Exchange-biased NiFe2O4/NiO nanocomposites derived from NiFe-layered double hydroxides as a single precursor
Layered double hydroxide, topotactic mechanism, interfacial interaction, exchange bias, magnetic stability
NiFe2O4 nanoparticles (<10 nm) embedded in a NiO matrix have been fabricated by calcining the corresponding NiⅡFeⅢ-layered double hydroxide (LDH) precursors at high temperature (500 °C). Compared with the NiFe2O4/NiO nanocomposite obtained by calcination of a precursor prepared by a traditional chemical coprecipitation method, those derived from NiFe-LDH precursors show much higher blocking temperatures (TB) (~380 K). The enhanced magnetic stability can be ascribed to the much stronger interfacial interaction between NiFe2O4 and NiO phases due to the topotactic nature of the transformation of the LDH precursor to the NiFe2O4/NiO composite material. Through tuning the NiⅡ/FeⅢ molar ratio of the NiFe-LDH precursor, the NiFe2O4 concentration can be precisely controlled, and the TB value as well as the magnetic properties of the final material can also be regulated. This work represents a successful example of the fabrication of ferro(ferri)magnetic (FM)/antiferrimagnetic (AFM) systems with high magnetic stability from LDH precursors. This method is general and may be readily extended to other FM/AFM systems due to the wide range of available LDH precursors.
Tsinghua University Press
Xiaofei Zhao,Sailong Xu,Lianying Wang,Xue Duan,Fazhi Zhang, Exchange-biased NiFe2O4/NiO nanocomposites derived from NiFe-layered double hydroxides as a single precursor. NanoRes.2010, 3: 200–210