Synthesis and characterization of structure and magnetic properties of ferrite nanoparticles prepared by thermal treatment method

Spinel ferrite nanocrystals are regarded as one of the most important inorganic nanomaterials because of their electronic, optical, electrical, magnetic, and catalytic properties. These properties are dependent on the chemical composition and microstructural characteristics in which the particle size and shape might be controlled in the fabrication processes. The preparation of spinel ferrite nanocrystals through different routes has become an essential in research and development. But,the most commonly applied synthesis methods are difficult to employ on a large scale because of their complicated procedures, high reaction temperatures, long reaction times, toxic reagents and by-products, and their potential harm to the environment. In this thesis a simple thermal treatment method is described for synthesis of spinel ferrite MFe2O4 (M = Ni, Co, Mn, Zn, or their binary metal) nanoparticles. In this method, an aqueous solution of poly (vinyl pyrrolidone) (PVP was prepared by dissolving the polymer in deionized water at 343 K before adding iron nitrate and respective metal nitrates and constantly stirring at 353 K for 2 h. The dissolved solution was heated until dried at 353 K for 24 h on a glass Petri dish. The solid and orange coloured transparent remains were crushed and ground in a mortar to form powder before calcinations at different temperatures for 3 h to decompose organic matters and crystallized the ferrite nanparticles. We concluded that the effect and role of PVP in the synthesis of cobalt ferrite nanoparticles by the thermal treatment method is astonishing. Briefly, as was discussed when we considered our XRD results, TEM images, and FT-IR spectra, PVP plays four crucial roles in synthesizing cobalt ferrite nanoparticles, i.e., (1) the control of the growth of the nanoparticles by varying the concentration of PVP; (2) the prevention of agglomeration of the nanoparticles; (3) the enhancement of the degree of the crystallinity of the nanoparticles, and (4) the production of nanoparticles that have a uniform distribution of shapes. Thermo-gravimetry analyses was used to estimate a range of calcination temperature where the polymer mass loss started at 678 K and has the maximum decomposition at 778 K. The optimum calcination temperature was confirmed by Fourier transform infrared spectroscopy (FTIR) measurement by the presence of metal oxide bands at all temperatures and the absence of organic bands at 723 and 823 K for NiFe2O4 and CoFe2O4 nanoparticles and at 873 K for,MnFe2O4, ZnFe2O4 and Nix Co1-x Fe2O4 nanoparticles. The transmission electron microscopy (TEM) images showed cubical spinel ferrite nanoparticles that were uniform in both morphology and particle size distribution. The x-ray diffraction (XRD) diffraction patterns showed crystalline phases that confirmed the formation of nanocrystalline single-phase spinel ferrite nanoparticles with a face-centered cubic structure, common structure for nanomaterials. The average particle sizes were determined from TEM images and found the particle size increased with the calcinations temperature from 7 to 47 nm for NiFe2O4, from 12.5 to 39 for CoFe2O4,from 12 to 22 nm for MnFe2O4, from 17 to 31 nm for ZnFe2O4 and from 14 to 25 nm for Nix Co1-x Fe2O4 nanoparticles. These sizes are in a good agreement with XRD results. The magnetic properties were determined by vibrating sample magnetometer (VSM),which showed that the calcined samples exhibited ferromagnetic, ferromagnetic or superparamagnetic behaviors. The VSM results displayed ferromagnetic behaviors for NiFe2O4, CoFe2O4, and Nix Co1-x Fe2O4 nanoparticles and super paramagnetic behaviors for MnFe2O4 and ZnFe2O4 nanoparticles. The magnetic properties acquired by VSM, such as saturation magnetization and coercivity field are dependent on the calcination temperatures. The magnetic properties were also confirmed by the use of electron paramagnetic resonance (EPR) spectroscopy, which revealed the existence of unpaired electrons and also measured peak-to-peak line width (ΔHpp), resonant magnetic field (Hr), and the g-factor for MnFe2O4 and ZnFe2O4 nanoparticles while NiFe2O4, CoFe2O4, and Nix Co1-x Fe2O4 nanoparticles did not exhibit resonance signal. This could be possibly due to the super exchange interaction produces that occurs in these nanoparticles. Our results show that we have succeeded in fabricating crystalline NiFe2O4,CoFe2O4, MnFe2O4, ZnFe2O4 and Nix Co1-x Fe2O4 nanoparticles by a simple thermal treatment method. This method is cost-effective, environmentally-friendly, has low reaction temperatures, and produced no by-product effluents. It can be extended to fabricating other spinel ferrite nanoparticles of interest or other metallic oxides nanocrystals

The amazing effects and role of PVP on the crystallinity, phase composition and morphology of nickel ferrite nanoparticles prepared by thermal treatment method

Nickel ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various concentrations of poly(vinylpyrrolidone) followed by calcination temperature. X-ray diffraction (XRD) analysis was performed to determine the degree of crystallinity of the ferrite nanoparticles. By transmission electron microscopy, the morphology and average particle size of the nickel ferrite nanoparticles were evaluated which had good agreement with the XRD results. Fourier transform infrared spectroscopy suggested the presence of metal oxide bands in all samples as well as the effective elimination of organic constituents after calcinations. Measurements of the extent of magnetization of the nickel ferrite nanoparticles synthesized in different concentrations were obtained at room temperature using a vibrating sample magnetometer

