Trigonal Research Articles

Formation of nanosized copper silicides in a high-speed electric discharge plasma jet

Relevance. The search for suitable materials for creating a new generation of anodes in lithium-ion batteries that have not only high capacity, but also high electrical conductivity. For this purpose, the attempts have been made to use silicon Si, which has a high specific capacitance, instead of graphite C, but this material does not have high electrical conductivity. Copper silicides, in addition to high specific capacity, have high electrical conductivity values, since they do not react with lithium during operation, and therefore can be used to solve problems in the development of the above-mentioned lithium-ion anodes. Aim. To obtain dispersed materials in a high-speed jet of electric discharge plasma in the Cu-Si-C system. Objects. Dispersed materials obtained in the Cu-Si-C system. Methods. Plasma dynamic synthesis, X-ray diffractometry (X-ray phase analysis), scanning electron microscopy, transmission electron microscopy. Results. The authors have carried out the experimental studies to obtain dispersed materials of the Cu-Si-C system in a high-speed electric-discharge plasma jet and studied the microstructure and composition of the synthesized materials. It was revealed that the product consists of nanodispersed particles, which is confirmed by the results of scanning and electron microscopy. According to the results of X-ray diffractometry, crystalline phases of copper of the cubic system and copper silicides Cu3Si and Cu7Si of the hexagonal system are identified in the composition of the synthesized material.

Cost-effective microbial induced ZnO synthesis for building material: Antibacterial, photocatalytic and mechanical characteristics

Utilization of effective and economical nanoparticles/nanocomposite materials in civil engineering is still remaining a significant challenge in current research arena. In this study, microbial-induced precipitation was formulated for integration of white cement mortar to enhance efficiency and evaluate its potential applications in antibacterial and photocatalytic degradation of methylene blue. Hexagonal wurtzite structure of synthesized ZnO exhibited high crystallinity with significant contribution of hydration product after 28days analysis. Morphology of produced material showed less homogeneity with high densification and morphology altered from needles-like structure to tube with the integration of adsorbent ratio from ZnO-0 to 2.5, presented all the required chemical components in EDXS analysis. The water absorption rate in sample slurry of ZnO-2.5 exhibited significant reduction of 52.75 % compared to baseline water absorption rate of 12.71 % in commercial ZnO and contact angle was noted higher as 89.54°, which indicates hydrophilic character of material. The highest compressive strength of sample ZnO-2.5 was noted 508.89 kgf/cm2 in 28days of wet curing method, indicated the effective gel formation of calcium silicate in samples. Maximum methylene blue dye degradation recorded 79.95 % in case of using ZnO-2.5, which showed another influential character with excellent efficiency. In addition, prepared sample has shown almost complete bactericidal efficiency under simulated sunlight. Compared to commercial white cement mortar, biological white cement mortar can save NT$149,531 per cubic meter at industrial scale. Therefore, results indicate that microbial-induced zinc precipitation incorporated using hydrothermal preparation of biological white cement mortar improves the surface properties for applications and reduces its cost of study.

Synthesis of hexagonal mesoporous silica from coal fly ash and their evaluation as adsorbent for gallium recovery

Adsorption of gallium (Ga) utilizing solid waste synthetic materials can achieve both high-value solid waste use and solve the supply–demand paradox of Ga. To efficiently recover Ga in solution, this article describes a hydrothermal synthesis technique of mesoporous materials from the acid leaching residue of coal fly ash (CFA). According to the findings, the mesoporous silica synthesized by hydrothermal reaction with CTAB: nSiO32-=1:0.085 around 120℃ during 24 h exhibits a maximum specific surface area (771.25 m2/g) along with hexagonal mesoporous structure. Pseudo-second-order kinetic model that has an excellent correlation coefficient (R2 > 0.99) can explain this adsorption system. Since Freundlich model fits this adsorption action better, the process is multi-molecular layer adsorption. The thermodynamic fitting results show that the adsorption of Ga by mesoporous silica is an endothermic and spontaneous chaotic reaction. The adsorption mechanism could be depicted using ion exchange and coupling. The adsorption efficiency of Ga is still higher than 80 % after the material has been regenerated by multiple resolution. In conclusion, mesoporous silica prepared by CFA acid leaching residue has the potential to adsorb Ga.

Two-Dimensional-Like Phonons in Three-Dimensional-Structured Rhombohedral GeSe-Based Compounds with Excellent Thermoelectric Performance.

