Title of article :
Synthesis of nanocrystalline γ-Fe2O3 in silica matrix by mechanical crystallization from precursor at room temperature
Author/Authors :
J.M. Xue، نويسنده , , Z.H. Zhou، نويسنده , , J. Wang، نويسنده ,
Issue Information :
ماهنامه با شماره پیاپی سال 2002
Abstract :
γ-Fe2O3 nanocrystallites dispersed in an amorphous silica matrix have been successfully synthesized for the first time by mechanical activation of a chemistry-derived precursor at room temperature. At the initial 10 h of mechanical activation, nanocrystallites of Fe3O4 were triggered to form a highly activated matrix. With increasing mechanical activation time, phase transformation from Fe3O4 to γ-Fe2O3 occurs. γ-Fe2O3 phase was well established when the precursor was mechanically activated for 30 h. Further increasing the mechanical activation time to 40 h induced the formation of α-Fe2O3. The mechanical activation-grown γ-Fe2O3 nanocrystallites are ∼10–12 nm in size and they are well dispersed in the silica matrix as observed using TEM. They demonstrated superparamagnetic behavior at room temperature when measured using a vibrating sample magnetometer (VSM). In addition, the γ-Fe2O3 derived from 30 h of mechanical activation exhibited a saturation magnetization of as high as 62.6 emu g−1.
Keywords :
?-Fe2O3 , Nanocrystallites , Superparamagnetic , Mechanical activation
Journal title :
Materials Chemistry and Physics
Journal title :
Materials Chemistry and Physics