title: Control of Surface Segregation in Bimetallic NiCr Nanoalloys Immersed in Ag Matrix.
abstract: 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.
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.|Mahindra Ecole Centrale, Survey no: 62/1A, Bahadurpally Jeedimetla, Hyderabad-500043, Telangana India.
authors.forename: Murtaza
authors.initials: M
authors.lastname: Bohra
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.
authors.forename: Vidyadhar
authors.initials: V
authors.lastname: Singh
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Grammatikopoulos
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.
authors.forename: Evropi
authors.initials: E
authors.lastname: Toulkeridou
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.
authors.forename: Rosa E
authors.initials: RE
authors.lastname: Diaz
authors.affiliation: Centre d'Elaboration de Materiaux et d'Etudes Structurales (CEMES), 29 rue Jeanne Marvig, 31055 Toulouse Cedex 4, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Bobo
authors.affiliation: Nanoparticles by Design Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha Onna-Son, Okinawa, 904-0495, Japan.|Nanotechnology Research Laboratory, Al-Quds University, East Jerusalem, P.O. Box 51000, Palestine.
authors.forename: Mukhles
authors.initials: M
authors.lastname: Sowwan