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

Abstract

To investigate the magnetic behaviour of starch coated cobalt ferrites, ve 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 con rmed 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 coprecipitation 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.

Light-Transmitting Measurements through Starch-Coated Cobalt Ferrite Ferrofluids Exposed to an External Magnetic Field

“…In group II, the nonzero coercive field values, , are higher than in the case of the samples in group I [22]. The sample with the highest obtained value (1219(1) emu/g) [22], synthesized in the microemulsion manner, almost showed the absence of the valley.…”

“…In group II, the nonzero coercive field values, , are higher than in the case of the samples in group I [22]. The sample with the highest obtained value (1219(1) emu/g) [22], synthesized in the microemulsion manner, almost showed the absence of the valley. Generally, the higher value, the broader the valley, as the consequence of the higher resistance of the investigated samples in group II to the external magnetic field.…”

“…Considering a need for alternative materials that exhibit improved magnetic properties, we have recently investigated the magnetic behavior of starchcoated cobalt ferrites prepared by coprecipitation, mechanochemical, ultrasonically assisted coprecipitation, microemulsion, and microwave-assisted hydrothermal methods. The choice of the synthesis procedure determines the magnetic properties of cobalt ferrites [22].…”

“…As a continuation of previous research [22], to examine the behavior and agglomeration of possible MRI contrast agents based on the synthesized starchcoated cobalt ferrites, the transmitted light measurements at the 655 nm wavelength were performed through the ferrofluid suspensions exposed to the external magnetic field of 200-400 mT. EXPERIMENT Ferrofluid suspensions were prepared from starchcoated cobalt ferrite powders [22]. 0.50 g of each starch-coated CoFe 2 O 4 was dispersed in 50 mL of deionized water.…”

Structural, morphological and magnetic investigations on cobalt ferrite nanoparticles obtained through green synthesis routes

“…These biomolecules increase the specificity toward cellular targets, prevent the agglomeration of the particles and also decrease the cytotoxicity of these particles [6]. The most commonly used biomolecules are the natural and synthetic polymers [7][8][9], the aminoacids [10], the polyhydroxycarboxylic acids and the bile acids [11].…”