Good Crystallinity Research Articles

Synthesis and characterization of new organometallic lanthanides metal complexes for photodynamic therapy

New Schiff base ligand: 4-methoxy salicaldhyde-2-2-phenyl-hydrazono acetaldehíyde prepared by facile method. The molecular structures characterized by elemental analysis and proton magnetic resonance spectra (1H-NMR spectra). This spectra at the chemical shifts (3.5–10.39 ppm) confirmed the types and the numbers of protons. The sharp melting point at the range 110–112 °C confirmed purity. New optically active metal (samarium, terbium and gadolinium) complexes of the Schiff base synthesized in a one pot reaction. Vibrational IR spectra confirmed functional groups. Scanning electron microscopy micrographs confirmed that the modified microstructure of the metal complexes differed in morphology than the ligand. Powder X-ray diffraction patterns confirmed good crystalline structure. The optically activity of the solid metal complexes confirmed from electronic absorption spectra. The UV absorbance band at the wavelength range 280–390 nm and the intense phosphorescence bands up to 830 nm enabled application in photo dynamic therapy for apoptosis cancer cells by conversion triplet oxygen in the tissues into reactive singlet oxygen. Low charge transfer energy: 2.59–2.61 eV, high molar extinction coefficients (ε) at the order of magnitude \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{10}^{6}$$\\end{document} M− 1 cm− 1 and the intense phosphorescence bands reflected good photodynamic activity. The metal complexes are thermally stable.

Evaluation of AlN insertion layer on the properties of heterogeneous integrated Ga2O3 films on sapphire

Integration of gallium oxide (Ga2O3) with highly thermal conductive AlN/sapphire substrate is more effective to dissipate heat in the Ga2O3-based devices. In this work, the properties of Ga2O3 films grown on sapphire and AlN/sapphire substrates via MOCVD were both examined via various experimental methods. The X-ray diffraction (XRD) analysis showed good crystallinity and different orientations of Ga2O3 and AlN thin films. The absorption properties and band gaps were extracted from UV/Vis spectra. The atomic force microscopy (AFM) scanning images showed smooth Ga2O3 surfaces on sapphire and AlN/sapphire substrates (RMSs of 2.4 nm and 4.8 nm, respectively). The scanning electron microscopy (SEM) highlighted well-defined grains of Ga2O3 and distinct boundaries of both heterostructures. X-ray photoelectron spectroscopy (XPS) analysis depicted the distributions of various components throughout the films. Finally, by using the time-domain thermoreflectance (TDTR) method, the thermal conductivity and the thermal boundary conductivity of Ga2O3 without AlN interlayer were found to be 3.1 W/(m·K) and 70.1 MW/(m2·K) respectively. By comparison, adding AlN interlayer made the thermal conductivity and thermal boundary conductivity rise to 3.3 W/(m·K) and 111.5 MW/(m2·K) respectively. These findings have demonstrated the high-quality Ga2O3/AlN integration and good heat dissipation provided by AlN interlayer, opening up new prospects for Ga2O3/AlN devices in the future.

Dysprosium chromite nanoparticles: A promising photocatalyst for the remediation of ciprofloxacin and methylene blue from wastewater

