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Journal ArticleDOI

Specific Absorption Rate Dependency on the Co2+ Distribution and Magnetic Properties in CoxMn1-xFe2O4 Nanoparticles.

TL;DR: In this paper, mixed ferrite and CoFe2O4 nanoparticles were synthesized by a simple chemical co-precipitation method using X-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, and Mossbauer spectrographs.
Abstract: Mixed ferrite nanoparticles with compositions CoxMn1-xFe2O4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were synthesized by a simple chemical co-precipitation method. The structure and morphology of the nanoparticles were obtained by X-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, and Mossbauer spectroscopy. The average crystallite sizes decreased with increasing x, starting with 34.9 ± 0.6 nm for MnFe2O4 (x = 0) and ending with 15.0 ± 0.3 nm for CoFe2O4 (x = 1.0). TEM images show an edge morphology with the majority of the particles having cubic geometry and wide size distributions. The mixed ferrite and CoFe2O4 nanoparticles have an inverse spinel structure indicated by the splitting of A1g peak at around 620 cm-1 in Raman spectra. The intensity ratios of the A1g(1) and A1g(2) peaks indicate significant redistribution of Co2+ and Fe3+ cations among tetrahedral and octahedral sites in the mixed ferrite nanoparticles. Magnetic hysterics loops show that all the particles possess significant remnant magnetization and coercivity at room temperature. The mass-normalized saturation magnetization is highest for the composition with x = 0.8 (67.63 emu/g), while CoFe2O4 has a value of 65.19 emu/g. The nanoparticles were PEG (poly ethylene glycol) coated and examined for the magneto thermic heating ability using alternating magnetic field. Heating profiles with frequencies of 333.45, 349.20, 390.15, 491.10, 634.45, and 765.95 kHz and 200, 250, 300, and 350 G field amplitudes were obtained. The composition with x = 0.2 (Co0.2Mn0.8Fe2O4) with saturation magnetization 57.41 emu/g shows the highest specific absorption rate (SAR) value of 190.61 W/g for 10 mg/mL water dispersions at a frequency of 765.95 kHz and 350 G field strength. The SAR values for the mixed ferrite and CoFe2O4 nanoparticles increase with increasing concentration of particle dispersions, whereas for MnFe2O4, nanoparticles decrease with increasing the concentration of particle dispersions. SARs obtained for Co0.2Mn0.8Fe2O4 and CoFe2O4 nanoparticles fixed in agar ferrogel dispersions at frequency of 765.95 kHz and 350 G field strength are 140.35 and 67.60 W/g, respectively. This study shows the importance of optimizing the occupancy of Co2+ among tetrahedral and octahedral sites of the spinel system, concentration of the magnetic nanoparticle dispersions, and viscosity of the surrounding medium on the magnetic properties and heating efficiencies.
Citations
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Journal ArticleDOI
TL;DR: In this article , high microwave response cobalt-substituted manganese ferrite (CMFO-0.5) was successfully synthesized as a heterogeneous catalyst for efficient peracetic acid (PAA) activation and tetracycline hydrochloride (TCH) degradation with singlet oxygen (1O2) as the dominated reactive oxidized species (ROS).

22 citations

Journal ArticleDOI
22 Sep 2021
TL;DR: In this article, an attempt to produce gadolinium-doped iron oxide nanoparticles for the purpose of utilization in magnetic fluid hyperthermia (MFH) was made.
Abstract: This study is an attempt to produce gadolinium-doped iron oxide nanoparticles for the purpose of utilization in magnetic fluid hyperthermia (MFH). Six gadolinium-doped iron oxide samples with varying gadolinium contents (GdxFe3−xO4,x=0, 0.02, 0.04, 0.06, 0.08, 0.1) were prepared using the hydrothermal method at 180 °C and high vapor pressure to incorporate gadolinium ions in the iron oxide structure. The samples were indexed as GdIO/x, with x varying from 0.0 to 0.1. The results reveal that gadolinium ions have a low solubility limit in the iron oxide lattice (x = 0.04). The addition of gadolinium caused distortion in the produced maghemite phase and formation of other phases. Based on X-ray diffraction (XRD) analysis and photoelectron spectroscopy (XPS), it was observed that gadolinium mostly crystalized as gadolinium hydroxide, Gd (OH)3 for gadolinium concentrations above the solubility limit. The measured magnetization values are consistent with the formed phases. The saturation magnetization values for all gadolinium-doped samples are lower than the undoped sample. The specific absorption rate (SAR) for the pure iron oxide samples was measured. Sample GdIO/0.04, pure iron oxide doped with gadolinium, showed the highest potential to produce heat at a frequency of 198 kHz. Therefore, the sample is considered to hold great promise as an MFH agent.

