DETERMINATION BY POLARIZED NEUTRON DIFFRACTION OF THE THREE PARTIAL STRUCTURE FACTORS OF A Co81.511B18.5 GLASS

1982 ◽  
Vol 43 (C9) ◽  
pp. C9-23-C9-29
Author(s):  
J. M. Dubois ◽  
P. Chieux ◽  
G. Le Caer ◽  
J. Schweitzer ◽  
J. Bletry
Keyword(s):  
Neutron Diffraction ◽  
Partial Structure ◽  
Structure Factors ◽  
Polarized Neutron

Consistent partial structure factors for amorphousNi0.33(ZryHf1−y)0.67using x-ray and neutron diffraction

1996 ◽  
Vol 53 (14) ◽  
pp. 8983-8992 ◽  
Author(s):  
Yan Xu ◽  
W. B. Muir ◽  
Z. Altounian ◽  
W. J. L. Buyers ◽  
R. L. Donaberger
Keyword(s):  
Neutron Diffraction ◽  
Partial Structure ◽  
X Ray ◽  
Structure Factors

Neutron Diffraction with the Metallic Glass Ni81B19 Using Isotopic Substitution

1981 ◽  
Vol 36 (4) ◽  
pp. 419-420 ◽  
Author(s):  
P. Lamparter ◽  
W. Sperl ◽  
G. Rainer-Harbach ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Metallic Glass ◽  
Isotopic Substitution ◽  
Partial Structure ◽  
Experimental Realization ◽  
Structure Factors ◽  
The Moment ◽  
Mathematical Evaluation ◽  
Structural Research

In the field of structural research of metallic T80M20-glasses (T = Fe, Co, Ni; M = B, P) at the moment large interest exists in the determination of the so called partial structure factors Smn, especially of the structure factor SMM which is determined by the arrangement of the met-alloid atoms. Since the mathematical evaluation of SMM from three measured total structur factors is rather uncertain, in [1] a method was proposed for the direct measuring of SBB in Ni81B19, the experimental realization of which will be reported in the present paper

Neutron diffraction, isotopic substitution and the structure of aqueous solutions

1980 ◽  
Vol 290 (1043) ◽  
pp. 553-566 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Aqueous Solutions ◽  
Scattering Amplitude ◽  
Partial Structure ◽  
Experimental Conditions ◽  
Primitive Model ◽  
Structure Factors ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Solutions Of Electrolytes

The structural properties of liquids that contain more than one atomic species are difficult to unravel. The essential reason for this is that conventional diffraction experiments measure a rather coarse average of all the ½ v ( v +l) partial structure factors that characterize a liquid containing v species. This paper describes the way that neutron diffraction experiments carried out on samples that are identical in all respects, except that the isotope of one or more of the species has been changed, can overcome this problem. It is shown that the systematic use of isotopes, by virtue of the dependence of the neutron scattering amplitude on isotope, enables partial structure factors to be extracted directly from diffraction data. A detailed account of the method applied to a range of aqueous solutions of electrolytes under various experimental conditions is given. In particular, first-order dfference experiments yield information on ion-water conformations. Data are now available for the cations Ni 2+ , Ca 2+ and Li + and these results will be discussed in detail. The data for Ni 2+ are of particular interest because they show that the substantial angle of tilt between the plane of the water molecule and the Ni-O axis gradually disappears as the concentration is reduced. The only anion studied so far is Cl - but the experiments have been carried out for a wide range of counter ions. We have shown that for such different electrolytes as CaCl 2 , NaCl and LiCl, the nature of the hydration around the Cl - ion is essentially the same. Finally, the method of second-order difference yields directly ion-ion correlations. The experiments described include Cl-Cl structure factors in NaCl and NiCl 2 solutions, and the Ni-Ni structure factor in NiCl 2 solutions. Comparisons made with theoretical predictions based on the primitive model of electrolytes show that in certain cases, the molecular nature of the water is a crucial factor in determining ion-ion correlations. In other cases, the primitive model contains most of the essential physics.