Fabrication, characterization, and magnetic properties of copper ferrite nanoparticles prepared by a simple, thermal-treatment method

Tetragonal copper ferrite nanoparticles were fabricated by a thermal-treatment method by using a solution that contained poly(vinyl alcohol) (PVA) as a capping agent and Cu and Fe nitrates as alternative sources of metal. Heat treatment was conducted at temperatures between 673 and 823 K, and final products had different crystallite sizes ranging from 11 to 42 nm. The influence of calcination temperature on the degree of crystallinity, morphology, microstructure, and phase composition was investigated by different characterization techniques, i.e., X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), and Fourier transform infrared (FT-IR) spectroscopy, respectively. The compositions of the samples were determined by energy dispersion X-ray analysis (EDXA), which revealed the presence of Cu, Fe, and O in the samples. The formed nanoparticles exhibited ferromagnetic behavior with unpaired electrons spins, which was confirmed by using a vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy

Synthesis and characterization of zinc ferrite nanoparticles by a thermal treatment method

Crystalline zinc ferrite (ZnFe2O4) was prepared by the thermal treatment method, followed by calcination at various temperatures from 723 to 873 K. Poly (vinyl pyrrolidon) (PVP) was used as a capping agent to stabilize the particles and prevent them from agglomeration. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle sizes of 1731 nm were obtained by TEM images, which were in good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands at all temperatures and the absence of organic bands at 873 K. The magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed super paramagnetic behaviors for the calcined samples. The present study also substantiated that, in ferrites, the values of the quantities that were acquired by VSM, such as the saturation magnetization and coercivity field, are primarily dependent on the methods of preparation of the ferrites. Electron paramagnetic resonance (EPR) spectroscopy showed the existence of unpaired electrons and measured the peak-to-peak line width (Δ Hpp), the resonant magnetic field (Hr), and the g-factor values

A simple thermal treatment synthesis and characterization of Ni-Zn ferrite (Ni0.5Zn0.5Fe2O4) nanocrystals

Cubic structured nickel-zinc ferrite nanoparticles (Ni0.5Zn0.5Fe2O4) have been synthesized by thermal treatment method. This simple procedure employed an aqueous solution containing only metal nitrates as precursors, polyvinyl pyrrolidone as a capping agent, and deionized water as a solvent. The solution was thoroughly stirred for 2 hour, dried at 353 K for 3 hour, the dried material crushed into powder and calcined the powder at 873 K to remove organic substances and crystallize the particles. The microstructure properties of the prepared ferrite nanoparticles were measured using FTIR, XRD, TEM, and EDX and the magnetic properties were determined using VSM and EPR. The average particle size increased from 7 to 22 nm with the increase of calcination temperature from 723 to 873 K. The saturation magnetization, coercivity field, and g-factor increased respectively from 24 emu/g, 11 G, and 2.0673at 723 K to 38 emu/g, 60 G, and 2.1227 at 873 K. This method offers simplicity, a low cost, and an environmentally friendly operation since it produces no by-product effluents

Simple synthesis and characterization of cobalt ferrite nanoparticles by a thermal treatment method

Crystalline, magnetic, cobalt ferrite nanoparticles were synthesized from an aqueous solution containing metal nitrates and polyvinyl pyrrolidone (PVP) as a capping agent by a thermal treatment followed by calcination at various temperatures from 673 to 923?K. The structural characteristics of the calcined samples were determined by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). A completed crystallization occurred at 823 and 923?K, as shown by the absence of organic absorption bands in the FT-IR spectrum. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors

Influence of chimney effect on the radon effective dose of the lung simulated for radon prone areas of Ramsar in winter season

One of the well-known radon prone areas of the world is Ramsar in Iran, which is surrounded by the Alborz Mountain in its southern part and Caspian Sea on the north. The annual effective dose in the district of Talesh-Mahalleh is higher than the annual dose limits for radiation workers. In this study, the indoor radon level and effective dose of the lung were estimated using a Prassi portable radon gas survey meter in a model house containing top soil samples from different parts of Ramsar. For the extremely hot samples, the effective dose of the lung in winter season was 27.75±2.55mSv, when the windows and exhaust part of chimney were closed. However, when the chimney was turned on and the exhaust part of chimney was open, the effective dose of the lung was reduced to 1.27±0.23mSv. Also the seasonal radon effective doses of the lung with other samples were reduced to low values. The results suggest by using chimney effect and chimney heaters a significant lessening of the radon seasonal effective dose in dwellings of Ramsar can be achieved

Laser based fabrication of chitosan mediated silver nanoparticles

We report fabrication of silver nanoparticles (Ag NPs) by laser ablation technique in different concentrations of aqueous chitosan solution. The ablation process of silver plate was carried out by using a nanosecond Q-switched Nd:YAG pulsed laser and the characterization of Ag NPs was done by Transmission electron microscopy, UV-Vis spectroscopy, and X-ray diffraction. UV-visible plasmon absorption spectra revealed that the formation efficiency as well as the stability of nanoparticles was increased by addition of chitosan. On the other hand, the size decrement of nanoparticles was more remarkable in the higher chitosan concentration

Silver nanoparticle fabrication by laser ablation in polyvinyl alcohol solutions

A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PVA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PVA is much higher and the sizes of particles are also smaller