The Characterization of Amorphous AZO-n/Si-p Hetrojunction Diode for Solar Cell Application

The aim of the present study is to verify the effect of annealing temperature variation on zinc oxide doped with aluminum (AZO) thin films deposited on p-type silicon (Si) substrates. Here, AZO/p-Si heterojunction was annealed in nitrogen environment and its structural, electrical, and optical characterizations were investigated. The results of XRD patterns showed the amorphous structure of AZO thin films. FE-SEM images illustrated the increase of grain size by increasing annealing temperature up to 500oC. The reflectance analysis showed that for this annealing temperature, that the energy band gap of AZO thin film was moved to higher energy level. The electrical properties were investigated by I–V measurement carried out in the light at room temperatures. The short circuit current (ISC), ideality factor, saturation current, and open circuit voltage (VOC) of the AZO/p-Si heterojunction strongly depended on annealing conditions due to charge carrier trapping and density of defect on interface. By considering IR and IF as reverse and forward current, the ration of IF/IR had the maximum value at 1 V which was belonged to n-AZO/p-Si heterojunction at 500oC annealing temperature.

Suitability of Iron (Fe)-Doped Tungsten Oxide (WO3) Nanomaterials for Photocatalytic and Antibacterial Applications

Pure and “Fe ([Formula: see text][Formula: see text]wt.%)-doped” WO[Formula: see text] nanoparticles were prepared by facile microwave irradiation method and that was investigated for strong photo catalytic and antibacterial activity applications for the first time. The primary aim of this work is to reveal the great importance of oxygen vacancies ([Formula: see text] due to dopant (Fe[Formula: see text] for photo catalytic and antibacterial activity applications. This work also discusses the contribution of oxygen vacancies and their dependence on surface area and phase formation which are of great research interest for water purification and biological sciences. Herein, pure and “Fe ([Formula: see text][Formula: see text]wt.%)-doped” WO[Formula: see text] nanoparticles were successfully synthesized by facile microwave irradiation (MWI) method (2.45 GHz/240W/10min) in ambient atmosphere. The phase formation and the crystalline nature of the prepared products were evaluated using powder X-ray diffraction (XRD). It confirmed the phase formation of orthorhombic and monoclinic phase formations for the pure (WO[Formula: see text]H2O) and annealed samples (W[Formula: see text]O[Formula: see text] and WO[Formula: see text], respectively. Optical behavior of the samples from UV-Vis diffuse reflectance analysis revealed that W[Formula: see text]O[Formula: see text] has remarkable bandgap values (1.96[Formula: see text]eV) that clearly emphasizes the transfer of oxygen ions which helps in the movement of oxygen vacancies inside the crystalline domain. The morphological nature of the prepared products was observed by FE-SEM analysis and the average dimension was found to be 0.2–3.2[Formula: see text][Formula: see text]m and 2–4[Formula: see text][Formula: see text]m for the pure and annealed products, respectively. The specific surface area from BET analysis explored that W[Formula: see text]O[Formula: see text] having 55.16[Formula: see text]m2g[Formula: see text] was found to be higher than that of commercially available WO3. The photocatalytic behavior of the prepared compounds morphologies was investigated via Rhodamine B (RhB) degradation under visible light irradiation. These results showed “Fe-doped” annealed WO3 nanoparticles have degradation efficiency of 86.9% along with high stable nature. On the other hand, to identify the suitability of the prepared products for antibacterial activity, the microbial strains of Gram-positive Bacillus sp. and Gram-negative strains of Pseudomonas sp. and Salmonella sp. were used for the antimicrobial assay[Formula: see text] The results indicated that W[Formula: see text]O[Formula: see text] showed enhanced antibacterial nature when compared to that of Stoichiometry tungsten oxide (WO[Formula: see text] nanomaterials. From these observations, this work emphasizes the importance of oxygen vacancies for antibacterial activity applications.

THE ZONATION OF COAL RANK IN MUARA ENIM FORMATION BASED ON THE REFLECTION STUDY

Coal is a sedimentary rock containing approximately 50% to 70% carbon derived from the accumulation of plant residue that had undergone chemical and physical changes. In this research, the petrographic analysis method of coal was conducted based on the following parameters, measuring vitrinite reflectance (Ro%), estimation of moisture, volatile matter, and carbon-hydrogen content. This study aims to determine the zonation of coal rank through the vitrinite reflectance analysis in Maura Enim Formation. The samples observed were obtained from the Muara Enim Formation, which had undergone certain geological events to form lignite and anthracite coal ranks, then analyzed using the descriptive method. The results showed that the reflectance value of vitrinite was between 0.20% - 0.44%, which was utilized in the sorting of coal from lignite - sub-bituminous, according to ASTM D2798-06 (2006). Furthermore, in the Southwest region, coal is formed through greater pressure than those in the Northeast. Generally, the level of difference is caused by pressure, temperature, and time factor. Therefore, this study is recommended as a guideline in determining coal rank through vitrinite reflectance analysis in different formations.

