nan Sunaryono

Nano-Structural Studies on Fe3O4 Particles Dispersing in a Magnetic Fluid Using X-Ray Diffractometry and Small-Angle Neutron Scattering

Ferrofluid (magnetite/Fe3O4 magnetic fluid) is colloidal suspension containing Fe3O4 nanoparticles dispersed in a liquid carrier. In this work, Fe3O4 particles in the fluid have been prepared by a simple co-precipitation route. The nano-structural behaviors such as phase purity and crystal structure of magnetite particles in ferrofluid were studied by means of X-ray diffractometry (XRD). Meanwhile, the form and structure factors were investigated by small-angle neutron scattering (SANS) spectrometer. The XRD pattern confirmed a single phase of spinel cubic Fe3O4 structure. Further XRD data analysis revealed that the magnetite has a lattice parameter of 8.38 Å. The SANS data was fitted by applying a lognormal spherical calculation as a form factor and a mass fractal model as a structure factor. It showed that the magnetite ferrofluid has primary particles of 7.6 nm in diameter with fractal dimension of 1.2, which can be associated with chain-like structure. The chain-like structured Fe3O4 ferrofluid based on local natural iron sand in this work opens new opportunities to be applied for novel prospective applications.

Small-Angle X-Ray Scattering Study on PVA/Fe3O4 Magnetic Hydrogels

A synchrotron small-angle X-ray scattering (SAXS) study on PVA/Fe3O4 magnetic hydrogels has been performed to investigate the effect of clustering on their magnetic properties. The hydrogels were prepared through freezing–thawing (F–T) processes. The structure, morphology and magnetic properties of magnetite (Fe3O4) nanoparticles (NPs) were investigated using X-ray diffractometry (XRD), transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer, respectively. In this study, SAXS data were used to reveal the structural dimensions of the magnetite and its distribution in the polymer-rich PVA and magnetic hydrogels. As calculated using the Beaucage and Teubner–Strey models, the average of the structural dimensions of the PVA hydrogels was 3.9nm (crystallites), while the average distance between crystallites was approximately 18nm. Further analysis by applying a two-lognormal distribution showed that the magnetite NPs comprised secondary particles with a diameter of 9.6nm that were structured by primary particles (∼3.2nm). A two-lognormal distribution function has also been used in describing the size distributions of magnetite NPs in magnetic hydrogels. The clusters of magnetite NPs in the magnetic hydrogels are significantly reduced from 30.4nm to 12.8nm with decreasing concentration of the NPs magnetite from 15wt.% to 1wt.%. The saturation magnetization values of the magnetite NPs, the 15% and 1% magnetic hydrogels were 34.67emu/g, 6.52emu/g and 0.37emu/g, respectively.

Various Magnetic Properties of Magnetite Nanoparticles Synthesized from Iron-sands by Coprecipitation Method at Room Temperature

Natural sand-based magnetite nanoparticles have been succesfully synthesized by coprecipitation method at room temperature. Magnetite nanoparticles were investigated by X-ray Diffractometer (XRD) and Vibrating Sample Magnetometer (VSM). The morphology of magnetite nanoparticles has been evaluated by Transmission Electron Microscopy (TEM). Qualitative analysis of XRD data reveals that the structure of magnetite nanoparticles have the same phase of ICSD No. 82237. On the other hand, quantitative analysis shows that the crystallite size of magnetite nanoparticles have ranges between 8.89 nm to 12.49 nm. The average diameter of magnetite nanoparticles increase with the increase the stirring rate of reaction when the stirring rate is lower than 1000 rpm, while the crystallite size of magnetite particles decrease with the increase the stirring rate when the stirring rate is higher than 1000 rpm. The stirring rate of reaction influence the the magnetic properties of magnetite nanoparticles. The results of the best magnetic respon are revealed for the stirring rate of 1000 rpm with the larger the crystallite size of magnetite nanoparticles due to its stronger saturation magnetization.

Spinel‐Structured Nanoparticles for Magnetic and Mechanical Applications

Nanoparticles of Fe3O4 have been successfully synthesized using a simple coprecipita‐ tion technique from natural iron sands, employing HNO3 and NH4OH as dispersing and precipitating agents, respectively. The substitution of Fe with Mn to result in Fe3‐ xMnxO4 (0 ≤ x ≤ 3) was conducted to control the magnetic strength of this nano‐sized spinel powder. It is shown that magnetic properties depend not only on the particle size and Mn doping but also on the particles clustering. The applications for magnetic fluids, gels, and coating are extensively described. Meanwhile, the spinel MgAl2O4 nanoparti‐ cles have also been prepared by the same simple method from commercial starting materials. This powder was used as a nano‐reinforcer of Al‐matrix composites. In addition, MgAl2O4 micro‐sized powder forming a thick layer was successfully grown by electroless plating on the interface of matrix‐filler in Al/SiC composites. The strengthening of mechanical properties with respect to the varying uses of these MgAl2O4 powders is discussed.