4 citations

Journal ArticleDOI
TL;DR: In this paper , the microstructural, optical, and magnetic properties and specific absorption rate (SAR) of bismuth ferrite/SiO2 nanoparticles were successfully investigated.
Abstract: In this study, the microstructural, optical, and magnetic properties and specific absorption rate (SAR) of bismuth ferrite/SiO2 nanoparticles were successfully investigated. The coprecipitation method was used to synthesize the nanoparticles. X-ray diffraction patterns showed the presence of sillenite-type Bi25FeO40 with a body-centered cubic structure. The crystallite size of Bi25FeO40 was 35.0 nm, which increased to 41.5 nm after SiO2 encapsulation. Transmission electron microscopy images confirmed that all samples were polycrystalline. The presence of Si–O–Si (siloxane) stretching at 1089 cm−1 in Fourier transform infrared spectra confirmed the encapsulation of SiO2. Magnetic measurements at room temperature indicated weak ferromagnetic properties of the samples. The coercivity of the bismuth ferrite nanoparticles was 78 Oe, which increased after SiO2 encapsulation. In contrast, their maximum magnetization, 0.54 emu g−1, reduced after SiO2 encapsulation. The determined bandgap energy of the bismuth ferrite nanoparticles was approximately 2.1 eV, which increased to 2.7 eV after SiO2 encapsulation. The effect of SiO2 encapsulation on the SAR of the samples was investigated using a calorimetric method. The SAR values of the bismuth ferrite nanoparticles were 49, 61, and 84 mW g−1 under alternating magnetic field (AMF) strengths of 150, 200, and 250 Oe, respectively, which decreased after SiO2 encapsulation. The maximum magnetization and the AMF strength influenced the SAR of the nanoparticles. The results showed that SiO2 has a significant effect in determining the microstructural, optical, and magnetic properties and SAR of the nanoparticles.

4 citations

Journal ArticleDOI
TL;DR: The Special Issue of Nanomaterials "Nanoparticles for Biomedical Applications" as discussed by the authors highlights the use of different types of nanoparticles for biomedical applications, including magnetic nanoparticles, mesoporous carbon nanoparticles.
Abstract: The Special Issue of Nanomaterials "Nanoparticles for Biomedical Applications" highlights the use of different types of nanoparticles for biomedical applications, including magnetic nanoparticles, mesoporous carbon nanoparticles, mesoporous bioactive glass nanoparticles, and mesoporous silica nanoparticles [...].

