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Lattice Site Occupancy in Ternary Ordered Ni_{3}Al_{1-x}Fe_{x} Alloys Estimated by EXAFS

100%

Ławniczak-Jabłońska K., Pascarelli S., Boscherini F., Kozubski R.

Extended X-ray absorption fine structure (EXAFS) spectroscopy offers additional experimental evidence to the solution of site occupancy problem in ternary NiAlX alloys. A study of local order in the stoichiometric Ni_{3}Al_{1-x}Fe_{x} ternary alloys (x = 0.02, 0.05, 0.10, 0.15, and 0.25) by EXAFS at the K-edge of Fe in the energy range from 7000 eV to 7600 eV are presented. Three models of substitutional behavior are considered - the preferential substitution of Fe atoms in: 1) Ni sites, 2) Al sites, 3) both sites. Data analysis was performed with theoretical and experimentally determined scattered photoelectron phases and amplitudes. The results of the EXAFS analysis are consistent with the picture in which most of the Fe atoms substitute Al sites and less than 25% of Fe atoms substitute Ni sites. Alloys with more than 10 at% of Fe showed higher tendency for ordering than those containing less than 10 at% Fe.

EXAFS Studies of Zn_{1-x}Mn_{x}S Ternary Compounds

76%

Zimnal-Starnawska M., Łażewski J., Kisiel A., Boscherini F., Pascareli S., Giriat W.

Acta Physica Polonica A

1994

vol. 86

issue 5

763-766

We performed extended X-ray absorption fine structure (EXAFS) measurements of Zn_{1-x}Mn_{x}S solid solution for various concentrations x in the range of 0 ≤ x ≤ 0.4. Data were collected on Zn and Mn K-edges with the use of synchrotron radiation from the ADONE storage ring in Frascati utilizing the Si(111) channel-cut monochromator. Applying the usual procedure of data reduction described elsewhere, we found well-defined different nearest-neighbor Zn-S and Mn-S distances, according to the previous results, almost independent on x. For Mn-S distances in the range of 0.1 ≤ x ≤ 1.0 we found, within the limit of experimental error, a constant value equal to 2.430±0.008 Å. For Zn-S distances for concentration changing from x = 0.0 to x = 0.4 we observed a weak, linear increase from 2.343±0.008 Å to 2.354 ± 0.008 Å, respectively.

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2 Acta Physica Polonica A

1 1994

1 1992

2 Boscherini F.

1 Giriat W.

1 Kisiel A.

1 Kozubski R.

1 Pascareli S.

1 Pascarelli S.

1 Zimnal-Starnawska M.

1 Ławniczak-Jabłońska K.

1 Łażewski J.

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Lattice Site Occupancy in Ternary Ordered Ni_{3}Al_{1-x}Fe_{x} Alloys Estimated by EXAFS

EXAFS Studies of Zn_{1-x}Mn_{x}S Ternary Compounds