Core-Shell Magnetic Material High-Frequency Permeability
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Solution Overview
Problem
Current magnetic materials fail to effectively control magnetic permeability (μ′ and μ″) at high frequencies, leading to issues such as increased transmission loss and thermal instability in high-frequency applications like antenna devices and electromagnetic wave absorbers, particularly in the GHz band.
Innovation Solution
A core-shell magnetic material is developed, comprising magnetic metal particles coated with an oxide layer and additional oxide particles, where the magnetic metal particles contain Fe, Co, or Ni, and nonmagnetic metals like Al or Si, with carbon or nitrogen, and oxide particles with a higher nonmagnetic metal/magnetic metal atomic ratio, enhancing magnetic permeability and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ferrite or amorphous alloy magnetic materials are used for high-frequency applications (1 MHz to 10 MHz), then high magnetic permeability real part (μ′) and low loss (low μ′′) are achieved, but magnetic permeability drops significantly in higher frequency ranges (10 MHz or higher)
Solution Approach 1:
The magnetic material is segmented into fine particles with average diameter of 0.1 μm to 10 μm, which improves high-frequency magnetic permeability by reducing eddy current losses and enhancing domain wall resonance characteristics
Solution Approach 2:
The invention uses composite magnetic materials combining ferrite and amorphous alloy phases, where ferrite provides high-frequency stability and amorphous alloy contributes to high magnetic permeability, achieving broad bandwidth performance from 1 MHz to GHz range
2Reliability
If thin film technique (sputtering or plating) is used to manufacture inductance elements, then excellent high-frequency characteristics are achieved, but large equipment is required, precise film thickness control is needed, and thermal stability at high temperature and high moisture is insufficient
Solution Approach 1:
The magnetic particles are coated with oxide layers through self-oxidation or controlled oxidation processes, eliminating the need for complex vacuum deposition equipment while achieving protective and functional coatings
Solution Approach 2:
The invention changes the manufacturing approach from precise thin film deposition to sintering of composite particles with controlled composition and size distribution, achieving high-frequency performance through particle physics rather than film thickness control
3Volume of moving object
If dielectric ceramics are used for antenna miniaturization, then space can be reduced, but dielectric loss increases causing large transmission loss and reduced transmission/reception sensitivity
Solution Approach 1:
The invention uses composite magnetic materials with ferrite and amorphous alloy phases that provide both miniaturization capability through high permeability and low loss characteristics, overcoming the high dielectric loss of ceramic materials
Solution Approach 2:
The invention changes the material parameter from dielectric constant to magnetic permeability for miniaturization, using high-μ magnetic materials instead of high-κ dielectric materials, thereby achieving size reduction without the associated dielectric losses
4Volume of moving object
If the antenna is miniaturized to reduce space, then transmission loss becomes more conspicuous and thermal stability deteriorates
Solution Approach 1:
The composite structure of ferrite particles coated with amorphous alloy provides thermal stability through the protective coating while maintaining miniaturization benefits, as the coating prevents oxidation and degradation at elevated temperatures
Solution Approach 2:
The segmented particle structure with core-shell configuration allows the core to provide magnetic properties for miniaturization while the shell provides thermal protection, enabling both small size and high thermal stability
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 core-shell magnetic material achieves high magnetic permeability with low loss, improved thermal stability, and broadened resonance frequency bands, suitable for high-frequency applications like antennas and electromagnetic wave absorbers.
Implementation Method 1
an oxide coating layer for coating surface of at least a part of the magnetic metal particles
Implementation Method 2
the oxide coating layer being made of an oxide containing at least one nonmagnetic metal contained in the magnetic metal particle
Implementation Method 3
the magnetic metal particle containing at least one magnetic metal selected from the group of Fe, Co, and Ni
Implementation Method 4
controlling μ′ and μ″ at high frequencies
Implementation Method 5
at least one nonmagnetic metal selected from the group of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, a rare-earth element, Ba, and Sr
Implementation Method 6
improved thermal stability
Data Source
AI summary
The present invention provides a core-shell magnetic material having an excellent characteristic in a high frequency band, particularly, in a GHz band. The core-shell magnetic material includes: core-shell magnetic particles including magnetic metal particles and an oxide coating layer, the magnetic metal particle containing magnetic metal selected from the group of Fe, Co, and Ni, nonmagnetic metal selected from the group of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, a rare-earth element, Ba, and Sr, and an element selected from carbon and nitrogen, and the oxide coating layer being made of an oxide containing at least one nonmagnetic metal as one of the components of the magnetic metal particle; and oxide particles existing at least a part between the magnetic metal particles and containing nonmagnetic metal selected from the group of Mg, Al, Si, Ca, Zr, Ti, Hf, Zn, Mn, a rare-earth element, Ba, and Sr, and in which nonmagnetic metal/magnetic metal (atomic ratio) in the particles is higher than that in the oxide coating layer.