Control of Surface Segregation in Bimetallic NiCr Nanoalloys Immersed in Ag Matrix

TY - JOUR

T1 - Control of Surface Segregation in Bimetallic NiCr Nanoalloys Immersed in Ag Matrix

AU - Bohra, Murtaza

AU - Singh, Vidyadhar

AU - Grammatikopoulos, Panagiotis

AU - Toulkeridou, Evropi

AU - Diaz, Rosa E.

AU - Bobo, Jean François

AU - Sowwan, Mukhles

N1 - Funding Information: This work was supported by funding from the Okinawa Institute of Science and Technology Graduate University.

PY - 2016/1/11

Y1 - 2016/1/11

N2 - Cr-surface segregation is a main roadblock encumbering many magneto-biomedical applications of bimetallic M-Cr nanoalloys (where M = Fe, Co and Ni). To overcome this problem, we developed Ni95Cr5:Ag nanocomposite as a model system, consisting of non-interacting Ni95Cr5 nanoalloys (5 ± 1 nm) immersed in non-magnetic Ag matrix by controlled simultaneous co-sputtering of Ni95Cr5 and Ag. We employed Curie temperature (TC) as an indicator of phase purity check of these nanocomposites, which is estimated to be around the bulk Ni95Cr5 value of 320 K. This confirms prevention of Cr-segregation and also entails effective control of surface oxidation. Compared to Cr-segregated Ni95Cr5 nanoalloy films and nanoclusters, we did not observe any unwanted magnetic effects such as presence Cr-antiferromagnetic transition, large non-saturation, exchange bias behavior (if any) or uncompensated higher TC values. These nanocomposites films also lose their unique magnetic properties only at elevated temperatures beyond application requirements (≥800 K), either by showing Ni-type behavior or by a complete conversion into Ni/Cr-oxides in vacuum and air environment, respectively.

AB - Cr-surface segregation is a main roadblock encumbering many magneto-biomedical applications of bimetallic M-Cr nanoalloys (where M = Fe, Co and Ni). To overcome this problem, we developed Ni95Cr5:Ag nanocomposite as a model system, consisting of non-interacting Ni95Cr5 nanoalloys (5 ± 1 nm) immersed in non-magnetic Ag matrix by controlled simultaneous co-sputtering of Ni95Cr5 and Ag. We employed Curie temperature (TC) as an indicator of phase purity check of these nanocomposites, which is estimated to be around the bulk Ni95Cr5 value of 320 K. This confirms prevention of Cr-segregation and also entails effective control of surface oxidation. Compared to Cr-segregated Ni95Cr5 nanoalloy films and nanoclusters, we did not observe any unwanted magnetic effects such as presence Cr-antiferromagnetic transition, large non-saturation, exchange bias behavior (if any) or uncompensated higher TC values. These nanocomposites films also lose their unique magnetic properties only at elevated temperatures beyond application requirements (≥800 K), either by showing Ni-type behavior or by a complete conversion into Ni/Cr-oxides in vacuum and air environment, respectively.

UR - http://www.scopus.com/inward/record.url?scp=84954163537&partnerID=8YFLogxK

U2 - 10.1038/srep19153

DO - 10.1038/srep19153

M3 - 文章

AN - SCOPUS:84954163537

SN - 2045-2322

VL - 6

JO - Scientific Reports

JF - Scientific Reports

M1 - 19153

ER -