A facile sol-gel synthesis method was employed to synthesize dysprosium chromite (DyCrO3) nanoparticles (NPs), which were subsequently calcined at 750 ∘C to investigate their structural, optical, and photocatalytic properties. Rietveld refinement of powder X-ray diffraction patterns revealed a single-phase orthorhombic structure for the DyCrO3 NPs, exhibiting good crystallinity and belonging to the Pbnm space group. Furthermore, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy imaging revealed a promising morphology with an average particle size of 30 ± 7 nm. Optical assessments indicated an energy band gap of 2.72 eV, suggesting potential for solar light harvesting as a photocatalyst. Mott-Schottky plots confirmed the n-type semiconductor behavior of the DyCrO3 NPs, and valence band X-ray photoelectron spectroscopy analysis supported these findings. Electronic band structure calculations showed a substantial conduction band minimum and a positive valence band maximum, essential for promoting oxygen reduction and oxidation reactions, respectively, which are crucial for photocatalytic activity. Moreover, the synthesized DyCrO3 NPs demonstrated significant potential as efficient photocatalysts, effectively decomposing the antibiotic ciprofloxacin (CIP) under solar light. Notably, the DyCrO3 NPs achieved 83 % degradation of CIP within 240 min of solar irradiation. Similarly, under identical conditions, the DyCrO3 NPs photocatalyst showed promise in degrading 70 % of the colored organic pollutant methylene blue (MB). Interestingly, during the first 120 min, the degradation of CIP was approximately 25 % greater than that of MB. The ability of DyCrO3 NPs to efficiently degrade both colored and colorless pollutants highlights the catalyst’s inherent photocatalytic nature, rather than merely relying on dye-sensitization effects. Furthermore, the presence of DyCrO3 NPs reduced the activation energy for CIP degradation from 31.657 kJ mol−1 K−1 to 20.846 kJ mol−1 K−1, providing additional evidence of their true catalytic efficacy. Apparent quantum yield values of 40 % for CIP and 35 % for MB degradation further illustrate their superior solar energy harvesting ability. A comprehensive mechanism was developed to explain the impressive photocatalytic performance of the synthesized NPs, highlighting their potential in degrading pharmaceutical antibiotics.

Comparative Study of Indium Oxide Films for High‐Mobility TFTs: ALD, PLD and Solution Process

AbstractDeposition of indium oxide base films for high‐mobility thin film transistors (TFTs) has been an important part in the implementation of high‐resolution and high‐frequency display back panels. In this study, three types of In2O3 (InO) films have been fabricated for TFTs using atomic layer deposition (ALD), pulsed laser deposition (PLD), and solution process, respectively. ALD‐derived InO films show controllable grain formation and optimized TFTs show the field effect mobility of ≈100 cm2 V−1s−1 in both the conventional transistor measurements and critical four‐probe measurements, reaching the level of low‐temperature polycrystalline silicon (LTPS). Combined spectroscopy investigations show that the ALD‐derived InO film features advantages as compared to those of the PLD‐deposited and solution‐processed InO film in providing a smoother surface morphology, good crystallinity, and more orderly atomic growth mode. Moreover, the bias‐stress stability of ALD‐derived TFTs can be improved with further passivation.

Influence of Substrate on Sb2Se3/CdS Heterojunction Thin Film Solar Cells and Evaluation of Their Performance by Dark J‐V Analysis

ABSTRACTA simple binary antimony selenide (Sb2Se3) absorber is evolving as an alternative photovoltaic material in thin film solar cells because of its unique properties and easy processing. Sb2Se3 thin films having good crystalline quality are grown via versatile thermal evaporation from pre‐synthesized near stoichiometric compound material on molybdenum‐coated soda lime glass (SLG) and borosilicate glass (BG) substrates. Following the systematic characterizations on the absorber films, substrate configured Sb2Se3/CdS heterojunction devices were fabricated and their photovoltaic characteristics have been studied using current density vs. voltage (J‐V), dark J‐V modeling, external quantum efficiency and capacitance vs. voltage measurements. The power conservation efficiency values of 4.88% and 5.04% were achieved for the devices fabricated on SLG and BG substrates, respectively with deficit in open circuit voltage. The obtained values are higher in comparison to the reported device efficiencies in substrate configured Sb2Se3 solar cells, in which the absorber is prepared through thermal evaporation. To understand the loss in open circuit voltage, a compact equivalent circuit model was considered and identified the contribution of different shunt leakage paths in the devices. In addition to that, the device fabricated on the SLG was stable with minimal changes in its photovoltaic performance for a period spanning over 200 days. The results obtained are encouraging with scope for improving the device performance through interface engineering and back surface passivation strategies.

