Analysis Of X-ray Diffraction Data Research Articles

Local structure anomaly with the charge ordering transition of 1T−TaS2

The quasi-two-dimensional $1T\text{\ensuremath{-}}{\mathrm{TaS}}_{2}$ displays a unique two-step charge density wave (CDW) transition, from incommensurate (ICDW) to nearly commensurate (NCDW), and from NCDW to commensurate (CCDW), which is reflected in the stepwise resistivity behavior. In this work, we show that the hysteresis observed in the resistivity across the NCDW-to-CCDW transition is coupled to a local structure anomaly, evident from the pair density function analysis of neutron and x-ray diffraction data. We find that upon cycling the system from high to low temperatures (through the NCDW-CCDW transition) and collecting data on warming, local distortions in the in-star Ta and out-of-plane S atoms become evident, disrupting the trigonal symmetry of the star of David structures, without breaking the lattice periodicity, and preserving the underlying $\mathrm{P}\overline{3}$ symmetry. When the system is warmed up from the NCDW to the ICDW state, the local distortions are absent and the stars are symmetric, indicating that it is the thermal cycling through the NCDW-CCDW that locks in the distortions. Furthermore, we verify the temperature dependence of the two types of stacking along the $c$ axis: at low temperatures, the layer stacking exhibits a $13{\mathrm{c}}_{o}$ order that disappears upon warming through the NCDW transition, while across the NCDW and ICDW phases, the layer stacking is $3{\mathrm{c}}_{o}$. The $3{\mathrm{c}}_{o}$ order gradually disappears in the ICDW state.

Synthesis and Structure of N-(1-(Bromomethyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-yl)benzenesulfonamide

A new bicyclic sulfonamide derivative, N-(1-(bromomethyl)-7,7-dimethylbicyclo[2.2.1]heptan-2-yl)benzenesulfonamide, was synthesized in the reaction of benzenesulfonamide and camphene in the presence of N-bromosuccinimide in acetonitrile. The proposed mechanism of investigated reaction involves the Wagner–Meerwein rearrangement stage. 3-(Bromomethylene)-2,2-dimethylbicyclo[2.2.1]heptane was isolated as a minor product. The products were characterized by IR, NMR spectroscopy, X-ray diffraction analysis, HRMS and elemental analysis data.

Interaction between dirhodium(II) tetraacetate and PAMAM dendrimer grafted onto magnetite nanoparticles: Effects on magnetic properties

In this study, we report on fabrication and characterization of a novel magnetic nanocarrier based on association of magnetite nanoparticles (NPs) with poly(amidoamine) (PAMAM) dendrimers loading dirhodium(II) tetraacetate complex (DiRh(II)). The pristine magnetite NP was coated with ATPS (3-aminopropyltriethoxysilane). The interaction between PAMAM dendrimer and DiRh(II) and its effects on magnetic properties were investigated. The magnetite spinel phase is confirmed via x-ray diffraction (XRD) and Raman spectroscopy data analysis. A mean crystallite size of 9.5 ± 0.3 nm of magnetite particles is assessed from XRD data, which is close to the values obtained via dynamic light scattering (DLS) and transmission electron microscopy micrographs. Our findings strongly suggest that the Rh(II) ions interact with lone electron pairs of nitrogen atoms in amide-II and primary amines of PAMAM surface-terminated moieties. The onset of an absorption peak at 283 nm in DiRh(II) containing sample, assigned to σRh-L→σ∗Rh-Rh electronic transition, revealed a direct interaction between Rh(II) ions and L moieties of PAMAM dendrimer. Magnetization results indicate that the presence of DiRh(II) attached to PAMAM dendrimer leads to the strong weakening of magnetic dipole–dipole interactions in ATPS- and ATPS + PAMAM coated magnetite nanoparticles.

