X-Ray Diffraction Analysis and Magnetic Properties of Pr-Fe-B HDDR Powders and Magnets

2008 ◽  
Vol 591-593 ◽  
pp. 42-47 ◽  
Author(s):  
S.C. Silva ◽  
José Hélio Duvaizem ◽  
Luís Gallego Martinez ◽  
M.T.D. Orlando ◽  
Rubens Nunes de Faria Jr. ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Diffraction Analysis ◽  
Cast Alloy ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Anisotropy ◽  
Crystallite Sizes ◽  
Phase Quantification ◽  
Cell Refinement

Fine magnetic powder has been produced using the hydrogenation disproportionation desorption and recombination (HDDR) process. The first goal of this work involved an investigation of a range of disproportionation/desorption temperatures between 800 and 900°C with the purpose of optimizing the HDDR treatment for a Pr14Fe80B6 alloy. The cast alloy was annealed at 1100°C for 20 hours for homogenization. The optimum disproportionation temperature for achieving high anisotropy was 820°C. The influence of the reaction temperature on the microstructure and magnetic properties of Pr14Fe80B6 HDDR powders and magnets has been shown. A second stage of this study involved the characterization, for each temperature, of the HDDR processed powder using X-ray diffraction analysis. Samples of the HDDR material have been studied by synchrotron radiation powder diffraction using the Rietveld method for cell refinement, phase quantification and crystallite sizes determination. Scanning electron microscopy (SEM) has also been employed to reveal the morphology of the HDDR powder.

Crystallite Size and Magnetic Properties of HDDR Powders Obtained from PrFeCoBNb Alloys

2010 ◽  
Vol 660-661 ◽  
pp. 308-313
Author(s):  
S.C. Silva ◽  
José Hélio Duvaizem ◽  
Rubens Nunes de Faria Jr. ◽  
Hidetoshi Takiishi
Keyword(s):  
Electron Microscopy ◽  
Magnetic Properties ◽  
Magnetic Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystallite Sizes ◽  
Phase Quantification ◽  
Scanning Electron

The first goal of this work involved the study of HDDR powders obtained from annealed alloys with the general formula: PrxFe77.9-xCo16B6Nb0.1 (x = 12; 12.5; 13; 13.5 and 14). The alloys were processed at desorption / recombination temperature of 840°C. The highest magnetic properties were obtained with 13.5 at. % Pr (Br= 1000mT and µ0iHc= 890mT). The alloy with a minimum praseodymium content (12 at. %) exhibited the lowest magnetic properties (Br= 350mT e iHc= 120mT). The second aim of the work involved the characterization of HDDR powders using X-ray diffraction for phase quantification and mean crystallite sizes determination of the hard magnetic phase. The processed powders were characterized by scanning electron microscopy (SEM).

X-ray diffraction analysis of cold-worked Cu-Ni-Si and Cu-Ni-Si-Cr alloys by Rietveld method

2011 ◽  
Vol 21 (3) ◽  
pp. 482-487 ◽  
Author(s):  
A. KHEREDDINE ◽  
F. HADJ LARBI ◽  
L. DJEBALA ◽  
H. AZZEDDINE ◽  
B. ALILI ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cold Worked

X-ray diffraction analysis of stacking and twin faults in f.c.c. metals: a revision and allowance for texture and non-uniform fault probabilities

2000 ◽  
Vol 33 (2) ◽  
pp. 296-306 ◽  
Author(s):  
L. Velterop ◽  
R. Delhez ◽  
Th. H. de Keijser ◽  
E. J. Mittemeijer ◽  
D. Reefman
Keyword(s):  
Diffraction Analysis ◽  
Line Profile ◽  
Intensity Distribution ◽  
Original Description ◽  
Powder Pattern ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Line Profile ◽  
Crystallite Sizes ◽  
Diffraction Peaks

A revision is presented of the original description by Warren [X-ray Diffraction, (1969), pp. 275–298. Massachusetts: Addison-Wesley] of the intensity distribution of powder-pattern reflections from f.c.c. metal samples containing stacking and twin faults. The assumptions (in many cases unrealistic) that fault probabilities need to be very small and equal for all fault planes and that the crystallites in the sample have to be randomly oriented have been removed. To elucidate the theory, a number of examples are given, showing how stacking and twin faults change the shape and position of diffraction peaks. It is seen that significant errors may arise from Warren's assumptions, especially in the peak maximum shift. Furthermore, it is explained how to describe powder-pattern reflections from textured specimens and specimens with non-uniform fault probabilities. Finally, it is discussed how stacking- and twin-fault probabilities (and crystallite sizes) can be determined from diffraction line-profile measurements.