Room temperature in situ growth of fluorinated covalent organic framework on electrospun nanofibers for efficient detection of benzoylurea insecticide residue in water samples

The accurate detection of benzoylurea insecticides (BUs) residues is vital for the environment and human health. In this work, a room-temperature synthesis strategy was developed to fabricate the covalent organic framework (COF)–polyacrylonitrile (PAN) nanofibers composite by an electrospinning technique. The COF was functionalized on PAN nanofibers via in situ polymerization of 1,3,5-tris(4-aminophenyl)triazine (TAPT) and 2,3,5,6-tetrafluoroterephthaldehyde (TFTA). The obtained TAPT-TFTA@PAN nanofibers showed a porous structure, high surface area, good crystallinity and excellent extraction efficiency to BUs. A sensitive method combining dispersive solid-phase extraction (DSPE) using TAPT-TFTA@PAN nanofibers as an adsorbent with liquid chromatography–ultraviolet detector was developed for trace analysis of four BUs in environment water samples. This method achieved a wide linear range of 0.5–200 ng·mL−1 for triflumuron and hexaflumuron, and of 0.5–150 ng·mL−1 for teflubenzuron and fluazuron. The limits of detection (S/N = 3) for four BUs ranged from 0.11 to 0.42 ng·mL−1. The accuracy of the proposed method was validated by measuring trace BUs in the spiked water samples with recoveries in the range of 98.3 %∼125.3 %. The results demonstrated that the TAPT-TFTA@PAN nanofibers have great potential as an extractant for effective enrichment of benzoylurea insecticide from complex water samples.

Structural and Electrochemical Properties of Binary ZnO:Al Nanocomposites as Anode for Lithium-ion Batteries

In conventional lithium-ion batteries (LIBs), carbon compounds are commonly utilised as the anode owing to their great performance, low cost, and abundance. However, due to the limited storage capability of pure carbon materials that restrict further improvement of LIBs, zinc oxide (ZnO) has been one of the promising anode materials to be used as an alternative to strengthen the electrochemical performance of LIBs due to its high theoretical capacity of 987 mAh g-1. This study aims to synthesise ZnO:Al nanowires using the hot-tube thermal evaporation method. Three types of samples are made using this method by varying the concentration of 0 wt% (S1), 3wt% (S2), and 6 wt% (S3) of aluminium (Al) during the Al deposition process. The EDX findings indicated that the sample has a high proportion of zinc (Zn) and oxygen (O), with the S3 sample having the highest Al concentration after being deposited. The most substantial diffraction peak for XRD of all samples was found at (101), exhibiting a single crystalline hexagonal structure with optimum growth direction on the c-axis. For EIS analysis, the S3 sample has the lowest bulk resistance and maximum ionic conductivity. In conclusion, the ZnO sample with 3 wt% of Al as a dopant was selected as the optimum result to synthesise a homogenous surface of ZnO:Al with good crystallinity by using a hot-tube thermal evaporation process and giving the best conductivity in electrochemical performance.

Construction of One-Dimensional Covalent-Organic Framework Coordinated with Main Group Metals for Selective Electrochemical Synthesis of H2O2.

Covalent-organic frameworks (COFs) are promising electrocatalysts for the selective synthesis of H2O2 through the two-electron oxygen reduction reaction (2e- ORR). However, the design and synthesis of efficient and stable COF-based electrocatalysts is still challenging. In this work, a predesigned 1,10-phenanthroline-based one-dimensional COF (PYTA-PTDE-COF) was constructed to anchor main group metal (In, Sn, and Sb) as electrocatalysts toward 2e- ORR. The catalysts are featured with fully exposed metalated side chains. Structural characterization revealed that PYTA-PTDE-M's (M = In, Sn, and Sb) are all quite similar, except for the coordinated metal ions with the maintenance of good crystallinity. They all exhibited satisfying activity and selectivity toward 2e- ORR under alkaline conditions. Among them, PYTA-PTDE-Sb exhibited the best performance (Eonset is 0.765 V, the H2O2 selectivity is 96%, and the yield rate is 209.2 mmol gcat-1 h-1). Moreover, it also delivered superior stability with almost no attenuation of current density during the long-time test. Theoretical calculations revealed that the Sb metal site in the COFs has the lowest adsorption strength of *OOH, which could be the main reason for its superior selectivity. The PYTA-PTDE-Sb assembled zinc-air battery realizes not only the supply of clean energy but also the production of green chemicals, showing it is highly promising in practical applications. This work offers an example for designing main group metal-coordinated 1D COFs and reveals fundamental structure-activity relationship toward 2e- ORR.

