Rhombohedral Structure Research Articles

Bio fabrication of Fe2O3 NPs and their analgesia efficiency for post-operative epidural anaesthetic applications- study of chronic inflammatory pain model in mice

ABSTRACT The current study reported the synthesis of ferric oxide nanoparticles (Fe2O3 NPs) using the leaf extract of Amaranthus spinosus Linn and studied their analgesia efficiency in chronic inflammatory pain model in mice. X-RD, TEM results showed that the spherical Fe2O3 NPs having rhombohedral crystalline structure with an average particle size of 10 nm. Additionally, inflammatory pain models were designed through FCA injection on the CD1 mice hind paw with various Fe2O3 NPs doses and analgesic behaviour was monitored. The prepared Fe2O3 NPs showed a dose-dependent analgesic activity with considerable decrease in inflammatory cells, ROS production and pro-inflammatory markers. Additionally, the expression of enzymes responsible for ROS production were decreased. The outcomes of present work revealed the local administration of Fe2O3 NPs caused the substantial analgesia through reduction of pro-inflammatory signalling and inflammatory cellular infiltration along with micro-environmental free radical scavenging in mouse inflammatory pain model.

Synthesis, Structure and Antiferromagnetic Large‐Distance Long‐Range Coupling of the Ruthenate(V) Sr3(Ag2/3Sr1/6)RuO6

AbstractBlack, air‐stable crystals of the new ruthenate(V) Sr3(Ag2/3Sr1/6)RuO6 were grown in a silver ampoule using KO2 as oxidative flux. X‐ray diffraction on single‐crystals revealed a rhombohedral structure with the space group R c. Sr3(Ag2/3Sr1/6)RuO6 crystallizes isostructural to Sr4PtO6 in the K4CdCl6 structure type. By sharing trigonal faces, alternating [RuO6] octahedra and [(Ag2/3Sr1/6□1/6)O6 trigonal prisms form segmented chains running parallel to the crystallographic c‐axis. Eightfold coordinated strontium cations are located between the rods. Regardless of the wide spatial separation of the magnetic cations (588 and 594 pm), Sr3(Ag2/3Sr1/6)RuO6 shows long‐range antiferromagnetic order below the relatively high Néel temperature of 79 K in magnetic fields up to at least 9 T, as measurements of the magnetic susceptibility and heat capacity show. Despite the pseudo one‐dimensional character of the structure, the characteristic of the susceptibility indicates a three‐dimensional coupling of magnetic ions.

Physicochemical Investigation of Synthesized Bismuth and Silver-Doped Bismuth Nanoferrites, And Their Dielectric Properties

Bismuth nano ferrite and silver-doped bismuth nano ferrite are synthesized by the sol-gel method. The synthesized compound is characterized through several characterization methods such as the X-ray diffraction method, Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and UV-Visible spectral studies. The X-Ray diffraction confirms bismuth nano ferrite has a Rhombohedral structure and belongs to the R-3m space group, and the silver-doped bismuth nano ferrite has an orthorhombic structure and belongs to the Cmcm space group. The crystallite size is calculated through Scherrer’s formula, the bismuth nano ferrite has a crystallite size of 20 nm, and the silver-doped bismuth nano ferrite has a crystallite size of 36.33 nm. FTIR studies confirm the formation of ferrite and indicate the metal ion group observed the peak shift after doping in the fingerprint region. The metal ion peaks are presented at 446.7 cm−1 and 527.8 cm−1 but after doping they shifted to 453 cm−1, 534 cm−1. The UV-Visible spectral analysis identifies the change in the energy band gap through a tauc plot, initially the energy band gap of bismuth nano ferrite is about 2.79 eV but after doping it reduces to 1.61 eV. the surface morphology is determined by SEM analysis and it provides 30 nm and for the doped compound 37 nm average particle size. Dielectric study confirms doping of silver to the bismuth gives more improved results which will be helpful at the application level such as in memory devices, photocatalysis, water splitting, and gas detection.

