Mechanochemical synthesis and characterization of pure Co$_2$B nanocrystals

Bulletin of Materials Science

关键词: Cobalt boride;    mechanochemical synthesis;    transition metals;    ball milling;    nanocrystals.;   

学科分类：材料工程

来源: Indian Academy of Sciences

【 摘 要 】

Cobalt boride (Co$_2$B) is a significant transition metal boride having a wide range of usage area due to its high oxidation, abrasion and corrosion resistance as well as its superior electrochemical, magnetic and anisotropicproperties. In this study, pure Co2B nanocrystals were synthesized with Co, B$_2$O$_3$ and Mg as starting materials via the mechanochemical synthesis (MCS) method by high-energy planetary ball mill in a hardened steel vial withhardened steel balls. All the experiments were conducted under Ar atmosphere at different rotational speeds and at 20:1–30:1–40:1 ball-to-powder ratios. Leaching of Co$_2$B $+$ MgO powder mixtures occurred after milling andpurified with acetic acid and pure Co$_2$B nanocrystals were obtained in solid form. The Co2Bs were characterized through X-ray diffraction, scanning electronmicroscopy, vibrating samplemagnetometer, Brunauer–Emmett–Tellerand specific density analyses, and effects of synthesis parameters on product properties were revealed. Surface areas of the powders synthesized at 40:1 ball-to-powder ratio at different rotational speeds were measured as 21.14,40.36 and 52.33 m$^2$ g$^{−1}$, respectively. Crystallite sizes of Co$_2$B nanocrystals were between 7.27 and 9.84 nm and their specific density varied between 7.61 and 7.78 g cm$^{−3}$. It was determined that all samples were saturated and exhibited hysteresis and ferromagnetic behaviours, and saturation magnetization was between 35 and 50 emu g$^{−1}$.

【 授权许可】

CC BY