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

Abstract

High permeability and high permittivity are hard to be achieved simultaneously, either in single-phased materials or in composite materials, such as ferrite-ferroelectric ceramic composites and ferrite-metal percolative composites. In this work, ultra-low percolation threshold is achieved in NiZnCu ferrite-Ag cofired ceramics, which endows the composite with both high permeability and high permittivity by minimizing the negative effect of nonmagnetic conductive fillers on magnetic properties. The percolation threshold is controlled by the temperature matching between ferrite densification and Ag melting. A thin and long percolative net forms between large ferrite grains under a proper cofiring process, which brings a low percolation threshold of 1.21vol%, more than one order of magnitude lower than the theoretical value of 16vol%. Near the ultra-low threshold, the composite exhibits a high permeability of 585 and a high permittivity of 78.

Ni/Al2O3/epoxy high-k composites with ultralow nickel content towards high-performance dielectric applications

“…Therefore, various strategies have been developed to obtain high-k according to percolation theory in composite materials, such as ferroelectric/polymer composites, [12][13][14] binary or ternary metal (or carbon)/polymer composites, [15][16][17] metal (or carbon)/ ceramic composites, etc. [18][19][20][21] In these composites, a certain volume fraction (lower than but still near the percolation threshold) of metal, carbon or ferroelectric powders should be dispersed into the matrix to achieve excellent dielectric performance. However, the percolation thresholds of the composites are usually high, leading to high leakage conductance loss, eddy current loss and dielectric loss.…”

Improving BaTiO3 Energy Storage Characteristics by Doping Bi(Mg2/3Ta1/3)

“…To increase energy storage, it is necessary to have a high maximum polarization value, a low residual polarization value, and a high polarization and breakdown strength. Generally, the commonly used dielectric materials in capacitors include three types of dielectric materials: linear dielectric, ferroelectric, antiferroelectric, and relaxor ferroelectric [3]. Although linear dielectric materials have high breakdown field strength and low dielectric loss, due to their own material limitations, their storage capacity is relatively low, which limits their use [4].…”

Dispersion Characteristics of Spin-Electromagnetic Waves in Planar Multiferroic Structures with Coplanar Transmission Line

“…The first experimentally investigated devices based on the ferrite-ferroelectric structures were resonators [4]. After that, a great number of theoretical and experimental work in this area was carried out (see, e. g., [5][6][7][8] and references therein). As is seen from the literature, the multiferroic structures had a great success in development of the microwave devices.…”