Enhanced electrical, optical and magnetic properties of BiFeO3 perovskite nanoparticles co-doped with Y and Cu

The present work includes the fabrication of pure BiFeO3 and Bi0.9Y0.1Fe1−xCuxO3 (x = 0.05, 0.10, 0.15) nanoparticles by the usual sol-gel route. The characterization of structural, morphological, optical, electrical, and magnetic properties of the synthesized samples was achieved through x-ray diffraction spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, an impedance analyzer, and a vibrating sample magnetometer. The Fourier transform infrared study confirmed the presence of Bi–O and Fe–O bonds. The x-ray diffraction patterns confirmed the rhombohedral (R3c) structure as a major phase with the orthorhombic (Pnma) structure as a secondary phase in all samples, and few amount of impurity phase of Bi25FeO40 was also determined. The surface morphology analysis showed the variation of particle size from 63 to 174 nm. The Raman spectra of 13 optical phonon modes, including 4A1 and 9E symmetric phonons, are observed for all samples, and the positions of these modes are almost similar, except the intensities of A1 modes. The optical measurements show a reduction in bandgap from 2.17 to 2.03 eV with co-doping, revealing itself as a more promising applicant in photovoltaics. An enhanced value of the dielectric constant is observed for different doped samples at different frequency regions from 100 Hz to 10 MHz. Magnetic investigation demonstrates the improved ferromagnetism with co-doping of Y and Cu due to distortion in the FeO6 octahedron. A maximum saturation magnetization of 0.26 emu/gm and a coercivity of 2915 Oe were found for Y concentration of 10% and Cu concentration of 15%.

Augmentation of optical and magnetic characteristics at ambient temperature in bismuth ferrite-titanium (BiFe1–xTixO3) multiferroic compounds

A facile sol–gel approach was utilized to synthesis BiFe1-xTixO3 multiferroic ferrites, denoted as BFO-xTi (with x from 0.00 to 0.10). XRD analysis revealed that the undoped BFO ferrite exhibited a rhombohedral structure, and a transition from the rhombohedral phase to the pseudo-cubic phase occurred as the Ti content increased. The optical band gap increased from 2.00 eV to 2.23 eV with a Ti substitution at 0.10 mol. The magnetic properties exhibited a transition from antiferromagnetic to ferromagnetic phase due to the structural phase transition and super-exchange interaction between the 3d orbitals of Ti4+ and Fe3+/Fe2+ at the B-sites through oxygen vacacies. The sample with a 0.10 mol Ti substitution demonstrated the highest M s and M r values of 3.68 emu g−1 and 7.21 × 10–3 emu g−1, respectively. Overall, the results suggest that the BiFe1-xTixO3 multiferroic ferrites with optimal composition hold promise for use in magneto-optical devices.

Preparation and electrochemical properties of a ceramic solid electrolyte with high ionic conductivity, Li1.3Al0.3Ti1.7(PO4)3

The emergence of lithium-ion solid electrolytes greatly increases the safety risk of liquid electrolytes. Among the many solid electrolytes, aluminum-doped Li1.3Al0.3Ti1.7(PO4)3(LATP) has become a research hotspot due to its high ionic conductivity and good air stability. However, the traditional high-temperature sintering process has the problems of lithium volatilization and secondary phase formation. Therefore, it is very difficult to prepare high-quality LATP solid electrolytes. The X-ray diffraction pattern and analysis showed that the LATP samples prepared in this paper showed rhombohedral structure and could be indexed by the R3c space group, and a new method of excess lithium compensation sintering was proposed, in which lithium compensation (LiNO3) could well reduce the impact of lithium volatilization. It can be used as a sintering additive to promote the sintering densification of LATP. In this paper, the optimal sample for sintering at 900°C was determined by measuring the microstructure and electrochemical properties of the electrolyte, and lithium doping was studied. The LATP solid electrolyte with 10 wt% lithium doped has a conductivity of 7.2× 10−4 S/cm and a low activation energy (0.278 eV). Its mechanical properties (elastic modulus and hardness) are the best, which are 103.024 GPa and 8.053 GPa, respectively, and the value of its elastic modulus is much greater than that of lithium metal shear modulus of 4.25 GPa, which can effectively inhibit the growth of lithium dendrites. And the magnitude of the grain boundary conductivity and particle size of the lithium-doped sample correspond to the dielectric constant results.