Stereoselective Approach to Hydroxyalkyl-1,2,3-triazoles Containing Cyclooctane Core and Their Use for CuAAC Catalysis

1,2,3-Triazoles bearing additional functional groups have found applications as the ligands in catalysis of a broad scope of reactions, synthesis of transition metals complexes for various practicable purposes, and design of metal-based drugs. Triazolyl ligands accelerating CuAAC reactions, such as TBTA and TTTA, are nowadays commonly used in organic synthesis, and the search for novel ligands with a less complicated structure represents an important task. In the present work a series of hydroxyalkyltriazoles, containing a cyclooctane core, were synthesized via cycloaddition of readily available individual diastereomers of azidoalcohols or diazidodiols with phenylacetylene. The obtained hydroxyalkyltriazoles were probed as ligands for CuAAC reactions of benzyl azide with acetylenes, and 1-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]cyclooctanol was demonstrated to act as an effective ligand for these processes. The complex salt of the abovementioned triazole and CuCl2 was readily obtained. According to X-ray diffraction analysis data, the complex contained two molecules of triazole, in which only N1-atoms of the triazole ring acted as coordination centers. Such a molecular structure correlates well with the efficiency of 1-[(4-phenyl-1H-1,2,3-triazol-1-yl)methyl]cyclooctanol as a ligand in CuAAC reactions: it is able to coordinate copper ions and, at the same time, it forms a sufficiently labile complex to not withdraw copper ions from the catalytic cycle.

PLA/MWCNT Nanocomposite: Improved Electrical, Thermal and Antibacterial Properties for Fused Deposition Modelling Additive Manufacturing Applications

Incorporation of nanoparticles in Polylactic Acid (PLA) for additive manufacturing is explored to alter the material property to suit its intended application. In this study, PLA is reinforced with multi-walled carbon nanotubes (MWCNT) using two-roll mill for fused deposition modeling (FDM) additive manufacturing. The chemical composition, thermal behavior, electrical, and antibacterial properties of the PLA/MWCNT nanocomposite were investigated. The Fourier transform infrared spectroscopy (FTIR) analysis showed the physical interaction of MWCNT to the PLA matrix. The x-ray diffraction analysis (XRD) data showed that increasing the MWCNT percentage increases the amorphous region and intensity, indicating the nucleating effect of MWCNT on PLA. Differential scanning calorimetry (DSC) analysis showed a decrease in the glass transition and melting temperatures compared to pure PLA by up to 9.36°C and 23.25°C, respectively, while introducing cold crystallization with the addition of MWCNT. The two point-probe resistance measurement showed a decreasing trend in the resistance of the composite which indicates an increase in conductivity as the the amount of MWCNT is increased. The analysis of disk diffusion test concluded that no bacterial growth of Escherichia coli and Staphylococcus aureus happened underneath the sample. Furthermore, the nanocomposite was successfuly extruded into a filament and test samples were 3D printed using FDM. The PLA/MWCNT produced are suitable for the production of a multifunctional filament with improved electrical, thermal and antimicrobial properties for different fused deposition modelling (FDM) additive manufacturing increasing the probable applications and competitiveness of this promising market niche.

A Double Perovskite BiFeMoO6: Microstructural, Optical, Dielectric and Transport Properties

In this communication, the synthesis (solid-state sintering) and characterization of a double perovskite BiFeMoO6 are reported. Analysis of X-ray diffraction (XRD) data provides monoclinic crystal symmetry with an average crystallite size of 85.6[Formula: see text]nm and lattice strain of 0.00078, respectively. The microstructural analysis of the sample was done using a scanning electron microscope (SEM) and the results show that grains are well-grown and distributed uniformly throughout the sample surface. The grains are visible clearly due to well-defined grain boundaries, and the effect on the mechanism of electrical ac conductivity was studied. The compositional purity of the sample was checked by energy dispersive X-ray (EDX) analysis spectrum which supports the presence of all constituent elements (Bi, Fe, Mo and O) in both weight and atomic percentages. The study of the Ultraviolet–Visible spectrum provides a bandgap energy of 1.8[Formula: see text]eV, suitable for photovoltaic applications. The measurements of the dielectric were used to confirm the existence of the Maxwell–Wagner type of dispersion. The study of impedance spectroscopy helps to understand the negative temperature coefficient of resistance (NTCR) character while the electrical modulus measurements claimed a non-Debye relaxation mechanism in the sample. The study of ac conductivity reveals the fact of thermally activated conduction mechanism in the sample. The presence of the semiconducting nature of the sample was checked from both Nyquist plots and Cole–Cole plots. The study of the resistance versus temperature reveals the fact of negative temperature coefficient (NTC) thermistor character and is suitable for some temperature sensor devices.

