Hexagonal Ferrite Powder Composition for Peak Frequency Tuning

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Solution Overview

Problem

Existing radio wave absorbers using magnetoplumbite-type hexagonal ferrites face challenges in adjusting the peak frequency to target frequency bands, limiting their effectiveness in diverse radio wave applications.

Innovation Solution

A method involving the adjustment of the pH of an aqueous solution containing Fe, Al, and metal salts to produce a magnetoplumbite-type hexagonal ferrite powder, allowing control over the Al to Fe ratio and thus the peak frequency, enabling the production of a radio wave absorber with a desired peak frequency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetoplumbite-type hexagonal ferrite is used as a radio wave absorber, then radio wave absorption performance is improved, but the peak frequency cannot be adjusted to target frequency bands

Engineering Contradiction:
Improveradio wave absorption performanceVSAvoidpeak frequency adjustment capability
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies parameter changes by controlling the pH value during the precipitation process to adjust the Al/Fe ratio in the magnetoplumbite-type hexagonal ferrite. By changing the pH parameter from conventional ranges (6-8) to a higher range (8-10), the invention achieves control over the peak frequency of the radio wave absorber, enabling it to be adjusted to target frequency bands while maintaining excellent radio wave absorption performance.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If conventional precipitation methods are used, then production process is simple, but the Al to Fe ratio cannot be controlled to achieve desired peak frequency

Engineering Contradiction:
Improveproduction process simplicityVSAvoidAl to Fe ratio control
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention maintains the simplicity of the conventional precipitation method while improving manufacturing precision by optimizing the pH parameter. By adjusting the pH to a specific range (8-10) during precipitation, the process achieves precise control over the Al to Fe ratio in the final ferrite product, enabling targeted peak frequency adjustment without complicating the overall production流程.

Inventive Principle:
Principle #35Parameter changes

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 method effectively produces a radio wave absorber with enhanced radio wave absorption performance across a wide frequency band, specifically achieving peak frequencies in the range of 70 GHz to 90 GHz.

Implementation Method 1

adjustment of the pH of an aqueous solution containing Fe, Al, and metal salts

Methodology Applied
Scientific EffectpH adjustment:

Implementation Method 2

adjustment of the pH of an aqueous solution containing Fe, Al, and metal salts to produce a magnetoplumbite-type hexagonal ferrite powder

Methodology Applied
Scientific EffectPrecipitation: Precipitation

Implementation Method 3

A radio wave incident to the radio wave absorber including a magnetic material generates a magnetic field in the magnetic material

Methodology Applied
Scientific EffectMagnetic field generation: Magnetic Field

Implementation Method 4

In a case where the generated magnetic field is reduced to radio wave energy, part of the energy is lost and absorbed

Methodology Applied
Scientific EffectEnergy conversion:

Implementation Method 5

a radio wave absorber absorbs unnecessary radio waves to prevent the reflection of the radio waves

Methodology Applied
Scientific EffectRadio wave absorption: Absorption (EM radiation)

Data Source

PatentEP3846185B1Method for producing powder of magnetoplumbite-type hexagonal ferrite and method of producing radio wave absorber
Publication Date: 2025.01.01 FUJIFILM CORP
  • EP3846185B1 patent drawingFigure 1

AI summary

A method for producing a powder of a magnetoplumbite-type hexagonal ferrite which is an aggregate of particles of a compound represented by Formula (1), the method including: a step A of adjusting a pH of an aqueous solution containing a Fe salt, an Al salt, and at least one metal element salt selected from the group consisting of a Sr salt, a Ba salt, a Ca salt, and a Pb salt to exceed 8.0, thereby obtaining a reaction product; a step B of drying the reaction product obtained in the step A, thereby obtaining a dried product; and a step C of firing the dried product obtained in Step B, thereby obtaining a fired product, and application. In Formula (1), A represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 1.5 ≤ x ≤ 8.0.         AFe(12-x)Al×O19     ··· Formula (1)