Co-Fe Ferrite Composition for Stable High-Frequency Permeability
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Solution Overview
Problem
Conventional Co-based ferrite materials experience significant attenuation of real magnetic permeability and rise of imaginary permeability in high frequency bands, leading to high magnetic losses.
Innovation Solution
A ferrite sintered body composed of Co and Fe, with specific mole percentages and optionally including Zn, Ni, and Cu, is developed, with controlled average particle size and BET specific surface area, processed through pre-calcination, pulverization, and calcination to maintain stable magnetic permeability across high frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Co-based ferrite is used to maintain real magnetic permeability at MHz frequencies, then the real part of magnetic permeability hardly attenuates, but the imaginary part of magnetic permeability rises from around 0.2 GHz, causing large magnetic loss
Solution Approach 1:
The patent changes the compositional parameters by precisely controlling the CoO content (38-60 mol%) and Fe2O3 content (40-50 mol%), along with optional ZnO, NiO, and CuO additives. This parameter optimization resolves the contradiction by achieving both stable real magnetic permeability and suppressed imaginary part rise at high frequencies
Solution Approach 2:
The patent creates a composite ferrite system combining Co, Fe, and optional Zn, Ni, and Cu elements. This composite approach allows synergistic effects where the multi-element composition simultaneously maintains real permeability stability while controlling magnetic loss through the imaginary part suppression
2Reliability
If ferrite particle size is reduced to improve magnetic properties, then high frequency performance improves, but particle size control becomes more difficult and manufacturing precision is required
Solution Approach 1:
The patent applies preliminary action through pre-calcination treatment before final sintering. This preliminary thermal processing step prepares the ferrite particles with appropriate size and structure, making the subsequent sintering process more controllable and achieving the target particle size range (1.0-5.0 μm) with manageable manufacturing precision
Solution Approach 2:
The patent optimizes sintering parameters including temperature, holding time, and atmosphere to achieve controlled particle growth. By carefully adjusting these parameters, the patent achieves the balance between obtaining sufficiently small particles for high-frequency performance while maintaining controllable manufacturing precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses the attenuation of real magnetic permeability and rise of imaginary permeability, enhancing coercive force and maintaining suitable magnetic properties in high frequency bands, making it suitable for inductance elements.
Implementation Method 1
the real part of the magnetic permeability hardly attenuates in a high frequency band, but the imaginary part of the magnetic permeability rises from a frequency band lower than 1 GHz
Implementation Method 2
a ferrite sintered body comprising Co and Fe
Data Source
AI summary
A ferrite sintered body comprising Co and Fe, wherein the Co is contained in an amount of from 38 mol % to 60 mol % in terms of CoO, the Fe is contained in an amount of from 40 mol % to 50 mol % in terms of Fe2O3, and the sintered body has an average particle size of from 1.0 μm to 5.0 μm.