Ferromagnetic carbon-coated iron and its compounds nanocrystallite synthesized at high metal to carbon rate and high yield by a modified AC arc method

Ferromagnetic: carbon-coated iron and its compounds nanocrystallite had bee n synthesized efficiently at high metal to carbon rate (up to 80 wt.%) and high yield (95%) by a new modified AC arc discharge. The mental to carbon r ate of the particles could be controlled by the pressure of the buffer gas. The morphology and structure of the carbon coating and materials enclosure were examined by high-resolution transmission electron microscopy (HRTEM) and X-ray diffractometer. The metal to carbon rate of the particles was det ermined by thermogravometric analysis (TG). The magnetic properties of thes e particles were measured with a vibrating sample magnetometer. Typical siz es of these particles were 10-30 nm. The metal to carbon rate ranged from 7 3.5 to 80.5 wt.% as the pressure of the He atmosphere charging from 0.06 to 0.01 MPa. The Br, Bs and Hc of particles made at the buffer gas pressure o f 0.01 MPa with a metal to carbon rate of 80 wt.% were 455.7 G, 3405 G and 219.4 Oe, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.