Bulletin of Materials Science最新文献

The world is shifting to greener alternatives such as biofuels due to larger carbon footprints and achieving sustainable goals. Biodiesel made from mixed oils by the transesterification process has tremendous prospects as an alternative fuel source. The quality and efficiency of biodiesel depend on the composition of the mixed oil. This paper focuses on optimizing the mixed oil ratio of the feedstock comprising waste cooking oil (WCO), jatropha oil (J) and karanja oil (K). The attributes of the manufactured biodiesel samples were examined against ASTM D6751 to determine its acceptability as a diesel alternative. Raw oils with free fatty acids (FFA) content exceeding 1% were pre-treated using the esterification method. After esterification, the FFA percentages of jatropha, karanja and waste cooking oil were reduced to 0.832, 1.75 and 0.467%, respectively. Transesterification is carried out at a temperature of 70°C by taking 1% (w/w) KOH as the catalyst for 2 h. Oil to methanol molar ratio was kept at 1:8. The biodiesel yield of the selected mixed oil ratios was approximately 91, 92 and 93%, respectively. These yields align closely with ASTM standards, highlighting the study’s effectiveness and significance. The ratio having a higher amount of jatropha (60:20:20) gave better results in terms of lower FFA content (0.07%), acid value (0.14%), cloud point (− 1°C), pour point (− 4°C), higher flash point (255°C) and fire point (260°C). In this case, the ratio with lower jatropha in it (20:60:20 J:K: WCO) showed better energy content due to its lower flash point (168°C) and fire point (175°C). This biodiesel production process generates minimal waste (primarily from the biodiesel washing stage) with the byproduct glycerin repurposed to make bioplastics and soap. Looking ahead, key directions in this study include developing ways for producing biodiesel from mixed oils utilizing effective catalysts in transesterification, presenting it as a sustainable alternative fuel to diesel.

Clays are layered structure and the layers can be separated by mechanical or chemical processes. In the present study, bentonite clay (BC) has been exfoliated by ultrasonication with distilled water as a medium. Sonication has been carried out for 30, 60 and 120 min. The clay samples have been characterized by X-ray diffraction, scanning electron microscopy and thermal analysis for phase, morphology and thermal stability, respectively. Sonication for 60 min leads to a better exfoliation and reduction in particle size of the clay. The clay powders have been utilized to prepare composites with polypropylene (PP). Compounding has been performed using a twin screw extruder by melt mixing technique and composite specimens have been prepared by the injection moulding technique. Tensile strength, Izod impact strength, hardness along with density have been evaluated for composites. It has been observed that the sample prepared with BC sonicated for 60 min shows the optimum properties due to better exfoliation of clay. Enhancement in tensile and impact strength has been 10.2% and 11.9% for the aforementioned composite as compared to untreated bentonite clay-based composite.

This work aims to study and calculate the efficiency of ruthenium dye-sensitized Ru(N719)-TiO₂ solar cells (DSSCs) based on quantitative theoretical approach to electron transfer in a hetero junction device. The J–V characteristics of Ru(N719)-TiO₂ hetero junction-based DSSC were calculated to solve the current density equation using MATLAB software. The energy levels of two materials in Ru(N719)-TiO₂ hetero junction device were assumed to be continuous levels for this purpose. Generally, the current and current density increased with increasing coupling constant. The efficiency of Ru(N719)-TiO₂ DSSC depends on many parameters. Transition energy, coupling constant and concentration play a critical role in the calculation of current density and fill factor and performance of Ru(N719)-TiO₂ DSSC. The results show a maximum efficiency in contacting ruthenium Ru(N719) with TiO₂ DSSC appeared at concentration (7 times 10^{18} ; {text{cm}}^{ - 3}) compared to the low efficiency at low concentration (3 times 10^{18} ;{text{cm}}^{ - 3}). These results showed that high concentration can increase the resulting efficiency value. The Ru(N719)-TiO₂ DSSC using acetonitrile solvent at a low carrier concentration of (3 times 10^{18} ;{text{cm}}^{ - 3}) demonstrates a low open circuit voltage and shortest circuit current density with a low fill factor under an optical density of (100 mW cm⁻²) at (AM 1.5) and minimum overall solar energy conversion efficiency Ru(N719)-TiO₂ DSSC, at higher carrier concentration of about (7 times 10^{18} ;{text{cm}}^{ - 3}) show high open circuit voltage and current density with a high fill factor to produce maximum solar energy conversion efficiency.

