Ahmad Taufiq

XRD line‐broadening characteristics of M‐oxides (M = Mg,Mg‐Al, Y, Fe) nanoparticles produced by coprecipitation method

Simple coprecipitation method has been used to produce nanoparticles of MgO (magnesia), MgO⋅Al2O3 (spinel), Y2O3 (yttria) and Fe3O4 (ferrite). The raw materials were, in respective, magnesium powder, magnesium and aluminium powders, ytrria powder, and natural sand. The coprecipitation included the use of suitable acid and base to dissolve the powders or sand and to produce precipitates, as well as the use of water to wash and purify the precipitates, and drying at relatively low temperatures, namely lower than 100° C, followed by heating at 450° C, 750° C, 600° C and 200° C to produce magnesia, spinel, yttria and ferrite nanopowders, respectively. X‐ray diffractometry was used to characterise the purity and nanocrystallinity of the final powders. It was found qualitatively that the powders were of high purity. Further line‐broadening analysis using single‐line and Rietveld‐based softwares was performed to reveal the nanocrystallinity of the powders. Different line breadth values were found for the powders...

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...

Analysis of Distribution of Polyvinyl Alcohol Hydrogel Nanocrystalline by using SAXS Synchrotron

Polyvinyl alcohol (PVA) hydrogel has been successfully synthesized through freezing-thawing (F-T) process by using time-variation. This work is aimed to investigate the distribution of nanocrystalline from the hydrogel. Fourier Transform Infrared (FTIR) Spectroscopy, Differential Thermal Analysis/Thermogravimetric (DTA/TG), and Synchrotron Small-Angle X-ray Scattering (SAXS) were used as the instruments in characterizing the PVA hydrogel, respectively to observe the frequency of absorption, thermal degradation, and structural dimensions. The functional groups which represent the PVA polymer chains were verified on the wavenumber of 1450-1480 cm-1 and 850-870 cm-1 which is in accordance with the stretching of –CH2 vibration mode. The absorption band of PVA polymer chains was also found on the wavenumber of 1090-1150 cm-1 which is in accordance with the stretching of carboxyl vibration mode (CO), and this wavenumber gave a contribution towards the crystallinity of PVA polymer. Furthermore, the PVA polymer only interacted with the distilled water in the sample of PVA hydrogel without experiencing any chemical interactions between the PVA polymer and other substances. Meanwhile, the graphic of PVA hydrogel thermal degradation shows three thermal decompositions which are indicated by three areas in which there was sample weight loss. The second decomposition with sample weight loss was equivalent to 61.62%-73.04% occurred at the temperature of 282-376 °C which became the highest sample weight loss due to polymer chain degradation. Teubner-Strey and Beaucage models were used to analyze the characterization of structural dimension and distribution of PVA Hydrogel nanocrystalline with SAXS Synchrotron. With a high compatibility between the model data and the experiment, the average structural dimension of PVA hydrogel nanocrystalline is the equivalent of 3.96 nm, with an inter-crystalline average distance of 16.9 nm. These results indicate that PVA hydrogel is very potential to be applied as a primary material for human implants.

The influence of iron- and copper- doped of PANi thin film on their structure and dielectric properties

Polyaniline (PANi) is one of conductive polymers which are widely studied. PANi has unique in the structure and physical properties that can be controlled by doping. In this work we report the role of CuCl2 and FeCl3 in the crystalline and dielectric properties of PANi/Ag films which was performed by means spin coating method. We employed sonochemical technic to form solutions of PANi ES II prior to spin coating method. The variation of FeCl3 and CuCl2 doped were used in the range of 0 M - 0.5 M. FTIR spectra of PANi EB and PANi ES clarified that the PANis were successfully synthesized. The crystallinity of the films were examined by menas of X-ray diffraction (XRD). While the polymeric grains were evaluated using SEM which is confirmed with the grain size analyses from X-RD data. Dielectric properties shows that introducing Fe and Cu doped could decrease their dielectric constant. The decreasing of dielectric constant was also achieved by increasing frequency.

Islamic Crash Course as a Leadership Strategy of School Principals in Strengthening School Organizational Culture

This study aimed to describe nyantri (Islamic crash course) program as a leadership strategy adopted by school principals in strengthening the school organizational culture. This study used a qualitative approach via theoretical phenomenology orientation and a multicase design. The data collection was done through observation, documentation, and in-depth interviews. The validity of the data was measured by data reduction, data presentation, and conclusion. The results of this study found three models of Islamic crash course performed: tashih, that is, Al-Qur’an reading competence, taushiyah (Islamic lecture) of leadership values, and apprenticeship for the application of a santri’s (Islamic crash course student) character values. The benefits for the teachers are the preservation of their Al-Qur’an reading competence and the improved intensity of the leadership and application of Islamic values, which form the school organizational culture. An integration of values rooted from the three models into the institutional vision could strengthen the school organizational culture to improve school achievement.