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

为了制备hcp-Co微粒，采用电弧蒸发法制备了含杂质金属元素（Pd、Os、Ru、Pt）的钴微粒。1.Co-Pd合金的饱和磁化强度M_s随Pd含量的增加而逐渐减小，当Pd含量为5at%时，M_s最大，约为140 emu/g。平均粒径强烈依赖于Pd的浓度，随着Pd含量的增加而减小，在50 at %Pd时，最小粒径约为4 nm。Co-Os合金的M_s随Os含量的增加而急剧减小，当Os含量为5at%时，M_s约为70 emu/g。平均粒径随Os含量的增加而减小，最小粒径约为8 nm。Co-Ru合金的M_s随Ru含量的增加而急剧减小，当Os含量为5at%时，M_s约为70 emu/g，平均粒径随Ru含量的增加而减小，最小粒径约为6 nm。4.Co-Pt合金的M_s随Pt含量的增加而减小，当Pt含量为5at%时，M_s约为100 emu/g。平均粒径强烈依赖于Pt浓度，随着Pt含量的增加而减小，最小粒径约为4 nm。Hc最大值为450 Oe，所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.