A comparison of coprecipitation with microemulsion methods in the preparation of magnetite
- 15 April 1999
- journal article
- Published by AIP Publishing in Journal of Applied Physics
- Vol. 85 (8), 5231-5233
- https://doi.org/10.1063/1.369953
Abstract
Coprecipitation and microemulsion were used to prepare nanosized magnetite. The average particle sizes of samples A and B were calculated by Brunauer–Emmett–Teller analysis and are 8.16 and 2.24 nm, respectively. The saturation magnetization of sample A at 300 K was 57.2 emu/g, but sample B was not saturated even 7.0 T. The blocking temperature for sample B was 17 K and the crystalline anisotropy energy was 1.2×105 J/m3. At 5 K, sample B is ferrimagnetic with σs=7.62 emu/g. This value is much lower than the σs=65.4 emu/g of the crystallized sample A at 50 K. Mössbauer spectra showed that sample A was ferrimagnetic at room temperature, but sample B was superparamagnetic at T>Tb (critical blocking temperature).Keywords
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