Objectives
Using a thermal plasma evaporation method where powder or liquid precursors containing some metal elements are supplied to the plasma, various metal oxides of multi-components can be synthesized as ultrafine particles or thin film. When the powder and liquid precursors were supplied to an RF thermal plasma, a ferro- or ferri-magnetic compound in Y-Fe-O system, having an XRD pattern not found in the JCPDS, was found in the synthesized powder. This led us to investigate the properties of the new phase and study the conditions at which we can synthesize it as pure single phase.
Results
To synthesize the new phase as a pure single-phase product, powder precursors prepared through the amorphous citrate gel method and liquid precursors of mixed nitrate solutions with various Y:Fe ratios were supplied to the plasma. The XRD patterns of products synthesized from powder precursors at S (side wall of collection chamber) in 4 experiments (E403, E405, E406, and E408) are shown in Fig. 1. All the products at S in these experiments were close to a pure single-phase form of the new phase. The smaller the Y:Fe ratio of the precursor becomes, the smaller the main peak of h-YFeO3 (30º) and the larger the peak near 32.7º becomes, which can probably
be ascribed to 
-Fe2O3. The XRD pattern of the product in E405, synthesized from the precursor with an Y:Fe ratio of 1:3.7, reveals that the new phase was synthesized as an almost pure single-phase product. Moreover, all these products, which were untreated after collection, had some magnetism.
Selected Publications
| 1) | Synthesis of Y-Fe-O Ultrafine Particles Using Inductively Coupled Plasma, J. Aerosol Sci. 29, 675-686, 1998. |
