Synthesis and characterization of cobalt carbide based nanomaterials

Permanent magnets are used heavily for multiple applications in industry and current electronic technologies. However, the current permanent landscape is muddled by high cost of materials and insufficient magnetic or thermal properties. The primary focus of this dissertation work is the synthesis and optimization of a new permanent magnetic material, in the form of cobalt carbide nanomaterials. Initially, the synthetic process used to produce cobalt carbide nanomaterials is optimized for crystal phase control of stable cobalt carbide phases: Co3C and Co2C. Phase control was accomplished by varying the amount of strong base (KOH) added to the solvent used, tetraethylene glycol. Controlled manipulation of crystal phase allowed for an in-depth material and magnetic characterization to be undertaken. Co3C showed moderate magnetization (50 emu/g) and moderate coercivity values (1.5 kOe); Co 2C has low magnetization (15 emu/g) and low coercivity values (<1 kOe). Maximum coercivity values were recorded for mixtures of Co3C and Co2C as a result of intraparticle exchange interactions, which were confirmed experimentally. Switching to an oleylamine solvent system, phase control was achieved by varying the amount of tetraethylene or triethylene glycol to the system. However, the cobalt carbide particle morphology produced in both the tetraethylene glycol and oleylamine solvent systems was disadvantageous for processing of a permanent magnetic material.;Particle shape is an essential property for the development of viable permanent nanomagnets. Through the use of a cobalt fumarate complex as cobalt precursor, anisotropic cobalt carbide particles were formed. The anisotropic particles showed increased coercivity values when compared to earlier work. Also, the particles were comprised mainly of Co3C which led to high magnetization values. Investigations into the thermal decomposition of metal fumarate complexes under inert conditions revealed the fumarate ligand to be an effective carbon source, inducing the formation of the carbide phase. Lastly, in order to develop a new economically efficient and lower temperature synthesis for cobalt carbide materials, cobalt particles were processed using ethanol as an inexpensive solvent and reducing agent. The dissertation work being presented identifies necessary synthetic parameters and the fundamental magnetic properties intrinsic to cobalt carbide based nanomaterials. With further development, the interesting properties of cobalt carbide nanomaterials could lead to their implementation as an alternative to current magnetic materials used in industrial and commercial technologies.