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Indian Journal of Pure & Applied Physics (IJPAP) >
IJPAP Vol.43 [2005] >
IJPAP Vol.43(12) [December 2005] >
| Title: | Dielectric tensor theory of electric field gradient in dilute transition metal based alloys: Application to vanadium alloys |
| Authors: | Pal, B
Singh, J |
| Keywords: | Electric field gradient
Point defects
Dielectric screening |
| Issue Date: | Dec-2005 |
| Publisher: | CSIR |
| IPC Code: | G01R31/12 |
| Abstract: | The electric field
gradient (EFG) in dilute alloys consists of two contributions valence effect
and size effect EFGs. In the estimation of valence effect EFG an electrostatic
screening approach is used to evaluate impurity scattering potential in
transition metal (TM) based alloys. The dielectric tensor is inverted using the
mixed band scheme where s-electrons
are represented in free electron approximation and d-electrons in simple tight binding approximation. In this scheme
the exact expression is obtained for the excess impurity potential  V(r) which consists of isotropic and anisotropic parts. The latter is
the manifestation of local field (LF) effects in TM based alloys. The numerical
results for V(r) are obtained for
vanadium (V) alloys with Ti, Cr, Mn, Fe, Mo and W impurities using non-interacting
model band structure. The size effect contribution to EFG is evaluated in the
elastic continuum approach. The EFG is calculated for the above mentioned
V-alloys including the LF effects. The calculated results for EFG are
consistent with experimental predictions and suggest that both the valence and
size effects are equally important to explain the experimental results. |
| Page(s): | 972-976 |
| ISSN: | 0975-1041 (Online); 0019-5596 (Print) |
| Source: | IJPAP Vol.43(12) [December 2005]
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