Study of the Radiation Damage Kinetics in NbTiVZr High-Entropy Alloys Irradiated by Heavy Ions

The purpose of this paper was to study the kinetics of accumulation of radiation damage in the near-surface layer of a high-entropy NbTiVZr alloy upon irradiation with heavy Kr15+ ions and fluences of 1010–1015 ion/cm2. According to the data of X-ray diffraction analysis, it was found that irradiation with heavy ions lead to structural changes associated with the accumulation of deformation distortions and stresses. In this case, the nature of deformation distortions was associated with tensile distortions of the crystal lattice and swelling of the near-surface layer. An analysis of the strength properties of the irradiated samples showed that the accumulation of deformation distortions in the near-surface layer lead to a decrease in the resistance to cracking and destruction of the near-surface layer. In this case, the main changes occurred at fluences above 1013 ion/cm2, which are characterized by an excess of the threshold for overlapping defective regions that appear along the trajectory of incident ions. Tribological tests showed that an increase in defective inclusions in the structure of the near-surface layer lead to an increase in friction and a decrease in crack resistance.

Aconicumines A–D, an advanced class of norditerpenoid alkaloids with an unprecedented N,O-diacetal motif from Aconitum taipeicum Hand.-Mazz., exhibit anti-inflammatory properties in vitro

Aconicumines A–D, an advanced class of norditerpenoid alkaloids, and seven known alkaloids, were isolated from Aconitum taipaicum Hand.-Mazz. (Ranunculaceae). The structures of the previously undescribed compounds, including their absolute configurations, were fully elucidated based on spectroscopic and single-crystal X-ray diffraction data analysis. Aconicumines A–D exhibit interesting cage-like structure, characterised by an unprecedented N,O-diacetal moiety (C6–O–C19–N–C17–O–C7) that has not been previously observed in diterpenoid alkaloids. Possible biosynthetic pathways for aconicumines A–D were proposed. Aconitine, hypaconitine, and aconicumine A showed significant inhibition of nitric oxide production in RAW 264.7 macrophages induced by lipopolysaccharide with IC50 values ranging from 4.1 to 19.7 μM compared to positive control (dexamethasone, IC50 = 12.5 μM). Furthermore, the primary structure–activity relationships for aconicumines A–D were also represented.

A combined powder x-ray and neutron diffraction studies on (1-x) NaNbO3-x Na0.50Bi0.50TiO3 solid solution

Solid solution of sodium niobate and sodium bismuth titanate [(1-x)NaNbO3-x(Na0.5Bi0.5)TiO3: xNBT)] is an important lead-free eco-friendly piezo-ceramic material. In the present work, we report an investigation of the phase stabilities of this solid solution using powder x-ray and neutron diffraction techniques for the entire range of composition. We observed the disappearance of certain peaks and changes in the main perovskite peaks in the powder diffraction data suggesting structural phase transitions with composition. Rietveld analysis of combined x-ray and neutron powder diffraction data is performed to obtain single correct structural model wherever possible. Detailed analyses of powder diffraction data for composition range 0.0 ≤ x ​< ​0.15 revealed the coexistence of orthorhombic (Pbma) and (Pmc21) phases and an orthorhombic phase with space group Pbnm and cell dimensions √2ap ​× ​√2 bp ​× ​6 cp gets stabilized for 0.15 ≤ x ​< ​0.20. On further increasing NBT content in NaNbO3 matrix (0.20 ≤ x ​< ​0.60), a mixed orthorhombic (Pbnm) phase and tetragonal (P4bm) phase is confirmed by Rietveld refinement. Further, in the composition range 0.60 ≤ x ​≤ ​0.80, the tetragonal (P4bm) phase coexists with the ferroelectric rhombohedral (R3c) phase and finally for composition x ​> ​0.80, it completely transforms to rhombohedral (R3c) phase. The presence of phase coexistence in various composition ranges indicates the first order nature of these phase transitions. A detailed structural phase diagram of the system is presented at ambient conditions.

Lead-Free Solid State Mechanochemical Synthesis of Cs2NaBi1-xFexCl6 Double Perovskite: Reduces Band Gap and Enhances Optical Properties.

