Properties of Ferrimagnetic Nanoparticles Vary with Wet Chemical Synthesis

By Surbhi JainAug 29 2022Reviewed by Susha Cheriyedath, M.Sc.

In an article recently published in the journal Powder Technology, researchers discussed different wet chemical synthesis techniques for ferrimagnetic nanoparticle creation and their impact on the surface shape and magnetic characteristics. 

Study: Synthesis and effect on the surface morphology & magnetic properties of ferrimagnetic nanoparticles by different wet chemical synthesis methods. Image Credit: HaHanna/Shutterstock.com

Ferrimagnetic Nanoparticles

Due to their distinct magnetic properties of nanoparticles (Fe₃O₄, Fe₂O₃) and synthesis methods, ferrimagnetic nanoparticles (FMNPs) have experienced substantial nanoscience growth in recent years.

Since ferrimagnetic nanoparticles are often tiny in size, they frequently display superparamagnetic properties, a high surface area to volume ratio, a stable response, nontoxicity, and simple surface-area-to-volume ratio separation to an external magnetic field.

The magnetic field response shifts from ferrimagnetic to superparamagnetic when magnetic nanoparticle size decreases. One of the most challenging steps that affect their magnetic properties is synthesizing. Furthermore, magnetic nanoparticles with high coercivity are frequently difficult to demagnetize in the super magnetic state. Continued size reduction, however, will cause the coercivity value to drop quickly and eventually approach zero.

Superparamagnetic Nanoparticles

Superparamagnetic Fe₃O₄ nanoparticles show no signs of hysteresis loop or coercive force. They can only be magnetized externally, unlike ferrimagnetic nanoparticles. The features, form, morphology, appearance, size, and dispersibility of ferrimagnetic nanoparticles have an impact on their usefulness in diverse domains. Therefore, research focuses on synthesizing ferrimagnetic nanoparticles using multiple synthesis techniques to control their size, morphology, and shape with tunable properties. 

Synthesis of Ferrimagnetic Nanoparticles

In this study, the authors used different techniques for the wet chemical synthesis of ferrimagnetic nanoparticles. The synthesis of ferrimagnetic nanoparticles specifically utilized the chemical co-precipitation method (CCPM), hydrothermal method (HM), sol-gel technique (SGM), and sonochemical method (SM).

The study intends to investigate how various synthesis techniques affect the structural and magnetic characteristics of synthesized ferrimagnetic nanoparticles.

The team used X-Ray diffraction (XRD), scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), particle size distribution, zeta potential, and vibrating sample magnetometer (VSM) to characterize the chemical composition, physical morphology, and magnetic properties of the ferrimagnetic nanoparticles.

To create Fe₃O₄ nanoparticles with various morphologies and functions, the researchers used changeable reaction parameters.

Characteristics of Synthesized Ferrimagnetic Nanoparticles

The experiments found that the ferrimagnetic nanoparticles made by CCPM had a stable cubical form of 11.80 nm. The chemical co-precipitation method outperformed the other wet-chemical approaches in terms of efficiency, cost, and time. However, ferrimagnetic nanoparticles made using the hydrothermal approach displayed stronger magnetic properties, measuring 89.34 electromagnetic unit/gram and having an appropriate particle size distribution of -24.43 millivolts. Sol-gel synthesis took the longest synthesis time, which was then followed by hydrothermal, sonochemical, and co-precipitation synthesis.

For Fe₃O₄ nanoparticles of higher intensity, the XRD profile of the sonochemical and hydrothermal production process showed a crisp and crystalline structure (311). The sol-gel and co-precipitation approach, on the other hand, showed a lower intensity. The size of the ferrimagnetic nanoparticles was in the decreasing order of HM<SM<SGM<CCPM, and the theoretical shape of the structure for the wet-chemical procedures was cubic. The O-H bonds' stretching and bending vibrations for CCPM, SGM, HM, and SM were represented by the ferrimagnetic nanoparticle samples' FTIR spectra at 3437.52, 3444.84, 3466.28, and 3437.39 centimeter^-1, respectively.

The cuboid structure of Fe₃O₄ nanoparticles was visible in the SEM micrographs and EDS data. The zeta potential analysis revealed the degree of dispersion, the stability of the suspension, and the direction of charged particles' movement in a suspension.

Ferrimagnetic nanoparticles were found to have zeta potentials of -25.56 millivolts for CCPM, -24.43 millivolts for HM, -23.03 millivolts for SGM, and -9.86 millivolts for SM, respectively. Additionally, it showed Z-Average (d.nm) values for CCPM of 453.96 nanometers, HM of 406.12 nanometers, SGM of 247.10 nanometers, and SM of 67.34 nanometers. The saturation magnetization (M_s) data showed that the samples' graph enlarged as the particle size decreased, which was consistent with VSM. 

Conclusions and Future Perspectives

In conclusion, this study discussed the development of numerous diverse types of dispersed nanocrystals with controllable optical properties, shape, size, and nanoparticle structure using the HM, SM, SGM, and CCPM methods.

It was discovered that when deciding on synthesis methods, ferrimagnetic nanoparticles in the colloidal form are crucial due to their numerous applications. The CCPM, HM, SGM, and SM techniques achieved significant advancements in synthesizing ferrimagnetic nanoparticles for use in nanotechnology. Due to its low equipment cost, CCPM was a cheap and affordable synthesis process in terms of cost-effectiveness. But because of the high cost of its equipment and other supporting equipment, SM was comparatively more expensive. 

Reference

Kumar, A., Gangawane, K. M. (2022). Synthesis and effect on the surface morphology & magnetic properties of ferrimagnetic nanoparticles by different wet chemical synthesis methods. Powder Technology, 117867. https://www.sciencedirect.com/science/article/abs/pii/S0032591022007483

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