The coupling of charge and phonon transport in solids is a long-standing issue for thermoelectric performance enhancement. Herein, two new narrow-gap semiconductors with the same chemical formula of GeSe0.65Te0.35 (GST) are rationally designed and synthesized: one with a layered hexagonal structure (H-GST) and the other with a non-layered rhombohedral structure (R-GST). Thanks to the three-dimensional (3D) network structure, R-GST possesses a significantly larger weighted mobility than H-GST. Surprisingly, 3D-structured R-GST displays an extremely low lattice thermal conductivity of ∼0.5 W m-1 K-1 at 523 K, which is comparable to that of layered H-GST. The two-dimensional (2D)-like phonon transport in R-GST stems from the unique off-centering Ge atoms that induce ferroelectric instability, yielding soft polar phonons, as demonstrated by the Boson peak detected by the low-temperature specific heat and calculated phonon spectra. Furthermore, 1 mol % doping of Sb is utilized to successfully suppress the undesired phase transition of R-GST toward H-GST at elevated temperatures. Consequently, a peak ZT of 1.1 at 623 K is attained in the rhombohedral Ge0.99Sb0.01Se0.65Te0.35 sample, which is 1 order of magnitude larger than that of GeSe. This work demonstrates the feasibility of exploring high-performance thermoelectric materials with decoupled charge and phonon transport in off-centering compounds.

Liquid-phase epitaxy and characterization of YAl3(BO3)4 thin layers coactivated by Er3+ and Yb3+

Epitaxial layers of YAl3(BO3)4 co-doped with Er3+ and Yb3+ are grown from K2Mo3O10–(Y/Yb/Er)2O3–B2O3 complex flux melt by means of liquid phase epitaxy (LPE) technique. The morphology, structure and composition of the layers are investigated. Epitaxial layers with a thickness of 110 μm were obtained on laser-quality substrates, corresponding to a growth rate of 4.6 μm per hour. The segregation coefficients for Er3+ and Yb3+ cations are close to unity. The layers exhibit hexagonal huntite-type structure (sp. gr. R32) and small unite cell misfit with respect to the substrate. Absorption and emission spectra as well as fluorescence lifetime were measured.

Negative thermal expansion performance of (NaMg)xCr2-x(MoO4)3 (0≤x≤1) ceramics

Cr2Mo3O12 ceramics show negative thermal expansion (NTE) in a narrow high-temperature range due to the phase transition around 385 °C. To widen its NTE temperature range, a series of (NaMg)3+ co-doped Cr2Mo3O12 ceramics has been synthesized via a solid reaction process in this work. The effects of double cation (NaMg)3+ co-doping on the phase composition, morphology, phase transformation, and thermal expansion performance of Cr2Mo3O12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. Results indicate that double cation (NaMg)3+ can partially substitute Cr3+ in Cr2Mo3O12, which causes a phase transition from monoclinic Cr2Mo3O12 to hexagonal (NaMg)xCr2-xMo3O12. The single-phase (NaMg)xCr2-xMo3O12 ceramics with hexagonal structure is obtained when x = 0.5. (NaMg)3+ co-doping promotes the growth of grains and the density of hexagonal (NaMg)0·5Cr1·5Mo3O12 ceramics. (NaMg)3+ co-doping also successfully eliminates the temperature-induced phase transition of Cr2Mo3O12 at 385 °C. Hexagonal (NaMg)0·5Cr1·5Mo3O12 ceramics presents a better NTE with a coefficient of thermal expansion (CTE) of −3.97 × 10−6 °C−1 over a larger temperature range from 30 °C to 700 °C.

Hexagonal rod-like Eu3+doped CaMoO4 phosphors: Structural, photoluminescence and photometric properties for display device applications