Pure and Ni-doped CoTiO₃ powders with a nominal composition of the Co_(1–x)Ni_xTiO₃ (with x = 0.00; 0.25; 0.50 and 0.75) were prepared by mechanical milling using solid-state reaction from NiO, Co₃O₄ and TiO₂ powders as raw materials in mole ratio. The effect of Ni²⁺ doping on structural, particle morphology, elemental composition, magnetic properties and microwaves absorption characteristics of Co_(1–x)Ni_xTiO₃ was investigated by X-ray diffraction, scanning electron microscope, energy dispersive spectroscopy, Raman spectroscopy, vibration samples magnetometer and vector network analyzer, respectively. It was found that all fabricated samples show in single phase with hexagonal structure. However, with the presence of Ni²⁺ ions dopant, the particle size and saturation magnetization (M_s) values decrease, whereas the microwave absorption capability increases.

The dielectric properties and AC conductivity behaviour of yttrium strontium silicate oxy-apatite (YSSO) compounds substituted with europium ions as rare earth, Y_8–xSr₂(SiO₄)₆O₂: xEu, x = 0, 0.10, 0.15, 0.20, 0.25 and 0.30 mol% (YSSO: xEu), prepared by solution combustion method has been reported here. The XRD and Rietveld refinement patterns confirmed the formation of a hexagonal closed-packed structure with space group P6₃/m and space group number 176. The morphological analysis was carried out by scanning electron microscopy, which showed random distribution of particles. The elemental analysis was done by EDXS, which gave the atomic% and weight% of all the initial elements present in the compound. The frequency- and temperature-dependent dielectric parameters (dielectric loss and dielectric constant) of the compounds have been carried out from 100 Hz to 100 kHz and from 50 to 500°C. Both of the dielectric parameters showed a decreasing trend with an increase in frequency. The highest dielectric loss value at a temperature of 500°C was obtained at ~4 for the undoped YSSO compound, and it reduced to ~1 after doping with x = 0.15 mol% of Eu³⁺ in YSSO: xEu compound. Impedance spectroscopy showed that the impedance values decreased with increasing frequency, resulting in an increase in electrical conductivity. The Nyquist plot indicated that the resistance contribution is dominant from the grain boundary effect and also, the NTCR behaviour of YSSO: xEu compounds was observed. The obtained low activation energy values (~0.04 eV) and low dielectric loss (~0.01–0.06) in high frequency across a broad temperature range indicate that the YSSO: xEu oxy-apatites can be used as paraelectric capacitors, electric power loss component, etc.

By applying non-equilibrium green’s function (NEGF) formalism combined with density functional theory (DFT), this study aims to investigate and compare the electron transport properties of tetracene molecules anchored with C₂₀, C₂₄ and C₂₈ fullerene molecules. The results indicate that tetracene molecule exhibits metallic behaviour with C₂₀ anchors, whereas C₂₄ and C₂₈ fullerenes, respectively, show semi-metallic and non-metallic nature. Various attributes such as transmission spectrum, density of states (DOS), molecular projected self-consistent Hamiltonian (MPSH) eigen states, conductance and current characteristics conclude that shifting of the molecular orbitals with variations in the bias voltage determines the current spectrum. The nonlinearity in the I–V curve and troughs in the G–V curve are attributed to the transitions seen in the active molecular orbitals, resulting in a variation in the HOMO–LUMO gap. Further, a multifunctional behaviour showing a clear negative differential resistance region with peak-to-valley current ratio of 1.70 and rectifying performance with a rectification ratio of 1.45 in the case of C₂₀–tetracene–C₂₀ molecular junction is observed. These results will pave a new road map for developing versatile molecular devices with targeted properties.

