Publication Date:
2017-09-02
Description:
In general, the technologically important ferrites nanoparticles, magnetite and maghemite, are converted from cubic to the more stable rhombohedral structure above 500-700 °C under air/vacuum/inert atmosphere. Here, we report, the superior thermal stability of polymer capped Fe 3 O 4 (PCIO) nanocluster (synthesized using microwave-assisted polyol approach) up to 1000 °C under vacuum and inert atmosphere. Raman spectra of post annealed PCIO nanoclusters show the Fe 3 O 4 phase with carbon signature due to the decomposition of polymer matrix. The carbon layer seems to act as a thermal shield and increases the activation energy thereby preventing the intrusion of heat, oxygen, volatiles mass into the magnetic core. The presence of carbon layer was further confirmed from the high resolution transmission electron microscopic image. After thermal annealing at 1000 °C, PCIO nanoclusters showed superparamagnetic behavior with a saturation magnetization of 89 emu/g, close to the bulk saturation magnetization of Fe 3 O 4 phase. In contrast, the uncoated Fe 3 O 4 (UCIO) nanoclusters decompose at 700 °C into α-Fe 2 O 3 and FeO phases under similar annealing conditions. Our findings open up new possibilities of stabilizing nanomaterials for high temperature applications. This article is protected by copyright. All rights reserved.
Print ISSN:
0002-7820
Electronic ISSN:
1551-2916
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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