Efficient and stable lead-free halide double perovskites (DPs) have attracted great attention for the future generation of electronic devices. Herein, we have developed a doping approach to incorporate Fe3+ ions into the Cs2NaBiCl6 crystal unit and reveal a crystallographic and optoelectronic study of the Cs2NaBi1-xFexCl6 double perovskite. We report a simple solid-state mechanochemical method that has a solvent-free, one-step, green chemistry approach for the synthesis of Cs2NaBi1-xFexCl6 phosphor. The analysis of powder X-ray diffraction (XRD) data determines the contraction of the lattice due to the incorporation of Fe3+ cations, and this effect is well supported by X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and solid-state nuclear magnetic resonance spectroscopy (ss-NMR). The band gap is reduced with increasing Fe content owing to the strong overlap of the Fe-3d orbitals with Cl-3p orbitals and shift of the valence band maxima (VBM) toward higher energies, as confirmed by ultraviolet photoelectron spectroscopy (UPS) and density functional theory (DFT) analyses. Photoluminescence (PL) studies of Cs2NaBi1-xFexCl6 phosphors exhibit a large Stokes shift, broadband emission, and increased PL intensity more than ten times for 15% of Fe content phosphor with enhancement in the average decay lifetimes (up to 38 ns) compared to pristine Cs2NaBiCl6 DP. These results indicate that the transition of dark self-trapping of excitons (STEs) into bright STEs enhances yellow emission. XRD, UV, and thermo-gravimetric analysis (TGA) confirmed that the Cs2NaB1-xFexCl6 DPs have good structural and thermal stabilities. Our findings indicate that the doping of Fe3+ cations into the Cs2NaBiCl6 lattice is a constructive strategy to enhance significantly the optoelectronic properties of these phosphors.

In-situ synthesis of PbS nanocomposites films in PEOX-PVA: Interaction effect of parent polymer matrix on structural and optical properties

This paper reports the in-situ synthesis of PbS nanoparticle films grown in the PEOX-PVA polymer matrix. The films have been prepared for various concentrations of PbS nanoparticles developed in blend polymer PEOX-PVA along with its parent polymers PEOX and PVA. The effect of polymer matrix on its structural properties has been studied using Rietveld analysis of x-ray diffraction data to determine the following parameters, i.e., crystal structure, space group, lattice parameter, and crystallite size. The chemical bonding and interaction effect of the parent polymer matrix with PbS nanoparticles have been analysed using FTIR and thermal gravimetry. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) have been used to observe the overall morphology of the nanocomposites. The variation in the bandgap of PbS nanocomposite films has been determined from 3.6 to 1.25 eV with varying concentrations of PbS (0.01 M–0.1 M) in all three polymer matrices. The refractive index of PbS nanocomposites films deduced at λ = 650 nm to be 1.4333 to 1.5612, which is much lower than the bulk value of 4.2. It is inferred from the present study that the interaction of polymer matrices with the PbS does not lead to mere addition. Detailed results are analysed considering the quantum confinement effect.

Crystal growth of CeMn0.85Sb2: Absence of magnetic order of Ce-sublattice

Single crystals of CeMn0.85Sb2 have been successfully synthesized by using the Bi as flux. Analysis of single crystal x-ray diffraction data confirms that CeMn0.85Sb2 crystallizes in the HfCuSi2-type structure with the space group P4/nmm (No. 129). In the case of H||c, CeMn0.85Sb2 displays a robust antiferromagnetic transition at ∼160 K for Mn-sublattice, and there is no sign of magnetic order regarding Ce-sublattice. In the case of H ⊥ c, the Mn-sublattice shows signs of magnetic order at 160 K and 116 K, indicating a possible spin reorientation. There is no sign of magnetic order for the Ce-sublattice either, but, alternating current magnetic susceptibility measurements reveal a spin glass state below 18 K in the case of H ⊥ c. Isothermal magnetization curves measured below magnetic order with H ⊥ c show saturation and even large hysteresis at 2 K, indicating the presence of a ferromagnetic component. In addition, a field-induced spin-flop transition is observed in the case of H ⊥ c, indicating a field-induced spin reorientation of Mn spins. Electrical resistivity measurements indicate a metallic nature for CeMn0.85Sb2 and large anisotropy which is consistent with its quasi-two-dimensional layered structure.

Phase diagram of the semiconductor GaSb–ferromagnet GaMn system

In this work we report the results of complex studies of basic properties and phase equilibria in GaSb–GaMn system within wide composition range. Investigated alloys were synthesized using regimes with relatively low crystallization speed, which resulted in a formation of stable monoclinic modification of GaMn, as suggested by the X-ray diffraction data analysis. The latter also suggested the negligible role of mutual solubility of components in agreement with spatial distribution of elements in studied alloys determined using energy dispersive X-ray spectroscopy. Combination of microstructural data and results of differential thermal analysis reveals the eutectic character of interaction in GaSb–GaMn system with eutectic composition corresponding to 45 mol.% of GaMn and melting temperature of 609 °C. This temperature is substantially lower than reported values of peritectic melting temperature of GaMn, which suggests the possibility of stabilizing hard ferromagnetic L10-GaMn modification in GaSb–GaMn system without substantial deterioration of crystal quality typical for GaMn compounds.

