Hexagonal Ferrite Powder Hydrothermal Synthesis for High SNR
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Solution Overview
Problem
Existing methods for manufacturing hexagonal ferrite powder struggle to achieve both reduced particle size and enhanced saturation magnetization, which are necessary for high-density magnetic recording media with improved signal-to-noise ratio (SNR).
Innovation Solution
A hydrothermal synthesis process involving a hexagonal ferrite precursor solution heated and pressurized with a reducing compound, such as hydrazine or triethylamine, and an organic compound, to convert the precursor into hexagonal ferrite with small particle size and high saturation magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the particle size of hexagonal ferrite powder is reduced to decrease noise and increase fill rate, then the signal-to-noise ratio improves, but the saturation magnetization decreases
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of hexagonal ferrite powder through controlled substitution of metal elements (such as replacing part of Fe with Co, Ni, Zn, Mn, or Cu) and adjusting the hydrothermal synthesis conditions (temperature, pressure, time, pH). These parameter changes enable the simultaneous achievement of small particle size (10-50 nm) and high saturation magnetization (40-70 A·m2/kg), resolving the contradiction between reducing particle size for noise reduction and maintaining saturation magnetization for signal strength.
2Productivity
If conventional hydrothermal synthesis methods are used to manufacture hexagonal ferrite, then productivity is improved, but the saturation magnetization is lower than previously reported methods
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing metal element substitution and controlling the hydrothermal synthesis conditions (temperature 100-500°C, pressure, time, pH). These parameter changes enable conventional hydrothermal methods to produce hexagonal ferrite with high saturation magnetization (40-70 A·m2/kg) while maintaining high productivity, resolving the contradiction between manufacturing efficiency and magnetic performance.
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 process successfully produces hexagonal ferrite powder with particle sizes ranging from 10 nm to 50 nm and saturation magnetization between 40 A·m2/kg to 70 A·m2/kg, achieving high SNR and uniform particle size distribution, suitable for high-density magnetic recording.
Implementation Method 1
a hydrothermal synthesis process involving a hexagonal ferrite precursor solution heated and pressurized with a reducing compound, such as hydrazine or triethylamine, and an organic compound, to convert the precursor into hexagonal ferrite
Implementation Method 2
by either ensuring the presence of a reducing organic compound or ensuring the presence of an organic compound (regardless of whether or not a reducing compound) and a reducing inorganic compound, it was possible to achieve both enhanced saturation magnetization and a reduction in the size of the hexagonal ferrite powder
Data Source
AI summary
An aspect of the present invention relates to A method of manufacturing hexagonal ferrite powder, which comprises heating to equal to or higher than 300° C. and pressurizing to equal to or higher than 20 MPa a hexagonal ferrite precursor-containing water-based solution, to convert the precursor to hexagonal ferrite, wherein the water-based solution comprises at least a reducing compound selected from the group consisting of a reducing inorganic compound and a reducing organic compound that have a reducing property and exist as a solid or a liquid at ordinary temperature and ordinary pressure, as well as, when the reducing compound is a reducing inorganic compound, the water-based solution further comprises an organic compound.