Structural, IR, and magnetic studies of annealed li-ferrite nanoparticles

Abstract

Nanoparticles of spinel Li-ferrite, Li 0.5 Fe 2.5 O 4 , were prepared by sol-gel autocombustion technique and annealed at different temperatures (T a = 673, 873, and 1073 K), i.e., at relatively low annealing temperatures to control the crystallite size. The saturation magnetization (M s ) increased, and the surface area decreased by increasing the crystallite size, while Curie temperature (T C ) remained almost constant. The critical crystallite size (D s ), 74 nm, which corresponds to a maximum value of coercivity was determined. Samples with crystallite sizes ≤ D s had low initial permeability μ i , while the other samples lying in the multidomain region showed very high μ i values indicating a reversible domain wall displacement mechanism. Hence, the crystallite size plays an important role in changing the physical and magnetic properties of Li-ferrite. © 2013 ASM International.