Modulated Structure Assisted Growth and Properties of Fe3O4 Nanoneedle Films Using a Thermal Oxidation Process in the Air

In the present work, a novel method for the modulated-structure assisted synthesis of 1-D Fe 3 O 4 nanoneedle arrays was introduced; that is, nanoneedles were first formed by thermal oxidation of the plated iron nanocrystalline layers in the air. The modulated structure consisted of three twined crystal planes with one straight crystal lattice along {110} crystal plane that played a key role in their growth and stabilization of the Fe 3 O 4 nanoneedles at high temperature in the air. The determining factors on the synthesis of the Fe 3 O 4 nanoneedles were systematically investigated, such as the plated nanocrystalline, the oxidation temperature and the plated metal kind and oxidation time. It was shown that the oxidation process was applicable to those of the easy-oxidized metal nanocrystlline layers. The growth of the nanoneedles was proposed because it is a self-limiting diffusion process under the local electrical field force at the solid/gas interface. The as-synthesized Fe 3 O 4 nanoneedles possessed excellent magnetic properties, and their field emission properties were first investigated, which showed it to be a potential material used as field emitter.