Grain Size Relationships between the Magnetic Layer and the Underlayers in CoCrPtTa Recording Media

2000 ◽  
Vol 614 ◽  
Author(s):  
Kai Ma ◽  
Robert Sinclair ◽  
Gerardo Bertero ◽  
Wei Cao
Keyword(s):  
Grain Size ◽  
Magnetic Layer ◽  
Recording Media ◽  
Processing Conditions ◽  
Magnetic Recording Media ◽  
Electron Microscopic ◽  
Grain Sizes ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
The Relationship

ABSTRACTThis article presents a transmission electron microscopic (TEM) investigation of the relationship between the magnetic and underlayer grain sizes in CoCrPtTa/CrMo longitudinal magnetic recording media. A great deal of effort has been expended on decreasing the underlayer grain size in order to decrease that of the magnetic layer. However, our results show that the two grain sizes may not always correlate. When the underlayer (CrMo) grains are sufficiently small, the magnetic layer (CoCrPtTa) grain size does not necessarily decrease with further underlayer grain size reduction. By carefully controlling the processing conditions, CrMo grain sizes were made to vary from 16nm down to 10nm. However, the corresponding CoCrPtTa grain sizes remained nearly the same. As the underlayer grain size decreased, the ratio of magnetic to underlayer grain size increased from 0.9 to 1.4.

Microstructural Characterization of Longitudinal Magnetic Recording Media

1999 ◽  
Vol 589 ◽  
Author(s):  
Robert Sinclair ◽  
Dong-Won Park ◽  
Claus Habermeier ◽  
Kai Ma
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Recording ◽  
Microstructural Characterization ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Grain Sizes ◽  
Transmission Electron ◽  
The Media

AbstractThe optimization of disc manufacturing conditions is required to increase the storage capacities of magnetic recording media, which is strongly related to both magnetic properties and microstructural features. Analyzing the microstructure requires transmission electron microscopy (TEM), since the small grain sizes of the media prevent other tools from characterizing them. This paper discusses several fascinating characteristics of TEM in understanding and analyzing the properties of the recording media.

Relations of Corrosion Resistance, Coercivity, and Magnetizability of Modified Nd-Fe-B Sintered Magnets to Their Microstructure

1991 ◽  
Vol 232 ◽  
Author(s):  
Satoshi Hirosawa ◽  
Koki Tokuhara ◽  
Shuji Mino ◽  
Toshiyuki Matsui ◽  
Kenji Morii ◽  
...  
Keyword(s):  
Grain Size ◽  
Corrosion Resistance ◽  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Beam Electron ◽  
Sintered Magnets ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Orthorhombic Cell ◽  
Diffraction Patterns

ABSTRACTBrief reviews on corrosion and coercivity mechanisms of sintered Nd-Fe-B magnets are given. Results of recently undertaken transmission electron microscopic study of Nd15 - Fe78-xCoxB7 sintered magnets (x = 3, 6 and 10) are presented. Micro-beam electron diffraction patterns obtained from Nd-Co phases in these magnets could be indexed according only to an orthorhombic cell of Nd3 Co among the binary Nd-Co compounds for x = 3 to 10. Relations of coercivity and magnetizability of this type of magnets to their microstructure are discussed in connection to the effects of V or Mo addition which are to enhance coercivity and to improve magnetizability. It is suggested that a decrease in the local demagnetization effects resulting from a decrease in the width of the grain size distribution due to these-additives is the origin of the enhancement of coercivity and the improvement of magnetizability.

