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Synthesis and characterization of rare earth ceramic nanomaterials
Since the preparation of the first stone tools, ceramic materials have been utilized in many important technological advances. The development of synthetic methods to prepare ceramic nanomaterials has created the possibility for the preparation of materials with previously unobserved properties. In this dissertation, the synthesis of four rare earth nanomaterials and the application of one of the materials are described. The use of the rare earth elements is found to produce nanomaterials with desirable electronic and catalytic properties. The first three materials described in this dissertation are classified as non-oxide ceramic materials. These materials are synthesized using low pressure chemical vapor deposition (LPCVD). The synthesis of erbium tetraboride (ErB4) and erbium hexaboride (ErB6) by a palladium nanoparticle-assisted synthetic technique is described in detail. The existence of ErB6, which had previously been questioned, is verified using techniques capable of characterizing nanostructures which were not available to previous researchers. The synthesis of gadolinium nitride (GdN) thin films by LPCVD is also described. The electronic band gap of this material is characterized for the first time using a combined ultraviolet photoelectron spectroscopy (UPS) and inverse photoemission spectroscopy (IPES) technique. The synthesis and application of an oxide ceramic catalyst, fluorite-structured cerium oxide (CeO2-x, 0 ≤ x ≤ 0.5), is described. The development of a microwave-based technique for the synthesis of cerium oxide nanorods which provides reaction temperature tunable aspect ratios from ~6:1 to 40:1 and lengths from <51 nm to>1.7 &mgr;m is reported. This control was achieved without the use of additives which are typically required. The synthesis of hybrid phosphotungstic acid (PWA)-cerium oxide catalysts and their application towards cellobiose hydrolysis is also described. The hybrid material exhibits a synergistic effect on the conversion of cellobiose to glucose and mannose. The role of leached cerium ions in mannose production is elucidated using 13C nuclear magnetic resonance (NMR) spectroscopy. As a comparison, PWA-titania and PWA-silica nanomaterials are also investigated for their ability to convert cellobiose to monosaccharides.
Gernhart, Zane Charles, "Synthesis and characterization of rare earth ceramic nanomaterials" (2015). ETD collection for University of Nebraska - Lincoln. AAI3689918.