IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308 _______________________________________________________________________________________ Volume: 05 Special Issue: 04 | ICESMART-2016 | May-2016, Available @ http://www.esatjournals.org 401 BULK MAGNETIC PROPERTIES OF NANOSIZED SPINEL FERRITES Hina Bhargava 1 , K.T. Vasudevan 2 , N. Lakshmi 3 , K. Venugopalan 4 1 Associate Professor, Department of Physics, T John Institute of Technology, Bangalore, Karnataka, India 1 Corresponding Author: hinaoza@tjohngroup.com 2 Professor, Department of Physics, T John Institute of Technology, Bangalore, Karnataka, India 3 Professor, Department of Physics, Mohanlal Sukhadia University, Udaipur, Rajasthan, India 4 Professor, Department of Physics, Mohanlal Sukhadia University, Udaipur, Rajasthan, India Abstract Nanosized Co0.5Zn0.5Fe2O4 and Cu0.5Zn0.5Fe2O4 were prepared using Co-precipitation method. Using a combination of x ray diffraction, Mössbauer studies and DC magnetization, the magnetic properties of nano sized Co0.5Zn0.5Fe2O4 and Cu0.5Zn0.5Fe2O4 have been studied. Although the preparation conditions were kept same, the particle size of Cu0.5Zn0.5Fe2O4 (2.4nm) were smaller than that of Co0.5Zn0.5Fe2O4 (5.8nm) as the formation of Cu0.5Zn0.5Fe2O4 is more exothermic in nature that the formation of Co0.5Zn0.5Fe2O4. The dependence of DC magnetization on particle size and cation distribution have been studied. Keywords: Spinel ferrites, Co-precipitation, magnetic properties, Mössbauer spectroscopy --------------------------------------------------------------------***---------------------------------------------------------------------- 1. INTRODUCTION: Magnetic ferrite materials have been intensively studied during the past few decades to understand fundamental phenomena as well as due to their technological importance. These materials are used in a numerous technological applications such as high density magnetic storage devices, electronic communication devices, targeted drug delivery, sensors, magnetic printing inks, applications in ferrofluid technology, magnetic refrigeration, catalysts and in magnetic resonance imaging enhancement [1]. The magnetic properties of these systems are not only because of the cation distribution in different sites but also due to the reduced size of the magnetic particle [2].For this reason, various methods such as the ceramic method, sol gel, coprecipitation, solvent evaporation, hydrothermal, combustion, microemulsion and precursor methods have been reported in literature for the preparation of these nanoscale spinel ferrites [3]. The coprecipitation method is widely used for the preparation of ferrites [4] because it is economical and time saving and has overriding advantages such as the ease of controlling the composition, homogeneity, ability to be processed at lower temperatures and superior properties. The aim of the present work is to investigate the structural and magnetic properties of Co 0.5 Zn 0.5 Fe 2 O 4 and Cu 0.5 Zn 0.5 Fe 2 O 4 prepared by chemical co-precipitation method. 1.1 Experimental: The nano particles of Co 0.5 Zn 0.5 Fe 2 O 4 and Cu 0.5 Zn 0.5 Fe 2 O 4 were prepared by chemical co-precipitation method at 333K. For this purpose A.R. grade CuCl 2 .2H 2 O , CoCl 2 .6H 2 O, ZnCl 2 , and Fe(NO 3 ) 3 .2H 2 O were weighed in stoichiometric ratios then were mixed then dissolved in water, maintained at temperatures 333 K. To maintain pH value 10, 25% solution of NH 4 OH was added to the prepared solution. For the complete precipitation the solution was continuously stirred, at a constant temperature of 333K for 2 hrs. The precipitate was then washed and dried at 373 K for 24 hours. Nano sized samples were prepared by annealing the dried samples at 573 K for 24 hours. X-ray diffraction (XRD) spectra was obtained for structural characterization and determination of the average sizes of nano sized samples. Rigaku-Miniflex X-ray diffractometer with Cu-Kα radiation was used for the same. A standard Austin drive and controller assembly, in the constant acceleration mode were used to record Mössbauer spectra. 12 mCi 57 Co in Rhodium matrix was used as Mössbauer source and velocity calibration was done using metallic iron foil. Magnetic measurements were done using a 7300 vibrating sample magnetometer (VSM). The blocking temperatures (T B ) of nano sized samples were determined by plotting M vs. T, where M is the magnetic moment and T is the temperature from the zero field cooled (ZFC) curves over a temperature range of 20 K to 300 K. A small DC field of 50 Oe was used for FC-ZFC measurements. 1.2 Results And Discussion: 1. X-Ray Analysis: X-ray spectra of Co 0.5 Zn 0.5 Fe 2 O 4 and Cu 0.5 Zn 0.5 Fe 2 O 4 annealed at 300 o C is shown in Figure 1. From the X-ray spectra it is evident that both the samples have single phased spinel structure. The increase in the broadening of most intense peak (311) shows decrease in the particle size with the replacement of Co by Cu [Table 1]. Average particle size for the prepared samples is calculated using Scherrer formula [Table 1]: