DepartmentofMaterialsScienceandEngineering,UniversityofWashington, Seattle,Washington98195-2120 Wefirstconsiderthepossiblereactionroutesleadingto theformationofeithersinglecrystallineormultiple-grained cobaltnanoparticlesinthereactioninvolvingdecomposition ofcobaltcarbonyl. 2,3 Atthebeginningofthesynthesis,a II.SYNTHESISSTRATEGY I.INTRODUCTION 0021-8979/2005/9710/10J317/3/$22.50 ©2005AmericanInstituteofPhysics 97,10J317-1 JOURNALOFAPPLIEDPHYSICS97,10J3172005 a