Stability Enhancement in Copper-Doped Iron Oxide Resistive Random Access Memory via RF Co-Sputtering

In the study, the ITO/Cu-doped Fe2O3/ITO thin film RRAM is prepared using an RF sputtering system. The XRD pattern shows that the Cu:Fe2O3 thin film has a rhombohedral structure and does not display secondary or impurity phases for copper. Results revealed that the standard deviation and average voltage of Cu:Fe2O3 thin film are −1.98 and 0.92 V for Vset, respectively, while those for Vreset are 1.31 and 0.39 V, respectively. The resistive switching cycles and data retention test times of the Cu:Fe2O3 thin film device show that the on/off ratio is 39.4 and over 104 s. These results indicated that the Cu-doped Fe2O3 thin film can improve the performance of RRAM.

Efficiency assessment of hydrothermally synthesized Mn2+/3+ modified LaCoO3 nanoparticles for advanced wastewater remediation

Abstract The use of light and a particular material known as a photocatalyst to degrade hazardous dyes in wastewater is an exciting new development in the field of photocatalytic dye degradation. In this study we investigated the characteristic properties and photocatalytic dye degradation of manganese doped lanthanum cobalt (LaCoO3 (LCO)) nanoparticles (NPs). The NPs were synthesised using hydrothermal synthesis techniques and analysed its properties by utilising diverse technologies such as XRD, FeSEM with EDAX, Raman Spectroscopy, Photoluminescence spectroscopy and UV-DRS. From XRD analysis we found that the Mn doped LCO NPs have single phase rhombohedral crystal structures with R 3 ‾ $\overline{3}$ c space group and doping cause expansion of lattice. Surface morphology of the synthesised NPs was found to be altered from spherical to spine/rod like microstructure when Mn is incorporated to LCO lattice. PL spectroscopies show broad photoemission at 360–490 nm after absorbing 310 nm light. From the UV–Vis spectroscopy the optical bandgap of the materials around 4.5 eV, indicating they can absorb visible light effectively. LCO can absorb both UV and visible light, expanding its potential for outdoor applications under natural sunlight. Doping LCO with other elements can modify its bandgap and improve its activity towards specific dyes. LCO exhibits good chemical and thermal stability, making it reusable for multiple cycles. While LCO shows promise as a visible light photocatalyst for dye degradation, its efficiency can vary significantly depending on the specific conditions. We tested Congo Red (CR) dye with prepared photocatalyst to study how well they breakdown in visible light. Studies have reported degradation rates for different dyes ranging from 50 to 90 % within an hour under optimized conditions. The LCMO nanoparticles exhibited noteworthy photocatalytic activity, as evidenced by a degradation efficiency of 77 % within a 30 min timeframe. Our findings indicate that LCMO nanoparticles possess significant potential for environmental clean-up.

Etching and Compositional Ratio Effect on the Surface Properties of Bismuth Telluride Thin Films

Bismuth telluride has garnered considerable attention owing to its versatile properties applicable in thermoelectric and antibacterial domains, as well as its intriguing topological insulating properties. In this work, our group fabricated bismuth telluride thin films with various ratios using radio frequency magnetron sputtering. The surface properties of these thin films were thoroughly analyzed by employing a diverse array of analytical techniques, including X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), four-point probe and contact angle (CA) measurements. Specifically, our XPS findings indicated that Bi is more susceptible to oxidation than Te following Ar+-ion etching. Pure Te thin films exhibited the highest Rq value of 31.2 nm based on AFM and SEM results due to their larger grain sizes. The XRD patterns revealed a peak at 27.75° for thin films with 20% Te, attributed to its rhombohedral structure. Moreover, thin films with 30% Te yielded the highest weighted average work function with a value of 4.95 eV after etching. Additionally, pristine Bi and Te thin films demonstrated the most robust hydrophobic properties compared to intermediate-composition thin films, as determined by CA measurements.

