TY - JOUR
T1 - Structures of the icosahedral clusters in Ni-Nb-Zr-H glassy alloys determined by first-principles molecular dynamics calculation and XAFS measurements
AU - Fukuhara, M.
AU - Fujima, N.
AU - Oji, H.
AU - Inoue, A.
AU - Emura, S.
N1 - Funding Information:
This work was supported by a Grant-In-Aid for Science Research in the priority Area ‘Research and Development Project on Advanced Metallic Glasses, Inorganic Materials and Joining Technology’ from the Ministry of Education, Science, Sports and Culture, Japan, and by the JSPS Asian CORE Program. The synchrotron radiation experiments were performed with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (Proposal No. 2007B1820).
PY - 2010/5/14
Y1 - 2010/5/14
N2 - To elucidate the hydrogen localization sites in the atomic clusters of Ni-Nb-Zr-H glassy alloys exhibiting room-temperature Coulomb oscillation, we investigated the effect of hydrogen on the electronic state of the elements forming the glassy alloys, as well as the coordinating position of the hydrogen atoms, by X-ray absorption fine structure (XAFS) analysis, referencing theoretical simulation results. The XANES (X-ray absorption near edge structure) part of the XAFS spectra for each (Ni, Zr and Nb) K-edge of (Ni0.36Nb0.24Zr0.40)89H11 shows clear multiple scattering effects caused by charged hydrogen atoms. The distorted Ni5Zr5Nb3 cluster with the maximum size of 0.55 nm is characterized by five Ni atoms constituting half a pentahedron and an opposite pentahedral Zr-Nb assembly. For the hydrogen localization sites, the first-principles calculations show that there are two Zr-Zr-Nb-Nb, four Zr-Zr-Zr-Nb, two Zr-Zr-Nb-Ni and two Zr-Zr-Zr-Ni tetrahedrons, in the order of stability.
AB - To elucidate the hydrogen localization sites in the atomic clusters of Ni-Nb-Zr-H glassy alloys exhibiting room-temperature Coulomb oscillation, we investigated the effect of hydrogen on the electronic state of the elements forming the glassy alloys, as well as the coordinating position of the hydrogen atoms, by X-ray absorption fine structure (XAFS) analysis, referencing theoretical simulation results. The XANES (X-ray absorption near edge structure) part of the XAFS spectra for each (Ni, Zr and Nb) K-edge of (Ni0.36Nb0.24Zr0.40)89H11 shows clear multiple scattering effects caused by charged hydrogen atoms. The distorted Ni5Zr5Nb3 cluster with the maximum size of 0.55 nm is characterized by five Ni atoms constituting half a pentahedron and an opposite pentahedral Zr-Nb assembly. For the hydrogen localization sites, the first-principles calculations show that there are two Zr-Zr-Nb-Nb, four Zr-Zr-Zr-Nb, two Zr-Zr-Nb-Ni and two Zr-Zr-Zr-Ni tetrahedrons, in the order of stability.
KW - Ab initio calculations
KW - Amorphous alloys
KW - Fine structure
KW - Structure of clusters
KW - XAFS
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U2 - 10.1016/j.jallcom.2010.02.188
DO - 10.1016/j.jallcom.2010.02.188
M3 - Article
AN - SCOPUS:77950923894
VL - 497
SP - 182
EP - 187
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
SN - 0925-8388
IS - 1-2
ER -