Extended x-ray absorption fine structure study on amorphous Nd–Fe–B alloys

1998 ◽  
Vol 13 (8) ◽  
pp. 2132-2138 ◽  
Author(s):  
Hiroyuki Kageyama ◽  
Kohei Kadono ◽  
Kohei Fukumi ◽  
Tetsuji Saito ◽  
Toshiro Kuji
Keyword(s):  
Local Structure ◽  
Amorphous Alloys ◽  
Crystallization Process ◽  
Nearest Neighbor ◽  
Amorphous Structure ◽  
Neighbor Distance ◽  
X Ray ◽  
Melt Spun ◽  
Nearest Neighbor Distance ◽  
X Ray Absorption

The local structure and crystallization behavior of Nd15Fe77Bx (x = 2−14) melt-spun alloys were studied by Nd L3 extended x-ray absorption fine structure (EXAFS). The conventional x-ray powder diffractometry studies showed that the Nd–Fe–B melt-spun ribbons had the amorphous structure regardless of the boron content. EXAFS studies of the local structure around the Nd atom confirmed that the Nd–Fe–B melt-spun alloys had the amorphous structure and virtually the same nearest neighbor distance from the Nd atom. The amorphous alloys were heated by a differential scanning calorimetry in order to investigate the variation in the local structure during the crystallization process by EXAFS measurements. Although no appreciable difference was found in the nearest neighbor distance of the Nd atom between the amorphous alloys and the crystallized alloys, the small variation in the nearest neighbor distance during the crystallization process was detected by EXAFS measurements.

Short Range Order Strucrures in Y-Pr-Ba-Cu-O System Studied by X-Ray Absorption Fine Structure (XAFS) Techniques

1990 ◽  
Vol 209 ◽  
Author(s):  
Y.H. Kao ◽  
A. Krol ◽  
Z.H. Ming ◽  
C.S. Lin ◽  
Y.L. Soo ◽  
...  
Keyword(s):  
Fine Structure ◽  
Local Structure ◽  
Short Range ◽  
Direct Evidence ◽  
Nearest Neighbor ◽  
Compound System ◽  
Local Distribution ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption

ABSTRACTLocal structure around the constituent atoms in the compound system Y1-xPrxBa2CU3O7-y has been investigated by means of x-ray absorption fine structure (XAFS) techniques. By comparing the local structure in the compound x=1 with its counterpart x=0, the XAFS results provide a direct evidence that Pr has replaced Y in the material. The nearest-neighbor structure in the CuO2 planes seems to remain intact as × varies from 0 to 1, indicating that substitution of Pr for Y does not disturb the local distribution of holes in the CuO2 planes. We suggest that local disorder and distortions in the second-neighbor bonding configuration could be responsible for suppression of superconductivity with increasing Pr content in the system.

EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND MAGNETOSTRICTIVE PROPERTY OF MELT-SPUN Fe85Ga15 RIBBONS

2013 ◽  
Vol 27 (30) ◽  
pp. 1350174 ◽  
Author(s):  
HAO LIU ◽  
HAIOU WANG ◽  
MENGXIONG CAO ◽  
WEISHI TAN ◽  
YANGGUANG SHI ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Fine Structure ◽  
High Resolution ◽  
Nearest Neighbor ◽  
Annealed Sample ◽  
X Ray Diffraction ◽  
X Ray ◽  
Absorption Fine ◽  
Melt Spun ◽  
X Ray Absorption

In order to study the microstructure of Fe – Ga alloy, Fe 85 Ga 15 ribbons prepared with different wheel velocity were studied by high resolution X-ray diffraction (HRXRD) and extend X-ray absorption fine structure (EXAFS). HRXRD patterns showed that only disordered A 2 phase was observed in as-cast Fe 85 Ga 15 alloy. A modified- DO 3 phase was detected in all of the melt spun samples. The HRXRD associated with EXAFS results indicated that Ga atoms were located as second-nearest neighbor along [100] orientation. A little DO 3 phase was found in ribbons annealed at 1000°C under 0.06 MPa Ar atmosphere. The result of magnetostriction measurement revealed that in the ribbon prepared with higher wheel velocity, more modified- DO 3 phase will enhance the magnetostriction. DO 3 phase in the annealed sample will deteriorate the magnetostrictive properties of Fe – Ga ribbons.