Advanced Hyperspectral Analysis of Sediment Core Samples from the Chew Bahir Basin, Ethiopian Rift, in the Spectral Range from 0.25 to 17 µm: Support for Climate Proxy Interpretation

Establishing robust environmental proxies at newly investigated terrestrial sedimentary archives is a challenge, because straightforward climate reconstructions can be hampered by the complex relationship between climate parameters and sediment composition, proxy preservation or (in)sufficient sample material. We present a minimally invasive hyperspectral bidirectional reflectance analysis on discrete samples in the wavelength range from 0.25 to 17 µm on 35 lacustrine sediment core samples from the Chew Bahir Basin, southern Ethiopia for climate proxy studies. We identified and used absorption bands at 2.2 μm (Al–OH), at 2.3 μm (Mg–OH), at 1.16 μm (analcime), and at 3.98 μm (calcite) for quantitative spectral analysis. The band depth ratios at 2.3/2.2 μm in the spectra correlate with variations in the potassium content of the sediment samples, which also reflect periods of increased Al-to-Mg substitution in clay minerals during drier climatic episodes. During these episodes of drier conditions, absorption bands diagnostic of the presence of analcime and calcite support this interpretation, with analcime indicating the driest conditions. These results could be compared to qualitative analysis of other characteristic spectral properties in the spectral range between 0.25 and 17 µm. The results of the hyperspectral measurements complement previous sedimentological and geochemical analyses, allowing us in particular to resolve more finely the processes of weathering in the catchment and low-temperature authigenic processes in the sediment. This enables us to better understand environmental changes in the habitat of early humans.

Mechanical Properties Enhancement of the Au-Cu-Al Alloys via Phase Constitution Manipulation

To enhance the mechanical properties (e.g., strength and elongation) of the face-centered cubic (fcc) α-phase in the Au-Cu-Al system, this study focused on the introduction of the martensite phase (doubled B19 (DB19) crystal structure of Au2CuAl) via the manipulation of alloy compositions. Fundamental evaluations, such as microstructure observations, phase identifications, thermal analysis, tensile behavior examinations, and reflectance analysis, have been conducted. The presence of fcc annealing twins was observed in both the optical microscope (OM) and the scanning electron microscope (SEM) images. Both strength and elongation of the alloys were greatly promoted while the DB19 martensite phase was introduced into the alloys. Amongst all the prepared specimens, the 47Au41Cu12Al and the 44Au44Cu12Al alloys performed the optimized mechanical properties. The enhancement of strength and ductility in these two alloys was achieved while the stress plateau was observed during the tensile deformation. A plot of the ultimate tensile strength (UTS) against fracture strain was constructed to illustrate the effects of the introduction of the DB19 martensite phase on the mechanical properties of the alloys. Regardless of the manipulation of the alloy compositions and the introduction of the DB19 martensite phase, the reflectance stayed almost identical to pure Au.

Análisis geoquímico y petrográfico de las formaciones Los Cuervos y Molino, Subcuenca Cesar (Colombia): implicaciones en la evolución del sistema petrolero

A geochemical characterization of Los Cuervos and Molino formations in the Cesar Sub-Basin was carried out using core samples obtained from the ANH-La Loma-1 Well. A total of 113 Rock-Eval pyrolysis analysis, total organic carbon (TOC), total sulphur content (TS) analysis, 13 vitrinite reflectance analysis (%Ro) and 30 thin-section petrographic analysis were performed. Based on these new data, it was possible to classify the quality of organic matter and the current thermal maturation of Los Cuervos and Molino formations. Additionally, a petrographic characterization of 30 samples allowed the correlation of the lithology with the geochemical results. Also, one-dimensional geochemical modelling was implemented in order to contribute to the knowledge of the evolution of the oil system in the Cesar Sub-Basin. The spatial distribution of the formations used in the modelling was obtained from 2 seismic lines two-way time. The results obtained indicate that Los Cuervos Formation presents TOC values from 0.29 to 66.55%, TS values from 0.02 to 11.29%, their organic matter consisted of type III kerogen which is consistent with an immature thermal maturation stage. In contrast, the Molino Formation presents TOC values from 0.23 to 2.28%, TS values from 0.001 to 1.39%, their organic matter consisted of type II/III kerogen this suggests an early entry to the oil window with a maximum pyrolysis temperature (Tmax) value of 442°C. The geochemical modelling tunes better with measured data from palaeo-geothermometers (%Ro and Tmax). The geochemical modelling shows that, between 60 - 40 million years ago (mya), the Cretaceous formations entered in the oil generation window and it is expected that, between 40 - 30 mya, the Lagunitas, Aguas Blancas, and La Luna formations will be at their peak of hydrocarbon generation.