Nanocomposites and nanomaterials

The formation amorphous and onion-like carbon at ball mill treatment of crystalline graphite 

Kirian I.M., Rud A.D., Lakhnik A.M.

G.V. Kurdyumov Institute for Metal Physics N.A.S. of Ukraine.
36 Academician Vernadsky Boulevard, Kiev 03142, Ukraine
E-mail: kiryan.inna@gmail.com
The amorphous carbon can be produced by high-energy ball-milling of graphite or high-frequency electrical discharge treatment of hydrocarbon precursors [1]. In our previous work, the onion-like structure was synthesis by high-frequency electric discharge treatment of propane-butane [1]. In this work, we have focused on the formation of different carbon allotropic forms at ball mill treatment of crystalline graphite.
Crystalline spectrally pure graphite powder was used as the starting material. The graphite was milled in argon gas atmosphere in the laboratory planetary ball mill at the room temperature for 0.5, 1, 2, 3.5, and 10 h. The rotation speed was 400 rpm. From XRD analysis it was found decreases of intensity and broadening of the diffraction peaks with increasing milling time. The increasing milling time to 3.5 h leads to formation amorphous phase in the milling process. After 10 h of ball milling (BM) treatment, complete amorphization of graphite takes place. The Raman spectra of the carbon materials produced at different BM times are characterized by intensive broad G- and D- bands. The structural parameters were calculated from the ratio of intensities of D-and G-bands – ID/IG. It was found the value of ID/IG increases with grinding time. It leads to a decrease in the sizes of blocks La along the direction а. From calculated data for 0.5, 1, 2, 3.5, and 10 h grinding La are 17.1, 13.7, 10.2, 9.6, and 7.4 nm, respectively. The electron microscopic studies were carried out for more detailed characterization of produced materials. High-resolution electron microscopy has shown that the individual particles have complex morphology which depends on the BM time. After 1 h of BM carbon materials characterized by an onion-like structure: an individual particle consists of multilayer partially closed defective graphene shells of irregular shape. In the middle of the particle is a disordered nucleus. The individual particles have a spheroidal shape with a size of ~ 10 nm. However, unlike the previous ones, after 10 hours of ball milling carbon nanomaterials are characterized by a disordered structure, which is typical for amorphous carbon.
The work was carried out within the framework of the youth project of the National Academy of Sciences of Ukraine № 06/01-2021(03).
1.	Rud A.D., Kiryan I.M. Quantitative analysis of the local atomic structure in disordered carbon // J. Non-Cryst. Solids. – 2014. – Vol. 386. – P. 1–7.