Synthesis and Magnetic Properties of BaFe12O19 Hexaferrite Nanoparticles by a Reverse Microemulsion Technique
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- 作者：Ping Xu ; Xijiang Han ; Maoju Wang
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：April 26, 2007
- 年：2007
- 卷：111
- 期：16
- 页码：5866 - 5870
- 全文大小：283K
- 年卷期：v.111,no.16(April 26, 2007)
- ISSN：1932-7455
文摘
BaFe12O19 hexaferrite nanoparticles, containing cetyltrimethylammonium chloride (CTAC), n-hexanol, andcyclohexane, were synthesized by a reverse microemulsion technique with a combination of (NH4)2CO3 andNH3·H2O as precipitator. Barium ferrite nanoparticles with 30 nm diameter and uniform flaky structure wereproved to be single magnetic domains, which have magnetic properties comparable to some of the best everreported for fine barium ferrite powders by chemical methods. Heat-treatment conditions can significantlyinfluence the formation of pure BaFe12O19 hexaferrite phase, where quenching and nonprecalcination wouldproduce intermediates of 
-Fe2O3 and BaFe2O4, as detected by X-ray diffraction (XRD) and Fourier transforminfrared (FT-IR) analyses, resulting in lower magnetic properties. High magnetocrystalline anisotropy constantK and energy barrier EA calculated from Stoner-Wohlfarth theory may also account for the high coercivityfor pure BaFe12O19. The variation of electrical conductivity during the formation and reaction of microemulsiondroplets suggests nonpercolating microemulsion conducting systems. Transmission electron microscopic (TEM)images of the microemulsion droplets from a microemulsion system with R = V(water):V(oil) = 1:8 displayedmicroemulsion droplets about 100 nm, containing a barium ferrite precursor "core" of about 30 nm in size,with collision and coalescence being discovered.
-Fe2O3 and BaFe2O4, as detected by X-ray diffraction (XRD) and Fourier transforminfrared (FT-IR) analyses, resulting in lower magnetic properties. High magnetocrystalline anisotropy constantK and energy barrier EA calculated from Stoner-Wohlfarth theory may also account for the high coercivityfor pure BaFe12O19. The variation of electrical conductivity during the formation and reaction of microemulsiondroplets suggests nonpercolating microemulsion conducting systems. Transmission electron microscopic (TEM)images of the microemulsion droplets from a microemulsion system with R = V(water):V(oil) = 1:8 displayedmicroemulsion droplets about 100 nm, containing a barium ferrite precursor "core" of about 30 nm in size,with collision and coalescence being discovered.