Optimization of hematite nanoparticles from natural ore as novel imaging agents: A Green Chemistry approach.

In this research, we propose an environmentally friendly method for producing hematite nanoparticles (H-NPs) from natural hematite ore, focusing on their application as efficient contrast agents in x-ray and computed tomography (CT) imaging for medical purposes. The process involves the reduction of iron oxide within the ore to attain the desired hematite phase, crucial for synthesizing H-NPs. To ensure sustainability, we adopted a Green Chemistry approach, utilizing a combination of carbon soot and limestone for the purification process, thereby achieving eco-conscious production. The produced H-NPs were thoroughly characterized using various analytical techniques, such as x-ray fluorescence (XRF), x-ray diffraction (XRD), Fourier transmission infrared spectroscopy (FT-IR), and FESEM-EDX (field emission scanning electron microscopy-energy-dispersive x-ray spectroscopy). XRD analysis confirmed the crystalline rhombohedral hexagonal lattice structure, while FT-IR spectra indicated the presence of characteristic Fe-O stretching modes in line with the expected molecular composition. FESEM-EDX imaging unveiled agglomerated particles, ranging in size from 54.6 to 149.9nm for iron ore and 22nm for H-NPs. These particles were primarily composed of iron (Fe) and oxygen (O). The magnetic properties of the H-NPs were investigated through vibrating sample magnetometer (VSM) studies, highlighting their distinct ferromagnetic behavior. Of particular significance, the H-NPs demonstrated exceptional performance as contrast agents in both x-ray and CT imaging. Even at minimal concentrations, they exhibited remarkable x-ray absorption capabilities. CT scans further validated their exceptional absorptive capacity. These findings emphasize the potential of H-NPs as valuable assets in medical imaging, serving as sustainable tools for enhanced diagnostic applications. The study showcases an eco-conscious approach to harnessing natural resources, paving the way for a greener and more effective utilization of H-NPs in the medical imaging landscape.

Enhancing thermoelectric behavior of Bismuth Selenide crystal via substitution of Sulfur and Tellurium

Sulfur and Tellurium substituted Bismuth Selenide (Bi2Se3-x-ySxTey, x = y = 0, 0.1, 0.15, 0.2) quaternary alloy crystals were synthesized by using vertical Bridgman technique. Energy dispersive analysis of X-rays confirmed elemental composition and purity of the grown crystals. Field emission scanning electron microscopy showed that the growth of crystals has occurred by layer growth mechanism. Rhombohedral crystal structure is validated through analysis of powder X-ray diffraction pattern. Thermoelectric parameters such as electrical conductivity, Seebeck coefficient and thermal conductivity were calculated from 303 K to 773 K and from that power factor as well as figure of merit have been determined for all grown crystals. Electrical conductivity significantly increased due to Sulfur and Tellurium incorporation and maximum value obtained is 147.72 S/cm at 503 K for Bi2Se2.6S0.2Te0.2. Seebeck coefficient and thermal conductivity showed decrement with incorporation of Sulfur and Tellurium. Reduction in thermal conductivity and enhancement in electrical conductivity resulted in the improvement of figure of merit. Sulfur and Tellurium substitution showed considerable improvement in ZT from 0.31 (533 K) for pristine Bi2Se3 to 1.28 (523 K) for Bi2Se2.6S0.2Te0.2.

