Effect of zinc substitution on Co-Zn and Mn-Zn ferrite nanoparticles prepared by co-pecipitation

Co(1-x)ZnxFe2O4 and Mn((1-x))ZnxFe2O4 (x = 0.1-0.5) nanoparticles less than 12nm are prepared by chemical coprecipitation method which could be used for ferrofluid preparation. X-ray diffraction (XRD), Transmission electron microscopy (TEM), Vibrational sample magnetometer (VSM) and Thermo gravimetric analysis (TGA) are utilized in order to study the effect of variation in the Zn substitution and its impact on particle size, magnetic properties like M-S H-C, Curie temperature, thermomagnetic coefficient and associated water content. Atomic absorption spectroscopy was used for the estimation of cobalt, zinc and manganese and Fe 31 ion was estimated using spectrophotometer. The saturation magnetization of the Co-Zn substituted ferrite nanoparticles decreases continuously with the increase in Zn concentration, whereas for the Mn-Zn substituted ferrite nanoparticle the saturation magnetization was maximum for x = 0.2 and decreases on further increase in Zn concentration. The particle size decreases with the increase in the Zn concentration for both Co-Zn and Mn-Zn ferrites. The estimation of associated water content, which increases with the Zn concentration, plays a vital role for the correct determination of cation contents. The Curie temperature and the temperature at which maximum value of thermomagnetic coefficient observed simultaneously decrease with the increase in the initial substitution degree of zinc. (C) 2004 Elsevier B.V. All rights reserved.