Magnetic and structural properties of M-type barium hexaferrite prepared by co-precipitation

Stoichiometric and single-phase barium hexaferrite (BaM) has been synthesized by co-precipitation and an additional solid state preparative method using high-purity nitrates, oxides and carbonates of iron (III), barium (II) and ammonium hydroxide. The isochronally and isothermally measured permeability and magnetic loss tangents over 1MHz–1GHz in frequency remained moderately constant until a sintering temperature of 1300 1C where relative permeability of 1.3 and loss tangent of 0.06 at 1GHz, indicate highfrequency magnetic characteristics for BaM. TGA/DTA studies showed the hexaferrite formation temperature was found to be 1050 1C. The apparent densities before and after each firing cycle showed a monotonic increase. X-ray diffraction studies established the presence of a single phase with the theoretical space group P63/mmc, and computed cell parameters of a 1⁄4 b 1⁄4 5.895 Å and c 1⁄4 23.199 Å. The samples exhibited a Curie point (Tc) of 452 1C and displayed ferromagnetic resonance characteristics centred on a frequency of 500MHz. r 2006 Elsevier B.V. All rights reserved.