Search

SrTiO3 perovskite possesses high dielectric properties and is potentially applicable for a high-temperature thermoelectric as well as supercapacitor materials. Theoretically, the physical properties of SrTiO3 can be improved by the doping process. Modification of local structure changes crystal field or geometric distortion will, in turn, influence its electrical conductivity. Currently, SrTiO3 has been widely studied with various dopants. However, there has not been a comprehensive study about structural modification using multivalent magnetic ion of Chromium (Cr) and external magnetic fields on the electrical conductivity. Cr ions have various valences of 2+, 3+, 4+, 5+, 6+, and the symmetry of 4h with six coordination numbers, which can change the local structure of SrTiO3. Besides, the radius of Ti ion in SrTiO3 is about 67 pm with 4+ valence, while Cr has the symmetry of 4h for the 3+ valence. Under these conditions, Cr is expected to reduce the lattice parameters and a slight shift of apical oxygen to the basal plane of its local octahedral structure. Since Cr interacts with an electromagnetic field in the range of visible light, it might be expected that this compound would show a shift of bandgap energy. As the valence also changes to a possible mixed state, the physical properties may exist in complex states. SrTi1-xCrxO3 samples were prepared via solid-state reaction in the various molar ratio of Cr doping. The phase and structure were analyzed using X-ray Diffraction. XRD confirmed that the SrTi1-xCrxO3 compounds phase was successfully formed, and a slight change in lattice parameters was observed. The local octahedral six-fold symmetry structure of SrTi1-xCrxO3 compounds also changed to be tetragonal with the presence of Cr. Based on the EDX data, the composition of SrTi1-xCrxO3 compounds corresponded to the designated composition. Furthermore, the magnetic field induced I-V conductivity measurement showed that higher Cr fraction enhanced its electrical conductivity. SrTi1-xCrxO3 (x = 0, 0.02, 0.04, and 0.1) optical band gap analysis from UV-Vis spectroscopy showed that the bandgap is in the range of semiconductor materials.

Many supercapacitor studies focus on materials that are inflexible and have low specific capacitance. The addition of low dimension metals such as silver nanoparticles (AgNP) into the BaTiO3-Graphite-Activated Carbon (AC)/Aluminum foil showed a change in structure and morphology. The AC and graphite are generally used as necessary materials for supercapacitors. Adding AgNP is expected to increases the general mobility and specific capacitance of BaTiO3-Graphite-AC/Aluminum foil. In this study, we report the effect of AgNP into Graphite-AC-BaTiO3/Al foil symmetric supercapacitors. In the first step, we prepared nanocomposite comprises (x)AgNP-graphite-AC-BaTiO3. The dense solution then deposited on to clean aluminum foil as an electrode. The symmetric supercapacitors were sandwiched using two electrodes separated by a separator and electrolyte. It is shown that the crystal structure and morphology change with the addition of AgNP. The Optimum capacitance of Ag-BaTiO3-Graphite-AC/Aluminum Foil supercapacitor obtained from LCR meter of 1.9×10−5 F/g and dielectric constant of 1.03×106. The cyclic voltammetry test for three-electrode systems produces a specific capacitance of 8.95 F/g and 0.83 F/g for testing two electrode systems. We obtained that the increase of AgNP increases the specific capacitance of the electrode and supercapacitor to the optimum at 0.06 g Ag.

This study investigated the influence of refraction index strength on the light propagation in refraction index-varied dielectric material. This dielectric material served as photonic lattice. The behavior of light propagation influenced by variation of refraction index in photonic lattice was investigated. Modes of the guiding light were determined numerically using squared-operator iteration method. It was found that the greater the strength of refraction index, the smaller the guiding modes.

Perovskite solar cells have attracted the researchers' attention because they are one of the most promising candidates that are cheap, easy to fabricate and high-efficiency solar cell. ZnO nanorods (ZnO NRs) can be used as an electron and hole recombination barrier to improve the perovskite solar cell performance. This research aimed to investigate the effect of growing time on the characteristics of ZnO NRs and its application for perovskite solar cell device. The ZnO NRs was synthesized on ITO substrate by hydrothermal method at the different growing times of 4, 6, and 8 hours. The CH3NH3PbI3 perovskite solar cells were deposited on the top of ZnO NRs/ITO thin films by a two-stage spin coating method. The solar cell devices were characterized by using XRD, SEM-EDX, FTIR, UV-vis, and LCR meter. The results showed that ZnO NRs/ITO thin films were formed homogeneously and vertically oriented on all ITO substrates with hexagonal structures of zincite phases. When the growing time of ZnO NRs increased, the degree of homogeneity, density, and length of the rods enhanced as well. All the samples have the bandgap around 3.05 eV. The FTIR results showed the absorbent functional forces at 870 cm−1 and 1250 cm−1 related with H-C-N wavelengths, and ZnO wavelength ranges from 400 to 515 cm−1. The CH3NH3PbI3 perovskite solar cell device still contained PbI2 as impurities phase. The longer the growing time, the rods resulted by ZnO NRs had the wider diameter and the longer length and they were more homogenous. Meanwhile, the effect of the number of PbI2 impurities resulted in the higher dielectric and smaller current.

In the last years, magnetite (Fe3O4) nanoparticles have been prepared with various methods to produce the Fe3O4 with high performance especially in microwave absorption properties. In general, the characterization of reflection loss using microwave of the Fe3O4 particles has been carried out in the range of 2-18 GHz. In this work, the rotational molecular model was developed to analyze the reflection loss peaks in the range of the frequency. The primary technique of simulation was an interpolation of peak frequencies originating from the molecular rotational transition of the Fe3O4 particles. The data analysis presented that the mechanism occurs at the electromagnetic absorption of the Fe3O4 particles is rotational molecular. Interestingly, it is presented that the result of the simulation is in line with the results of the characterizations of several materials that have been reported in some literature.

ZnO nanorods were successfully synthesized via two stages, that is deposition of ZnO seed layers on ITO substrate and growth of ZnO nanorods via solvothermal method. A characterization by using XRD was employed to investigate the structure and size of the crystals. SEM characterization was used to study the size and morphology of the particles. UV-Vis and FTIR characterizations were used to investigate the bandgap and functional group of the samples. The data analysis presented that the ZnO particles had a crystal structure of hexagonal with rod morphology. The diameter size of the ZnO nanorods growth on the substrate surface for the growth time of 4, 6, and 8 hours were respectively 138, 230, and 236 nm with the length of the rods of 570, 934, and 1280 nm, respectively. The bandgaps of the ZnO nanorods for growth times of 4, 6, and 8 hours were respectively 3.14, 3.12, and 3.05 eV, while the ZnO seed layers had 3.22 eV band gap. FTIR spectrum showed that the main peaks were 400-515, 870, and 1250 cm-1 showing the functional groups of ZnO and H-C-N.