Abstract
Maghemite (gamma-Fe(2)O(3)) is usually synthesized by magnetite under oxidizing conditions a few hours or a few days under temperature 300 degrees C. This paper introduces maghemite formed by quick heating to 700 degrees C of synthetic fine-grained (pseudo single domain, PSD, dominantly) magnetite. This maghemite shows almost completely reversible thermomagnetic behavior between room temperature and up to 700 degrees C. We used X-ray powder diffraction and Mossbauer spectroscopy to confirm the identity of this maghemite by comparing its magnetic hysteresis, high temperature magnetization and low temperature susceptibility with those of original preheated magnetite. Our study indicates that the thermal stability of maghemite is affected not only by its purity (stoichiometry), but also by its heating temperature and duration. Almost completely thermally stable maghemite can be formed by such rapid, high temperature oxidation of fine PSD magnetite. This implies that not all maghemite is thermally unstable, and that some maghemite, produced in certain heating environments, should be able to carry thermal remanent magnetization.
Original language | English |
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Title of host publication | Magnetic materials |
Subtitle of host publication | research, technology and applications |
Editors | Jacob I. Levine |
Place of Publication | New York |
Publisher | Nova Science Publishers |
Pages | 265-276 |
Number of pages | 12 |
ISBN (Electronic) | 9781606921456 |
Publication status | Published - 2009 |
Keywords
- CHINESE LOESS DEPOSITS
- SUSCEPTIBILITY
- PEDOGENESIS
- HYSTERESIS
- DEPENDENCE
- MINERALOGY
- STABILITY
- ORIGIN
- SOIL