Due to environmental health concerns, the usage of toxic lead (Pb) based alloys in electronic applcations has been strictly banned. Thus, Pb-free solders are noted as potential alloys in electronic industries to replace Pb-based solders. Sn–Cu (Pb-free solder) alloy has attracted wide attention. However, investigations on the effect of cooling modes on tribological properties of tin–copper (Sn–Cu) solder are scant. Usually, the mode of solidification controls the grain structure of alloys and, hence, the mechanical properties. Better hardness (mechanical) and wear (tribological) properties are essential for the higher reliability of Sn–Cu alloy in real working applications, such as in aerospace avionics and electronic systems. Hence in the current research study, an effect of grain morphology, hardness and wear properties were assessed for the Sn–Cu alloy cooled in different moulds (copper and graphite around oil).

An approximate solution to the position-dependent effective mass one-dimensional Schrödinger equation was obtained using the BenDaniel and Duke technique under a Morse potential. The modelling was conducted in a GaAsSb-based valence-band quantum well to investigate the combined effects of non-resonant intense laser fields and externally applied electric fields. For the first time, the spatial dependence of the effective mass of a heavy hole was estimated relative to the Morse geometry of the confinement potential. The Schrödinger equation was solved to examine the electronic bound states and the corresponding wave functions using the Finite Element Method, incorporating the Kramers–Henneberger transformation and the Floquet method. Utilizing the density matrix formalism, the linear and third-order nonlinear optical responses were evaluated by calculating light absorption coefficients and refractive index changes under externally applied laser and electric fields. The electronic studies revealed that the laser-dressed confinement effects were diminished in the presence of a positive electric field, while enhanced confinement effects were observed when the laser-dressed quantum well was exposed to a negative electric field. Additionally, the laser-dressed optical responses were found to be red-shifted with a positive electric field and blue-shifted with a negative electric field.

This article describes a new synthesis of nanoscaled Y₂O₃ that is bioinspired. It has been confirmed that Callistemon viminalis flower extract works well as a chelator when used to bioengineer high-shape anisotropy nanorods of single-phase Y₂O₃. X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy and photoluminescence spectroscopy were used to analyse the structural, morphological, surface and optical features. The photoluminescent spectra of the bio-engineered nanorods show blue emissions. As the annealing temperature was increased from 300 to 500°C, the blue colour purity values of the synthesized Y₂O₃ nanorods were 58.1, 80.7 and 77.0% at 300, 400 and 500°C respectively. The chromaticity coordinates (0.2020, 0.1931), (0.1660, 0.1082) and (0.1714, 0.1226) from the photoluminescence spectra of the biosynthesized Y₂O₃ nanorods were used to determine these values. The CIE y-component coordinate values of the bioengineered blue-emitting nanophosphors suggest their potential for applications in display technology and white light-emitting diodes.

The application of fluorescent small molecules is greatly limited because they tend to photobleach and cause potential harm to organisms. However, SiO₂ with fluorescent properties can be obtained by incorporating fluorescent small molecules into the preparation process using Stöber’s method. In this study, we successfully synthesized and prepared nanosized SiO₂ spheres doped with sodium fluorescein (FS). The resulting fluorescent material exhibited excellent optical properties similar to FS and demonstrated good optical stability. Additionally, the surface of SiO₂ spheres was easily modified, allowing for the introduction of foreign groups or small molecules. By incorporating 4-dimethylaminobenzoic acid (DBA), the final FS@SiO₂@DBA fluorescent material enhanced the affinity for latent fingerprints. The use of FS@SiO₂@DBA composites for latent fingerprint development demonstrated significant development effects on various substrates, including slides, metal locks, rough marble, galvanized iron sheets, quartz crucibles and blue plastic housings. These findings suggest that FS@SiO₂@DBA has a significant impact on latent fingerprint development.