Heat capacities and thermodynamic properties of urea phosphate and its aqueous solutions at various temperatures

Urea phosphate was produced through a complexation reaction of phosphoric acid and urea and subsequent cooling crystallization. The elemental composition analysis, XRD, and FTIR all confirmed that the prepared urea phosphate had high purity and good crystallinity, and showed a clear onset melting temperature of 118.12℃ and corresponding enthalpy change of 222.10 J∙g−1 in TG/DSC measurement. Meanwhile, the heat capacities of urea phosphate and its aqueous solution were carefully measured using microcalorimetry with an expanded relative uncertainty better than 2 %. The experimental results revealed that the heat capacity of urea phosphate rises rapidly with temperature, with an increase of 41 % from −20 to 100℃. The experimental heat capacity data were correlated with semi-empirical models of Maier-Kelley equation, Khodakovsky equation and Debye-Einstein equation which all give excellent reproduction of the measured data with very close average deviation around 0.5 %. The enthalpy, entropy, and Gibbs free energy of solid urea phosphate were estimated at various temperatures by integrating heat capacity against temperature with Maier-Kelley equation and the results confirmed urea phosphate is thermally quite stable below 100℃. The heat capacity of urea phosphate aqueous solution increases with concentration and temperature, and there is a strong linear relationship between the solution’s heat capacity and temperature when the composition remains constant. The apparent molar heat capacity of urea phosphate in solution is positive and increases with concentration and temperature. The extrapolated partial molal heat capacity of urea phosphate is temperature independent and shows an average value of −709.4 J·K−1·mol−1. Due to the partial dissociation and partial ionization of urea phosphate in solution, the excess molar heat capacities show positive deviation from that of ideal solution, which also increases with the increase of concentration and temperature.

Excitonic origin of the optical properties of CsPbBr3

The optical properties of CsPbBr3 are studied with temperature dependent spectroscopic techniques. The samples are obtained from a method that has 10 % Pb waste compared with conventional ones. The dependence with temperature between 30 K and room temperature of the optical transmittance and photoluminescence is measured. Near bandgap optical properties are governed by structures originated in free excitons. Using the Elliott model for excitonic absorption, the dependence with temperature of bandgap energy and exciton binding energy are obtained. Both increase with temperature increase. Also, the width of the excitonic absorption and the inter-band absorption, which is assimilated to Urbach energy, were studied. Several models are used to extract parameters from these data. The excitonic absorption width follows the Segall model giving an exciton optical phonon interaction as the dominant term at room temperature. From several fittings, an effective optical phonon energy between 23 and 32 meV is obtained. The Urbach energy at 30 K reaches 10 meV which is related to a good crystalline quality of the samples. Several experimental results show that the origin of the photoluminescence is produced by direct recombination of free excitons. The first one is the similarity of the temperature dependence of photoluminescence width with the one of excitonic absorption. The second one is based in the activation energies obtained from the dependence of the integrated photoluminescence with temperature, one of which coincides with Excitonic Biding Energy. The third one is related to the dependence of the Stokes Shift with temperature which corresponds to the Gurioli model of excitonic thermalization. The last one comes from the dependence of the time resolved photoluminescence. Using rate equations, a radiative and non-radiative monomolecular time constant between 32 and 50 ns and an exciton-exciton annihilation rate constant between 1.0 and 6.0 × 10−7 cm3/s are obtained.

Enhanced electrocatalytic activity of hafnium doped tungsten oxide (Hf-WO3) for ultrasensitive detection of nonsteroidal anti-inflammatory drug