scholarly journals X-ray Diffraction Analysis of NdCl3 Melt

1990 ◽  
Vol 45 (5) ◽  
pp. 623-626 ◽  
Author(s):  
Kazuo Igarashi ◽  
Mineo Kosaka ◽  
Masahiro Ikeda ◽  
Junichi Mochinaga
Keyword(s):  
Coordination Number ◽  
Short Range ◽  
Nearest Neighbor ◽  
Correlation Method ◽  
Neighbor Distance ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Nearest Neighbor Distance ◽  
Short Range Structure

Abstract The structure of molten NdClj at 800 CC has been investigated by X-ray scattering and the correlation method. The nearest neighbor distance and coordination number of Nd-Cl are 2.77 Ä and 5.5 A, respectively. The Nd-Nd and CI-CI distances are 5.08 and 4.04 Ä, respectively. The average nearest neighbor distance and coordination number decrease markedly on melting, and the resulting short range structure of the melt is approximately octahedral

Exafs Study of Co/Cu Multilayers: Mbe Versus Sputtered

1994 ◽  
Vol 375 ◽  
Author(s):  
C. L. Foiles ◽  
M. R. Franklin ◽  
R. Loloee ◽  
Roy Clarke ◽  
T. I. Morrison
Keyword(s):  
Local Structure ◽  
Nearest Neighbor ◽  
Thickness Dependence ◽  
Neighbor Distance ◽  
Exafs Data ◽  
Exafs Study ◽  
Nearest Neighbor Distance ◽  
Nearest Neighbor Distances

AbstractEXAFS data are used to probe the local structure of Co/Cu multilayers having comparable dimensions but prepared by two different techniques, MBE and sputtering. Significant differences are found. The nearest neighbor distance in all Co layers increases about the same amount relative to the bulk value and MBE Co layers are less disordered than sputtered Co layers. Nearest neighbor distances in thinner Cu layers are less than bulk values but approach bulk value for thicker Cu layers. Nearest neighbor distances in thin MBE Cu layers are more contracted and have a more rapid thickness dependence than in sputtered Cu layers.

The Local Structure of Molten CdBr2

2005 ◽  
Vol 60 (1-2) ◽  
pp. 81-84
Author(s):  
Hideaki Shiwakua ◽  
Yoshihiro Okamoto ◽  
Tsuyashi Yaita ◽  
Shinichi Suzuki ◽  
Kazuo Minato ◽  
...  
Keyword(s):  
Fine Structure ◽  
High Temperature ◽  
Local Structure ◽  
Molten Salts ◽  
Room Temperature ◽  
Nearest Neighbor ◽  
Structural Parameters ◽  
Molten State ◽  
X Ray ◽  
X Ray Absorption

The local structure of molten CdBr2 was investigated by high temperature X-ray absorption fine structure (XAFS) analysis. The quartz cell designed for hygroscopic high temperature molten salts was successfully used in the measurement. At room temperature the nearest neighbor Cd2+-Br− distance decreased from 2.71 Å in solid state to 2.60 Å in the molten state. The coordination number decreased from 6 to 4 on melting. The obtained structural parameters showed that (CdBr4)2− is predominant in molten CdBr2.

scholarly journals Crystallization Process and Microstructural Evolution of Melt Spun Al-RE-Ni-(Cu) Ribbons

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 443
Author(s):  
Francisco G. Cuevas ◽  
Sergio Lozano-Perez ◽  
Rosa María Aranda ◽  
Raquel Astacio
Keyword(s):  
Crystallization Process ◽  
Primary Crystallization ◽  
Amorphous Structure ◽  
Intermetallic Phases ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Melt Spun ◽  
The Stability

The crystallization process, both at the initial and subsequent stages, of amorphous Al88-RE4-Ni8 alloys (RE = Y, Sm and Ce) has been studied. Additionally, the consequences of adding 1 at.% Cu replacing Ni or Al were studied. The stability of the amorphous structure in melt spun ribbons was thermally studied by differential scanning calorimetry, with Ce alloys being the most stable. The effect of Cu to reduce the nanocrystal size during primary crystallization was analyzed by transmission electron microscopy. This latter technique and x-ray diffraction showed the formation of intermetallic phases at higher temperatures. A clear difference was observed for the Ce alloy, with a simpler sequence involving the presence of Al3Ni and Al11Ce3. However, for the Y and Sm alloys, a more complex evolution involving metastable ternary phases before Al19RE5Ni3 appears, takes place. The shape of the intermetallics changes from equiaxial in the Ce alloys to elongate for Y and Sm, with longer particles for Sm and, in general, when Cu is added to the alloy.

