Core-Shell Particle Design for Uniform Epsilon Iron Oxide Synthesis
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Solution Overview
Problem
Existing methods for synthesizing epsilon type iron oxide particles for magnetic recording media result in aggregated particles with large variations in primary particle diameter, leading to deteriorated signal-to-noise ratio (SNR) and running durability.
Innovation Solution
The development of core-shell particles with a core of iron oxide and a shell of polycondensate metal alkoxide, where the core is coated independently to prevent aggregation during calcination, achieving a small coefficient of variation in primary particle diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If epsilon type iron oxide is synthesized by calcinating FeCo alloy powder included in a matrix formed of SiO2, then epsilon type iron oxide particles can be obtained, but the particles become aggregated and the primary particle diameter and its variation increase
Solution Approach 1:
The invention divides the synthesis process into distinct stages: first forming discrete core particles of iron oxide, then separately coating each core with a shell material. This segmentation prevents aggregation by ensuring each particle is independently formed and coated, rather than being synthesized as a bulk matrix where particles aggregate during calcination.
Solution Approach 2:
The invention performs preliminary coating of the core particles with shell material (such as silica or alumina) before the final calcination step. This preliminary action protects the core particles from aggregating during subsequent high-temperature treatment, maintaining uniform primary particle diameter and improving reliability.
2Length of moving object
If the average primary particle diameter is reduced to 15 nm or smaller, then recording density improves, but the coefficient of variation of particle diameter remains large and SNR deteriorates
Solution Approach 1:
The invention applies different materials and properties to different parts of the particle structure: the core region contains iron oxide with specific magnetic properties and size, while the shell region provides protective and stabilizing functions. This local differentiation allows precise control of core particle size and uniformity without being constrained by aggregation issues in bulk synthesis.
Solution Approach 2:
The shell material acts as an intermediary between the core iron oxide particles and the external environment. This intermediary layer prevents direct interaction and aggregation between cores, enabling maintenance of small and uniform primary particle diameters while improving coefficient of variation through independent particle stabilization.
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 produces epsilon type iron oxide-based compound particles with improved SNR and running durability in magnetic recording media by controlling the primary particle diameter and its variation.
Implementation Method 1
a core-shell particle comprising: a core including at least one iron oxide selected from the group consisting of Fe2O3 and Fe3O4, or iron oxyhydroxide; and a shell that coats the core
Implementation Method 2
a shell that coats the core, the shell including a polycondensate of a metal alkoxide
Data Source
AI summary
The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe2O3 or Fe3O4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.