Open AccessCorrelation between local vibrations and metal mass in AlB 2 ‐type transition‐metal diborides
Author(s) -
Chu W. S.,
Zhang S.,
Yu M. J.,
Zheng L. R.,
Hu T. D.,
Zhao H. F.,
Marcelli A.,
Bianconi A.,
Saini N. L.,
Liu W. H.,
Wu Z. Y.
Publication year - 2009
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s0909049508030628
Subject(s) - extended x ray absorption fine structure , transition metal , anisotropy , decoupling (probability) , metal , materials science , boron , phonon , lattice vibration , condensed matter physics , molecular vibration , vibration , superconductivity , x ray absorption fine structure , lattice (music) , molecular physics , chemistry , absorption spectroscopy , spectroscopy , molecule , physics , optics , biochemistry , organic chemistry , quantum mechanics , control engineering , acoustics , metallurgy , engineering , catalysis
Lattice vibrations have been investigated in TiB 2 , ZrB 2 and HfB 2 by temperature‐dependent extended X‐ray absorption fine structure (EXAFS) experiments. Data clearly show that the EXAFS oscillations are characterized by an anomalous behavior of the Debye–Waller factor of the transition‐metal–boron pair, which is suggested to be associated with a superposition of an optical mode corresponding to phonon vibrations induced by the B sublattice and an acoustic mode corresponding to the transition‐metal (TM) sublattice. Data can be interpreted as a decoupling of the metal and boron vibrations observed in these transition‐metal diborides (TMB 2 ), a mechanism that may be responsible for the significant reduction of the superconducting transition temperature observed in these systems with respect to the parent MgB 2 compound. The vibrational behavior of TM–TM bonds has also been investigated to study the occurrence of anisotropy and anomalies in the lattice vibrational behavior of TM–TM bonds.