2 citations

Journal ArticleDOI
TL;DR: In this paper , bismuth ferrite nanoparticles were successfully synthesized by the co-precipitation method and modified by polyethylene glycol (PEG) 4000.
Abstract: Bismuth ferrite nanoparticles were successfully synthesized by the co-precipitation method and modified by polyethylene glycol (PEG) 4000. X-ray diffraction patterns showed a sillenite structure of bismuth ferrite (Bi25FeO40) with a crystallite size of 35.0 nm and the new phase appeared after surface modification. The new phase was Bi2Fe4O9. Crystallite size increased after surface modification of nanoparticles with PEG. The highest increase of crystallite size after surface modification with PEG was 40.1 nm. Transmission electron microscopy images showed that samples before and after surface modification were polycrystalline and still agglomerated. Spectra of Fourier transform infrared showed the presence of C-O stretching at 1080 cm-1 and C-H bending vibration at 1342 cm-1 in the bismuth ferrite/PEG sample, which did not appear in bismuth ferrite sample. The magnetic measurement indicated the weak ferromagnetic properties of the samples. Saturation magnetization did not appear after a maximum external magnetic field (15 kOe) was applied. The maximum magnetization of nanoparticles was 0.5 emu/g and tended to decrease to 0.2 emu/g after surface modification with PEG. Optical properties analysis showed a shift in the maximum absorption peak of bismuth ferrite nanoparticles towards a lower wavelength (blue shift) after surface modification of the nanoparticles. The specific absorption rate (SAR) value of nanoparticles increased by increasing an alternating magnetic field (AMF) strength. The SAR values of bismuth ferrite nanoparticles were 48.8, 61.4, and 84.4 mW/g and decreased to 32.0, 45.2, and 83.3 mW/g after surface modification at the AMF strength of 150, 200, and 250 Oe, respectively.
References
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Journal ArticleDOI
TL;DR: In this paper, the specific loss power of magnetic nanoparticles for hyperthermia was investigated with respect to optimization of the SLP for application in tumour hyper-thermia and the dependence of the loss power on the mean particle size was studied over a broad size range from superparamagnetic up to multidomain particles.
Abstract: Loss processes in magnetic nanoparticles are discussed with respect to optimization of the specific loss power (SLP) for application in tumour hyperthermia. Several types of magnetic iron oxide nanoparticles representative for different preparation methods (wet chemical precipitation, grinding, bacterial synthesis, magnetic size fractionation) are the subject of a comparative study of structural and magnetic properties. Since the specific loss power useful for hyperthermia is restricted by serious limitations of the alternating field amplitude and frequency, the effects of the latter are investigated experimentally in detail. The dependence of the SLP on the mean particle size is studied over a broad size range from superparamagnetic up to multidomain particles, and guidelines for achieving large SLP under the constraints valid for the field parameters are derived. Particles with the mean size of 18 nm having a narrow size distribution proved particularly useful. In particular, very high heating power may be delivered by bacterial magnetosomes, the best sample of which showed nearly 1 kW g −1 at 410 kHz and 10 kA m −1 . This value may even be exceeded by metallic magnetic particles, as indicated by measurements on cobalt particles.

919 citations

Journal ArticleDOI
TL;DR: In this article, the effect of nanoparticles concentration on heating efficiency was investigated in both Brownian and Neel-dominated regimes and it was shown that increasing nanoparticle concentration leads to a decrease in magnetic relaxation time with increasing nanoparticles.

603 citations

Journal ArticleDOI
TL;DR: Nanotechnology provides a novel and original solution with magnetic hyperthermia, which is based on the use of magnetic nanoparticles to remotely induce local heat when a radiofrequency magnetic field is applied, provoking a temperature increase in those tissues and organs where the tumoral cells are present.

423 citations

Journal ArticleDOI
TL;DR: This work discusses some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange an isotropy and dipolar interactions, and some physical and practical limitations of using MNPs in magnetic hyperthermia.
Abstract: Localized magnetic hyperthermia using magnetic nanoparticles (MNPs) under the application of small magnetic fields is a promising tool for treating small or deep-seated tumors. For this method to be applicable, the amount of MNPs used should be minimized. Hence, it is essential to enhance the power dissipation or heating efficiency of MNPs. Several factors influence the heating efficiency of MNPs, such as the amplitude and frequency of the applied magnetic field and the structural and magnetic properties of MNPs. We discuss some of the physics principles for effective heating of MNPs focusing on the role of surface anisotropy, interface exchange anisotropy and dipolar interactions. Basic magnetic properties of MNPs such as their superparamagnetic behavior, are briefly reviewed. The influence of temperature on anisotropy and magnetization of MNPs is discussed. Recent development in self-regulated hyperthermia is briefly discussed. Some physical and practical limitations of using MNPs in magnetic hyperthermia are also briefly discussed.

349 citations