Antimicrobial Activity of ZnO Nanoparticles Prepared Using a Green Synthesis Approach

Zinc oxide nanoparticles (ZnO NPs) were synthesized from cinnamon and bay leaves using chemical and environment-friendly synthesis approaches. The biosynthesized NPs were characterized using X-ray diffraction (XRD), which confirmed their crystalline nature. The morphology of the NPs was analyzed using scanning electron microscopy. The XRD analysis data showed average grain sizes of 9.968, 18.547, and 29.983 nm for the ZnO NPs. Energy-dispersive X-ray spectrum and XRD patterns showed that the synthesized ZnO NPs were unadulterated. These ZnO NPs were then used as antibacterial agents against Gram-positive (<i>Staphylococcus aureus</i> and <i>Staphylococcus epidermidis</i>) and Gram-negative bacteria (<i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i>). The antifungal activity of the biosynthesized NPs was also tested against common unicellular fungi (<i>Candida albicans</i>). The results showed that ZnO NPs extracted from cinnamon demonstrated a higher antibacterial activity compared with those of the NPs extracted from bay leaves or the chemically prepared ones.

Investigation of the -Mercaptobenzothiazole (2-MBT) organic single crystals and Third Order Nonlinear optical applications

2-mercaptobenzothiazole (2-MBT) organic single crystal was grown by using the slow evaporation method with a seeding attempt. The grown crystal was confirmed through the powdered X-ray diffraction data analysis. The transparency of the grown crystal was observed from Ultra violet near infrared (UV-NIR) studies. Mechanical properties of the grown crystal of different magnitudes (25, 50, and 100 g) were applied with a fixed interval of time. Dielectric Loss and constant were measured with different frequencies through the dielectric analysis. Third-order nonlinear susceptibility χ(3), nonlinear refractive index (n2), and nonlinear absorption coefficient (β) were analyzed from the third harmonic generation studies.

Ph2Te2: An Accessible Main Group Organometallic Target for Spectral Characterization and Modeling

A straightforward protocol for the preparation of the colorful and air-stable diphenyl ditelluride is described. In one laboratory session, students isolate their product and characterize it via melting point determination, mass spectrometry, and NMR spectroscopy (1H, 13C{1H}, and 125Te{1H}). The alternative application of a Grignard reagent serves as a bridge between common organic laboratory experiences and this exercise. Students have the opportunity to see the advantages and disadvantages of the assortment of characterization techniques and, for MS and NMR, the distinctness of their application specifically to inorganic compounds. Analysis of single crystal X-ray diffraction data and molecular modeling results of Ph2Te2 and its lighter congeners (Ph2E2, E = O–Se) provide students with a data-supported understanding of the inert pair effect.

Excellent Structural Stability-Driven Cyclability in P2-Type Ti-Based Cathode for Na-Ion Batteries

In the current study, we have synthesized Ti-based P2-type Na0.7Ni0.2Cu0.1Ti0.65O2 (NNCT) through the sol–gel route and characterized it for its structural, electrical, and electrochemical properties. The analysis of X-ray diffraction (XRD) data confirmed the existence of a single P2 phase for the sample calcined at 950 °C with suppressed Na-ion vacancy ordering. Impedance studies and chronoamperometric data revealed that NNCT exhibited a poor conductivity of ∼1.37 × 10–7 S cm–1 at room temperature, with the electronic conductivity contribution to the total electrical conduction being only 0.4%. The sample exhibited specific capacities of 83, 54, and 42 mA h g–1 at discharge rates of 0.1C, 0.5C, and 1C, respectively, with remarkable cyclic stability of 96% capacity retention after 700 cycles at 0.5C which makes NNCT an attractive cathode for Na-ion batteries in stationary storage applications. The ex situ XRD analysis confirmed that NNCT maintains a single P2 phase during cycling between 2.0 and 4.2 V. NNCT also exhibited moisture stability, thus enabling the use of a cost-effective water-based slurry for cathode layer fabrication.

