Mechanical strain characteristics of cold worked Fe72Al28 and Fe75Ni25 alloys: A positron annihilation coincidence Doppler broadening view

2008 ◽  
Vol 16 (3) ◽  
pp. 440-446 ◽  
Author(s):  
Brajesh Pandey ◽  
H.C. Verma
Keyword(s):  
Positron Annihilation ◽  
Mechanical Strain ◽  
Doppler Broadening ◽  
Cold Worked ◽  
Coincidence Doppler Broadening

Positron annihilation lifetime and coincidence Doppler broadening study of γ-irradiated polyethylene

2005 ◽  
Vol 313 (1-3) ◽  
pp. 63-69 ◽  
Author(s):  
R.S. Yu ◽  
T. Suzuki ◽  
N. Djourelov ◽  
K. Kondo ◽  
Yasuo Ito ◽  
...  
Keyword(s):  
Positron Annihilation ◽  
Doppler Broadening ◽  
Positron Annihilation Lifetime ◽  
Coincidence Doppler Broadening

Ni-Substitution Induced Inversion in ZnFe2O4 Seen by Positron Annihilation

2012 ◽  
Vol 733 ◽  
pp. 219-223 ◽  
Author(s):  
P.M.G. Nambissan ◽  
O. Mondal ◽  
C. Chakrabarty ◽  
M. Pal
Keyword(s):  
Positron Annihilation ◽  
Spinel Structure ◽  
Positron Lifetime ◽  
Drastic Change ◽  
Doppler Broadening ◽  
Positron Trapping ◽  
Normal Spinel ◽  
Ni Substitution ◽  
Positron Lifetimes ◽  
Coincidence Doppler Broadening

We report in this work about the inversion of the spinel structure of ZnFe2O4induced by the substitution of Zn2+by Ni2+ions. Positron lifetimes were measured in Zn1-xNixFe2O4with different concentrations (x) of doped Ni2+ions and a drastic change across x = 0.4 – 0.6 was observed, which is attributed to this transformation. The interchange of positions of the cations on doping leaves a fraction of them unoccupied and these vacancies act as positron trapping centres. Since Ni2+is smaller in size than Zn2+, defects due to non-stoichiometry are less in NiFe2O4than in ZnFe2O4. The increase in positron lifetime implies the trapping of positrons being shifted from A- to B-sites and is an indication of the transformation from inverse to normal spinel configuration. Coincidence Doppler broadening measurements supported these findings.

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