MORPHOLOGY AND MAGNETIC-PROPERTIES OF ULTRAFINE ZNFE2O4 PARTICLES

Well-crystallized ultrafine ZnFe2O4 particles of several nanometers in size have been prepared by the coprecipitation method, and their particle morphology and magnetic properties, especially at low temperatures, examined. Room-temperature X-ray diffraction, transmission electron microscopy, magnetization measurements at various temperatures from 300 K to 4.2 K, and Mössbauer spectroscopy at various temperatures from 300 K to 4.2 K, and at 4.2 K with a longitudinal magnetic field of 16.4 kOe applied have been employed. The formation of short-range and long-range magnetic order in small ZnFe2O4 particles above and below approximately 30 K is discussed. Below 30 K, the appearance of spontaneous magnetization and its hysteretic property is confirmed for small ZnFe2O4 particles. © 1990 Springer-Verlag.