Quantifying Li-content for compositional tailoring of lithium ferrite ceramics

Owing to their multiple applications, lithium ferrites are relevant materials for several emerging technologies. For instance, LiFeO2 has been spotted as an alternative cathode material in Li-ion batteries, while LiFe5O8 is the lowest damping ferrite, holding promise in the field of spintronics. The Li-content in lithium ferrites has been shown to greatly affect the physical properties, and in turn, the performance of functional devices based on these materials. Despite this, lithium content is rarely accurately quantified, as a result of the low number of electrons in Li hindering its identification by means of routine materials characterization methods. In the present work, magnetic lithium ferrite powders with Li:Fe ratios of 1:1, 1:3 and 1:5 have been synthesized, successfully obtaining phase-pure materials (LiFeO2 and LiFe5O8), as well as a controlled mixture of both phases. The powders have been compacted and subsequently sintered by thermal treatment (Tmax = 1100 °C) to fabricate dense pellets which preserve the original Li:Fe ratios. Li-content on both powders and pellets has been determined by two independent methods: (i) Rutherford backscattering spectroscopy combined with nuclear reaction analysis and (ii) Rietveld analysis of powder X-ray diffraction data. With good agreement between both techniques, it has been confirmed that the Li:Fe ratios employed in the synthesis are maintained in the sintered ceramics. The same conclusion is drawn from spatially-resolved confocal Raman microscopy experiments on regions of a few microns. Field emission scanning electron microscopy has evidenced the substantial grain growth taking place during the sintering process – mean particle sizes rise from ≈ 600 nm in the powders up to 3.8(6) µm for dense LiFeO2 and 10(2) µm for LiFe5O8 ceramics. Additionally, microstructural analysis has revealed trapped pores inside the grains of the sintered ceramics, suggesting that grain boundary mobility is governed by surface diffusion. Vibrating sample magnetometry on the ceramic samples has confirmed the expected soft ferrimagnetic behavior of LiFe5O8 (with Ms = 61.5(1) Am2/kg) and the paramagnetic character of LiFeO2 at room temperature. A density of 92.7(6)% is measured for the ceramics, ensuring the mechanical integrity required for both their direct utilization in bulk shape and their use as targets for thin-film deposition.

Influence of magnetic (Fe) and non-magnetic (In) doping on structural, magnetic, and weak anti-localization properties of Bi2Te3 topological insulator

In this article, we have studied the changes in structural, magnetic, and magneto-transport properties of Bi2Te3 topological insulator doped with magnetic (Fe) as well as non-magnetic (In) elements. The un-doped along with Fe, In-doped Bi2Te3 are grown using a melt growth technique. The Rietveld analysis of x-ray diffraction data expresses that both In and Fe-dopants substituted the Bi-position with a little bit of interstitial incorporation in host Bi2Te3. It is also noticed that In-doping is slightly more favorable for Bi-substitution than Fe. The magnetic characterization reveals a mixing of diamagnetic and Pauli paramagnetic behavior of un-doped and In-doped Bi2Te3, whereas, Fe-doping shows overall paramagnetism with local anti-ferromagnetic interactions among Fe-ions without long-range order. The electrical-transport study represents the metallic response of host Bi2Te3, which is well-maintained for In-doping; however, Fe-doping exhibits prominent anomalies in ρ xx –T profiles. Importantly, magneto-conductance research indicates a notable deviation of host quantum feature, weak anti-localization effect (WAL) upon magnetic (Fe) doping, whereas non-magnetic In-doping shows a comparatively weak deviation in WAL effect for high doping limit.

Synthesis of Graphite-Encapsulated Ni Micro- and Nanoparticles Using Liquid-Phase Arc Discharge

In this work, the synthesis of nickel particles encapsulated in a few-layer graphene shell was carried out using the method of electric arc discharge in the liquid phase, in various media: deionized water, alcohol, and toluene. Nickel and graphite were used as electrodes. The study was carried out to analyze how various liquids, acting as a cooling medium and a source of carbon, affect the formation of a protective shell around metal particles. Raman studies, analysis of X-ray diffraction data, and scanning electron microscopy confirmed the formation of spherical encapsulated nickel particles in all types of liquid media. It was found out that the use of toluene as a cooling medium increased the number of particles with a graphite shell and allowed obtaining micro- and nanoparticles covered with monolayer graphene. The absence of oxygen in the composition of toluene, in contrast with alcohol and especially water, prevents the oxidation of nickel particles during the synthesis. This fact, along with the initial basic hexagonal carbon structure of toluene, makes it a good medium for the formation of metal particles covered with a protecting graphite shell as a result of arc discharge in the liquid phase.