Enhanced dielectrics, ferroelectric and optical properties of lithium niobate for high temperature applications using potassium oxide (K2O) additive

Dielectrics, Ferroelectric and Optical properties of Lithium Niobate has been examined using Potassium Oxide (K2O) as an additive on the samples prepared by solid state reaction method using high energy ball milling. The crystal structure analysis by Rietveld structure refinement confirms that the LiNbO3 (LN) with K2O additive also exhibit the rhombohedral structure with R3c space group. The SEM characterization of the microstructure reveals that the samples sintered at a temperature of 1050 °C, have regular and uniform grain morphology and better density. The average grain size decreases for the K2O added compositions in the beginning and increases later for higher concentration of additive. Thermal study with TGA suggests that as the activation energy is decreases, the polarization is enhanced and the LN composition with 2.72 wt% K2O additive shows the best thermal stability. The frequency and temperature dependent dielectric properties were investigated in a wide range of frequency and a substantial enhancement in the dielectric constant of LN is obtained by K2O addition. A useful enhancement in permittivity is obtained with increase of temperature. The band gap values for direct and indirect band gaps for the various compositions are also determined. The least direct band gap is discovered to be 2.36 eV for the composition with 2.72 wt% K2O additive. The composition-dependent photoluminescence (PL) emission studies reveal that the emission spectra for both the pure LiNbO3 and K2O added LiNbO3 compositions lies in the UV–visible region. All the investigated compositions exhibit distinct green, yellow, and red emission peaks. The LN with 2.72 wt% K2O additive shows the best dielectric, thermal stability and polarization response with maximum polarization Ps ∼1.16 μC/cm2. The present investigations suggest that properties of LN can be significantly improved by using K2O additive for sustainable, low cost, environmental friendly energy storage material for high temperature applications.

Influence of the Synthesis Process on the Physical Property Characteristics of BiFeO3 Ceramics Prepared by Flux-based Molten Salt and Solid-state Reaction Route: A Comparative Study

This work reports the influence of the solid-state reaction (SSR) and molten-salt synthesis (MSS) routes on the physical properties of the multiferroic BiFeO3 (BFO) compound exploited for capacitors and memory devices. Rietveld refinement reveals that the MSS-derived BFO ceramics have exhibited a pure-phase distorted rhombohedral perovskite structure at low temperatures (650 °C) compared to the SSR method. The FE-SEM illustrates the uniform distribution of spherical-shaped BFO grains. By altering the fabrication route, the calculated bandgap values of BFO were tuned within the range of (2.14 ± 0.02) to (2.05 ± 0.02) eV based on Tauc’s plot. The suppression of oxygen vacancies led to better dielectric characteristics at higher frequencies in the MSS-prepared BFO nanoceramics. Also, the MSS-derived BFO ceramics possessed a typical canted-AFM loop with a higher MR value of ∼2.73×10−2 emu g−1. These observations suggest that fabrication techniques have a decisive effect on the phase formation kinetics and multiferroic properties of BFO ceramics.

Reducing anisotropy of rhombohedral Bi-rich phase for high-performance Ag-alloyed Sn–Bi low-temperature solders

The rhombohedral structure is with anisotropic properties, leading to brittle mechanical properties. However, it is one of the major constituent phases, the (Bi) phase, in the Sn–Bi-based low-temperature solders, which is demanding in the electronic industry for reducing the soldering temperature and alleviating the warpage in high-density fine-pitch electronic packaging. Herein, we proposed a high-performance Ag-alloyed Sn–Bi (SBA) low-temperature solder by reducing the fraction and, more importantly, the anisotropy of the (Bi) phase. We found that the (Bi) phase exhibited considerable solubility for Ag and Sn, even after thermal aging, without any nanoprecipitates as confirmed with both CALPHAD-type thermodynamic modeling and high-resolution TEM. The solution effects of Ag and Sn in the (Bi) phase is elaborated based on in situ nano-indentation, EPMA compositional analyses, EBSD characterizations, and ab initio calculations. The presence of Ag and Sn in the (Bi) phases resulted in both solid solution hardening and softening effects, depending on the Schmid factor of the grain. As a result, in (Bi) polycrystals, alloying could effectively mitigate the anisotropic mechanical properties of the (Bi) phase and facilitated a more uniform dispersion of forces exerted among (Bi) grains in all orientations. Consequently, the designed SBA solder exhibited superior mechanical properties, e.g., an ultimate tensile strength (UTS) of 55 MPa, elongation of 46%, and toughness of 20.6 × 106 J/m3 at a strain rate of 0.0005 s−1. This understanding opens the door for enhanced rhombohedral phase in alloy design for various applications.

