Selected Area Diffraction Research Articles

Layered 2H-MoTe2: A novel anode material for lithium-ion batteries

Transition metal dichalcogenides with well-developed two-dimensional layers and high structural stability provide superior Li+ storage property in lithium-ion batteries (LIBs). For this study, the MoTe2 polycrystalline powder sample is prepared using a facile solid-state route. Transmission electron microscopy (TEM) along with selected area diffraction (SAD) patterns, Field emission scanning electron microscopy (FE-SEM) combined with energy dispersive X-ray spectroscopy (EDX) have been performed to obtain crystallographic, morphological, and chemical information of the as-prepared MoTe2 powder. SAD patterns and the high-resolution transmission electron microscopy (HRTEM) study reveal the well-developed crystalline layered structure of the MoTe2 powder. The as-prepared MoTe2 electrode showed an initial specific discharge capacity of ~ 452 mAh g−1 versus lithium metal and a corresponding specific discharge capacity of ~ 279 mAh g−1 is achieved after 40 cycles at 1.0 A g−1 current density.

The effect of an inhomogeneous magnetic field on the structure of thin Co films obtained by magnetron sputtering

The strong influence of the orientation of an external magnetic field of a system of permanent magnets on the crystal structure of cobalt films grown on an amorphous carbon sublayer was revealed by the methods of transmission electron microscopy and selected area diffraction. While the horizontal component of the magnetic field strength impedes the process of cobalt grains growth, the vertical one, on the contrary, contributes to this process. The vertical component of the magnetic field promotes strong growth of crystalline cobalt grains with an axis [0001] perpendicular to the film surface at the expense of grains with different orientations. As the strength of the vertical component of the magnetic field increases to H ≈ 1.2 × 104 Oe, the size of some crystalline grains with orientation [0001] reaches about 1 μm in the cobalt film with a nominal thickness of 8 nm. In a horizontal magnetic field of the order of 1.2 × 104 Oe, the average grain size is only 16 nm, which is only twice the nominal film thickness. The paper discusses issues related to the influence of magnetic crystallographic anisotropy and external magnetic field on the processes of nucleation during structure rearrangement.

Dy3+ doped Y2MoO6 nanopowders for white light emission: Spectroscopic and transport properties for optoelectronic and energy harvesting applications

In this communication, we report the white light emitting Dy3+ ions doped Y2MoO6 (YMO) nanopowders (NPs) prepared via green combustion synthesis route by utilizing the Aloe vera (AV) gel as surfactant. For the convenient to the readers, we represent Y2MoO6:Dy3+ as YMOD. The cubic structure of the YMOD is confirmed by the results of powder X-ray diffraction (PXRD). The energy band gap values are studied by diffuse reflectance spectra (DRS) plots and the observed values are found to be in the range of 3.33–3.43 eV. The block-like structures of the fabricated nanopowders is analyzed by means of scanning electron microscope (SEM) images. Transmission electron microscope (TEM) images are castoff to evaluate the particle size of the prepared powders. The crystallinity and interplanar spacing are analyzed by means of selected area diffraction (SAED) and high-resolution TEM (HRTEM) images respectively. In order to study the luminescence behaviour of the fabricated powders, the photoluminescence spectra are recorded in the range of 400–675 nm under 386 nm excitation wavelength. There are three prominent peaks positioned at 480, 575 and 637 nm which are corresponding to the 4F9/2 → 6H15/2, 13/2 and 11/2 respectively. The direct current conductivity is studied in the temperature range from 30 to 400 °C. The DC conductivity of NPs increases with increase in temperature. The color emission of the fabricated powders is studied by means of color diagrams namely, CIE and CCT. It is noticed from the color diagrams that, the emission color lies in the bright white region (0.33, 0.33) which is a characteristic emission of the Dy3+ doped powders. The obtained CCT value (5426 K) indicates that the prepared powders can be effectively utilized for cool LED sources in the indoor lighting applications. The average color purity (CP) values are found to be 80%. The quantum efficiency of the prepared nanopowders is found to be ~86.82%. The above findings substantiate the ability of YMO: Dy3+ phosphor to be used in photovoltaic and display device applications.

Effect of De-Twinning on Tensile Strength of Nano-Twinned Cu Films.

Tensile tests were carried on the electroplated Cu films with various densities of twin grain boundary. With TEM images and a selected area diffraction pattern, nano-twinned structure can be observed and defined in the electroplated Cu films. The density of the nano-twin grain structure can be manipulated with the concentration of gelatin in the Cu-sulfate electrolyte solution. We found that the strength of the Cu films is highly related to the twin-boundary density. The Cu film with a greater twin-boundary density has a larger fracture strength than the Cu film with a lesser twin-boundary density. After tensile tests, necking phenomenon (about 20 μm) occurred in the fractured Cu films. Moreover, by focused ion beam (FIB) cross-sectional analysis, the de-twinning can be observed in the region where necking begins. Thus, we believe that the de-twinning of the nano-twinned structure initiates the plastic deformation of the nano-twinned Cu films. Furthermore, with the analysis of the TEM images on the nano-twinned structure in the necking region of the fractured Cu films, the de-twinning mechanism attributes to two processes: (1) the ledge formation by the engagement of the dislocations with the twin boundaries and (2) the collapse of the ledges with the opposite twin-boundaries. In conclusion, the plastic deformation of nano-twinned Cu films is governed by the de-twinning of the nano-twinned structure. Moreover, the fracture strength of the nano-twinned Cu films is proportional to the twin-boundaries density.

