Novel gold intermetallics with unique properties and bonding patterns

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dc.contributor.advisor Gordon Miller
dc.contributor.advisor Vitalij Pecharsky
dc.contributor.author Celania, Christopher
dc.contributor.department Materials Science and Engineering
dc.date 2018-08-11T19:16:11.000
dc.date.accessioned 2020-06-30T03:08:48Z
dc.date.available 2020-06-30T03:08:48Z
dc.date.copyright Sun Jan 01 00:00:00 UTC 2017
dc.date.embargo 2001-01-01
dc.date.issued 2017-01-01
dc.description.abstract <p>Gold has drawn the fascination of society through its brilliant color, malleability, and chemical resistance (hence its chemical nobility) since its discovery in ancient times. Today, this material is still highly coveted by consumers, but also for research within the scientific realm. The inclusion of gold in intermetallics often leads to notably unique structural and bonding features due to the pronounced relativistic effects on its 5d and 6s orbitals. Examples include quasicrystals and their approximants, unique gold clusters such as isolated Au7 clusters in A4Au7X2 (A = K, Rb, Cs; X = Ge, Sn), one dimensional columns such as Au zig-zag chains through Ca3Au3In, two dimensional slabs, such as in K2Au3, as well as three dimensional gold networks as observed in the interconnected trigonal bipyramids in KAu5, hexagonal diamond-like frameworks of Au tetrahedra in Au-rich Sr-Au-Al systems; and combinations of tetrahedral and fourfold planar Au atoms in Rb3Au7.</p> <p>In recent years, compounds in the gold-rich region of the R-Au-M system (R = rare earth, M = groups 13-15) have come under increased study. Many compounds within this system produce varied electronic and magnetic properties such as Pauli paramagnetism, superconductivity, thermoelectricity, etc. The shielded 4f electrons of the added rare earth elements provide the unpaired spins that lead to the wealth of interesting magnetic properties in their compounds. Metals and metalloids from groups 13-15 may then be used as a bank of available options useful in tuning the valence electron count of the R-Au system toward the formation of stable compounds.</p> <p>Exploration of the Gd-Au-Sb system by utilizing common solid state synthesis techniques frequently used for the production of intermetallics (such as arc melting and high-temperature furnaces for self-flux reactions with low melting components) has yielded rich outcomes. These results include the discovery of a new R3Au9Pn series of compounds (R = Y, Gd-Ho; Pn = Sb, Bi), which undergo interesting metamagnetic transitions, varied coloring schemes for Sb substitutions in the known R14Au51 compound forming R14(Au, M)51 (R = Y, La-Nd, Sm-Tb, Ho, Er, Yb, Lu; M = Al, Ga, Ge, In, Sn, Sb, Bi), and a complex tetragonal Gd-Au-Sb structure with significant Sb site mixing and positional disorder, as well as preliminary structure results of several other previously unreported compounds within the R-Au-M family.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/etd/16113/
dc.identifier.articleid 7120
dc.identifier.contextkey 11456899
dc.identifier.doi https://doi.org/10.31274/etd-180810-5742
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/16113
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/30296
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/etd/16113/Celania_iastate_0097E_16939.pdf|||Fri Jan 14 20:55:22 UTC 2022
dc.subject.disciplines Chemistry
dc.subject.disciplines Materials Science and Engineering
dc.subject.disciplines Mechanics of Materials
dc.subject.keywords Gold
dc.subject.keywords Intermetallics
dc.subject.keywords Rare earth elements
dc.title Novel gold intermetallics with unique properties and bonding patterns
dc.type article
dc.type.genre dissertation
dspace.entity.type Publication
relation.isOrgUnitOfPublication bf9f7e3e-25bd-44d3-b49c-ed98372dee5e
thesis.degree.discipline Materials Science and Engineering
thesis.degree.level dissertation
thesis.degree.name Doctor of Philosophy
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