A Facile Method for Synthesis of α-Fe2O3 Nanoparticles and Assessment of Their Characterization

Recently, magnetic nanomaterials have gained much attention from researchers because of their various unique physical and chemical properties and usage in a wide range of technological aspects. In this study, the synthesis of α-Fe2O3 nanoparticles was performed by a simple co-precipitation method. The synthesis of α-Fe2O3 nanoparticles was carried out by mixing ferric nitrate and oxalic acid in an aqueous solution followed by evaporation, resulting in the solution’s dried form. The synthesized nanoparticles were analyzed by XRD, FTIR, Raman spectra, SEM-EDX, DSC, BET, and Zeta potential for detailed examination of the morphology, structure, and other physicochemical characteristics. The XRD results confirmed that the nanoparticles formed were Hematite (α-Fe2O3) after the evaluation of obtained spectra compared to the Joint Committee on Powder Diffraction Standards Database (JCPDS). The FTIR spectra showed various bonds among functional groups, O-H bending, Fe-O group, and within-vibration bonds. The phase study of the α-Fe2O3 nanoparticles was performed by using Raman spectroscopy. SEM depicted a sphere-like or rhombohedral (hexagonal) structure, and the EDX spectrum confirmed the peaks of iron and oxygen.

Structural study of nickelate based heterostructures

Heterostructures consisting of SmNiO3 and NdNiO3 alternating layers with additional LaAlO3 spacer layers were grown and fully characterized by means of x-ray diffraction, atomic force microscopy, and scanning transmission electron microscopy. A change in the orientation of the orthorhombic long-axis of the nickelate layers is observed when a single unit cell of LaAlO3 is inserted between SmNiO3 and NdNiO3, in agreement with density functional theory calculations. At the same time, the structure of the ultra-thin rhombohedral LaAlO3 layers is affected by their proximity to orthorhombic nickelate layers, with both scanning transmission electron microscopy studies and density functional theory calculations revealing a weak antipolar motion of the La-cation in the LaAlO3 layers that is not present in the bulk rhombohedral structure of this compound.

Microwave Assisted Synthesis of PtxRu1−x-NiTiO3: A Novel Hybrid Nanostructured Electrocatalyst for Direct Methanol Oxidation

In the present investigation, we have explored the preparation of PtxRu1-x-NiTiO3 hybrid electrocatalysts for the application of methanol oxidization. The XRD and Raman analysis of PtxRu1-x-NiTiO3 confirmed the rhombohedral crystal structure of NiTiO3 and cubic-structured Pt(Ru) nanoparticles. TEM analysis signifies that Pt(Ru) nanoparticles is decorated on the surface of the NiTiO3. The mean size of the Pt(Ru) nanoparticles calculated from the TEM profile is around 2 nm which corroborates with the crystallite size estimated from XRD. The XPS analysis confirms the presence of metallic Pt along with its oxidized components (Pt2+ and Pt4+). The cyclic voltammetry analysis evidence that Pt0.5Ru0.5-NiTiO3 has shown better activity in methanol oxidation compared with the other compositions of PtxRu1−x-NiTiO3 along with the maximum current density of 65.41 mA cm−2 with less carbon poisoning. Chronoamperometry and polarization studies represent the stability and electrochemical activity of the Pt0.5Ru0.5-NiTiO3 electrocatalysts towards methanol oxidation. Based on the research carried out in this work, it is concluded that the PtxRu1−x-NiTiO3 would be a promising candidate as an electrocatalyst for methanol oxidation in direct methanol fuel cells.

