A study on structural analysis and magnetic behaviour of barium hexaferrite nanomaterial

2021 ◽  
Vol 128 (1) ◽  
Author(s):  
S. Thiyagaraj ◽  
Vishal Vrashabhanath Samaje ◽  
Nagaiah Kambhala ◽  
A. Christy Ferdinand ◽  
K. Munirathnam
Keyword(s):  
Structural Analysis ◽  
Barium Hexaferrite ◽  
Magnetic Behaviour

Structural analysis of barium hexaferrite embedded in an amorphous matrix

2006 ◽  
Vol 60 (8) ◽  
pp. 1076-1079 ◽  
Author(s):  
S.A. Palomares-Sánchez ◽  
S. Ponce-Castañeda ◽  
J.R. Martínez ◽  
Yu. M. Chumakov ◽  
F. Leccabue ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Amorphous Matrix ◽  
Barium Hexaferrite

Oriented Barium Hexaferrite Thick Films Prepared by Electrophoretic Deposition in a Magnetic Field

2010 ◽  
Vol 67 ◽  
pp. 92-97 ◽  
Author(s):  
Simona Ovtar ◽  
Darja Lisjak ◽  
Miha Drofenik
Keyword(s):  
Magnetic Field ◽  
Electrophoretic Deposition ◽  
Magnetic Measurements ◽  
Barium Hexaferrite ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
Crystalline Anisotropy ◽  
Degree Of Orientation ◽  
20 Nm ◽  
Magneto Crystalline Anisotropy

Stable suspensions of nanosized barium hexaferrite particles were prepared with the addition of surfactants. Hydrothermally prepared particles with sizes from 5 to 20 nm and commercial particles with sizes from 10 to 160 nm were used. The films with thicknesses from 1.5 to 9.5 μm were prepared with electrophoretic deposition in an external magnetic field. The orientation of the grains in the films was due to the magneto-crystalline anisotropy of the barium hexaferrite and was determined with X-ray diffraction analysis, scanning electron microscopy and magnetic measurements. The highest degree of orientation in the films with anisotropic magnetic behaviour was 90 %.

scholarly journals The mechanically induced structural disorder in barium hexaferrite, BaFe12O19, and its impact on magnetism

2014 ◽  
Vol 170 ◽  
pp. 121-135 ◽  
Author(s):  
V. Šepelák ◽  
M. Myndyk ◽  
R. Witte ◽  
J. Röder ◽  
D. Menzel ◽  
...  
Keyword(s):  
Barium Hexaferrite ◽  
Structural Disorder ◽  
High Energy ◽  
Magnetic Behaviour ◽  
Hexagonal Structure ◽  
Ferrite Nanoparticles ◽  
Atomic Scale ◽  
Valuable Insight ◽  
Near Surface ◽  
Surface Shell

The response of the structure of the M-type barium hexaferrite (BaFe12O19) to mechanical action through high-energy milling and its impact on the magnetic behaviour of the ferrite are investigated. Due to the ability of the 57Fe Mössbauer spectroscopic technique to probe the environment of the Fe nuclei, a valuable insight on a local atomic scale into the mechanically induced changes in the hexagonal structure of the material is obtained. It is revealed that the milling of BaFe12O19 results in the deformation of its constituent polyhedra (FeO6 octahedra, FeO4 tetrahedra and FeO5 triangular bi-pyramids) as well as in the mechanically triggered transition of the Fe3+ cations from the regular 12k octahedral sites into the interstitial positions provided by the magnetoplumbite structure. The response of the hexaferrite to the mechanical treatment is found to be accompanied by the formation of a non-uniform nanostructure consisting of an ordered crystallite surrounded/separated by a structurally disordered surface shell/interface region. The distorted polyhedra and the non-equilibrium cation distribution are found to be confined to the amorphous near-surface layers of the ferrite nanoparticles with the thickness extending up to about 2 nm. The information on the mechanically induced short-range structural disorder in BaFe12O19 is complemented by an investigation of its magnetic behaviour on a macroscopic scale. It is demonstrated that the milled ferrite nanoparticles exhibit a pure superparamagnetism at room temperature. As a consequence of the far-from-equilibrium structural disorder in the surface shell of the nanoparticles, the mechanically treated BaFe12O19 exhibits a reduced magnetization and an enhanced coercivity.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

