Majid Farahmandjou

In this research, ceria (Ce)- doped alumina (Al₂O₃) nanoparticles (NPs) were fabricated in different level of cerium using coprecipitation method. To characterize the morphology, crystal structure and optical properties, the FESEM, XRD, TEM, UV-DRS and FTIR analyses were performed. The structure analysis of undoped samples showed the multiple phases of γ, δ and θ–alumina, and the structure remained unchanged when cerium atom was doped into the alumina. The morphology and structure studies were carried out to investigate the effect of Ce doping on the polycrystalline alumina nanoparticles. The optical analysis was also done to study of the bandgap energy of the Al₂O₃ NPs. The novelty of this work is the synthesis of Ce-doped Al₂O₃ NPs with new precursors and improving their optical properties.

Background: The synthesis of Fe₂O₃/ZnO nanocomposites has gained wide acceptance in recent years due to its magnetic, photoluminescence and catalytic properties, and as an active element in gas sensors. This type of composite particle has potential biological and biomedical applications such as the detection of cancer cells, bacteria and viruses, and for magnetic separation. Objective: In the present study, first we synthesized the Fe₂O₃/ZnO nanoparticles, and then the structural, optical and surface morphological properties were investigated by XRD, HRTEM, FESEM, XRF and FTIR analyses. Methods: Fe₂O₃-ZnO nanoparticles were fabricated by a solgel synthesis method by combining iron chloride hexahydrate and zinc sulfate heptahydrate. In the beginning, 2g of Polyvinylpyrrolidone (PVP) stabilizer was dissolved in 100 mL deionized water and then 5 g FeCl3 was added to the solution with stirring at room temperature. Then 5g of ZnSO4 was added to the solution and synthesis temperature was increased to 100 °C. The product was evaporated for 3 hours, cooled to room temperature and finally calcined at 600 °C for 3 hours. Result: The XRD results showed single-phase Fe₂O₃-ZnO nanocomposites with a hexagonal wurtzite structure of ZnO and spinel phase of rhombohedral α-Fe₂O₃. The crystallite size of as-prepared sample was determined at about 45 nm and annealed one was calculated around 40 nm. The SEM images showed that the Fe-Zn nanoparticles changed from spherical shape to rod shape by increasing the temperature after annealing. The TEM studies showed the core-shell nanoparticles with a mean diameter of 47 nm. The sharp peaks in the FTIR spectrum determined the stretching vibrations of Fe and Zn groups in the frequencies of 620, 565 cm^-1 and 410 cm^-1. Conclusion: The XRD data indicates a single-phase Fe₂O₃-ZnO structure. The SEM images show that the nanoparticles changed from sphere-like shape to rod-like shape by increasing the annealing temperature. TEM image exhibits the core-shell Fe-Zn nanoparticles with an average diameter of about 37 nm. From the FTIR data, it is shown that the presence of Fe-Zn stretching mode and the intensity of the peaks increased by increasing the annealing temperature. XRF analysis showed peaks of iron and ferrite elements, and an increase in the Zn weight percent was observed from 26.35 %Wt. to 49.26 %Wt. with increasing temperature.

Background and Introduction: Metal oxides (MOs) have been extensively used in a large range of engineering and medical applications. Methods: FeCo nanoparticles (NPs) were successfully synthesized by the solgel method in the presence of a powerful reducing agent-sodium borohydride (NaBH₄). The structure, morphology, and optical properties of NPs were analyzed by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) at room temperature. Results: The XRD spectrum showed the body center cubic (BCC) structure of the samples after heat treatment at 500 °C. The SEM analysis exhibited that the particle size of as-synthesized and annealed samples was approximately 40 nm and 22 nm, respectively. Conclusion: The TEM investigations showed the rod-shaped sample of annealed NPs. The optical studies of the FTIR analysis revealed the starching bound of Fe-Co at the frequencies of 673 cm^-1, 598 cm^-1, and 478 cm^-1.

In this paper, α-Fe2O4@ZnO nanoparticles (NPs) were synthesized by coprecipitation method in the presence of PVP and EG surfactants. The samples were charactrized by x-ray fluorescence (XRF), x-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and fourier transform infrared spectroscopy (FTIR). The XRD results exhibited rhombohedral α-Fe2O3 and wurtzite structure of ZnO. The SEM images showed that the NPs changed from rod-shape to nanoleaves particles after heat treatment. The TEM studies displayed the formation of Fe2O3@ZnO core-shell of as-synthesized NPs. The stretching vibrations peaks in FTIR in the wavenumber of 532 cm-1 and 473 cm-1 ascribed to the Fe and Zn groups. The XRF data indicated decreasing of the Fe weight percent from 22 %Wt. to 25 %Wt., after heat treatment.

Titanium dioxide nanoparticles (TiO2) have been extensively investigated because of its high chemical sustainability, optic properties, and adaptation to the environment. These studies include applications in heterogeneous catalysts, solar cells, coating technology, and electrical devices. TiO2 particles in the nanometer scale can remove limitations, such as the absorbance of organic materials, because of a high surface area to volume ratio. Titanium dioxide nanoparticles, were synthesized using a simple wet chemical method. Their physico-chemical properties were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. The TEM results showed that the mean size of as-synthesized TiO2 was 5 nm with high crystalline anatase phase. The SEM observations revealed that the size of nanoparticles increased with annealing temperature and the morphology of the particles changed to the spherical shape. The crystal structure of the nanoparticles before and after annealing was done by XRD analysis. The rutile phase was formed after heat treatment at 600oC for 3 hours.

Alumina (Al2O3) is a very interesting material with broad applicability as a support for various catalytically active phases and ceramic materials. Aluminium oxide (Al2O3) Nanoparticles were synthesized by aluminium chloride hexahydrate as precursor and polyvinylpyrrolydon (PVP) as surfactant and polymer agent. The samples were characterized by high resolution transmission electron microscopy (HRTEM), field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD) and electron dispersive spectroscopy (EDS). XRD pattern exhibited gamma-Al2O3 to alpha- Al2O3 structural phase transition in the samples. The mean diameter of sphere-like as-prepared nanoparticles was around 26 nm and mean diameter of annealed sample was around 10 nm as estimated by XRD technique and direct HRTEM observation. The surface morphological studies from SEM depicted the size of alumina decreases with increasing annealing temperature. The effect of PVP surfactant on the morphology of the alumina nanoparticles has been investigated. EDS showed peaks of aluminium and oxygen in prepared Al2O3.