The magnetization density of hexacyanoferrate(III) ion measured by polarized neutron diffraction in Cs 2 KFe(CN) 6

1988 ◽  
Vol 419 (1857) ◽  
pp. 205-219 ◽  
Keyword(s):  
Neutron Diffraction ◽  
Iron Atom ◽  
Theoretical Calculations ◽  
Electronic Configuration ◽  
Dipole Approximation ◽  
Ligand Field ◽  
Cubic Symmetry ◽  
Structure Factors ◽  
Magnetization Density ◽  
Polarized Neutron

A polarized neutron diffraction experiment on Cs 2 KFe(CN) 6 gave 292 unique magnetic structure factors. These were analysed by using a model for the magnetization density of multipoles and valence functions on the iron and ligand atoms, with the dipole approximation for orbital effects. Neither the ligand nor the iron atom densities retain the cubic symmetry of the free ferricyanide ion. The natural axes of quantization of the iron atom are rotated by significant amounts from the Fe-CN vectors. The iron electronic configuration was found to be d -0.64(8) xy d 0.78(6) xz d 0.72(5) yz d -0.06(6) z 2 d 0.17(7) x 2 - y 2 corresponding to the cubic t 5 2g configuration of the low-spin d 5 Fe III ion perturbed to put all spin in the d xz and d yz orbitals. The negative spin in the d xy orbital and the 6% of negative spin on the carbon atoms conform with the qualitative predictions of previous ab initio theoretical calculations, although for d xy there are large manifestations of spin polarization. The 12% of spin delocalized onto nitrogen atoms reflects covalence. The ligand populations depart considerably from those for cubic symmetry, and can be understood in terms of spin occupation of molecular orbitals involving 3d-t 2g orbitals with coefficients d xy < d xz < d yz . These observations can be rationalized by an empirical model in which the ligand field components exerted by the cyanide groups are influenced by details of the crystal structure.

Structure of the Molten 37 a/o Cu-63 a/o Sb Alloy Using the Isotopic Substitution Method in Neutron Diffraction

1978 ◽  
Vol 33 (4) ◽  
pp. 472-479 ◽  
Author(s):  
W. Knoll ◽  
S. Steeb
Keyword(s):  
Neutron Diffraction ◽  
Pair Correlation ◽  
Neutron Diffraction Study ◽  
Number Density ◽  
Partial Structure ◽  
Distance Correlation ◽  
Structure Factors ◽  
Total Structure ◽  
The Fourier Transform ◽  
Strong Segregation

A neutron diffraction study of the eutectic Cu-Sb-melt containing 37 a/o Cu has been performed using isotopically enriched samples. The three partial structure factors describing the Cu-Cu, Cu-Sb, and Sb-Sb correlations have been determined as well as a second set of partial structure factors relating to the distance correlation of fluctuations in number density and concentration. Unsmoothed total structure factors were used. By Fourier-transformation the corresponding pair correlation functions were obtained. A strong segregation tendency was found. Concentration fluctuations with a correlation length of 2.4 Å could be determined. From the Fourier-transform of SCC the product N̄1α1 was obtained confirming the segregation tendency. The distance of nearest Cu-Cu neighbours in the eutectic Cu-Sb melt was found to be smaller than in pure molten Cu, whereas the Sb-Sb distance is larger than in pure Sb. According to Faber-Ziman theory the electrical resistivity was calculated and compared with experimental data.

Partial Atomic Distribution Functions of Liquid Fe75B25

1988 ◽  
Vol 43 (2) ◽  
pp. 177-180 ◽  
Author(s):  
N. Mattern ◽  
W. Matz ◽  
H. Hermann
Keyword(s):  
Neutron Diffraction ◽  
Short Range ◽  
Short Range Order ◽  
Distribution Functions ◽  
Range Order ◽  
Experimental Results ◽  
Partial Structure ◽  
X Ray ◽  
Atomic Distribution ◽  
Structure Factors

Abstract Partial structure factors and atomic distribution functions for liquid Fe75 B25 were determined for the Fe-Fe and Fe-B pairs by means of X-ray and neutron diffraction. The experimental results show a strong chemical short-range order in the melt which is similar to that of amorphous Fe75B25.

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