A multicolored LED illumination device is a compact, durable, easy to obtain color-adjustable output illumination source. It is frequently utilized in the domains of room illumination and exterior displays. However, the advancement of multicolor LEDs has been hampered by the rise in price and the fall in luminous efficacy while changing illumination colors. In the present investigation we have prepared intense red emitting Eu3+ doped CaMoO4 phosphor nanopowders via simple solid-state reaction technique. The powder X-ray diffraction (PXRD) studies reveal the crystalline nature of the samples with scheelite–type mono phase tetragonal structure with I41/a space group. The band gap (Eg) energy values were estimated and found to range between 4.63–5.32 eV. Scanning electron microscopy (SEM) studies reveled the hexagonal rod-like structures with different Aloe Vera gel concentrations. The particle size was found to be around 40 nm. The vibrational modes of the prepared powders were evaluated by using Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. It was observed from the results that, there were 26 vibrational modes of CaMoO4 (Γ=3Ag + 5Au + 5Bg + 3Bu + 5Eg + 5Eu) 8 of which (4Au and 4Eu) were infrared active and 13 (Ag, Bg, and Eg) are Raman active. Photoluminescence (PL) emission intensity increases up to 5 mol% of Eu3+ ions load and subsequently it declines due to the concentration quenching phenomenon and effective energy transfer from Mo-O charge transfer band (CTB) to 5D0 levels of Eu3+. It was noticed from PL emission spectra that, four intense peaks located at 5D0 → 7F1 (590 nm), 5D0 → 7F2 (613 nm), 5D0 → 7F3 (654 nm), 5D0 → 7F4 (702 nm) of Eu3+ respectively. The Commission International de I'Eclairage (CIE) diagram indicates the red color emission and average correlated color temperature (CCT) value was found to be 2050 K. Further, the external quantum efficiency (QE) and color purity (CP) were calculated to check the phosphor efficiency and found to be 92% and 72% respectively. The present investigation opens up a new avenue in the fabrication of low-cost display devices with high color purity and luminous efficacy.

Research on the formation and evolution mechanism of cracks in laser stealth dicing of silicon carbide crystals

In this study, to enhance the cutting efficiency and precision of the chip while minimizing waste from cutting damage, molecular dynamics simulation is used to investigate the formation mechanism of defects and cracks of silicon carbide crystals during the laser stealth dicing. The results showed that the high thermal stress generated by the laser scanning induced the production and expansion of cracks. Thus, the crack propagates in the direction of [100], and subsequently forms branches in the directions of [101] and [101‾]. It also can be found that the silicon carbide crystals produced dislocation slip, and the dislocation lines moved along the slip surface, which impeded the crack extension in the directions of [101‾] and [1‾01‾]. In addition, atomic phase transformation and loss is occurred under the high-temperature environment of the laser heating process. Cubic diamond crystal structure atoms are partially transformed into amorphous structure, while a small portion transformed into hexagonal diamond structure. The crystal structural arranged orderliness temporarily increased and then rapidly decreased due to prefabrication defects, and new unknown crystal structures are produced.

Synthesis, Characterization, and Photocatalytic Activity of Magnetically Separable Fe3O4@SiO2@ZnO–Ag Composite Photocatalyst

AbstractMagnetically separable Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO–Ag composites are synthesized using hydrothermal and wet chemistry methods. The samples obtained are characterized in terms of morphology, composition, optical, and magnetic properties using TEM, SEM‐EDS, XRD, FTIR, VSM, XPS, and UV–vis, and the photodegradation of Acid Blue 161 dye under UV irradiation is investigated. As a result of SEM and TEM analyses, the diameters of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO–Ag composites are determined as 210, 220, 230 and 235 nm, respectively. The magnetic properties of the samples are determined by VSM analysis. In VSM analyses, magnetization saturation values of Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO–Ag composites are determined as 81, 64, 41 and 20 emus × g−1, respectively. In XRD analysis, the face‐centered cubic structure of Fe3O4 particles and the hexagonal wurtzite structure of ZnO are determined and it is determined that they are compatible with standard diffraction cards. According to UV–Vis analysis, Eg values for Fe3O4, Fe3O4@SiO2, Fe3O4@SiO2@ZnO, and Fe3O4@SiO2@ZnO–Ag composites are found as 1.3, 1.68, 2.21, and 2.15 eV, respectively. Among the photocatalysts prepared, Fe3O4@SiO2@ZnO–Ag composite Acid Blue 161 shows superior removal and recyclability against photodegradation of the dyestuff.

Both the ionic and covalent bonds stabilize the W@Si12 cluster

Si is an important semiconductor material in the development of modern industry. With the miniaturization trend of semiconductor devices, the size of Si has reached the cluster size. The search for stable Si clusters is an important issue. In this work, the electronic structures and stability mechanism of the W@Si12 cluster are calculated by the first-principle calculations. Different from a C2v hexacapped trigonal prism structure of Si12, the W@Si12 cluster presents an embedded hexagonal prism structure with D6h symmetry. The addition of W atom leads to a higher stability. The molecular orbitals show obvious superatomic characteristics for the W@Si12 cluster, and their energy levels are more degenerate than that of the Si12 cluster. The population analysis indicates that a total charge of 2.21e is transferred from Si atoms to the center W atom, which suggests an ionic bond for W-Si. The electron localization function further proves a covalent bond for Si–Si. The enhanced stability of the W@Si12 cluster is attributed to the combination of the ionic and covalent bonds.

