Hexagonal Ferrite Powder Composition for High-Density Magnetic Recording
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for producing hexagonal ferrite magnetic powder with high saturation magnetization and small particle size struggle to maintain high recording density and signal-to-noise ratio (SNR) in magnetic recording media.
Innovation Solution
The development of hexagonal ferrite magnetic powder with a Bi/Fe molar ratio of 0.035 or less, a saturation magnetization of 42.0 Am2/kg or more, and a Dx volume of 1,800 nm3 or less, achieved through a Bi elution treatment using a chelating agent that forms a complex with Bi.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If the firing temperature is decreased to reduce particle size (Dx volume), then the particle size is reduced, but the saturation magnetization is largely decreased
Solution Approach 1:
The invention changes the chemical composition parameters by adding Bi in a specific amount (Bi/Fe ratio of 0.005 or more) to the raw material mixture. This parameter change allows the system to maintain high saturation magnetization even when particle size is reduced through lower firing temperatures, resolving the contradiction between particle size reduction and magnetization retention
Solution Approach 2:
The invention creates a composite material system by incorporating Bi into the hexagonal ferrite structure. This composite approach (hexagonal ferrite with Bi addition) produces particles with both small size and high saturation magnetization, simultaneously achieving the benefits of fine particle size and high magnetic properties that cannot be obtained with conventional single-component ferrite
2Quantity of substance
If Bi is added to maintain saturation magnetization during particle refinement, then saturation magnetization is improved, but the capability for high density recording and high SNR is still insufficient
Solution Approach 1:
The invention optimizes the Bi content parameter by specifying a Bi/Fe ratio of 0.005 or more, which is carefully controlled to achieve the optimal balance between maintaining saturation magnetization and enabling high-density recording with high SNR. This precise parameter control resolves the insufficiency of previous Bi addition methods
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
This approach significantly enhances the saturation magnetization of hexagonal ferrite magnetic powder, allowing for higher recording density and SNR in magnetic recording media, while maintaining small particle sizes.
Implementation Method 1
immersing hexagonal ferrite magnetic powder containing Bi in a solution having dissolved therein a compound X that forms a complex with Bi, so as to elute a part of Bi existing in the hexagonal ferrite magnetic powder into the solution
Data Source
AI summary
A hexagonal ferrite magnetic powder is significantly more useful for achieving simultaneously both the enhancement of the recording density and the enhancement of the SNR of a magnetic recording medium. The hexagonal ferrite magnetic powder contains Bi at a Bi/Fe molar ratio in a range of 0.035 or less, has a saturation magnetization σs of 42.0 Am2/kg or more and a Dx volume calculated based on the crystallite diameters of 1,800 nm3 or less. A method for producing hexagonal ferrite magnetic powder includes a step of performing a treatment of immersing hexagonal ferrite magnetic powder containing Bi in a solution having dissolved therein a compound X that forms a complex with Bi, so as to elute a part of Bi existing in the hexagonal ferrite magnetic powder into the solution.