| This thesis describes the synthesis, structure, morphology, and magnetic property relations of electrodeposited magnetite. Thin film magnetite was synthesized on polycrystalline brass or Au/Cr/glass substrates using an aqueous electrodeposition technique. Magnetite formation in electrolytes (containing KCH3COO and Fe(SO4)2(NH 4)2) required temperatures between 60°C and 85°C, and deposition potentials between -0.300 V and 0.575 V or galvanostatic current densities between 50 muA/cm2 and 88 muA/cm2. Magnetite crystallites had an octahedral habit when grown from electrolytes with low acetate concentrations, and a more rounded morphology when grown from acetate-enriched electrolytes. Magnetic hysteresis studies show that magnetite grown with lower acetate concentrations displays monotonically increasing coercivity (100-300 Oe), and monotonically decreasing squareness (80-35%), with increasing overpotential. In contrast, magnetite grown from acetate-enriched electrolytes had a much lower squareness (∼25%) and coercivity (∼50 Oe). This evidence suggests that potential and electrolyte composition can be adjusted to change domain behaviour from pseudo-single domain type (for low overpotentials and low acetate concentrations) to multi-domain type (for either high overpotentials or high acetate concentration).;Magnetic hysteresis data also show that an exchange bias is present in samples containing both magnetite and iron oxide hydroxides. A preliminary study has shown that it is difficult to electrodeposit distinct bilayers of magnetite and the antiferromagnetic iron hydroxide goethite (alpha-FeOOH). |
