Self heating efficiency of CoFe2O4 nanoparticles: A comparative investigation on the conventional and microwave combustion method
Abstract In the present study, we have focused on opuntia dilenii haw mediated green synthesis of cobalt ferrite (CoFe 2 O 4 ) nanoparticles through microwave combustion method (MCM) and it is further compared with the conventional combustion method (CCM). The effect on structural, morphological, optical and magnetic properties of the synthesized nanoparticles was investigated systematically. In addition, the efficiency of self heating measurements was investigated for hyperthermia applications. X-ray diffraction studies confirmed the formation of single phase crystalline nature of CoFe 2 O 4 nanoparticles. The crystallite size of 58 nm and 49 nm is obtained for CCM and MCM respectively. The functional groups occurred at 597 cm −1 , 599 cm −1 , 427 cm −1 and 437 cm −1 that corresponds to Fe-O and Co-O bands at tetrahedral and octahedral sites are analyzed by FT-IR studies. Scanning electron microscopy images of the samples revealed the morphology as spherical with the average particle size range of 40–200 nm. The existence of Co, Fe, O present in the sample is confirmed by EDX analysis which shows the purity of the samples. UV–Visible diffuse reflectance spectroscopy is used to analyze the optical band gap energy of the samples estimated from Kubelka-Munk function as 2.01 eV, 1.93 eV for CCM and MCM respectively. The structural defects present in the samples are investigated by photoluminescence studies and the samples emit the light at two different wavelengths of 494 nm, and 621 nm. Vibrating sample magnetometer is carried out to analyze the magnetic properties of the samples at room temperature. The saturation magnetization of the CoFe 2 O 4 nanoparticles is found to be 77.29 emu/g and 68.76 emu/g for MCM and CCM respectively. The results obtained in this work suggested that the value of crystallite size, particle size, band gap value, luminescence intensities, and coercivity values increases with an increase in calcination temperature in conventional combustion method. Specific absorption rate (SAR) increases with a decrease in the crystallite size and particle size in microwave combustion method. The gradual increase in SAR is due to the hysteresis loss that occurs because of the ferromagnetic nature obtained by the microwave combustion method. An overview of the present work gives a summary on the green synthesis of magnetic nanoparticles, which provides comprehensive evaluation of hyperthermia through self heating process. Finally, from our results, the SAR obtained by microwave combustion method has higher efficiency compared to the conventional combustion method.