The role of citric acid for formation of nanocrystalline MnFe2O4 ferrite

The Nanocrystalline MnFe2O4 ferrite samples have been successfully synthesized by the sol gel method. The amount of citric acid play an important role in the formation of nano particle. The amount of citric acid is minimal, we have achieved a small particles size through this method. It is quite simple and cost-effective. The XRD Patterns confirms the cubic spinel single phase crystal structure. The crystallite size of three samples have been found less than 10 nm. The TEM images show the quantum dot size almost 2 nm which supports the FESEM results. The Energy Dispersive X-ray spectra confirms the appropriate doping in the sample. The Raman spectrum shows existing bands information in the sample. Raman spectrum also confirms the formation of nano particles in the MnFe2O4 ferrite sample. The FTIR spectra of the samples show formation of the nanoparticles. The sample of small particle shows the superparamagnetic behavior at room temperature. Conversely, the larger particle size sample, displayed ferromagnetic behavior at 300 K. Sample lowest particle size sample exhibits a transition in the ZFC mode at 73 K, whereas the highest particle size sample does not show any transition temperature. This behavior indicates that lowest particle size sample contains quantum-dot particles (less then 10 nm), while highest particle size sample exhibits typical of bulk samples behavior. The χ−1-T plots for both samples S1 and S7 are showing a Curie temperature at 73 K.