| Results pertaining to the effects of microstructural defects on the coercivity of polycrystalline and electrodeposited microcrystalline and nanocrystalline nickel are presented. Particular emphasis in this study was on the influence of grain size, sulfur and carbon impurities, and operating frequency on the coercivity of these materials as determined by a magnetic hysterisgraph.; For nanocrystalline nickel, it was found that the coercivity decreased by ∼60% when the grain size was reduced from 45 nm to 17 nm. On the other hand, for polycrystalline nickel, the coercivity decreased ∼80% as the grain size was increased from 11 μm to 75 μm after annealing in an argon atmosphere. While coercivity changed with the sulfur content in the electrodeposits it was found that grain size had a much stronger effect than the impurities. Frequency had a pronounced effect on the coercivity of polycrystalline nickel samples. However for the nanocrystalline counterparts, coercivity was relatively independent of frequency in the 1–400 Hz range. |