Efficient hafnium-doped tungsten oxide nanoparticles (Hf-WO3) were developed by hydrothermal approach and characterization was carried out by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), high resolution-transmission electron microscopy (HR-TEM), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) techniques. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques were employed to assess the electrochemical response of the fabricated carbon paste electrodes (CPE) for the analysis of mefenamic acid (MA). The objective of this work is to develop and optimize parameters to enhance the selectivity and sensitivity of Hf-WO3 modified sensor for the trace-level detection of MA, addressing its critical importance in both pharmaceutical and environmental analysis. The Hf-WO3 predominantly showed a monoclinic phase with some hexagonal peaks, confirming its good crystallinity and 1-D structure, which enhances charge transport and catalytic sites. XPS analysis confirmed the formation of pure Hf-WO3 by showing distinct W and Hf peaks and verifying their valences: W in the +6 state and Hf in the +4 state. CV showed that the Hf-WO3/CPE greatly enhances the electrochemical oxidation of MA compared to unmodified and tungsten oxide-modified electrodes, with a six-fold increase in peak current and notable redox activity attributed to improved surface properties and charge transfer efficiency. Under optimum experimental conditions, the Hf-WO3/CPE exhibits a low limit of detection (LOD) of 3.94 nM with dynamic concentration linearity ranging from 0.01 to 100.0 μM with good sensitivity of 1.74 μAμM−1cm−2. Furthermore, the Hf-WO3/CPE was employed in real-time analysis of MA in spiked urine samples and pharmaceutical tablet samples, which showed satisfactory recovery results ⁓ 98 %. Moreover, the electrode showed good stability over multiple measurements, and these results demonstrate that Hf-WO3/CPE is a promising sensor for MA detection.

High-quality GaN thin film deposition at low temperature by ECR plasma-assisted sputter deposition method and its dependence of sapphire substrate misorientation angle

Gallium nitride (GaN) thin films were deposited by electron cyclotron resonance (ECR) plasma-assisted sputtering, which combines GaN-magnetron sputtering with argon and nitrogen plasma assistance using an ECR high-density plasma. GaN films on the misorientation-angle-0.0° (just) sapphire substrate showed very good crystallinity with a GaN(0002) rocking curve (XRC) full width at half maximum (FWHM) of 0.042° and epitaxial growth confirmed by φ-scan measurements at a low heating temperature of 350 °C. However, the GaN thin film had a rough surface with circular grains about 100 nm in diameter and a surface root-mean-square height (Sq) of 1.21 nm. Therefore, the misorientation angle of the sapphire substrate was varied from 0.2° to 10.0°. As a result, the grains observed on the just substrate disappeared at 0.5°. The film had Sq: 0.33 nm, and the FWHM of the XRC of GaN(0002) was 0.066°, indicating improved surface flatness while maintaining crystallinity. This is considered to be due to the step flow, which promotes ECR plasma-assisted diffusion on the terrace even at the low temperature of 350 °C. The polarity of the GaN thin film was analyzed by time-of-flight atomic scattering surface analysis and found to be N-polar on all substrates.

Carbon fiber/boron nitride fillers for enhancing through-plane thermal conductivity of poly(vinylidene fluoride): Synergistic effect and mechanism

Two series of thermally conductive poly(vinylidene fluoride) (PVDF) composites were prepared by adding boron nitride (BN) and carbon fiber (CF) of different mass ratios via hot-pressing. The synergistic effects of the dual fillers on the thermal conductivity enhancement were investigated. The morphology, thermal conductivity, crystallinity, thermal stability, mechanical properties, and long-term chemical stability of the PVDF composites were characterized. The results demonstrated a significant synergistic effect between the BN and the CF on enhancing the thermal conductivity of the PVDF-based composites. The maximum thermal conductivity of 1.89 W/(m·K) with an improvement of 1014 % was achieved when 15 wt% BN and 15 wt% CF were added in the PVDF matrix. The synergistic effect resulted in the formation of efficient three-dimensional thermally conductive networks with a synergistic efficiency up to 113 %. The Agari model was employed to illustrate the thermal conduction mechanism, revealing the improved ability of the dual fillers to form conductive pathways. The PVDF composites showed good crystallinity, thermal stability, mechanical strength, and long-term chemical stability. This study highlights the potential of the PVDF/BN/CF composites for applications in membrane heat exchangers and provides significant insights into the design of high-performance thermally conductive polymer composites.

