Nickel Ferrite Core-Shell Particles for Gigahertz Low Loss
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Solution Overview
Problem
Current magnetic materials used in high-frequency applications, such as spinel ferrites, often exhibit high magnetic loss and insufficient bandwidth, particularly in the gigahertz range, due to high resistivity and eddy currents.
Innovation Solution
Development of magnetic particles comprising a nickel ferrite core with an iron nickel shell, where the nickel ferrite core has the formula Ni1−xMxFe2+yO4 and the iron nickel shell is formed through heat treatment in a hydrogen atmosphere, reducing magnetic loss and enhancing permeability by controlling the shell thickness and composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If ferrite materials are used to reduce component size, then electronic component dimensions are reduced, but bandwidth is insufficient and magnetic loss increases at gigahertz frequencies
Solution Approach 1:
The iron nickel shell composite structure combines the advantages of ferrite (low dielectric loss, small size capability) with iron nickel (high permeability, low magnetic loss), enabling miniaturized components to maintain low magnetic loss at gigahertz frequencies where conventional ferrites fail
Solution Approach 2:
The patent changes the material parameters by introducing an iron nickel shell with controlled thickness (5-50 nm) and composition (FeNi, FeNi3, or FeNi5 intermetallic phases). This parameter modification transforms the magnetic properties of the particle, achieving high permeability (>1.4) and low magnetic loss tangent (<0.05) at gigahertz frequencies while maintaining small size
2Loss of energy
If nickel ferrite core with iron nickel shell is used, then magnetic loss is reduced and permeability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent employs a self-service approach where the iron nickel shell forms automatically on the nickel ferrite core through heat treatment in a hydrogen atmosphere. The shell forms in-situ during the sintering process without requiring separate deposition steps, reducing manufacturing complexity despite the sophisticated core-shell structure
Solution Approach 2:
The nickel ferrite core is prepared in advance with controlled composition (Ni1-xMxFe2+yO4 where M is Zn, Mg, Co, Cu, Al, Mn, or Cr) and crystal structure before the shell formation process. This preliminary preparation of the core with optimized properties enables the subsequent shell formation to proceed automatically, simplifying the overall manufacturing process
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 magnetic particles achieve low magnetic loss and high permeability, making them suitable for high-frequency applications, with a magnetic loss tangent less than 0.05 and permeability greater than 1.4 at gigahertz frequencies, effectively addressing the limitations of existing materials.
Implementation Method 1
heat treating a plurality of nickel ferrite particles in a hydrogen atmosphere to form the plurality of magnetic particles having the iron nickel shell on the nickel ferrite core
Implementation Method 2
heat treating a plurality of nickel ferrite particles in a hydrogen atmosphere to form the plurality of magnetic particles having the iron nickel shell
Data Source
AI summary
In an aspect, a composition comprises a plurality of magnetic particles. The magnetic particles each independently comprise a nickel ferrite core having the formula Ni1−xMxPe2+yO4, wherein M is at least one of Zn, Mg, Co, Cu, Al, Mn, or Cr; x is 0 to 0.95, and y=−0.5 to 0.5; and an iron nickel shell at least partially surrounding the core, wherein the iron nickel shell comprises iron, nickel, and optionally M. In another aspect, a method of forming the magnetic particles comprises heat treating a plurality of nickel ferrite particles in a hydrogen atmosphere to form the plurality of magnetic particles having the iron nickel shell on the nickel ferrite core. In yet another aspect, a composite can comprise the magnetic particles and a polymer.