Magneto-elasticity in hydrogels containing Fe3O4 nanoparticles and their potential applications

The magnetic hydrogels have been fabricated via standard method of polymer preparation. Hydrogels were the mixture of polyvinyl alcohol (PVA) and water by certain ratio of mass. Magnetism in hydrogels was presented by introduction of magnetic Fe3O4 nanoparticles with crystal size ranging from 11 nm to 15 nm, prepared by coprecipitation technique from iron-sands. According to the magnetic induction experiment, it has shown that the magneto-elasticity of gels containing Fe3O4 of around 2.5% – 15% tends to decrease as increasing Fe3O4 concentration. The magneto-elasticity responses of the gels clearly form hysteresis in the increasing and decreasing applied magnetic field, where in turn open the potential applications of these magnetic hydrogels.

Studies on Nanostructure and Magnetic Behaviors of Mn-Doped Black Iron Oxide Magnetic Fluids Synthesized from Iron Sand

Manganese (Mn)-doped black iron oxide (Fe3O4) magnetic fluids in the system of MnxFe3−xO4 were successfully synthesized from natural magnetite (iron sand) by using co-precipitation method at room temperature. The analyses of the small angle neutron scattering (SANS) data by applying a log-normal sphere with a mass fractal models for x=0 and x=0.25 and two log-normal spheres with a single mass fractal models for x=0.5, 0.75 and 1 revealed that the primary particles of the MnxFe3−xO4 fluids tended to decrease from 3.8nm to 1.5nm along with the increasing fraction of Mn contents. The fractal dimension (D) increased from about 1.2 to 2.7 as the Mn contents were increasing; which physically represents an aggregation of the MnxFe3−xO4 particles in the fluids growing up from 1 to 3 dimensions to consolidate a more compact structure. The magnetization curves of the fluids exhibited an increasing saturation magnetization from x=0 to x=0.25, and a decreasing on x=0.5 and 0.75, with the maximum achievement of x=1. T...

The synthesis of Fe3O4/MWCNT nanocomposites from local iron sands for electrochemical sensors

The aim of this research is producing the electrochemical sensor, especially for working electrodes based on the nanocomposites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sands. The sonochemical method by ultrasonic horn was successfully used for the synthesis of the nanocomposites. The characterizations of the sample were conducted via X-Ray Diffractometer (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) method for surface area, Vibrating Sample Magnetometer (VSM) and Cyclic Voltammetry (CV). The analysis of X-Ray Diffraction (XRD) pattern showed two phases of crystalline, namely MWCNT and Fe3O4, peak of MWCNT comes from (002) plan while peaks of Fe3O4 come from (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) plans. From XRD data, MWCNT has a hexagonal structure and Fe3O4 has inverse spinel cubic structure, respectively. The FTIR spectra revealed that the functionalization process of MWCNT successfully generated carboxyl and carbonyl groups to bind Fe3O4 on MWCNT surfaces. Moreover, the functional groups of Fe-O bonding that showed the existence of Fe3O4 in the nanocomposites were also detected in those spectra. Meanwhile, the SEM and TEM images showed that the nanoparticles of Fe3O4 attached on the MWCNT surface and formed agglomeration between particles due to magnetic forces. Through Brunauer-Emmett-Teller (BET) method, it is identified that the nanocomposite has a large surface area 318 m2/g that makes this material very suitable for electrochemical sensor applications. Moreover, the characterization of magnetic properties via Vibrating Sample Magnetometer (VSM) showed that the nanocomposites have superparamagnetic behavior at room temperature and the presence of the MWCNT reduced the magnetic properties of Fe3O4. Lastly, the electrochemical characterization with Cyclic Voltammetry (CV) proved that Fe3O4/MWCNT nanocomposites with iron sands as the starting materials have high sensitivity and serve as excellent electron transfer materials. Based on the results of the research, the Fe3O4/MWCNT nanocomposites from iron sands are much recommended for electrochemical sensor.The aim of this research is producing the electrochemical sensor, especially for working electrodes based on the nanocomposites of multi-walled carbon nanotube (MWCNT) and magnetite (Fe3O4) nanoparticles from iron sands. The sonochemical method by ultrasonic horn was successfully used for the synthesis of the nanocomposites. The characterizations of the sample were conducted via X-Ray Diffractometer (XRD), Fourier Transform Infra-Red (FTIR) Spectrometer, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Brunauer-Emmett-Teller (BET) method for surface area, Vibrating Sample Magnetometer (VSM) and Cyclic Voltammetry (CV). The analysis of X-Ray Diffraction (XRD) pattern showed two phases of crystalline, namely MWCNT and Fe3O4, peak of MWCNT comes from (002) plan while peaks of Fe3O4 come from (2 2 0), (3 1 1), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) plans. From XRD data, MWCNT has a hexagonal structure and Fe3O4 has inverse spinel cubic structure, respectively. The FTIR spectra revea...