Probing morphology-dependent PDI/g-C3N4 heterostructures for co-production of H2O2 and 2,5-diformylfuran

Perylene diimide/Carbon nitride (PDI/CN) is an excellent photocatalyst consisting of self-assembled PDI with a π-π stacking structure, and has wide applications. But the effect of PDI morphology over their photocatalytic performance has been scarcely investigated. Herein, we successfully synthesized three different morphologies of PDI, inducement formed by different organic solvents, and coupled them with CN, respectively. For simultaneous production of H2O2 and DFF, their photocatalytic activity has the order of PDI-F/CN > PDI-S/CN > PDI-B/CN. H-stacked PDI-F/CN exhibits good crystallinity, larger specific surface area, higher π-conjugation and large dipole moment, which could improve charge-carrier separation, and its activity was 4.2-fold higher than that of CN. Theoretical calculation results indicated that the PDI-F/CN heterojunction could benefit the adsorption of O2 and 5-HMF and lower the energy barrier, which is an important factor for the enhanced photocatalytic activity. This work provides a new and excellent photocatalyst for biomass oxidation.

N-doping of β-ketoenamine based covalent organic frameworks (COFs) for enhancing photocatalytic oxidation activity

β-ketoenamine-based COFs are widely investigated due to their high stability, good crystallinity and tunable skeleton structures. Nitrogen doping is one of the effective ways to enhance the catalytic activity of COFs. Herein, N-doping of β-ketoenamine-based (0N-TP-COF, 1N-TP-COF, 2N-TP-COF) COFs were successfully constructed by the Schiff base condensation reaction between 1,3,5-tiformylphloroglucinol (TP) and p-phenylenediamine containing different numbers of nitrogen atoms. Studies showed that the as-prepared COFs exhibited more suitable electronic structure and more electron-rich active sites with the increasing of N atoms. Furthermore, the photocatalytic performance of 4-formylphenylboronic acid transformation was 0N-TP-COF (99 %, 48 h) < 1N-TP-COF (99 %, 32 h) < 2N-TP-COF (99 %, 16 h), and the photocatalytic performance of benzylamine coupling was 0N-TP-COF (99 %, 16 h) < 1N-TP-COF (99 %, 3.5 h) <2N-TP-COF (99 %, 1.5 h), respectively. Note that all N-doping COFs have excellent catalytic activity as well as stability, and 2N-TP-COF exhibits the highest catalytic activity. This work demonstrates that doping of nitrogen atoms is an effective way to enhance photocatalytic performance.

Growth of CuO NPs layers on TiO2 NTs using vacuum thermal evaporation

CuO/TiO2 composites have been reported to exhibit higher potential for various applications (electronics, energy storage, and sensor technology…). This study investigates the impact of different film thicknesses on the properties of CuO NPs on TiO2 NTs. CuO NPs were deposited onto TiO2 NTs using vacuum thermal evaporation, with thicknesses ranging from 5 to 30 nm. A quartz crystal monitor measured evaporation rate and film thickness at a substrate temperature of 350 °C. Following the deposition process, the samples were thermally treated through air annealing at 400 °C for 1 h.XRD analysis showed that all films had an anatase phase. The annealed sample also had a confirmed CuO phase, indicating good crystallinity. Crystallite size and strain varied with film thickness, assessed using the Williamson-Hall method and Rietveld refinement. The deposition and distribution of CuO on TiO2 NTs were verified using Scanning Electron Microscopy (SEM) combined with energy dispersive spectroscopy (EDS). Optimizing the materials nanostructures requires controlling film thickness and annealing. Insights from this study can improve nanomaterial fabrication techniques, which could enhance their performance in technological applications.

Removal of hexavalent chromium using activated and magnetic Ziziphus Jujube seed biochar — a column study

ABSTRACT In this study, activated and magnetic biochar prepared from Ziziphus Jujube Seeds (ZJS) is used to remove Hexavalent Chromium (Cr(VI)) using Fixed Bed Column Experiment. Physicochemical characteristics of the activated and magnetic biochar such as functional groups, surface area, morphological study, and magnetic properties were analyzed. The column experiment was carried out for varying bed heights (2, 4, 6, 8, 10 cm), flow rates (20, 30 ml/min), and initial chromium concentrations (40, 60, 80 ppm) to determine adsorption performance of the studied biochar. The characteristic study found that magnetic biochar (MB) has good magnetic properties and crystallinity nature with essential functional groups such as C-O, FeO. The study found that Magnetic Biochar (MB) effectively removed 99% of hexavalent chromium through column adsorption under optimal conditions, including bed height of 6 cm, 60ppm Chromium concentration, and flow rate of 20 ml/min. Kinetic model study showed that Magnetic Biochar (MB) showed very good agreement with Adam Bohart Model, with R2 of 0.97, which is best fit model than other model studies whereas the other model showed a lesser R2 value. The study reveals that magnetic biochar from Ziziphus Jujube Seed is optimal adsorbent for removal of Cr(VI) through column adsorption experiment.

