Novel material synthesis was investigated in this thesis to show two major promising ceramic material Fe-Si-O composites and Na3MnCO3PO4... Show moreNovel material synthesis was investigated in this thesis to show two major promising ceramic material Fe-Si-O composites and Na3MnCO3PO4 composite. Major processing factors in forming Fe2SiO4=SiO2 and Fe2O3=SiO2 powders via sol-gel synthesis followed by solid-state reactions are investigated. The results clearly indicate that the chemical compositions of the precursors, the ratio of the precursors, the nature of the catalyst used, and the gas atmosphere during solid-state reactions can all a ect the outcome of the reaction product(s). The formation of Fe2SiO4=SiO2 is enhanced by using the precursor iron(III) acetylacetonate as the Fe source with the precursor ratio of iron(III) acetylacetonate to tetraethylorthosilicatebeing 1:1 and the addition of formic acid. Otherwise, crystalline Fe and Fe3C are formed in place of Fe2SiO4. By altering the gas atmosphere during solid-state reactions from argon to oxygen, the reaction products change from Fe2SiO4=SiO2 to Fe2O3=SiO2. All of the observed phenomena can be rationalized via the degree of mixing of the Fe-O and Si-O domains at the molecular level in the gel network during sol-gel reactions and the presence of a reducing or oxidizing atmosphere during the solid-state reaction. Hydrothermal method was applied in synthesizing Na3MnCO3PO4 composite which was studied as a high energy density material for Na ion battery (NIBs). In order to improve electronic conductivity for NIBs battery, ball milling with graphite was introduced for the as-synthesized material. This thesis will investigate the roles played by the ionic conductivities and crystal structure changes introduced by high energy ball milling. Such a study has never been conducted before, and thus can o er guidelines to unlock a gateway to truly low cost Na3MnCO3PO4 cathode NIBs with superior performance. M.S. in Materials Engineering, May 2014 Show less
