Journal of Metastable and Nanocrystalline Materials Vol. 38

Abstract: In this work, we successfully synthesized a magnetic nanocomposite material (Fe₃O₄@ZnO/TiO₂) with an iron oxide core and a zinc oxide/TiO₂ shell (Fe₃O₄@ZnO/TiO₂). The purpose of this study was to characterize the Crystal Structure, Morphology, and Magnetic Properties of Magnetic Nanocomposites with Iron Oxide Core and Zinc Oxide/Titanium Oxide Shell. The crystal structure of the sample was analyzed using X-ray diffraction, which identified three distinct phases: Fe₃O₄, ZnO, and TiO₂. These phases respectively exhibited cubic spinel, hexagonal wurtzite, and tetragonal crystal structures. Transmission Electron Microscopy (TEM) characterization confirmed that the sample had a magnetic core–shell structure, with superparamagnetic properties and excellent stability owing to its spinel cubic structure, which is the primary magnetic material structure of the sample. The successful formation of the Fe₃O₄@ZnO/TiO₂ nanocomposite represents a significant advancement in the synthesis of materials. This could serve as a basis for further investigations into magnetic materials, opening up possibilities for their application across diverse fields.

Abstract: The Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites were synthesized using co-precipitation and solid-state reaction methods. The Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites were success formed. This was confirmed by characterization using FTIR instrument. The Fe-O, C-O, and C-H₂ functional groups were the representation of Mn_0.3Fe_2.7O₄, PEO/PMMA, and AC respectively. Investigation of crystal structure was characterized using XRD instrument. According to X-Ray Diffraction analysis, the crystal size was 10.82 nanometers and the peak of AC was detected on 2θ around 24.85^o. In addition, the investigation of magnetic properties was characterized using VSM instrument. This result showed that the Mn_0.3Fe_2.7O₄/PEO/PMMA/AC nanocomposites behave as a superparamagnetic material with a saturation magnetization value was around 12.55 emu/gram.

Abstract: The aim of this research is to identify the crystal structure, surface area, and magnetic properties of The Mn_0.25Fe_2.75O₄-rGO (reduced Graphene Oxide) nanocomposites (NCs). The synthesis of Mn_0.25Fe_2.75O₄-rGO nanocomposites used the co-precipitation method. The rGO was obtained from the chemical reduction of GO by hydrazine hydrate as the reduction agent. The ratio between Mn_0.25Fe_2.75O₄ nanoparticles and rGO was 1:1 that ultrasonicated at 200 Hz for an hour. The IR spectra of NCs from the FTIR instrument showed that the absorption band around 580 cm^-1 and 1622 cm^-1 corresponds to the stretching mode of Fe-O and C=C respectively. According to X-Ray Diffraction (XRD) pattern analysis, peak of Mn_0.25Fe_2.75O₄ was detected on 2θ at 30.1°, 35.5°, 53.5°, 57.1°, 62.7° and the peak of rGO phases was amorphous that detected on 2θ between 17º and 30º. The XRD pattern analysis and FTIR spectra have proved the completion of NC’s synthesis. The crystallite size was between 10.3 nm by Scherer's formula. The Specific Surface Area showed that the surface area of the nanocomposites was 100.61 m²/g and the Molecular cross-sectional area was 0.162 nm² by BET Theory. The Magnetic properties show that the NCs were Superparamagnetic material that has a saturation magnetization of 9.34 emu/g. The material has many potentials to be explored by the researcher around the world.

Abstract: Single-domain M-type Strontium Ferrite nanoparticles are prepared by the co-precipitation method. The crystallite size of the M-SrFe Nps is 58.1 nm, as determined by the XRD pattern. The SEM micrographs reveal the hexagonal morphology. M-SrFe Nps is depicted in EDS analysis. According to VSM characterization, the sample is a hard magnetic material with high coercivity. With its outstanding magnetic characteristics, hexaferrite is typically employed in permanent magnetic materials and recording devices. The band gap energy is determined to be 1.95 eV from the UV-DRS reflectance data using the Kubelka-Munk plot. The absorbed wavelength with the highest intensity peak in PL analysis is 629.9 nm. The TG-DTA investigations support the remarkable thermal stability of M-SrFe Nps. The resistivity of the sample, 0.312 Ωm is calculated using the four-probe method.

