Ferrite Sintered Magnet Composition for High Br and Stable HcJ
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ferrite sintered magnets struggle to achieve high residual magnetic flux density (Br) and coercive force (HcJ) at ordinary temperatures.
Innovation Solution
A ferrite sintered magnet with a magnetoplumbite-type crystal structure, comprising metal elements A (primarily Ca) and R (primarily La), along with Fe, Co, Zn, and B, within specific atomic ratios and content ranges, to enhance magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If various elements are added to improve magnetic properties, then residual magnetic flux density (Br) and coercive force (HcJ) increase, but the complexity of material composition and manufacturing process increases
Solution Approach 1:
The patent optimizes the atomic ratios of metal elements A and R in the ferrite phase, specifically setting the ratio of metal element A to be 0.05 ≤ ratio ≤ 0.50 and metal element R to be 0.45 ≤ ratio ≤ 0.95. This parameter optimization achieves high Br (4200G or more) and HcJ (4500Oe or more) while controlling material composition complexity through defined compositional ranges.
Solution Approach 2:
The patent creates a composite ferrite phase containing multiple metal elements (A and R) in specific ratios within the AFe12O19 structure. This composite approach combines the benefits of different elements - metal element A for structural stability and metal element R for enhanced magnetic properties - achieving superior Br and HcJ while maintaining a controlled composite structure.
2Reliability
If metal element R is increased to improve magnetic properties, then Br and HcJ increase, but the temperature coefficient of HcJ increases in absolute value
Solution Approach 1:
The patent carefully balances the atomic ratio of metal element R (0.45 ≤ ratio ≤ 0.95) against metal element A (0.05 ≤ ratio ≤ 0.50) to achieve an optimal compromise. This parameter optimization ensures high HcJ (4500Oe or more) while suppressing the absolute value of the temperature coefficient to 0.20% or less, preventing excessive sensitivity to temperature changes.
Solution Approach 2:
The patent introduces metal element A as a stabilizing component that locally counteracts the temperature sensitivity introduced by metal element R. By positioning metal element A in the A-site of the ferrite structure with controlled ratios, it provides local structural stabilization that reduces the overall temperature coefficient while preserving the high coercive force benefits of metal element R.
Data Source
AI summary
A ferrite sinter magnet has a ferrite phase having a magnetoplumbite-type crystal structure, and contains at least a metal element A, a metal element R, Fe, Co, Zn, and B. The element A is at least one kind of element selected from the group consisting of Sr, Ba, Ca, and Pb, and essentially includes Ca. the element R is at least one kind selected from the group consisting of Bi and rare-earth elements including Y, and essentially includes La. Atomic ratios of the metal elements satisfy the following Expressions (1) to (5),A1-rReFexCoyZnz (1)0.40≤r≤0.70 (2)8.20≤x≤9.34 (3)0.05≤y≤0.50 (4)0<z≤0.20 (5)The content of Si is 0 to 0.60% by mass in terms of SiO2, and the content of B is 0.1-0.70% by mass in terms of B2O3.