Magnetic and electromagnetic properties of RuZn and RuCo substituted BaFe12O19

Abstract

Polycrystalline samples of M-type hexaferrites BaFe12-2xRuxZnxO19 and BaFe12-2xRuxCoxO19 with 0≤x≤0.45 have been prepared by a classical sintering method. The evolutions with x of the cell parameters, the saturation magnetization and the magnetic transition temperature have been measured; in this range of small doping ratios, saturation magnetization and Curie temperature of substituted hexaferrites remain close to those of the undoped BaFe12O19. X-ray diffraction measurements on oriented powders show that a change of magnetocrystalline anisotropy from axial to planar occurs in both cases for a small substituting ratio xc=0.375. Microwave electromagnetic characteristics have been studied on the ceramic samples from 0.1 to 10GHz. The behaviour of the magnetic losses (μ″) corroborates the anisotropy change when doping; a convolution of the dissipation mechanisms (domain wall motions and gyromagnetism) is obtained for xc. The level of the magnetic losses is discussed in relation with others substituted Ba-hexaferrites. © 2002 Elsevier Science B.V. All rights reserved.