Low-fired Y-type hexagonal ferrite for hyper frequency applications

Abstract

Y-type hexagonal ferrite with planar magnetocrystalline anisotropy has ultrahigh cut-off frequency up to GHz and excellent magnetic properties in hyper frequency range, so that is regarded as the most suitable material in correpongding inductive devices and components. The technology of low temperature cofired ceramics for surface-mounted multilayer chip components needs ferrite to be sintered well under 900 ℃ to avoid the melting and diffusion of Ag inner electrode during the cofiring process. To lower the sintering temperature of Y-type hexagonal ferrite, there are several methods, (1) using nano-sized starting powders, (2) substitution by low-melting elements, (3) adding sintering additives, and (4) introducing lattice defect. In this paper, the effects of different methods on the sintering behavior and the magnetic properties were discussed in detail.

Modification of the Magnetic Properties of Co₂Y Hexaferrites by Divalent and Trivalent Metal Substitutions

“…Magnetic materials are widely used as essential components for a large variety of industrial and technological applications including, and not limited to, automotive industry, consumer electronic, data storage and processing, and next generation microwave (MW) devices [1][2][3][4][5][6][7][8]. Ferrites with a hexagonal structure (hexaferrites) were discovered in 1950s [9], and extensive research work involving the fabrication and control of the physical properties of these ferrites demonstrated their feasibility of replacing other ferrites and magnetic materials in a large variety of applications [10][11][12].…”

Ultra-low percolation threshold in ferrite-metal cofired ceramics brings both high permeability and high permittivity

“…Introducing nonmagnetic Ag in the soft magnetic ferrite matrix will interrupt the magnetic lines of force and produces the demagnetizing field, which can be regarded as an increase of equivalent magnetocrystalline anisotropy. The effects of magnetocrystalline anisotropy K 1 and saturation magnetization M s on the permeability follow 24 , Since the induced field around metal inclusions weakens rapidly with distance, the thin percolation net can minimize the negative effect on magnetic property. The NCZ1-Ag composite has a high permeability of 585 near the f c , about 55% of pure ferrite's permeability.…”

Magnetic anisotropy of Y-type ferrites: Role of the local lattice structure

“…The MA energy of Fe 3 + is low owing to the closed shell structure of the electron configuration 3d 5 for Fe 3 + , as in an M-type ferrite [20,22]. The average MA energy gives a uniaxial MA K u , which is 0.068 and 0.029 MJ m −3 for Fe 3 + in a Co 2 Y and Zn 2 Y lattice, respectively.…”

“…W-type ferrites also exhibit uniaxial MA; however, they have not yet applied to commercial use because of complex fabrication process for permanent magnets. Both Y-and Z-type ferrites are known as candidate materials for applications to high-frequency devices in MHz to GHz range [4][5][6][7][8][9].…”