Isotherm and Kinetic Studies on Adsorption of Yellow Azo Dyes (Sunset Yellow, Tartrazine) using <i>Kigelia africana</i> (Lam.) Benth., Leaf Extract Mediated Iron Nanoparticles

Sunset yellow and tartrazine are commonly used azo dyes extensively employed in beverages and food products such as soda, fruit juices, confectionery, and cakes. These dyes hold the distinction of being the second and third most frequently utilized colour additives in a wide array of beverage products. The discharge of these synthetic food dyes into industrial wastewater can lead to significant environmental and health issues. Due to its aromatic structure, this dye is resistant to breaking down into harmless compounds, and its removal through effective adsorption presents an economical and efficient solution. The use of renewable bioresources for the eco-friendly production of metallic nanoparticles represents a recent and growing trend in nanotechnology research, offering enhanced environmental safety. In this current research, we achieved the green and cost-effective synthesis of monodispersed Iron Nanoparticles (FeNPs) with exceptional stability by utilizing an aqueous extract of Kigelia africana (Lam.) Benth is the primary bioresource for this synthesis. The FeNPs were noticed to be uniformly distributed spherical-shaped particles having smooth surfaces with a 26-34 nm size range and an average particle size of 28 ± 0.86 nm. The XRD results confirm that the FeNPs were rhombohedral phase structures with 71.43% of elemental iron. These synthesized nanoparticles were applied for the removal of sunset yellow and tartrazine dyes were investigated and more than 90% were removed. The adsorption isotherm study was best fitted with the Langmuir model, and the maximal adsorption capacity was found to be 76.29 and 47.22 mg/g for sunset yellow and tartrazine respectively. The adsorption reaction follows pseudo-first-order kinetics with a high correlation coefficient. Repeated cycles of regeneration, reuse and stability showed very high removal efficiency and stability. In conclusion, the biosynthesis of metal nanoparticles demonstrates substantial promise for applications in environmental protection.

Emergence of the isotropic Kitaev honeycomb lattice α− RuCl3 and its magnetic properties

We present a comprehensive investigation of the crystal and magnetic structures of the van der Waals antiferromagnet α− RuCl3 using single crystal x-ray and neutron diffraction. The crystal structure at room temperature is a monoclinic ( C2/m ). However, with decreasing temperature, a remarkable first-order structural phase transition is observed, leading to the emergence of a rhombohedral ( R3ˉ ) structure characterized by three-fold rotational symmetry forming an isotropic honeycomb lattice. On further cooling, a zigzag-type antiferromagnetic order develops below TN=6∼6.6 K. The critical exponent of the magnetic order parameter was determined to be β=0.11(1) , which is close to the two-dimensional Ising model. Additionally, the angular dependence of the magnetic critical field of the zigzag antiferromagnetic order for the polarized ferromagnetic phase reveals a six-fold rotational symmetry within the ab− plane. These findingsreflect the symmetry associated with the Ising-like bond-dependent Kitaev spin interactions and underscore the universality of the Kitaev interaction-dominated antiferromagnetic system.

Enhancement in thermoelectric performance of hydrothermally synthesized Ca and Sb co-doped Bi2Te3 nanostructures

−Ca & Sb co-doped Bi2Te3 compounds have been prepared by hydrothermal method at 210 °C for 24 h and investigated their thermoelectric properties. Phase purity and crystallinity were analyzed by XRD. All the prepared samples have rhombohedral crystal structure with space group R-3m. The hexagonal nanoplate-like morphology was examined by FESEM. Elemental analysis was done with EDX. Band gap energy of prepared samples has values in the range of ∼0.40–0.65 eV, obtained by Tauc plot. The Raman shift was obtained at a lower frequency with doping. Carrier concentration increased with doping from 3.18 × 1020 cm−1 to 9.34 × 1020 cm−1. The high value of power factor (PF) of ∼10.8 × 10–4 Wm−1K−2 was obtained due to high carrier concentration. An ultralow lattice thermal conductivity of ∼0.28 and ∼0.63 W mK−1 at 420 K, was obtained for Ca0.06Bi1.88Sb0.06Te3 and pure Bi2Te3, respectively. A maximum ZT of ∼0.78 at 386 K was obtained for Ca0.03Bi1.94Sb0.03Te3. The value of ZT thus obtained is about ∼ 51% higher than the ZT of pure Bi2Te3 (∼0.39 at 386 K).