Segregation In Cocrptta/Cr Magnetic Recording Media Measured By Eftem

1999 ◽  
Vol 5 (S2) ◽  
pp. 136-137
Author(s):  
J. Bentley ◽  
J.E. Wittig ◽  
T.P. Nolan
Keyword(s):  
Magnetic Recording ◽  
Alloy Composition ◽  
Recording Media ◽  
Hard Disks ◽  
Processing Conditions ◽  
Structure Property ◽  
Magnetic Recording Media ◽  
Magnetic Exchange ◽  
Material Development ◽  
Transmission Electron

Development of high-density longitudinal magnetic recording media (used for computer hard disks) with good noise performance and high thermal stability requires optimization of both alloy composition and processing methods. In CoCr(PtTa) thin films, intergranular Cr segregation is responsible for decoupling the magnetic exchange between the small ferromagnetic grains. The corresponding Cr depletion within the grains affects the “bulk” magnetic anisotropy. However, the nanoscale structural and chemical details that are needed for modeling and for guiding material development are not well understood. Energy-filtered transmission electron microscopy (EFTEM) has been used to characterize a series of CoCrTa/Cr, CoCrPt/Cr, and CoCrPtTa/Cr media sputtered under various processing conditions, in order to understand their structure-property-processing relationships.Processing typical for hard-disk media was used: 30 or 60-nm films of a Cr underlayer followed by a Co alloy were d.c. magnetron sputtered onto a NiP-plated Al substrate pre-heated to 250°C.

The blister of porphyria cutanea tarda: A Scanning and Transmission Electron Microscopic study

1986 ◽  
Vol 44 ◽  
pp. 334-335
Author(s):  
Veronika Burmeister ◽  
R. Swaminathan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basement Membrane ◽  
Middle Age ◽  
Porphyria Cutanea Tarda ◽  
Minor Trauma ◽  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.

TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

1996 ◽  
Vol 54 ◽  
pp. 910-911
Author(s):  
J. W. Horn ◽  
B. J. Dovey-Hartman ◽  
V. P. Meador
Keyword(s):  
Osmium Tetroxide ◽  
Potassium Ferricyanide ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Cacodylate Buffer ◽  
Transmission Electron Microscopic ◽  
Glutaraldehyde Solution ◽  
Temperature Impact ◽  
The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

Radial mass analysis of unstained STEM images of molluscan hemocyanins

1990 ◽  
Vol 48 (3) ◽  
pp. 810-811
Author(s):  
M.G. Hamilton ◽  
T.T. Herskovits ◽  
J.S. Wall
Keyword(s):  
Image Analysis ◽  
Hollow Cylinder ◽  
Electron Micrographs ◽  
Side View ◽  
Mass Analysis ◽  
Mass Measurements ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

Transmission Electron Microscopic Observations of Al3Li and Al3Ti Precipitation in A Rapidly Solidified Al-3Li-0.2Ti ALLOY

1980 ◽  
Vol 38 ◽  
pp. 336-337
Author(s):  
J. E. O’Neal ◽  
K. K. Sankaran ◽  
S. M. L. Sastry
Keyword(s):  
Rapid Solidification ◽  
Metallic Substrate ◽  
Deformation Characteristics ◽  
Phase Decomposition ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Supersaturated Solid Solutions ◽  
Transmission Electron Microscopic ◽  
Rapidly Solidified ◽  
Microstructural Homogeneity

Rapid solidification of a molten, multicomponent alloy against a metallic substrate promotes greater microstructural homogeneity and greater solid solubility of alloying elements than can be achieved by slower-cooling casting methods. The supersaturated solid solutions produced by rapid solidification can be subsequently annealed to precipitate, by controlled phase decomposition, uniform 10-100 nm precipitates or dispersoids. TEM studies were made of the precipitation of metastable Al3Li(δ’) and equilibrium AL3H phases and the deformation characteristics of a rapidly solidified Al-3Li-0.2Ti alloy.

Structural Investigation of Iron Particles Used for Magnetic Recording Media

1980 ◽  
Vol 38 ◽  
pp. 406-407
Author(s):  
Alfred Baltz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Structural Investigation ◽  
Magnetic Interaction ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Recording Medium ◽  
Iron Particles ◽  
Transmission Electron

As part of a program to develop iron particles for next generation recording disk medium, their structural properties were investigated using transmission electron microscopy and electron diffraction. Iron particles are a more desirable recording medium than iron oxide, the most widely used material in disk manufacturing, because they offer a higher magnetic output and a higher coercive force. The particles were prepared by a method described elsewhere. Because of their strong magnetic interaction, a method had to be developed to separate the particles on the electron microscope grids.

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