Effects of size reduction on the structure and magnetic properties of core-shell Ni3Si/silica nanoparticles prepared by electrochemical synthesis

JOURNAL OF ALLOYS AND COMPOUNDS

卷:584

Article

Pigozzi, Giancarlo¹  Mukherji, Debashis²  Elerman, Yalcin³  Strunz, Pavel⁴  Gilles, Ralph⁵  Hoelzel, Markus⁵  Barbier, Bruno⁶  Schmutz, Patrik¹ 

[1] Empa, Swiss Fed Labs Mat Sci & Technol, CH-8600 Dubendorf, Switzerland

[2] Tech Univ Carolo Wilhelmina Braunschweig, Inst Werkstoffe, D-38106 Braunschweig, Germany

[3] Ankara Univ, Fac Engn, Dept Engn Phys, TR-06100 Ankara, Turkey

[4] Acad Sci Czech Republic, Inst Nucl Phys, CZ-25068 Rez, Czech Republic

[5] Tech Univ Munich, Forsch Neutronenquelle Heinz Maier Leibnitz MLZ, D-85747 Garching, Germany

[6] Steinmann Inst, D-53115 Bonn, Germany

关键词: Intermetallics;    Nanostructured materials;    Transition metal alloys and compounds;    Electrochemical synthesis;    Crystal structure;    Magnetic measurements;   

DOI  :  10.1016/j.jallcom.2013.09.035

来源: Elsevier

【 摘 要 】

Nanostructured nickel silicides find application in electronics, high-temperature alloys, electrode materials and catalysis. In this work, the effect of size reduction on the structure and magnetic properties of beta(1)-Ni3Si intermetallic phase nanoparticles is studied. Electrochemical selective phase dissolution (ESPD) was used to produce the beta(1)-Ni3Si nanoparticles of different sizes (from 20 to 215 nm) by extracting beta(1) nano-size precipitates from two-phase Ni-Si and Ni-Si-Al precursor alloys. The extracted nanoparticles have a core-shell structure with beta(1)-Ni3Si core and an amorphous silica shell. Particles size and shape are controlled by the composition and thermal treatment of the precursor alloys. Precipitates size is scaled without modifying the ordered L1(2) lattice structure. The bulk beta(1)-Ni3Si is ferromagnetic below 260 K with low saturation magnetization (2 emu/g), while the core-shell Ni3Si/silica nanoparticles are superparamagnetic at low temperatures (<9-11 K) with low coercivity (<90 Oe) and magnetization >20 emu/g at 5 T. It is suggested that weak particle magnetic moments and low magnetic anisotropy of the L12 structure are responsible for these properties. The shell on one hand protects the core from degradation; however the oxidation of the core/shell interface region can influence the magnetic behavior of the nano-powders. (C) 2013 Elsevier B. V. All rights reserved.

【 授权许可】

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