Structural elucidation, morphological properties, dielectric properties and their physical interpretation of cerium-substituted cobalt and barium-based M-type hexagonal nano ferrites

This research uses the sol–gel method to look into how adding Co2+ and Ce3+ dopant cations changes the structure, shape, and electrical properties of M-type Ba hexagonal ferrites that have been synthesized. x-ray diffraction (XRD) analysis confirms the successful formation of the targeted hexagonal M-type crystal structure. We observed a reduction in unit cell volume and lattice parameters as the dopant concentration increased, indicating the effective incorporation of dopant ions into the crystal lattice. When the doping process happened, needle-like grain shapes appeared, which could be seen with a field emission scanning electron microscope (FESEM). As the concentration of the dopant increased, the dielectric spectroscopic measurements revealed an increase in the loss tangent (tan δ) from 0.05 to 3.68, and a decrease in the dielectric constant (ε′) from 283 to 3.41. This suggests a reduction in polarization and dielectric permittivity, as well as increased energy dissipation within the material. The electric modulus spectra showed relaxation behaviour that was non-Debye-type, which is another sign that there are complex and multifaceted ways for charges to move. The measurements of relaxation time and AC conductivity showed that the relaxation intervals were not regular and that the conductivity dropped from 2.22*10–4 Ω−1m−1 to 1.4*10–7 Ω−1m−1 as the doping concentration increased. Based on these findings, it seems that the processes of conductivity and dielectric relaxation play a big role in how charges move around in the doped ferrites. We validated complex impedance data obtained through electrochemical impedance spectroscopy (EIS) software against calculated impedance values. The derived grain and grain boundary characteristics also agreed with the observed grain distribution and boundaries from the micrographs, further corroborating the analysis.

Green Synthesis of ZnO Nanoparticles and Ag-Doped ZnO Nanocomposite Utilizing Sansevieria trifasciata for High-Performance Asymmetric Supercapacitors.

This study provides a comprehensive analysis of a biofabricated nanomaterial derived from Sansevieria trifasciata root extract, evaluating its structural, morphological, and optical properties for use in asymmetric supercapacitors. The nanomaterial comprises pristine ZnO nanoparticles (ZnO NPs) and a 1% Ag-doped ZnO nanocomposite (Ag@ZnO NC), synthesized through a green-assisted sol-gel autocombustion method. Employing techniques such as X-ray diffraction, ultraviolet-visible near-infrared, scanning electron microscopy-energy-dispersive X-rayspectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy, the study confirms a hexagonal wurtzite structure and nanocrystallites with spherical and hexagonal shapes (30 nm). Optical analysis reveals a red shift in the band gap with Ag doping, indicating improved conductivity. The material shows potential applications in solar cells, optoelectronics, spintronics, wastewater treatment, and high-performance asymmetric supercapacitors. Raman spectra validate the wurtzite phase and identify intrinsic defects. Electrochemical tests demonstrate remarkable supercapacitive behavior with a 94% capacitance retention after 10,000 cycles, highlighting its promise as advanced asymmetric supercapacitors.

Enhancement of the anomalous Hall effect by distorting the Kagome lattice in an antiferromagnetic material

In topological magnetic materials, the topology of the electronic wave function is strongly coupled to the structure of the magnetic order. In general, ferromagnetic Weyl semimetals generate a strong anomalous Hall conductivity (AHC) due to a large Berry curvature that scales with their magnetization. In contrast, a comparatively small AHC is observed in noncollinear antiferromagnets. We investigated HoAgGe, an antiferromagnetic (AFM) Kagome spin-ice compound, which crystallizes in a hexagonal ZrNiAl-type structure in which Ho atoms are arranged in a distorted Kagome lattice, forming an intermetallic Kagome spin-ice state in the ab-plane. It exhibits a large topological Hall resistivity of ~1.6 µΩ-cm at 2.0 K in a field of ~3 T owing to the noncoplanar structure. Interestingly, a total AHC of 2,800 Ω-1 cm-1 is observed at ~45 K, i.e., 4 TN, which is quite unusual and goes beyond the normal expectation considering HoAgGe as an AFM Kagome spin-ice compound with a TN of ~11 K. We demonstrate further that the AHC below TN results from the nonvanishing Berry curvature generated by the formation of Weyl points under the influence of the external magnetic field, while the skew scattering led by Kagome spins dominates above the TN. These results offer a unique opportunity to study frustration in AFM Kagome lattice compounds.

