scholarly journals Complex correlations between microstructure and magnetic behavior in SrFe12O19 hexaferrite nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Pierfrancesco Maltoni ◽  
Sergey A. Ivanov ◽  
Gianni Barucca ◽  
Gaspare Varvaro ◽  
Davide Peddis ◽  
...  
Keyword(s):  
Permanent Magnets ◽  
Profile Analysis ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Line Profile Analysis ◽  
X Rays ◽  
Hard Magnetic Materials ◽  
Tem Analysis ◽  
Complex Relation ◽  
Transmission Electron

AbstractThe magnetic properties of SrFe12O19 (SFO) hard hexaferrites are governed by the complex relation to its microstructure, determining their relevance for permanent magnets´ applications. A set of SFO nanoparticles obtained by sol–gel self-combustion synthesis was selected for an in-depth structural X-Rays powder diffraction (XRPD) characterization by means of G(L) line-profile analysis. The obtained crystallites´ size distribution reveal a clear dependence of the size along the [001] direction on the synthesis approach, resulting in the formation of platelet-like crystallites. In addition, the size of the SFO nanoparticles was determined by transmission electron microscopy (TEM) analysis and the average number of crystallites within a particle was estimated. These results have been evaluated to illustrate the formation of single-domain state below a critical value, and the activation volume was derived from time dependent magnetization measurements, aiming to clarify the reversal magnetization process of hard magnetic materials.

scholarly journals Complex Correlations between Microstructure and Magnetic Behavior in SrFe12O19 Hexaferrite Nanoparticles

2021 ◽  
Author(s):  
Pierfrancesco Maltoni ◽  
Sergey Alexander Ivanov ◽  
Gianni Barucca ◽  
Gaspare Varvaro ◽  
Davide Peddis ◽  
...  
Keyword(s):  
Permanent Magnets ◽  
Profile Analysis ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Line Profile Analysis ◽  
X Rays ◽  
Hard Magnetic Materials ◽  
Tem Analysis ◽  
Complex Relation ◽  
Transmission Electron

Abstract The magnetic properties of SrFe12O19 (SFO) hard hexaferrites are governed by the complex relation to its microstructure, determining their relevance for permanent magnets´ applications. A set of SFO nanoparticles obtained by sol-gel self-combustion synthesis was selected for an in-depth structural X-Rays powder diffraction (XRPD) characterization by means of G(L) line-profile analysis. The obtained crystallites´ size distribution reveal a clear dependence of the size along the [001] direction on the synthesis approach, resulting in the formation of platelet-like crystallites. In addition, the size of the SFO nanoparticles was determined by transmission electron microscopy (TEM) analysis and the average number of crystallites within a particle was estimated. These results have been evaluated to illustrate the formation of single-domain state below a critical value, and the activation volume was derived from time dependent magnetization measurements, aiming to clarify the reversal magnetization process of hard magnetic materials.

Determination of Nanocrystalline Fe80Cr20 Powder Based Alloys Using Williamson-Hall Method

2010 ◽  
Vol 129-131 ◽  
pp. 999-1003 ◽  
Author(s):  
Hendi Saryanto ◽  
S. Khaerudini Deni ◽  
Pudji Untoro ◽  
Mat Husin Saleh ◽  
Darwin Sebayang
Keyword(s):  
Mechanical Alloying ◽  
Crystallite Size ◽  
Line Profile ◽  
Profile Analysis ◽  
Line Profile Analysis ◽  
X Rays ◽  
Diffraction Line Profile ◽  
Transmission Electron ◽  
Microstructure Morphology ◽  
Hall Method

The aim of this study is to determine the nanocrystalline size by using Williamson-Hall method of Fe80Cr20 powder which prepared by mechanical alloying process. X-rays diffraction line profile analysis was adopted to analyze the crystallite size and microstrains of Fe80Cr20 alloys powder. Transmission Electron Microscopy (TEM) was used to examine the microstructure morphology of the nanosized of Fe80Cr20 alloys. The crystallite size, microstrain, and lattice parameters were estimated by Williamson–Hall plot. The results showed that the mechanical alloying processes resulted the final product in nanocrystalline size range (below 12 nm) which confirmed by TEM observation and XRD line profile analysis.