RNA polymerase: Preparation and structural analysis of helical polymers

1984 ◽  
Vol 42 ◽  
pp. 152-153
Author(s):  
E. Loren Buhle ◽  
Pamela Rew ◽  
Ueli Aebi
Keyword(s):  
Structural Analysis ◽  
Rna Polymerase ◽  
Molecular Level ◽  
X Ray Diffraction ◽  
Helical Polymers ◽  
X Ray ◽  
E Coli ◽  
The Past ◽  
Ordered Arrays ◽  
Low Ionic Strength

While DNA-dependent RNA polymerase represents one of the key enzymes involved in transcription and ultimately in gene expression in procaryotic and eucaryotic cells, little progress has been made towards elucidation of its 3-D structure at the molecular level over the past few years. This is mainly because to date no 3-D crystals suitable for X-ray diffraction analysis have been obtained with this rather large (MW ~500 kd) multi-subunit (α2ββ'ζ). As an alternative, we have been trying to form ordered arrays of RNA polymerase from E. coli suitable for structural analysis in the electron microscope combined with image processing. Here we report about helical polymers induced from holoenzyme (α2ββ'ζ) at low ionic strength with 5-7 mM MnCl2 (see Fig. 1a). The presence of the ζ-subunit (MW 86 kd) is required to form these polymers, since the core enzyme (α2ββ') does fail to assemble into such structures under these conditions.

Interpreting HVEM of muscle-cell impulse networks

1992 ◽  
Vol 50 (1) ◽  
pp. 126-127
Author(s):  
Paul DeCosta ◽  
Kyugon Cho ◽  
Stephen Shemlon ◽  
Heesung Jun ◽  
Stanley M. Dunn
Keyword(s):  
Structural Analysis ◽  
Muscle Cell ◽  
Electron Micrographs ◽  
Relative Size ◽  
Automatic Classification ◽  
Nerve Fibers ◽  
Analysis Algorithm ◽  
Structural Networks

Introduction: The analysis and interpretation of electron micrographs of cells and tissues, often requires the accurate extraction of structural networks, which either provide immediate 2D or 3D information, or from which the desired information can be inferred. The images of these structures contain lines and/or curves whose orientation, lengths, and intersections characterize the overall network.Some examples exist of studies that have been done in the analysis of networks of natural structures. In, Sebok and Roemer determine the complexity of nerve structures in an EM formed slide. Here the number of nodes that exist in the image describes how dense nerve fibers are in a particular region of the skin. Hildith proposes a network structural analysis algorithm for the automatic classification of chromosome spreads (type, relative size and orientation).

Crystallization of barium hexaferrite

1992 ◽  
Vol 50 (1) ◽  
pp. 362-363
Author(s):  
Chung-kook Lee ◽  
Yolande Berta ◽  
Robert F. Speyer
Keyword(s):  
Size Distribution ◽  
Raw Materials ◽  
Barium Hexaferrite ◽  
Recording Media ◽  
Magnetic Recording Media ◽  
Promising Candidate ◽  
Crystallization Method ◽  
Temperature Heat ◽  
High Density Magnetic Recording ◽  
Temperature Heat Treatment

Barium hexaferrite (BaFe12O19) is a promising candidate for high density magnetic recording media due to its superior magnetic properties. For particulate recording media, nano-sized single crystalline powders with a narrow size distribution are a primary application requirement. The glass-crystallization method is preferred because of the controllability of crystallization kinetics, hence, particle size and size distribution. A disadvantage of this method is the need to melt raw materials at high temperatures with non-reactive crucibles, e.g. platinum. However, in this work, we have shown that crystal growth of barium hexaferrite occurred during low temperature heat treatment of raw batches.

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