Synthesis of nanoscale materials has been the focus of inorganic chemistry since the late twentieth century. Fascination with nanoscale materials originates from their properties that can be significantly different than their bulk counterparts. Single metal nanoparticles and binary semiconductors are probably the most studied nanomaterials. Synthesis of ternary nanomaterials has seen rapid growth during the past decade in both versatility of methods and number of materials produced. Study of these materials on nanoscale is important due to their potential impact on current technologies. Nanoscale ternary oxides are particularly interesting materials due to the range of interesting electronic, magnetic, catalytic and optical properties their bulk counterparts possess. Alkalide reduction is a low temperature solution phase synthesis method capable of producing wide range of single element nanomaterials, binary and ternary nanoparticles.
Alkalides are salts of alkali metal cations, complexed by crown ethers or cryptands, charge balanced by alkali metal anions. Upon dissolution in ethers, solvated alkali anions are formed. Alkali anions are one of the most powerful reducing agents in any given solvent, outdone only by solvated electron. Alkalide reduction of metal salts results in the formation of metal colloids consisting of nanoscale particles (∼ 3-10 nm). Variation of alkalide salt to metal cation ratio can result in nanoscale materials with different structures, thus enabling access to metastable phases that are not easily accessible by other synthesis methods. Expanding the range of metal cations reduced by alkalides has been one of the goals of this thesis. Co-reduction of two metal salts can result in binary nanoscale alloys that can lead to ternary (BaTiO 3) or quaternary (K0.5W0.5Nb0.5O 3) nanomaterials. Nanorod morphology of ternary oxides can be favored by high heating rates of alkalide reduction products. Here we present synthesis by alkalide reduction and characterization of several ternary nano-oxides such as tungsten bronzes, fluorescent terbium doped yttria, potassium tantalates, potassium niobates, and alkali earth titanates.
|Advisor:||Wagner, Michael J.|
|Commitee:||Cahill, Cristopher L., Miller, Houston J., Reeves, Mark E., Sadtchenko, Vladislav|
|School:||The George Washington University|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 70/12, Dissertation Abstracts International|
|Subjects:||Inorganic chemistry, Nanoscience|
|Keywords:||Alkalide reduction, Nanomaterials, Nanorods, Ternary oxides|
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