Abstract: A wide range of Light Emitting Diodes (LEDs) applications, from general lighting to transmission sources of the Visual Light Communication (VLC) system, makes the LEDs very important to be developed. This research focuses on comparing LED performance due to the variation in surface size and shape of the LED. The research method is carried out with a simulation and an experimental approach. Before the experiment, the LED was simulated with nanopattern variations to determine the best fabrication parameter. The simulation method is carried out using Ansys Lumerical FDTD 2021. The experiment method used to fabricate nanopatterns on the surface of a semiconductor LED layer uses the nanoimprint lithography method. Stamps for nanoimprint lithography are made using Polydimethylsiloxane (PDMS), and the nanopattern sources are obtained from DVD and Blu-ray grating patterns. The characterization of nanoscale patterns was carried out using a Scanning Electron Microscope (SEM). The light emission intensity is measured using a lux meter at a series of emission angles. The results obtained from this research are that the smaller the width and the periodicity of the grating nanopattern, the light produced will be distributed at a wider angle, but the light intensity will decrease; conversely, for a planar surface without a grating nanopattern, level of focus and intensity of light will be higher. In addition, the thicker the ZnS:Cu layer, the better the intensity of the light produced.

Abstract: Porous Anodic Aluminum oxide (PAAO) is a porous oxide layer resulting from anodization. The structure of PAAO is influenced by anodization parameters, i.e., voltage and electrolyte composition. Increasing anodization voltage can affect the process of pore formation and oxide growth during anodization. Adding additives such as ethanol, propanol, and polyethylene glycol (PEG) can increase pore regularity and affect the structure of PAAO. In this study, tobacco extract (TE) was added to the oxalic acid-based anodizing solution. TE has many active compounds that may affect pore formation and oxide growth. Morphological analysis shows decreased pore diameter when adding tobacco extracts with concentrations of 0, 0.1, and 0.5 g/L, namely 43.92, 41.42, and 37.8 nm at anodization voltage 40 V. In anodization with a voltage of 60 V, a decrease in pore diameter was obtained with 46.47, 34.24, and 26.8 nm for adding tobacco extract 0, 0.1, and 0.5 g/L. The thickness of PAAO increases from 6.45 µm to 16.87 µm with increasing anodization voltage and tobacco extract concentration. The increase of tobacco extract concentration can lead to the decrease of the XRD peak intensity, where the sequence of the most significant decrease was observed for the peaks of (111), (220), (200), and (311), respectively. A decrease in the intensity ratio of (111) and (220) AAO peaks indicates the influence of tobacco extract on the anodization process. Further thermal analysis by Thermo-gravimetric (TG) shows an increase in mass loss from 1.47 to 5.37% with increasing tobacco extract concentration from 0 g/L to 0.5 g/L. TG results indicate the incorporation of tobacco extract in the inner pore wall.

Abstract: Titanate nanosheets are a type of 2-dimensional nanomaterial with vast applications in electronics, energy storage, and photocatalysis due to their superior properties, such as their large specific surface area and excellent electrical conductivity. Titanate nanosheets are expected to be the material precursor of TiO₂ nanostructures with further treatment. The current research aims to synthesize titanate nanosheets using the natural mineral ilmenite from Indonesia through the hydrothermal method. X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunaeur-Emmett-Teller (BET) analysis were used to characterize the chemical composition, crystal structure, shape, size, and specific surface area of the prepared samples. The structure phase of the as-synthesized sample is known to be layered titanate. The as-synthesized nanosheet sample has a diameter ranging from 2.5 to 4 μm and BET surface areas of approximately 40 m²/g. This concise hydrothermal method could create 2-dimensional structured nanomaterials from Indonesian local minerals.