Type

Journal Article

Authors

Michael A. Morris
Olga Kazakova
Mark P Copley
David J Otway
Justin D. Holmes
Louise Barry

Subjects

Chemistry

Topics
low temperature nickel sulfide chemistry magnetics curie temperature nanotechnology nickel nanoparticles

Unusual magnetism in templated NiS nanoparticles. (2010)

Abstract Nanostructured NiS was prepared by inclusion into anodic alumina templates. The resultant particles were found to be stoichiometric and highly crystalline. The particles displayed small particle superparamagnetism, and a low temperature (at 48 K (T(sg))) spin-freezing phenomenon (a spin-glass) and higher temperature (170 K) thermal blocking of small particle magnetic moment fluctuations were both observed for the first time for a sulfide material. Very unusually, these NiS materials are quite distinct from antiferromagnetic nanoparticulate sulfide materials, as they display a high temperature ferromagnetic-like phase. The saturation magnetization, the remanent magnetization, the coercivity and the ferromagnetic mass susceptibility were measured as 0.58 emu g( - 1) (at 100 K), 0.19 emu g( - 1), 219.5 Oe (at 170 K) and ∼ 900 × 10( - 6) emu Oe( - 1) g( - 1) respectively and these are consistent with a moderately strong ferromagnetism. The materials had an unexpectedly high Curie temperature of 390 K. The decrease of the saturation magnetization value at 30 K suggests that the ferromagnetic response is a surface phenomenon and the high coercivity of the paramagnetic component well above T(sg) suggests that the core can be described as superparamagnetic.
Collections Ireland -> University College Cork -> PubMed

Full list of authors on original publication

Michael A. Morris, Olga Kazakova, Mark P Copley, David J Otway, Justin D. Holmes, Louise Barry

Experts in our system

1
Michael A. Morris
University College Cork
Total Publications: 164
 
2
Justin D. Holmes
University College Cork
Total Publications: 287