Identification of a Ni-vacancy defect in Ni-Mn-Z (Z = Ga, Sn, In): an experimental and DFT positron-annihilation study
Fecha
2019Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
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10.1103/PhysRevB.99.064108
Resumen
By means of experimental positron-annihilation-lifetime measurements and theoretical density functional
theory (DFT) positron-lifetime calculations, vacancy-type defects in Ni50Mn50−xSnx (x = 25, 20, 15, 13, 10) and Ni50Mn50−xInx (x = 25, 20, 16, 13) systems are systematically studied. The study is extended to Ni-Mn-Ga systems as well. Experimental results are complemented with electron-positron ...
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By means of experimental positron-annihilation-lifetime measurements and theoretical density functional
theory (DFT) positron-lifetime calculations, vacancy-type defects in Ni50Mn50−xSnx (x = 25, 20, 15, 13, 10) and Ni50Mn50−xInx (x = 25, 20, 16, 13) systems are systematically studied. The study is extended to Ni-Mn-Ga systems as well. Experimental results are complemented with electron-positron DFT calculations carried out within the local density approximation and generalized gradient approximation, where five different parametrizations accounting for the γ (r) enhancement factor are analyzed. Theoretical results indicate that the Boronski-Nieminen parametrization of γ (r) is the one that best predicts the experimental results, which ultimately enables us to identify VNi as the vacancy present in the studied samples. The characteristic positron lifetime related to VNi ranges between 181 and 191 ps in Ni-Mn-Sn/In systems. Positron-annihilation-lifetime spectroscopy results in these two systems delimit the lower bound of the achievable vacancy concentration, which is much larger compared with the reported values in Ni-Mn-Ga systems. The present work, along with setting the basis for positron simulations in Ni-Mn based Heusler alloys, delimits the effect that the variation of vacancies has in the martensitic transformation in Ni-Mn-Sn systems. [--]
Materias
Defects,
First order phase transitions,
Vacancies,
Heusler alloys,
Density functional theory,
Electron correlation calculations,
Positron annihilation spectroscopy
Editor
American Physical Society
Publicado en
Physical Review B 99, 064108 (2019)
Departamento
Universidad Pública de Navarra. Departamento de Ciencias /
Nafarroako Unibertsitate Publikoa. Zientziak Saila /
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. Institute for Advanced Materials and Mathematics - INAMAT2
Versión del editor
Entidades Financiadoras
This work is supported by Eusko Jaurlaritza under Grants
No. IT-1005-16 and No. IT-756-13 and by Spanish Ministry of
Economy and Competitiveness under Grant No. MAT2015-
65165-C2-R (MINECO/FEDER). I. Unzueta also wants to
acknowledge Eusko Jaurlaritza for Grant No. PRE-2014-214.