The magnetization of a grain boundary in nickel

Magnetization of electrodeposited nickel: Role of interstitial carbon

“…The onset of grain growth in nanocrystalline nickel is above 600 K, although strain release begins at lower temperature. 13 The recovery of the Curie point on annealing was already noted by Cziráki et al, 8 but this is not the source of any change in moment in our foils; reducing T C from 627 to 608 K in itself reduces the room-temperature magnetization by less than 1%. We can envisage two possibilities: A significant, nonequilibrium concentration of ͑i͒ interstitial defects ͑nickel, hydrogen, carbon͒ or ͑ii͒ substitutional defects ͑nickel vacancies, carbon, oxygen͒.…”

“…On the other hand, a small-angle neutron scattering study of a planar 19.7°g rain boundary revealed a substantial increase of nickel moment in a low-density region of half-width 4 nm at the defect. 13 In the course of an investigation of the magnetization and magnetoresistance of electrodeposited Ni-Cu alloys, 14 we have found that some of these materials had a magnetization that was much lower than it ought to be according to the literature on annealed alloys. Here we focus on pure nickel in an effort to see if it also has a reduced magnetization and to understand the changes occurring on annealing.…”

Modeling of mechanical resonators used for nanocrystalline materials characterization and disease diagnosis of HIVs

“…Due to the ease of fabrication, most of micro/nano mechanical resonators are made of nanocrystalline silicon or nanocrystalline diamond (Tao et al 2014). Due to their distinct atomic structure (Gleiter et al 2000;Wang et al 2003;Kim and Bush 1999;Zhou et al 2007;Duan et al 2005;Fitzsimmons et al 1995;Swygenhoven et al 1999;Sanders et al 1997), grain boundaries have lower Young's moduli than the interior of the grains in polycrystalline materials (Sanders et al 1997;Fougere et al 1995;Xing et al 1998;Shen et al 1995;Wang et al 1995;Spriggs 1961;Boccaccini et al 1993). The grain boundary volume fraction could be as high as 50 % for a NcM whose grain average size is 5 nm (Sharma and Ganti 2003).…”

“…It had been attributed to the increase in the volume fraction of the grain boundary which has a lower Young's modulus due to the increase in the interatomic spacing and the increase in the amount of impurities residing in the grain boundary (Mohr et al 2014;Gleiter et al 2000;Wang et al 2003;Kim and Bush 1999;Zhou et al 2007;Duan et al 2005;Fitzsimmons et al 1995;Swygenhoven et al 1999;Sanders et al 1997). Thus, the atomic structure as well as the Young's modulus of the grain boundary significantly affects the behavior of NcMs in different applications.…”

“…In this research study, we propose a strategy which is based on a distributed-parameter model for the beam's structure and a micromechanical model for the beam's material, to estimate the Young's modulus of NcMs and Young's modulus of their grain boundaries. The density of the grain boundary of NcMs is also investigated with the aid of the density results for nickel reported by (Fitzsimmons et al 1995). Then, an atomic lattice model is proposed in order to mathematically estimate the effective Young's modulus of the material.…”