Isolation of Elusive Fluoflavine Radicals in Two Differing Oxidation States.

Facile access and switchability between multiple oxidation states are key properties of many catalytic applications and spintronic devices yet poorly understood due to inherent complications arising from isolating a redox system in multiple oxidation states without drastic structural changes. Here, we present the first isolable, free fluoflavine (flv) radical flv(1-•) as a bottleable potassium compound, [K(crypt-222)](flv•), 1, and a new series of organometallic rare earth complexes [(Cp*2Y)2(μ-flvz)]X, (where Cp* = pentamethylcyclopentadienyl, X = [Al(OC{CF3}3)4]- (z = -1), 2; X = 0 (z = -2), 3; [K(crypt-222)]+ (z = -3), 4) comprising the flv ligand in three different oxidation states, two of which are paramagnetic flv1-• and flv3-•. Excitingly, 1, 2, and 4 constitute the first isolable flv1-• and flv3-• radical complexes and, to date, the only isolated flv radicals of any oxidation state. All compounds are accessible in good crystalline yields and were unambiguously characterized via single-crystal X-ray diffraction analysis, cyclic voltammetry, IR-, UV-vis, and variable-temperature EPR spectroscopy. Remarkably, the EPR spectra for 1, 2, and 4 are distinct and a testament to stronger spin delocalization onto the metal centers as a function of higher charge on the flv radical. In-depth analysis of the electron- and spin density via density functional theory (DFT) calculations utilizing NLMO, QTAIM, and spin density topology analysis confirmed the fundamental interplay of metal coordination, ligand oxidation state, aromaticity, covalency, and spin density transfer, which may serve as blueprints for the development of future spintronic devices, single-molecule magnets, and quantum information science at large.

Improved surface morphology and reduced V-pits density of lattice-matched AlInN films grown by atmospheric pressure metalorganic chemical vapor deposition

AlInN has emerged as a promising material for advanced optoelectronic and electronic devices due to its unique properties. However, achieving AlInN layers with excellent surface morphology remains challenging. Here, Al0.83In0.17N layers lattice-matched to GaN/sapphire were grown by atmospheric-pressure metalorganic chemical vapor deposition at 875 °C. The lowest surface roughness measured by atomic force microscopy was 0.37 nm after optimizing the growth temperature and flux of precursors. The roughness value was constant in the range of 15–72 nm film thickness. Introducing a TMI pre-flow period before AlInN growth, further reduced roughness to 0.28 nm, although a graded inclusion of Ga into the AlInN near the GaN/AlInN interface was observed. This improved surface morphology was interpreted by the In-surfactant effect enriched by the pre-flow in the early stage of AlInN. Additionally, the V-pits density was as low as 2×105 cm−2, primarily due to high growth pressure and also influenced by relatively high growth temperature. Analysis of Al incorporation using second-order reaction model suggests that the severe parasitic reactions between TMA and NH3 at atmospheric pressure can be effectively eliminated by a high total gas flow rate of 72 slm, ensuring in-plane uniformity in surface morphology and relatively good crystalline quality.

Enhanced crystallinity of (Sr,Ba)Nb2O6 films on sapphire and alumina substrates

Barium-strontium niobate in thin film form can be considered as a prospective ferroelectric material for microwave applications due to high dielectric nonlinearity. Its performance is linked to film structure quality, and one method to achieve high-quality films on microwave substrates goes through the process of annealing. (Sr,Ba)Nb2O6 films of good crystallinity were formed on sapphire and alumina substrates by magnetron sputtering. The processes of recrystallization of films on single- and polycrystalline substrates under the conditions of ex situ annealing at temperatures of 1100–1200 °C were studied. Highly (00l) oriented films on sapphire substrate were obtained by the deposition in oxygen atmosphere at a substrate temperature of 900 °C with post-growth annealing in air at an annealing temperature of 1150 °C.