Synthesis, microstructure and hardness of bulk ultrahard BN nanocomposites

2008 ◽  
Vol 23 (4) ◽  
pp. 981-993 ◽  
Author(s):  
D. Rafaja ◽  
V. Klemm ◽  
M. Motylenko ◽  
M.R. Schwarz ◽  
T. Barsukova ◽  
...  
Keyword(s):  
Profile Analysis ◽  
Weight Fraction ◽  
Partial Coherence ◽  
Line Profile Analysis ◽  
X Rays ◽  
Orientation Relationships ◽  
Transmission Electron ◽  
Crystallite Sizes ◽  
Average Size ◽  
Main Component

Ultrahard boron nitride compacts containing nanosized domains of the cubic (c-BN), wurtzitic (w-BN), and hexagonal (h-BN) phase were synthesized at high-pressure/high-temperature (HP/HT) conditions. Hot-pressed and pyrolytic BN, both containing h-BN as a main component, were used as starting materials. The HP/HT products were investigated by x-ray diffraction via Rietveld and line-profile analysis, as well as high-resolution transmission electron microscopy. c-BN was the dominant phase in all products, complemented by up to 25 wt% w-BN and some remaining “compressed h-BN.” In particular samples, partial crystallographic coherence of adjacent crystallites to x-rays was observed, which has been previously found in superhard transition metal nitride-based nanocomposite coatings. In the BN nanocomposites, the partial coherence of nanocrystallites to x-rays was improved by their strong local preferred orientation, which is made possible by the well-known orientation relationships among h-BN, w-BN, and c-BN phases. The correlation between the weight fraction and the average size of the c-BN crystallites helped to describe the formation of c-BN/(w-BN) nanocomposites from submicron-sized h-BN domains in the starting materials. The Knoop and Vickers hardness of specimens with crystallite sizes ranging from 6 to ∼50 nm was found to be significantly higher than that of c-BN single crystals, despite the presence of residual h-BN.

scholarly journals Correlation between subgrains and coherently scattering domains

2005 ◽  
Vol 20 (4) ◽  
pp. 366-375 ◽  
Author(s):  
T. Ungár ◽  
G. Tichy ◽  
J. Gubicza ◽  
R. J. Hellmig
Keyword(s):  
Electron Microscopy ◽  
Line Profile ◽  
Profile Analysis ◽  
Subgrain Size ◽  
Domain Size ◽  
Line Profile Analysis ◽  
X Rays ◽  
X Ray ◽  
Transmission Electron ◽  
Dislocation Walls

Crystallite size determined by X-ray line profile analysis is often smaller than the grain or subgrain size obtained by transmission electron microscopy, especially when the material has been produced by plastic deformation. It is shown that besides differences in orientation between grains or subgrains, dipolar dislocation walls without differences in orientation also break down coherency of X-rays scattering. This means that the coherently scattering domain size provided by X-ray line profile analysis provides subgrain or cell size bounded by dislocation boundaries or dipolar walls.

Line profile analysis: pattern modellingversusprofile fitting

2006 ◽  
Vol 39 (1) ◽  
pp. 24-31 ◽  
Author(s):  
Paolo Scardi ◽  
Matteo Leoni
Keyword(s):  
Line Profile ◽  
Powder Diffraction ◽  
Profile Analysis ◽  
Domain Size ◽  
Systematic Errors ◽  
Powder Pattern ◽  
Line Profile Analysis ◽  
Microstructural Parameters ◽  
Profile Fitting ◽  
Transmission Electron

Powder diffraction data collected on a nanocrystalline ceria sample within a round robin conducted by the IUCr Commission on Powder Diffraction were analysed by two alternative approaches: (i) whole-powder-pattern modelling based upon a fundamental microstructural parameters approach, and (ii) a traditional whole-powder-pattern fitting followed by Williamson–Hall and Warren–Averbach analysis. While the former gives results in close agreement with those of transmission electron microscopy, the latter tends to overestimate the domain size effect, providing size values about 20% smaller. The origin of the discrepancy can be traced back to a substantial inadequacy of profile fitting with Voigt profiles, which leads to systematic errors in the following line profile analysis by traditional methods. However, independently of the model, those systematic errors seem to have little effect on the volume-weighted mean size.

scholarly journals Influence of sintering temperature and pressure on crystallite size and lattice defect structure in nanocrystalline SiC

2007 ◽  
Vol 22 (5) ◽  
pp. 1314-1321 ◽  
Author(s):  
J. Gubicza ◽  
S. Nauyoks ◽  
L. Balogh ◽  
J. Labar ◽  
T.W. Zerda ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Defect Structure ◽  
Sintering Temperature ◽  
Profile Analysis ◽  
Lattice Defect ◽  
Line Profile Analysis ◽  
Crystallite Growth ◽  
X Ray ◽  
Transmission Electron ◽  
Temperature And Pressure

Microstructure of sintered nanocrystalline SiC is studied by x-ray line profile analysis and transmission electron microscopy. The lattice defect structure and the crystallite size are determined as a function of pressure between 2 and 5.5 GPa for different sintering temperatures in the range from 1400 to 1800 °C. At a constant sintering temperature, the increase of pressure promotes crystallite growth. At 1800 °C when the pressure reaches 8 GPa, the increase of the crystallite size is impeded. The grain growth during sintering is accompanied by a decrease in the population of planar faults and an increase in the density of dislocations. A critical crystallite size above which dislocations are more abundant than planar defects is suggested.

