Effects of zinc loss on the magnetic properties of plasma-sprayed MnZn ferrites

Energy dispersive X-ray analysis performed on plasma-sprayed MnZn ferrite (MZF) single 'splats' shows a variation in zinc content within splats of different sizes after the spray process, even though the powder has the same starting stoichiometry. A simple model indicates that smaller particles have a higher zinc evaporation rate during the in-flight time. However, the significant decrease of zinc in smaller ferrite particles is mainly attributed to their large surface-to-volume ratio. Compositional differences due to a random cation distribution condition results in magnetic property variations among MZF splats. The coating inhomogeneity due to zinc loss increases the coercivity of the plasma-sprayed MnZn ferrites. The magnetic properties of the MnZn ferrites can be improved through long-range (diffusion) and short-range (ordering) cation redistribution upon low temperature annealing.