Utilizing Pometia Pinnata leaf extract in microwave synthesis of ZnO nanoparticles: Investigation into photocatalytic properties

In this work, ZnO photocatalyst has been synthesized using matoa (Pometia pinnata) leaf extract under various microwave irradiation powers at 360, 540, and 720 Watts for 3 minutes on each. The UV-Vis absorption spectra of ZnO exhibited a peak in the ultraviolet region 300-360 nm. UV-Vis absorption analysis revealed a decrease in the band gap energy from 3.15 eV to 3.10 eV as the irradiation power increased. Field emission scanning electron microscopy (FESEM) images displayed spherical and nanoplatelet morphology with a decrease in particle size observed from 773 to 709 nm with increasing irradiation power. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite structure of ZnO with crystallite sizes in the range of ~18-20 nm. The synthesized ZnO nanoparticles was successfully employed as a photocatalyst in 4-nitrophenol degradation, achieving the highest degradation percentage of 82.7% at 540 Watts with a corresponding reaction rate constant of 0.0126/min. In conclusion, the microwave-assisted synthesis of ZnO using on matoa leaf extract demonstrated significant potential for the degradation of organic pollutants, thereby contributing to water purification efforts.

Spectral-luminescence characteristics of solid solutions ZrO2-Eu2O3 crystals

Data on the structure of (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27) have been presented. The crystals with x = 4 have a hexagonal structure, while those with x = 8 are a mixture of cubic and tetragonal phases. The crystals with x = 10, 12 and 15 have a cubic structure, and those with x = 27 are two-phase and contain cubic modification and pyrochlore phase.Luminescent spectra of the (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solutions have been taken in the as-grown and air-annealed states. The presence of Eu2+ ions was revealed in (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27) after growth, the content of which decreases significantly after heat treatment in air. It has been shown that in (96-85) mol.% ZrO2 - (4–15) mol.% Eu2O3 crystals the relative proportion of optical centers of Eu3+ surrounded by oxygen seven-vertex is lower compared to crystals (96.7–85) mol.% ZrO2 - (3.6–15) mol.% Gd2O3 - 0.1 mol.% Eu2O3. The (73, 80) mol.% ZrO2 - (20, 27) mol.% Eu2O3 crystals contain optical centers of Eu3+ surrounded by oxygen six-vertex with two oxygen vacancies along the diagonal faces of the cubic crystal lattice. Their percentage being higher than in the (79.9, 76.9) mol.% ZrO2 - (20, 33) mol.% Gd2O3 - 0.1 mol.% Eu2O3 crystals.In crystals of (100-x) mol.% ZrO2 - х mol.% Eu2O3 solid solution concentration series (x = 4, 6, 8, 10, 12, 15, 20, 27), the presence of concentration quenching was revealed with increasing concentration of europium ions.

High-performance asymmetric supercapacitor based on hierarchical hydrothermally grown CuS nanostructures

In this work, various hierarchical CuS were fabricated via an efficient one-step hydrothermal process with different surfactants (polyvinyl pyrrolidine (CS-P), Citric acid (CS-C), Oleic acid (CS-O)) and examined as electrode materials for supercapacitors. XRD, FESEM, HRTEM and BET analysis reveal the fabrication of a hexagonal crystal structure with porous microspheres of CuS-PVP having a BJH pore diameter of 16.241 nm. Among these, the CS-P electrode exhibits a superior specific capacitance of 414.28F/g at 1 A/g of current density in the KOH electrolyte. Additionally, an asymmetric supercapacitor built with CS-P as positive and Activated carbon as negative electrodes exhibited a specific energy of 27.95 Wh/kg at 624.96 W/kg of specific power at 2 A/g and demonstrated outstanding cycling stability with 80.6 % persistence of capacitance for 2500 GCD cycles at 10 A/g. Additionally, an ASC device created for use in real life and tested by charging it for 30 s managed to reach a 3-minute 50-second self-discharging duration. Hence, these favourable electrochemical findings indicate that the hydrothermally grown hierarchical CuS-PVP electrode is a bright potential material in energy storage applications.

