Lorentz Electron Microscopy of cobalt borides in a platinum cobalt matrix

The presence of cobalt borides significantly increases the intrinsic coercivity (Hic) of a Pt-Co alloy. Whereas the maximum Hic for a binary Pt-Co alloy is less than 5 kOe, a ternary Pt42Co45B13 (at%) alloy exhibits intrinsic coercivity as large as 15.2 kOe. The optimum microstructure for the maximum Hic consists of a dispersion of cobalt boride precipitates having the orthorhombic Co3B structure in an Ll0 Pt-Co matrix. Lorentz electron microscopy of the magnetic structure of these cobalt borides has been used to elucidate their strong influence on the magnetic properties of this alloy. Magnetic domain wall thickness measurements assist with modeling of the magnetic hardening mechanism.Processing the Pt42Co45B13 (at%) material utilized an initial rapid solidification step followed by annealing at 800°C. Samples for Lorentz electron microscopy were prepared by dimple grinding and ion milling to electron transparency. The Lorentz imaging employed the standard Fresnel contrast method by operating a Philips CM20T at 200 kV in the low magnification (LM) mode.

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In situ investigation of the magnetic domain wall in Permalloy thin film by Lorentz electron microscopy

Materials Letters ◽

10.1016/j.matlet.2008.01.006 ◽

2008 ◽

Vol 62 (17-18) ◽

pp. 2654-2656 ◽

Cited By ~ 4

Author(s):

H.H. Liu ◽

X.K. Duan ◽

R.C. Che ◽

Z.F. Wang ◽

X.F. Duan

Keyword(s):

Thin Film ◽

Electron Microscopy ◽

Domain Wall ◽

Magnetic Domain ◽

Magnetic Domain Wall ◽

In Situ Investigation

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A theory of intrinsic coercivity in narrow magnetic domain wall materials

Journal of Physics C Solid State Physics ◽

10.1088/0022-3719/12/18/027 ◽

1979 ◽

Vol 12 (18) ◽

pp. 3811-3825 ◽

Cited By ~ 36

Author(s):

A R Bishop ◽

W F Lewis

Keyword(s):

Domain Wall ◽

Magnetic Domain ◽

Magnetic Domain Wall ◽

Intrinsic Coercivity ◽

Wall Materials

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Magnetic domain wall contrast under zero domain contrast conditions in spin polarized low energy electron microscopy

Ultramicroscopy ◽

10.1016/j.ultramic.2019.02.026 ◽

2019 ◽

Vol 200 ◽

pp. 132-138 ◽

Cited By ~ 3

Author(s):

Chao Zhou ◽

Gong Chen ◽

Jia Xu ◽

Jianhui Liang ◽

Kai Liu ◽

...

Keyword(s):

Electron Microscopy ◽

Domain Wall ◽

Magnetic Domain ◽

Low Energy ◽

Energy Electron ◽

Magnetic Domain Wall ◽

Spin Polarized ◽

Low Energy Electron

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Comments on "Magnetic domain wall dislocation analogy and intrinsic coercivity"

IEEE Transactions on Magnetics ◽

10.1109/tmag.1975.1058554 ◽

1975 ◽

Vol 11 (1) ◽

pp. 81-82 ◽

Cited By ~ 1

Author(s):

H. Hilzinger ◽

H. Kronmuller

Keyword(s):

Domain Wall ◽

Magnetic Domain ◽

Magnetic Domain Wall ◽

Intrinsic Coercivity

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Magnetic hardening mechanism in sintered R–Fe–B permanent magnets

Journal of Materials Research ◽

10.1557/jmr.1988.0045 ◽

1988 ◽

Vol 3 (1) ◽

pp. 45-54 ◽

Cited By ~ 56

Author(s):

M. Sagawa ◽

S. Hirosawa

Keyword(s):

Temperature Dependence ◽

Permanent Magnets ◽

Spontaneous Magnetization ◽

Short Review ◽

Experimental Results ◽

Surface Conditions ◽

Hardening Mechanism ◽

Intrinsic Coercivity ◽

Field Coefficient ◽

Magnetic Hardening

After a short review on temperature dependence of the intrinsic coercivity in sintered Nd–Fe–B-type magnets is given, recent experimental results concerning the coercivity-anisotropy (HC–HA) correlation in B-rich Pr–Fe–B and Nd–Fe–B sintered magnets and the influence of the surface conditions of the sintered Nd–Fe–B magnets on the coercivity are reported. The results are interpreted in terms of the μoHc vs cμoHA – NIs plot, where Is is the spontaneous magnetization of R2Fe14B (R = Pr or Nd) and N is the effective demagnetization field coefficient.

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Electron microscopy of the magnetic material SmCo5

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109495 ◽

1978 ◽

Vol 36 (1) ◽

pp. 470-471

Author(s):

J. Fidler ◽

P. Skalicky

Keyword(s):

Electron Microscopy ◽

Magnetic Material ◽

Permanent Magnets ◽

Elastic Anisotropy ◽

Magnetic Domain ◽

Growth Direction ◽

Crystal Defects ◽

Ion Milling ◽

Thin Foils ◽

Very High

The magnetic material SmCo5 has attracted considerable interest for the use in permanent magnets. Microscopic investigations should provide information on the interaction of crystal defects and precipitates with the magnetic domain structure and thus about the special magnetic properties of this material. Single crystals of SmCo5 which has a CaCu5-structure were grown from 99,9 purity Sm and Co by the Bridgman technique in pyrolytic BN crucibles. Thin foils for TEM-investigations were prepared by ion-milling perpendicular to the growth-direction which always was <1216> or <0113>.Electron microscopy revealed growth-dislocations, stacking-faults and Sm2Co17 precipitates, the density of defects beeing very low. The material has a very high magnetic anisotropy but a relative low elastic anisotropy characterized by Acomp= = 0,67 and Ashear = 1,03. The low anisotropy makes it possible to determine Burgers vectors of dislocations with the help of the invisibility criterion under two-beam conditions.

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