폴리올 공정을 통한 코발트 나노 입자 합성

Abstract

Cobalt particles have been utilized in various fields such as secondary battery cathode materials, additional elements of super heat-resisting alloys, binders of WC/Co hard materials. Also cobalt nanoparticle have been utilized in various catalyst because high specific surface of nanoparticles and magnetic recording and in medical sensors and bio medicine by magnetic properties. Research on the use of cobalt nanoparticles are increasing in these application fields. It is necessary the further studies on the synthesis of fine cobalt nanoparticles. In this study, cobalt nanoparticles were synthesized by polyol process. Polyol process has various advantages such as thermal stability, low cost and available controlling the cobalt size during the nucleation stage. However, cobalt is not generated by instantaneous nucleation but is generated by sequential nucleation over time. In the end, the growth of the particles occurs by continuous secondary nucleation during the polyol process and leads to problems controlling particle size. To overcome this problem, it is necessary to inhibit particle growth via the introduction of homogeneous nucleation. To overcome this problem it is necessary to inhibit particle growth. So sonication generates shock waves which form cavitation bubbles with high temperature and pressure. It is increasing the supply of electrons which are used for reducing cobalt ions via high energy source. Sonication was carried out for 50 minute ~ 120 minute the reaction ends in order to synthesize fine and uniform cobalt through the instantaneous nucleation of the cobalt ions. And the stabilized and dispersed by adding with (PVP), resulting in average cobalt nanoparticles size of 26.6 nm were synthesized. So that the improved results are obtained on this study is the synthesis of cobalt nanoparticles through the improved recovering method without PVP. Finally, cobalt nanoparticles of 20 nm to 30 nm were successfully synthesized by improved recovering method. The element of the synthesized cobalt nanoparticles was examined through X-ray Diffraction (XRD). The morphology of the synthesized cobalt nanoparticles was examined via field emission scanning electron microscopy (FE-SEM). Cobalt nanoparticle size and particle size distribution were measured by using a particle size analyzer (PSA).