Comparative Study of Mechanical Scaling Effects of Origami-Inspired Motion Generation Mechanisms with Multi-Degree Vertices

Origami exhibits the remarkable ability to transform into diverse shapes, including quadrilaterals, triangles, and more complex polygons. This unique property has inspired the integration of origami principles into engineering design, particularly in the development of foldable mechanisms. In the field of robotics, when combined with actuators, these foldable mechanisms are referred to as active origami. Origami-based mechanisms play a pivotal role as versatile end effectors or grippers, enabling them to accurately trace desired trajectories. The performance of these mechanisms heavily relies on their specific fold patterns. To shed light on their capabilities, this study focuses on five representative structures using spherical mechanisms: oriceps, Miura ori, MACIOR, and two hexagonal structures. To assess their potential, a comparative analysis is conducted, evaluating their kinematic and scaling performances. The analysis employs the “scaling factor” as a metric, which quantifies the mechanical advantage of these mechanisms. This metric aids in the selection of appropriate structures for various applications.

Sustainable green synthesis and characterization of nanocomposites for synergistic photocatalytic degradation of Reactive Orange 16 in textile wastewater using CuO@A-TiO2/Ro-TiO2

This paper explores the photocatalytic degradation of Reactive Orange 16 (RO16) dye in textile wastewater employing a novel CuO@A-TiO2/Ro-TiO2 nanocomposite. The nanocomposite was synthesized via a hydrothermal technique, resulting in a monoclinic phase of leaf-shaped CuO loaded on a hexagonal wurtzite structure of rod-shaped ZnO, as confirmed by FE-SEM and XRD analyses. Optical experiments revealed band gap energies of 1.99 eV for CuO, 2.19 eV for ZnO, and 3.34 eV for the CuO@A-TiO2/Ro-TiO2 nanocomposite. Photocatalytic degradation experiments showcased complete elimination of a 100 mg/L RO16 solution (150 mL) after 120 min of UV light illumination and 100 min of sunlight illumination, emphasizing the nanocomposite's efficiency under both light sources. The study further delves into the application of the CuO@A-TiO2/Ro-TiO2 nanocomposite for the degradation of actual textile wastewater samples under sunlight irradiation. The results underscore the nanocomposite's remarkable efficacy in treating RO16 in textile wastewater, positioning it as a promising candidate for sustainable and efficient wastewater treatment applications. This research contributes valuable insights into the development of advanced photocatalytic materials for textile dye degradation in wastewater treatment.

First-principles calculation to investigate phase transition and associated changes in electronic, excitonic, and optical behavior of RbMgH3 perovskite polymorphs

Motivated by recent experimental and theoretical research on the ability to store and release hydrogen from a hydride perovskite with a large ionic character called RbMgH3, we conducted a study using density functional theory (DFT) to investigate the optoelectronic behavior of RbMgH3 in both Cubic and Hexagonal structures, as well as its phase transition.Our findings reveal that RbMgH3 exhibits an indirect band gap of 2.41 eV in the Hexagonal phase and a direct band gap of 2.15 eV in the Cubic phase. Additionally, we calculated the Gibbs energy to predict the occurrence of the phase transition. It was determined that RbMgH3 undergoes a structural transformation from Cubic to Hexagonal at a pressure of 1.78 GPa. This transition has the potential to enhance the storage kinetics of hydrogen, making RbMgH3 suitable for various applications.

Synthesis and characterization of lead-doped copper ferrite nanoparticles

Magnetic nanoparticles of lead-doped copper ferrite, PbxCu1−xFe2O4, where x = 0.0, 0.1, and 0.2, were synthesized by the combustion method. The samples were characterized by X-ray diffraction (XRD) to determine crystallographic phases and crystallite sizes. The results showed the presence of trigonal and tetragonal phases for x = 0, with crystallite sizes of 37 nm and 72 nm, respectively, and for x = 0.2, with crystallite sizes of 23 nm and 21 nm, respectively. For x = 0.1, only the trigonal phase was observed, with a crystallite size of 27 nm. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) showed cubic, hexagonal, and rod-shaped structures for all values of x, indicating a polycrystalline material with various spatial orientations. Energy-dispersive X-ray spectroscopy (EDS) identified the chemical elements present in the samples and Mössbauer spectroscopy revealed the formation of spinel-type ferrite. Vibrating sample magnetometry (VSM) displayed typical ferrimagnetic behavior and the Jahn-Teller effect was observed in all samples.