Magnetic Chalcospinels Nanocrystals en_US
dc.type thesis
dc.type text University of Alabama. Department of Chemistry and Biochemistry Analytical chemistry The University of Alabama doctoral Ph.D.

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