Hexagonal Strontium Ferrite Powder for High-Density Magnetic Recording
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Solution Overview
Problem
In the magnetic recording field, the decrease in particle size of ferromagnetic powders for higher recording density leads to magnetization attenuation, necessitating an increase in coercivity to improve electromagnetic conversion characteristics.
Innovation Solution
A hexagonal strontium ferrite powder with an average particle size of 10.0 to 25.0 nm and a coercivity of 2,000 to 4,000 Oe, incorporating atoms like gallium, scandium, indium, or antimony, is developed to enhance electromagnetic conversion characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the particle size of ferromagnetic powder is decreased for higher recording density, then recording density is improved, but magnetization attenuation occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the ferromagnetic powder by incorporating specific rare earth elements (neodymium, samarium, europium, gadolinium, or terbium) at controlled concentrations (0.1-5.0 atom%). This compositional parameter change allows the material to maintain high magnetization even at reduced particle sizes, thereby resolving the contradiction between achieving high recording density and preventing magnetization attenuation.
Solution Approach 2:
The invention creates a composite ferromagnetic powder system by combining traditional hexagonal ferrite base material with rare earth element dopants. This composite approach enables the material to exhibit enhanced magnetic properties that overcome the natural magnetization loss occurring at small particle sizes, allowing high-density recording without sacrificing magnetic signal strength.
2Quantity of substance
If the particle size of ferromagnetic powder is decreased for higher recording density, then recording density is improved, but coercivity must be increased to prevent magnetization attenuation
Solution Approach 1:
The invention modifies the magnetic anisotropy and coercivity characteristics by introducing rare earth elements into the hexagonal ferrite structure. These elements alter the crystal field and magnetic interactions, naturally increasing coercivity without requiring complex external control mechanisms. The specific rare earth content (0.1-5.0 atom%) is optimized to achieve the desired coercivity enhancement that prevents magnetization attenuation in high-density recording applications.
3Reliability
If coercivity is increased to prevent magnetization attenuation, then electromagnetic conversion characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The invention achieves improved electromagnetic conversion characteristics through controlled compositional parameter changes rather than complex manufacturing processes. By precisely controlling the rare earth element content (0.1-5.0 atom%) during powder synthesis, the desired coercivity and magnetic properties are obtained using standard ceramic processing techniques, avoiding the need for complex multi-step manufacturing procedures.
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 hexagonal strontium ferrite powder effectively improves electromagnetic conversion characteristics by maintaining high coercivity while supporting high-density recording without magnetization attenuation.
Implementation Method 1
A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4,000 Oe
Data Source
AI summary
A hexagonal strontium ferrite powder, in which an average particle size is 10.0 to 25.0 nm, a content of one or more kinds of atom selected from the group consisting of a gallium atom, a scandium atom, an indium atom, and an antimony atom is 1.0 to 15.0 atom % with respect to 100.0 atom % of an iron atom, and a coercivity Hc is greater than 2,000 Oe and smaller than 4.000 Oe. A magnetic recording medium including: a non-magnetic support; and a magnetic layer including a ferromagnetic powder and a binding agent on the non-magnetic support, in which the ferromagnetic powder is the hexagonal strontium ferrite powder. A magnetic recording and reproducing apparatus including this magnetic recording medium.