Thermal plasma synthesis of zinc ferrite nanopowders

Nanosized zinc ferrite spinel powders of various compositions were produced in a radiofrequency (RF) thermal plasma from oxide mixtures and from co-precipitated hydroxides. Bulk and surface chemical compositions of the products were measured by ICP-AES and XPS. Phase conditions were determined by XRD. Morphology was investigated by SEM and TEM. In spite of the short residence time of reagents in the plasma reactor, a high degree of spinel formation was achieved. The Zn enrichment on the surface determined by quantitative XPS is attributed to a thin ZnO layer on the surface of the zinc ferrite particles. In zinc ferrous ferrites. an inhomogeneous distribution of Zn inside the grains may also exist. (C) 2001 Elsevier Science B.V. All rights reserved.