Structural, Microscopy Analysis and Compressive Strength of ZnO–CuO Nanocomposites

2020 ◽  
Vol 12 (2) ◽  
pp. 163-167
Author(s):  
K. Kavitha ◽  
T. Subba Rao ◽  
R. Padma Suvarna ◽  
M. Prasanna Kumar
Keyword(s):  
Compressive Strength ◽  
Sol Gel ◽  
Average Particle Size ◽  
Testing Machine ◽  
Research Area ◽  
Strength Analysis ◽  
Average Particle ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Active Research

Currently, researches on nanocomposites become an active research area due its unique properties. Earlier, many researches are done for synthesizing the multidimensional structures for developing efficient and new Nano devices. In this present work, we synthesized ZnO–CuO nanocomposites using sol–gel method. The obtained nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) analysis and Compressive strength analysis using compressive testing machine (CTM). Herein, the structure and size of the ZnO–CuO nanocomposites were studied using XRD. And the average particle size was found to be 34 nm. The TEM analysis has the evidence of the XRD result. The enhancement in compressive strength of the ZnO–CuO nanocomposites was determined using CTM machine up to 4 wt.%.

scholarly journals Structure and morphology of shape-controlled Pd nanocrystals

2015 ◽  
Vol 48 (5) ◽  
pp. 1534-1542 ◽  
Author(s):  
Jose Solla-Gullon ◽  
Emmanuel Garnier ◽  
Juan M. Feliu ◽  
Matteo Leoni ◽  
Alberto Leonardi ◽  
...  
Keyword(s):  
Profile Analysis ◽  
Line Profile Analysis ◽  
Narrow Size Distribution ◽  
Miller Index ◽  
X Ray ◽  
Structure And Morphology ◽  
Surface Electrochemistry ◽  
Diffraction Line Profile ◽  
Transmission Electron ◽  
Shape Controlled

Pd nanocrystals were produced with uniform truncated-cube shape and a narrow size distribution, yielding controlled surface area fractions from low Miller index ({100}, {110}, {111}) crystalline facets. Details on the structure and morphology of the nanocrystals were obtained by combining X-ray powder diffraction line profile analysis, high-resolution transmission electron microscopy and surface electrochemistry based on Cu underpotential deposition.

Microstructure and Magnetic Behavior of One-Dimensional Co0.5Zn0.5Fe2O4 Nanofibers

2011 ◽  
Vol 284-286 ◽  
pp. 861-865
Author(s):  
Jun Xiang ◽  
Guang Zhen Zhou ◽  
Yan Qiu Chu ◽  
Xiang Qian Shen
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Magnetic Behavior ◽  
Average Diameter ◽  
Diffraction Field ◽  
One Dimensional ◽  
Morphological Variations ◽  
Transmission Electron

One-dimensional Co0.5Zn0.5Fe2O4 nanostructures (nanofibers) with an average diameter of 154 nm were fabricated by electrospinning. These nanofibers were characterized by X–ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Magnetic hysteresis loops were measured for randomly oriented and aligned Co0.5Zn0.5Fe2O4 nanofibers, in comparison with the corresponding powder sample synthesized using the conventional sol-gel process. The differences in magnetic properties are observed between the Co0.5Zn0.5Fe2O4 nanofibers and powders, and these differences mainly arise from the grain size and morphological variations between these two materials. In determining the magnetization ease axis for the aligned Co0.5Zn0.5Fe2O4 nanofibers the shape anisotropy is slightly dominant competing with the magnetocrystalline anisotropy.

scholarly journals Microstructure and texture analysis of δ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction

2014 ◽  
Vol 47 (1) ◽  
pp. 303-315 ◽  
Author(s):  
Zhiyang Wang ◽  
Ulf Garbe ◽  
Huijun Li ◽  
Yanbo Wang ◽  
Andrew J. Studer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Neutron Diffraction ◽  
Profile Analysis ◽  
Zirconium Alloys ◽  
Average Density ◽  
Line Profile Analysis ◽  
Hydride Precipitation ◽  
Diffraction Line Profile ◽  
Transmission Electron ◽  
Order Of Magnitude

This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66generally follows the δ(111)//α(0001) and δ[1{\overline 1}0]//α[11{\overline 2}0] orientation relationship with the α-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.

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