Synthesis and Characterization of γ-Al2O3/SiO2 Composite Materials

This article reports the synthesis process of γ-alumina/SiO2 composite from aluminium powders and amorphous nanosilica through the means of tetra-methyl-ammonium hydroxide (TMAH) as the mixing medium which produced aluminium hydroxide Al(OH)3 in the form of white powders. The crystal structures, microstructures, and mapping of the atomic constituent of γ-Al2O3 and γ-Al2O3/SiO2 samples were respectively analyzed via X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray SEM-EDX. At the calcination temperature to 300 °C, the samples still had boehmite phase, and the boehmite phase transformation to γ-alumina phase occurred at temperature of 700-900 °C. The γ-alumina phase began to form at the calcination temperature of 500-700 °C with the crystal structure of (440), (511), (400), (222), (311), and (111). The similar diffraction pattern was also shown by the γ-Al2O3/SiO2 composite for the calcination temperature of 700 °C and 900 °C. The microstructure analysis of the γ-Al2O3/SiO2 showed that SiO2 particles were smaller and round while the γ-Al2O3 particles were bigger and elongated. Additionally, the mapping results showed SiO2 and γ-Al2O3 particles were homogenously distributed.

Structural, Optical, and Antifungal Characters of Zinc Oxide Nanoparticles Prepared by Sol-gel Method

The preparation of zinc oxide nanoparticles has been successfully done by employing a sol-gel route. The x-ray diffraction data analysis presented that the zinc oxide particles crystallized as hexagonal wurtzite structure and sized in nanometric scale of 35.8 nm. The scanning electron microscopy image showed that the sample had agglomeration pattern with the particles size of 38.2 nm. Such results were confirmed by a synchrotron small-angle x-ray scattering that the prepared sample agglomerated in 3-dimensional structure with a fractal dimension of about 3. The functional group of the Zn-O as the main component of zinc oxide were observed at the wavelengths of about 454 and 523 cm−1. Moreover, the optical band gap energy of the zinc oxide nanoparticles was of 3.53 eV. Excitingly, the powdered sample in this work had an average inhibition zone diameter of 4.59 mm for Candida albicans fungus. Therefore, the prepared zinc oxide nanoparticles exhibited imperative materials for antifungal agent.

Synthesis and Characterization of ZnO Nanorods by Hydrothermal Methods and Its Application on Perovskite Solar Cells

The aim of this research is to investigate the effect of ZnO Nanorods (ZnO NRs) morphology synthesized by the hydrothermal method to electrical properties of CH3NH3PbI3/ZnO NRs perovskite solar cell (PSCs). ZnO nanorods were synthesized on the ITO substrate by a hydrothermal method. ZnO NRs were synthesized using hexamethylenetetramine (HMT) and zinc nitrate with a 1:1 molar ratio for 6 h. The growth temperature varied at 90°C and 100°C. The zinc nitrate concentration also varied at 25mM and 50 mM. The perovskite was made through a two-step deposition by spin coating with PbI2 and CH3NH3I as the main ingredients. The effects of the synthesis conditions on ZnO NRs and Perovskite films were systematically investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), LCR AC meters and multimeters. The SEM results showed that as the temperature and concentration of zinc nitrate increase the size of the diameter and length of the rods are increasing. ZnO NRs synthesized with 50 mM concentrations of zinc nitrate at a growth temperature of 90 °C temperature showed the best results in terms of ZnO NRs morphology. The XRD characterization results showed that the formed CH3NH3PbI3 film contained PbI2 impurities. The existence of PbI2 was suspected in opening the gap of recombination causing in low current and high dielectric constant.