Abstract
In this work, magnetic properties of activated carbon coal, which is also named amorphous carbon, were investigated. Composition and structure analysis was performed by XRD, SEM and EDS techniques. Position and width of peaks on XRD pattern confirmed amorphous structure of coals with small degree of graphitization. Magnetic measurements were performed by SQUID magnetometer. According to thermomagnetic measurements, in part of the samples, antiferromagnetic transition was observed near 120 K. Nature of such phenomena, as well as effect of oxygen and magnetic contaminations on thermomagnetic measurements are discussed referring to similar results from previous researches and data from literature.
Highlights
From ancient times carbon materials are widely used for many applications
Many researches have demonstrated impurity-free carbon materials, where spontaneous magnetization was observed (e.g. Ref. [2, 3]). Such possibility for carbon materials is predicted by many theoretical works (e.g. Ref [4]), meaning that magnetic carbon does not confront to general principles of magnetism
The X-ray diffraction (XRD) pattern demonstrated two broad peaks at 2θ ≈ 25° and 2θ ≈ 45°, which correspond to reflection from graphite (002) and (101) planes respectively
Summary
From ancient times carbon materials are widely used for many applications. After recent discoveries of fullerenes, carbon nanotubes and graphene, carbon-based materials became one of the most promising and universal materials. Among a variety of their outstanding mechanical, conductive and many other characteristics [1], exists a number of controversial topics. One of such problematic areas is possibility of making carbon materials magnetic. While the defect-induced paramagnetic behaviour is acknowledged, the problem of possibility of magnetic ordering in carbon materials is not solved yet. Many researches have demonstrated impurity-free carbon materials, where spontaneous magnetization was observed [2, 3]) Such possibility for carbon materials is predicted by many theoretical works (e.g. Ref [4]), meaning that magnetic carbon does not confront to general principles of magnetism. The question of intrinsic or extrinsic character and problem of the reproducibility of such results exists far
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