M-Type Hexaferrite Particles for GHz Band Absorption
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Solution Overview
Problem
Conventional electromagnetic-wave-absorbing materials for vehicles in the GHz band suffer from limited absorption ability and reflection issues, which lead to adverse effects on other vehicle parts, and existing ferrite-based materials lose magnetic permeability at high frequencies, making them ineffective for high-frequency electromagnetic waves.
Innovation Solution
The development of M-type hexaferrite-based electromagnetic-wave-absorbing particles, mixed with a polymer resin and a permittivity-adjusting agent like graphite, which utilize a magnetic loss mechanism through spin vibration to absorb electromagnetic waves effectively across several to tens of GHz, with a composition such as Sr1-xRxFey-2zM2zO19 and Sr1-xRxFey-2zZnzTizO19, and the addition of a reaction accelerator to optimize absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional carbon-based powders and metal-based powders are mixed with polymer resin to absorb electromagnetic waves through conductive mechanism, then electromagnetic wave absorption is achieved, but absorption ability is limited and reflection occurs causing adverse effects on other parts
Solution Approach 1:
The patent changes the absorption mechanism from conductive loss to magnetic loss by using M-type hexaferrite particles. This parameter change in the loss mechanism enables effective absorption in GHz band while minimizing reflection, as magnetic loss through spin vibration does not cause the same reflection issues as conductive mechanisms.
Solution Approach 2:
The patent creates a composite material system combining M-type hexaferrite particles with polymer resin. This composite structure leverages the magnetic properties of ferrite for absorption while the polymer matrix provides structural support, achieving both effective absorption and reduced reflection.
2Loss of energy
If Mn-Zn-based ferrite and Ni-Zn-based ferrite are used as absorbing bodies, then magnetic loss mechanism is utilized, but magnetic permeability values are lost at high frequency GHz band making them ineffective
Solution Approach 1:
The patent modifies the ferrite composition to M-type hexaferrite structure with specific doping elements (Co, Ni, Zn, Mn, Cu) to change the magnetic resonance frequency parameter. This composition modification maintains high magnetic permeability at GHz frequencies by adjusting the crystal structure and magnetic anisotropy, unlike conventional Mn-Zn or Ni-Zn ferrites.
Solution Approach 2:
The patent applies local quality by doping specific elements at specific sites in the hexaferrite crystal structure. The empirical formula Sr1-xRxFey-2zM2zO19 shows localized substitution of elements (R = Ba, Ca, La; M = Zn, Ti, Zr) to optimize magnetic properties at different crystallographic positions, enabling frequency-specific absorption performance.
3Speed
If electromagnetic wave absorption materials are designed for GHz band, then high frequency absorption is achieved, but absorption mechanism must be fundamentally changed from dielectric or conductive loss to magnetic loss through spin vibration
Solution Approach 1:
The patent substitutes the conventional dielectric or conductive loss mechanism with a magnetic loss mechanism based on spin vibration. This mechanism substitution enables fundamental absorption in the GHz band by utilizing magnetic resonance of electron spins, which operates at higher frequencies than dielectric relaxation or conductive loss mechanisms.
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
These particles achieve maximum absorption in specific GHz bands, minimizing reflection and effectively blocking electromagnetic waves, thereby preventing interference with other vehicle components, and the use of a permittivity-adjusting agent allows for precise tuning of absorption frequencies.
Implementation Method 1
capable of absorbing electromagnetic waves through a magnetic loss mechanism caused by a spin vibration in the GHz band
Implementation Method 2
absorbing electromagnetic waves through a magnetic loss mechanism caused by a spin vibration in the GHz band
Implementation Method 3
addition of a permittivity-adjusting agent like graphite, allows for precise tuning of absorption frequencies
Data Source
AI summary
Electromagnetic-wave-absorbing particles for a GHz band are represented by the following [Empirical Formula 1] and include M-type hexaferrite as a major phase:Sr1-xRxFey-2zM2zOa, [Empirical Formula 1]where R is one or more selected from Ba, Ca, and La, M is one or more selected from Zn, Ti, and Zr, 0<x≤0.8, 8≤y≤14, 0<z≤1.5, and a is 19.