Fine pole-pitch magnetizing method for Nd–Fe–B isotropic magnet with high coercivity

2007 ◽  
Vol 101 (9) ◽  
pp. 09K104 ◽  
Author(s):  
H. Komura ◽  
M. Kitaoka ◽  
T. Kiyomiya ◽  
Y. Matsuo
Keyword(s):  
High Coercivity ◽  
Isotropic Magnet

Lorentz electron microscopy of magnetic domains in rapidly solidified and annealed Pt-Co-B alloys

1991 ◽  
Vol 49 ◽  
pp. 784-785
Author(s):  
N. Qiu ◽  
J. E. Wittig
Keyword(s):  
Rapid Solidification ◽  
Ion Beam ◽  
Magnetic Behavior ◽  
High Coercivity ◽  
Magnetic Domains ◽  
Beam Angle ◽  
Tem Analysis ◽  
Intrinsic Coercivity ◽  
Hard Magnets ◽  
Rapidly Solidified

PtCo hard magnets have specialized applications owing to their relatively high coercivity combined with corrosion resistance and ductility. Increased intrinsic coercivity has been recently obtained by rapid solidification processing of PtCo alloys containing boron. After rapid solidification by double anvil splat quenching and subsequent annealing for 30 minutes at 650°C, an alloy with composition Pt42Co45B13 (at.%) exhibited intrinsic coercivity up to 14kOe. This represents a significant improvement compared to the average coercivities in conventional binary PtCo alloys of 5 to 8 kOe.Rapidly solidified specimens of Pt42Co45B13 (at.%) were annealed at 650°C and 800°C for 30 minutes. The magnetic behavior was characterized by measuring the coercive force (Hc). Samples for TEM analysis were mechanically thinned to 100 μm, dimpled to about 30 nm, and ion milled to electron transparency in a Gatan Duomill at 5 kV and 1 mA gun current. The incident ion beam angle was set at 15° and the samples were liquid nitrogen cooled during milling. These samples were analyzed with a Philips CM20T TEM/STEM operated at 200 kV.

Transmission Electron Microscopy of oriented Co84Cr14Ta2 thin films for longitudinal magnetic recording

1991 ◽  
Vol 49 ◽  
pp. 756-757
Author(s):  
T. P. Nolan
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Cost ◽  
Low Noise ◽  
Information Storage ◽  
High Coercivity ◽  
Magnetic Alloy ◽  
Magnetic Media ◽  
Transmission Electron

Thin film magnetic media are being used as low cost, high density forms of information storage. The development of this technology requires the study, at the sub-micron level, of morphological, crystallographic, and magnetic properties, throughout the depth of the deposited films. As the microstructure becomes increasingly fine, widi grain sizes approaching 100Å, the unique characterization capabilities of transmission electron microscopy (TEM) have become indispensable to the analysis of such thin film magnetic media.Films were deposited at 225°C, on two NiP plated Al substrates, one polished, and one circumferentially textured with a mean roughness of 55Å. Three layers, a 750Å chromium underlayer, a 600Å layer of magnetic alloy of composition Co84Cr14Ta2, and a 300Å amorphous carbon overcoat were then sputter deposited using a dc magnetron system at a power of 1kW, in a chamber evacuated below 10-6 torr and filled to 12μm Ar pressure. The textured medium is presently used in industry owing to its high coercivity, Hc, and relatively low noise. One important feature is that the coercivity in the circumferential read/write direction is significandy higher than that in the radial direction.

Interdiffusion Induced High Coercivity of Rare-Earth Free Alnico Thin Films

2019 ◽  
Author(s):  
Xiao Han ◽  
Hoyun Won ◽  
Minyeong Choi ◽  
Liping Guo ◽  
Zhongqi Liu ◽  
...  
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
High Coercivity

Magnetic Domain Observation on Melt-Spun Nd-Fe-B Ribbons Using Magnetic Force Microscopy

1999 ◽  
Vol 577 ◽  
Author(s):  
A. Gavrin ◽  
C. Sellers ◽  
S.H. Liouw
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Magnetic Measurements ◽  
Magnetic Domain ◽  
Domain Size ◽  
High Coercivity ◽  
Uniform Domain ◽  
Cross Sectional ◽  
Force Microscopy ◽  
Melt Spun

ABSTRACTWe have used Magnetic Force Microscopy (MFM) to study the magnetic domain structures of melt-spun Nd-Fe-B ribbons. The ribbons are commercial products (Magnequench International, Inc. MQP-B and MQP-B+) with a thickness of approximately 20 microns. These materials have identical composition, Nd12.18B5.36Fe76.99Co5.46, but differ in quenching conditions. In order to study the distribution of domain sizes through the ribbon thickness, we have prepared cross-sectional samples in epoxy mounts. In order to avoid artifacts due to tip-sample interactions, we have used high coercivity CoPt coated MFM tips. Our studies show domain sizes typically ranging from 50-200 nm in diameter. This is in agreement with studies of similar materials in which domains were investigated in the plane of the ribbon. We also find that these products differ substantially in mean domain size and in the uniformity of the domain sizes as measured across the ribbon. While the B+ material shows nearly uniform domain sizes throughout the cross section, the B material shows considerably larger domains on one surface, followed by a region in which the domains are smaller than average. This structure is presumably due to the differing quench conditions. The region of coarse domains varies in thickness, disappearing in some areas, and reaching a maximum thickness of 2.75 µm in others. We also describe bulk magnetic measurements, and suggest that.

scholarly journals High-Coercivity Fe-Co Nanoparticles Prepared by Pulsed Arc Plasma Deposition

2016 ◽  
Vol 57 (2) ◽  
pp. 207-211 ◽  
Author(s):  
Daiki Horiyama ◽  
Masashi Matsuura ◽  
Tetsuro Yamamoto ◽  
Nobuki Tezuka ◽  
Satoshi Sugimoto
Keyword(s):  
Plasma Deposition ◽  
High Coercivity ◽  
Arc Plasma ◽  
Co Nanoparticles ◽  
Pulsed Arc

Effect of Additives on the Formation of SmCo Magnetic Nanoparticles by Chemical Synthesis

2014 ◽  
Vol 809-810 ◽  
pp. 9-16 ◽  
Author(s):  
Jian Jun Tian
Keyword(s):  
Magnetic Nanoparticles ◽  
Vinyl Pyrrolidone ◽  
Polyol Synthesis ◽  
High Coercivity ◽  
Preparation Process ◽  
Effect Of Additives ◽  
Dispersing Agent ◽  
Base Solution ◽  
Poly Vinyl Pyrrolidone ◽  
Inorganic Precursors

Monodispersed magnetic SmCo nanoparticles have been prepared by polyol synthesis using non-toxic inorganic precursors (nitrates). The effect of the additives of NaOH, HNO3, CH3COOH and poly vinyl pyrrolidone (PVP) on the formation of SmCo nanoparticles is studied in this paper. The results indicate that base solution can boost the reduction of Co while acid solution is helpful for the formation of SmCo due to decreasing the reduction velocity of Co. CH3COOH is appropriate additive for the synthesis of SmCo nanoparticles, but more addition of CH3COOH will result in the emergence of CoC2 phase and decrease the coercivity of the resultants. The additive of PVP not only is a dispersing agent, but can prevent them from oxidating during preparation process. The SmCo nanoparticles with a size of 5-8 nm have the ferromagnetic properties of high coercivity (>1000 Oe).

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