SYNTHESIS AND MAGNETIC PROPERTIES OF HCP COBALT FINE PARTICLES ENCAPSULATED IN CARBON NANOCAPSULES

以制备hcp-Co细颗粒为目的，采用电弧蒸发法制备了含有外源金属元素（Pd、Os、Ru、Pt）的钴颗粒。研究了碳纳米胶囊包裹Co合金颗粒的晶体结构和磁性能。随着Pd浓度的增加，Co-Pd合金的饱和磁化M_s逐渐减小，当Pd浓度为5%时，最大磁化M_s约为140 emu/g。平均粒径与Pd浓度密切相关，随Pd含量的增加而减小；在50% at %Pd时，最小尺寸约为4 nm。当粒径小、M_s大时，矫顽力H_c值较大；H_c的最大值为550 Oe.2。Co-Os合金随着Os浓度的增加而急剧下降；在% o时，M_s约为70 emu/g。平均粒径与Os浓度密切相关，随Os含量的增加而减小；最小尺寸约为8 nm。H_c的最大值为400oe .3。随着Ru浓度的增加，Co-Ru合金ym_s急剧下降；在% o时，M_s约为70 emu/g。平均粒径与Os浓度密切相关，随Ru含量的增加而减小；最小尺寸约为6 nm。H_c的最大值为450 o4。Co-Pt合金随Pt浓度的增加而降低；当Pt含量为5%时，平均粒径约为100 emu/g。平均粒径与Pt浓度密切相关，随Pt含量的增加而减小；最小尺寸约为4 nm。H_c的最大值为450 Oe。本研究制备的合金颗粒均为fcc结构，而非hcp结构。

Aiming at producing hcp-Co fine particles, particles of cobalt containing foreign metal elements (Pd, Os, Ru, Pt) were produced by arc evaporation. Crystal structures and magnetic properties of these Co alloy particles entrapped in carbon nanocapsules were investigated.1.Co-Pd alloySaturation magnetization M_s decreased gradually with the increase of Pd concentration, with the maximum M_s of about 140 emu/g at 5 at% Pd. Mean particle size was strongly dependent on Pd concentration, decreasing with the increase of Pd contnent ; the minimum size was about 4 nm at 50 at %Pd. Coercive force H_c showed large values when the particle size was small and the M_s was large ; the maximum of H_c was 550 Oe.2.Co-Os alloyM_s decreased steeply with the increase of Os concentration ; M_s was about 70 emu/g at 5 at% Os. Mean particle size was strongly dependent on Os concentration, decreasing with the increase of Os content ; the minimum size was about 8 nm. The maximum of H_c was 400 Oe.3.Co-Ru alloyM_s decreased steeply with the increase of Ru concentration ; M_s was about 70 emu/g at 5 at% Os. Mean particle size was strongly dependent on Os concentration, decreasing with the increase of Ru content ; the minimum size was about 6 nm. The maximum of H_c was 450 Oe.4.Co-Pt alloyM_s decreased with the increase of Pt concentration ; M_s was about 100 emu/g at 5 at% Pt. Mean particle size was strongly dependent on Pt concentration, decreasing with the increase of Pt content ; the minimum size was about 4 nm. The maximum of H_c was 450 Oe.All the alloy particles produced in the present study had the fcc structure instead of the hcp.