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|Title:||Dielectric tensor theory of electric field gradient in dilute transition metal based alloys: Application to vanadium alloys|
|Keywords:||Electric field gradient;Point defects;Dielectric screening|
|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.|
|ISSN:||0975-1041 (Online); 0019-5596 (Print)|
|Appears in Collections:||IJPAP Vol.43(12) [December 2005]|
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