Application of Gel Technology in Preparation of High-Tc Perovskite Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
R. S. Liu ◽  
G. C. Lin ◽  
H. M. Sung ◽  
Y. C. Chen ◽  
O. C. C. Lin
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Diffraction Analysis ◽  
Dicarboxylic Acids ◽  
X Ray Diffraction ◽  
Chemical Homogeneity ◽  
High Tc ◽  
X Ray ◽  
Electrical And Magnetic Properties ◽  
High Degree

ABSTRACTLa-Ba-Cu-O and Y-Ba-Cu-O superconducting systems have been successfully prepared by gel techniques with high degree of chemical homogeneity. The precursor gel was synthesized from mixture of the corresponding metallic nitrates and di-carboxylic acids. The sintered oxides prepared from the different dicarboxylic acids were all Tc = 90K perovskite superconductors. However differences in electrical and magnetic properties were also observed. Effects due to the different acids elucidated by magnetic susceptibility measurements and X-ray diffraction analysis will be discussed.

Grain Size Dependent Magnetic Properties of Nanocrystalline Sm [BE]Co [BD][BJ]/Cu

2001 ◽  
Vol 703 ◽  
Author(s):  
L. Bessais ◽  
C. Djéga-Mariadassou ◽  
J. Zhang ◽  
V. Lalanne ◽  
A. Percheron-Guégan
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size Dependent ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Magnetic Metal ◽  
Chemical Distribution

ABSTRACTThe evolution of both micro structural and magnetic properties of the Sm[BE]Co[BD][BJ] Cu powder, is studied as a function of soft co-milling time. The average grain size in the range 20 - 50 nm was determined by transmission electron microscopy coupled with x-ray diffraction using the Rietveld method. The particle shape and chemical distribution were investigated by elemental mapping, using wavelength dispersive x-ray analysis with electron microprobe analysis. The coercivity evolution shows that an optimum value of 6 kOe is obtained after 5 h co-milling. The microstructure analysis indicates that both materials are well mixed in nanometer scale. This technique appears as a potential route to synthesize nanocrystalline Sm[BE]Co[BD][BJ] isolated by non-magnetic metal Cu.

scholarly journals Infinite octamolybdate chains cross-linked by paramagnetic iron (II) centers

2004 ◽  
Vol 2 (2) ◽  
pp. 323-333
Author(s):  
Adrian Patrut ◽  
Adrian Nicoara ◽  
Dragos Margineanu ◽  
Michael Koop ◽  
Paul Kögerler ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sodium Cations

AbstractThe paper presents a new polymeric polyoxomolybdate cluster with infinite octamolybdate chains cross-linked by iron (II) centers. The layer-type substance contains sodium cations sandwiched between the [Fe(H2O)4Mo8O27]∞ layers. The structure was determined by single crystal X-ray diffraction analysis. Magnetic properties, due to the presence of paramagnetic iron (II) centers, are presented and discussed.

Structural Change and Magnetic Properties of Mechanically Alloyed Spinel Ferrite CoFe2O4

2020 ◽  
Vol 855 ◽  
pp. 108-116
Author(s):  
Novrita Idayanti ◽  
Dedi ◽  
Azwar Manaf
Keyword(s):  
Magnetic Properties ◽  
Sintering Temperature ◽  
Spinel Ferrite ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
A Value ◽  
Hall Plot ◽  
Crystallite Sizes ◽  
The Mean

Magnetic property studies and the crystallite structures evolution of spinel ferrite CoFe2O4 particles are reported in this paper. The ferrite was prepared through mechanical milling of all alloy precursors and sintered at various temperatures of 800, 900, 1000, and 1100 °C to promote the crystalline structure. X-ray diffraction (XRD) and Williamson-Hall plot were used to calculate the mean crystallite size and microstrain. Changes in the microstructure and crystallite sizes were occurring due to sintering treatments. It is found that the remanence (Mr) and saturation magnetization (Ms) increase with increasing sintering temperature, but a decrease occurred only at the temperature of 1100 °C. The optimum magnetic properties were obtained in a sample sintered at 1000 °C with a value of Mr = 36.00 emu/g and Ms= 74.05 emu/g.

In situX-ray diffraction analysis of iron ore sinter phases

2004 ◽  
Vol 37 (3) ◽  
pp. 362-368 ◽  
Author(s):  
Nicola V. Y. Scarlett ◽  
Ian C. Madsen ◽  
Mark I. Pownceby ◽  
Axel N. Christensen
Keyword(s):  
Iron Ore ◽  
Rietveld Method ◽  
Structural Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intermediate Phases ◽  
Iron Ore Sinter ◽  
Phase Quantification ◽  
Bonding Phase

Owing to the depletion of world lump iron ore stocks, pre-treated agglomerates of fine ores are making up a growing proportion of blast-furnace feedstock (∼80%). These agglomerations, or `sinters', are generally composed of iron oxides, ferrites (most of which are silicoferrites of calcium and aluminium, SFCAs), glasses and dicalcium silicates (C2S). SFCA is the most important bonding phase in iron ore sinter, and its composition, structural type and texture greatly affect its physical properties. Despite its prevalence and importance, the mechanism of SFCA formation is not fully understood.In situpowder X-ray diffraction investigations have been conducted into the formation of SFCA, allowing the study of the mechanism of its formation and the observation of intermediate phases with respect to time and temperature. Studies have been carried out to investigate the effects of changing the substitution levels of aluminium for iron. The use of the Rietveld method for phase quantification gives an indication of the order and comparative rates of phase formation throughout the experiments.

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