The influence of the starch coating on magnetic properties of nanosized cobalt ferrites obtained by different synthetic methods

Abstract

To investigate the magnetic behaviour of starch coated cobalt ferrites, five well established synthetic methods, i.e. co-precipitation, mechanochemical, ultrasonically assisted co-precipitation, microemulsion, and microwave-assisted hydrothermal syntheses were chosen for the materials’ preparation. Obtained cobalt ferrites had pure single-phase spinel structures. Scanning and transmission electron microscopy analyses revealed that the morphology of samples is not uniform, and aggregation of individual particles is a dominant process in all cases. Fourier-transform infrared spectra confirmed the presence of starch in all coated samples. The unusually higher magnetization of starch-coated samples than the magnetization of their as-prepared analogs obtained by co-precipitation, ultrasonically assisted co-precipitation and microwave-assisted hydrothermal methods might be explained by the Ostwald ripening mechanism induced by coating process. On the other hand, the decrease of saturation magnetization value was noticed for starch-functionalized nanomaterials synthesized in mechanochemical and microemulsion manner, in comparison to their as-prepared analogs, showing that the size distribution of such nanoparticles is narrow and the average diameter of the grains is near critical for the Ostwald ripening process.

A Novel Trace-Level Ammonia Gas Sensing Based on Flexible PAni-CoFe2O4 Nanocomposite Film at Room Temperature

“…FE-SEM analysis was performed to visualize the morphology of the as-synthesized CoFe 2 O 4 NPs, PET-PAni and PET-PAni-CoFe 2 O 4 (50%) sensors, Figure 6 . According to the results of FE-SEMSEM, the CoFe 2 O 4 NPs, Figure 6 a, have a tendency to agglomerate that is attributed to their ferrimagnetic properties [ 42 ] and sponge-like structure with porous morphology, which may have a great impact on the sensing properties. Despite the agglomeration and the blurred edges of CoFe 2 O 4 , the NPs are still uniform spheres with particle sizes of 70–80 nm.…”

Anti-Bacterial Iron Oxide Magnetic Nanoparticles based on Orange Peel Extract

“…Raman spectra was acquired in the range of 100-2000 cm -1 . Nonetheless, the active Raman bands for magnetite and maghemite are within 100-800 cm -1 (53,54). Therefore, Figure 3c shows the Raman spectrum of the 50GS-MNPs-Fe sample in 100-800 cm -1 .…”

“…The green synthesis (GS) of MNPs-Fe proposes reducing or replacing the conventional agents that are dangerous in their handling and has toxic composition, e.g., ammonium hydroxide (NH4OH) or sodium hydroxide (NaOH) (52)(53)(54)(55), with plant extracts obtained from leaves, fruits, seaweeds, and so on (56). These extracts have functional groups that act as reducing agents and stabilizing agents in the formation of the MNPs-Fe (57).…”