Ferrite magnetic material, ferrite magnet, and ferrite sintered magnet
A ferrite magnet and a ferrite sintered magnet including a ferrite magnetic material are provided. A main phase of the ferrite magnetic material includes a ferrite phase having a hexagonal crystal structure, and metal element composition expressed by Ca1-w-x-yR wSr xBayFezMm wherein 0.25<w<0.5, 0.01<x<0.35, 0.0001<y<0.013, y<x, 8.7<z<9.9, 1.0<w/m<2.1, 0.017<m/z<0.055 and Si component is at least included as a sub-component, and wherein; when content y1 mass % of the Si component in the ferrite magnetic material, with respect to SiO2, is shown on Y-axis and a total content x1 of z and m is shown on X-axis, a relation between x1 and y1 is within a range surrounded by 4 points placed on X-Y coordinate having the X and Y axes.
1. A ferrite magnetic material, in which its main phase comprises:
a ferrite phase having a hexagonal crystal structure, and
metal element composition constituting the ferrite magnetic material is expressed by the following formula (1),
Ca 1-w-x-y R w Sr x Ba y Fe z M m (1)
wherein:
R in formula (1) is at least one element selected from the group consisting of rare-earth element, including Y, and Bi, which at least includes La,
M in formula (1) is at least one element selected from the group consisting of Co, Mn, Mg, Ni, Cu, and Zn, which at least includes Co,
w, x, y, z, and m in formula (1) respectively satisfies the following formulas (2), (3), (4), (5), (6), (7) and (8)
25 ≦w≦ 0.5 (2)
0.01 ≦x≦ 0.35 (3)
0.0001≦ y≦ 0.013 (4)
y<x (5)
8.7≦ z≦ 9.9 (6)
1.0< w/m< 2.1 (7)
0.017< m/z< 0.055 (8), and
an Si component is at least included as a sub-component, and wherein;
when content y1 mass % of the Si component in the ferrite magnetic material, with respect to SiO 2 , is shown on Y-axis and a total content x1 of z and m is shown on X-axis, a relation between x1 and y1 is within a range surrounded by 4 points a(8.9, 1.2), b(8.3, 0.95), c(10.0, 0.35) and d(10.6, 0.6), placed on X-Y coordinate having the X and Y axes,
residual flux density Br is from 392.0 to 478.5 mT,
coercive force HcJ is from 301.0 to 434.4 kA/m, and
squareness ratio Hk/HcJ is from 78.5% to 95.1%.
2. A ferrite magnet comprising the ferrite magnetic material as set forth in claim 1 .
3. The ferrite magnet as set forth in claim 2 , wherein a degree of crystal orientation Or(f)=Σ(001)/Σ(hkl) obtained by X-ray diffraction measurement is 0.9 or more.
4. The ferrite magnet as set forth in claim 2 , wherein:
within a cut surface of crystal grains constituting the ferrite magnet, which is cut by a plane parallel to c-axis direction of hexagonal crystal structures, maximum and minimum values of a grain size which go through a gravity center of each grain in a crystal cross-section are respectively obtained, and when an average of said maximum and minimum values of the sizes in crystal grains of a predetermined number or more are respectively determined as L(μm) and S(μm),
said L and S satisfy the below formulas (9) and (10):
L≦1.4 (9)
L/S≦2.4 (10).
5. A ferrite sintered magnet comprising the ferrite magnetic material as set forth in claim 1 .
6. The ferrite sintered magnet as set forth in claim 5 , wherein a degree of crystal orientation Or(f)=Σ(001)/Σ(hkl) obtained by X-ray diffraction measurement is 0.9 or more.
7. The ferrite sintered magnet as set forth in claim 5 , wherein:
within a cut surface of crystal grains constituting the ferrite magnet, which is cut by a plane parallel to c-axis direction of hexagonal crystal structures, maximum and minimum values of a grain size which go through a gravity center of each grains in a crystal cross-section are respectively obtained, and when an average of said maximum and minimum values of the sizes in crystal grains of a predetermined number or more are respectively determined as L(μm) and S(μm), said L and S satisfy the following formulas (9) and (10):
L≦1.4 (9)
L/S≦2.4 (10).