Influence of Aluminum Addition on the Structure and Feathers of V2O5 Oxide Prepared by Mechanochemical Activation

The defect structure of the samples formed under mechanochemical activation (MCA) of V2O5 and mixed Al/V2O5 oxides has been analyzed. Al/V2O5 mixture is one of the most perspective thermites, and using the MCA, one can considerably increase the rate of its combustion, for example, by creating high concentration of the defects. To our knowledge, this scientifically interesting and probably applicable system has not been investigated in detail. Samples were characterized by X-ray diffraction, scanning electron microscopy, BET measurements, and X-band electron paramagnetic resonance spectroscopy. MCA of V2O5 at the split-stage was accompanied by forming the nanosized (∼80 nm) particles which contained various defects: boundaries of coherent scattering areas, microstrains, and paramagnetic centers (PCs) of two types. The first type of PCs contains the isolated defects (V4+ ions) located on the surface of nanoparticles, and the second type of PCs is a kind of clusters formed by V4+ PCs with a very high local concentration of defects. Increasing of the milling time results in dominance of friction processes accompanied by the increase of particle sizes and decreasing the specific surface area but, at the same time, the increase of grain surfaces, sizes of microstrains, and the PCs concentration. The aluminum addition stimulates aggregation processes of particles into composites, but the high concentration of different defects is preserved. We assume that our results concerning the Al/V2O5 system will be a serious supplement to the investigation of thermites prepared as a mixture of aluminum with different metal oxides.