Density and Packing in Uranium Based Metallic Glasses

1985 ◽  
Vol 57 ◽  
Author(s):  
A. J. Drehman
Keyword(s):  
Metallic Glasses ◽  
Excess Volume ◽  
Nearest Neighbor ◽  
Glass Composition ◽  
Neighbor Distance ◽  
Compositional Dependence ◽  
X Ray Diffraction ◽  
X Ray ◽  
Wide Compositional Range ◽  
Nearest Neighbor Distance

AbstractDensity and x-ray diffraction measurements were performed over a wide compositional range of U-Fe and U-Co metallic glass ribbons. The compositional dependence of both the density and the average nearest neighbor distance exhibits a change in slope at approximately 28 at.% transition metal. This suggests an “ideal” glass composition possessing a minimum excess volume. A qualitative model of atomic packing is proposed, which is based on the compositional dependence of the atomic volume and nearest neighbor distance.

Local Structure and Vibrational Properties of α-Pu, α-U, and the α-U Charge Density Wave

2005 ◽  
Vol 893 ◽  
Author(s):  
Erik J. Nelson ◽  
Patrick Allen ◽  
Kerri J. Blobaum ◽  
Mark A. Wall ◽  
Corwin H. Booth
Keyword(s):  
Charge Density ◽  
Local Structure ◽  
Charge Density Wave ◽  
Nearest Neighbor ◽  
Density Wave ◽  
Debye Model ◽  
Vibrational Properties ◽  
Temperature Dependent ◽  
X Ray ◽  
X Ray Absorption

AbstractThe local atomic environment and vibrational properties of monoclinic α-Pu, orthorhombic α-U, and the α-U charge-density-wave (CDW) modulation are examined by extended x-ray absorption fine structure spectroscopy (EXAFS). Debye-Waller factors from temperature-dependent EXAFS measurements are fit to a correlated Debye model. The observed Pu-Pu bond Debye temperature is θcD(α-Pu) = 162 ± 5 K for the pure α-Pu phase. The temperature dependence of the U-U nearest neighbor and second nearest neighbor Debye-Waller factors exhibits a sharp discontinuity in slope near TCDW = 43 K, the transition temperature at which the charge-density wave (CDW) in α-U occurs. Our measurement of the CDW using EXAFS is the first observation of the structure of the CDW in polycrystalline α-U.

FLUCTUATIONS OF THE EXCHANGE INTERACTION IN AN AMORPHOUS FERROMAGNET Gd68Cu32

1993 ◽  
Vol 07 (01n03) ◽  
pp. 954-957
Author(s):  
IKUO NAKAI ◽  
HIRONOBU MAEDA ◽  
AKIR AISHII
Keyword(s):  
Magnetic Properties ◽  
Fine Structure ◽  
Exchange Interaction ◽  
Local Structure ◽  
Heisenberg Model ◽  
Amorphous Materials ◽  
Nearest Neighbor ◽  
X Ray ◽  
Amorphous Ferromagnet ◽  
X Ray Absorption

We have carried out magnetization and extended X-ray absorption fine structure measurements on an amorphous Gd68Cu32 ferromagent to investigate the relation between magnetic properties and the local structure in amorphous materials. Fluctuations in the exchange interaction for the ferromagnet are estimated experimentally within the framework of the nearest neighbor Heisenberg model.

Pre-edge peak of Ti K XANES: Determined by Short- or Medium-Range Structure?

2008 ◽  
Vol 1152 ◽  
Author(s):  
Nan Jiang
Keyword(s):  
Multiple Scattering ◽  
Nearest Neighbor ◽  
Main Peak ◽  
Scattering Method ◽  
Neighbor Distance ◽  
X Ray ◽  
Medium Range ◽  
Fine Structures ◽  
Multiple Scattering Method ◽  
X Ray Absorption

ABSTRACTThe calculations of Ti K-edge X-ray absorption near-edge structures (XANES) in fresnoite Sr2TiSi2O8 are carried out using multiple-scattering method. The origins of the pre-edge peak along with the fine structures in the main peak of Ti K-edge XANES are interpreted by comparing the calculations in various modified structure models. It concludes that the pre-edge peak is dominantly determined by the structure (including both coordination and bond lengths) within the nearest-neighbor distance, while the fine structures beyond the pre-edge peak region are sensitively determined by the structure extending to the medium-range distance

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