Effect Of Grain Size On The Structural And Magnetic Properties Of Nanocrystalline Al3Fe5O12 By Aqueous Coprecipitation Method

Abstract

Al3Fe5O12 (AIG) nanopowders were synthesized at different pH using aqueous co-precipitation method. The effect of pH on the phase formation of AIG is characterized using XRD, TEM, FTIR and TG/DTA. From the Scherer formula, the particle sizes of the powders were found to be 15, 21, 25 and 30 nm for pH= 9, 10, 11 and 12, respectively. It is found that as the pH of the solution increase the particle size also increases. It is clear from the TG/DTA curves that as the pH is increasing the weight losses were found to be small. The nanopowders were sintered at 900°C/4hrs using conventional sintering method. The phase formation is completed at 800°C/4h which is correlated with TG/DTA. The average grain size of the samples is found to be ~55 nm. As the pH increases the magnetization values are also increasing. The saturation magnetization was found to be 4 emu/g, 6 emu/g, 7 emu/g and 9 emu/g corresponding to pH= 9, 10, 11 and 12, respectively which clearly shows that the magnetization values are dependent on pH. Room temperature magnetization measurements established these compounds to be soft magnetic. The dielectric and magnetic properties (εʹ, εʺ, µÊ¹ and µÊº) of AIG was studied over a wide range of frequency (1GHz-50GHz). With increase of pH both εʹ and µÊ¹ increased. This finding provides a new route for AIG materials that can be used in the gigahertz range.