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Large Magnetocaloric Effect, Moment, and Coercivity Enhancement after Coating Ni Nanoparticles with Ag
Author(s) -
Srinath Sanyadanam,
Poddar Pankaj,
Das Raja,
Sidhaye Deepti,
Prasad Bhagavatula Lakshmi Vara,
Gass James,
Srikanth Hariharan
Publication year - 2014
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300886
Subject(s) - coercivity , materials science , magnetic refrigeration , nanoparticle , superparamagnetism , condensed matter physics , magnetization , magnetic moment , pulmonary surfactant , magnetic nanoparticles , chemical engineering , nanotechnology , magnetic field , physics , quantum mechanics , engineering
We observe a large magnetocaloric effect in monodisperse Ni and Ni core Ag shell nanoparticles in the superparamagnetic region. The organically passivated Ni nanospheres show a large magnetic entropy change of 0.9 J kg −1 K for a 3 T magnetic field change. In comparison to the surfactant‐coated Ni nanoparticles, the Ni core Ag shell nanoparticles show an enhanced coercivity, magnetization, and magnetocaloric effect (1.3 kg K for a 3 T magnetic field change). The coercivity at 10 K increases from 360 Oe for Ni nanoparticles to nearly 610 Oe for Ni core Ag shell particles. This large enhancement is attributed to the enhanced inter‐particle interaction, which is mediated by the metallic shell, over the relatively weaker dipolar interaction in the surfactant‐coated Ni nanoparticles, and to modification of the surface spin structure.