Structural, electronic and magnetic properties of L10 ordered CoPt nanoparticles: An experimental and DFT study

CoPt nanoparticles (NPs) were synthesized by sol-gel route from metal chloride precursors. NPs annealed at 800 °C under hydrogen atmosphere which reveals the formation of bimetallic L10 face centered tetragonal (FCT) CoPt alloy NPs confirmed by XRD study and selected area diffraction (SAED) pattern. Here the magnetic properties were investigated from room temperature down to 77 K by vibrating sample magnetometer (VSM). Magnetic measurement revealed that NPs possess ferromagnetic property with a high coercivity 143.24 kAm−1 and remanence because of high anisotropic behavior. However, low temperature magnetization shows an anomalous antiferromagnetic nature of CoPt NPs due to spin canting effect. The band structure and electronic density of states (DOS) calculation indicate the metallic nature of the L10 FCT CoPt NPs. The magnetic moment arises due to electronic spin polarization which is found to be 2.38 μB, calculated using spin density of states (SDOS).

Detecting minute amounts of nitrogen in GaNAs thin films using STEM and CBED

Nitrogen (N) is a common element added to GaAs for band gap engineering and strain compensation. However, detection of small amounts of N is difficult for electron microscopy as well as for other chemical analysis techniques. In this work, N in GaAs is examined by using different transmission electron microscopy (TEM) techniques. While both dark-field TEM imaging using the composition sensitive (002) reflections and selected area diffraction reveal a significant difference between the doped thin-film and the GaAs substrate, spectroscopy techniques such as electron energy loss and energy dispersive X-ray spectroscopy are not able to detect N. To quantify the N content, quantitative convergent beam electron diffraction (QCBED) is used, which gives a direct evidence of N substitution and As vacancies. The measurements are enabled by the electron energy-filtered scanning CBED technique. These results demonstrate a sensitive method for composition analysis based on quantitative electron diffraction.

Hydroxyapatite-Coated SPIONs and Their Influence on Cytokine Release.

Hydroxyapatite- or calcium phosphate-coated iron oxide nanoparticles have a high potential for use in many biomedical applications. In this study, a co-precipitation method for the synthesis of hydroxyapatite-coated nanoparticles (SPIONHAp), was used. The produced nanoparticles have been characterized by dynamic light scattering, X-ray diffraction, vibrating sample magnetometry, Fourier transform infrared spectrometry, atomic emission spectroscopy, scanning electron microscopy, transmission electron microscopy, selected area diffraction, and energy-dispersive X-ray spectroscopy. The results showed a successful synthesis of 190 nm sized particles and their stable coating, resulting in SPIONHAp. Potential cytotoxic effects of SPIONHAp on EL4, THP-1, and Jurkat cells were tested, showing only a minor effect on cell viability at the highest tested concentration (400 µg Fe/mL). The results further showed that hydroxyapatite-coated SPIONs can induce minor TNF-α and IL-6 release by murine macrophages at a concentration of 100 µg Fe/mL. To investigate if and how such particles interact with other substances that modulate the immune response, SPIONHAp-treated macrophages were incubated with LPS (lipopolysaccharides) and dexamethasone. We found that cytokine release in response to these potent pro- and anti-inflammatory agents was modulated in the presence of SPIONHAp. Knowledge of this behavior is important for the management of inflammatory processes following in vivo applications of this type of SPIONs.

Rice grain like Bi2S3 nanorods and its photocatalytic performance

Rice grain like Bi2S3nanorods (Asianrice) were successfully prepared through thioglycolic acid (HSCH2COOH, TGA) assisted reflux approach. The phase, morphology and size, crystalline nature were identified by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area diffraction (SAED), and energy-dispersive X-ray analysis (EDX). The calculated bandgap via Tauc plot is found to be 1.4 eV which is more than the bulk material (1.3 eV) due to larger average particle size (61.68 nm). The photocatalytic experiment was performed under visible light using methylene blue as a model dye pollutant. Furthermore, a possible growth mechanism for prepared rice grain like Bi2S3nanorods was illustrated. Moreover, the limitations of Bi2S3 nanorods synthesized using thioglycolic acid have been discussed.

Color tunable orange-red light emitting Sm3+ doped BaZrO3 nanopowders: Photoluminescence properties for w-LED applications

In this communication, we report the orange-red light emitting Sm3+ ions doped BaZrO3 (BZO) nanopowders (NPs) prepared via green combustion synthesis route by utilizing the local available Aloe vera (AV) gel as the surfactant. For convenient to the readers, we represent BaZrO3:Sm3+ as BZOS. The cubic structure of the BZOS is confirmed by the results of powder X-ray diffraction (PXRD). The energy band gap values are studied by diffuse reflectance spectra (DRS) plots and found to be in the range of 4.71–5.55 eV. The spherical structure of the fabricated nanopowders is analyzed by means of scanning electron microscope (SEM) images. Transmission electron microscope (TEM) image are castoff to evaluate the particle size of the prepared powders. The crystallinity and interplanar distance are analyzed by selected area diffraction (SAED) and high-resolution TEM (HRTEM) images. The luminescence studies are performed at RT. The strong absorption in NUV spectral region is observed. Upon excitation at 403 nm wavelength the emission peaks centered at 565, 607 and 649 nm ascribed to Sm3+ ions 4f-4f characteristics. The explanation for this quenching of focus has been explored in depth. In the pure orange field, the pixel coordinates (0.579, 0.419) for improved BZO: Sm3+ phosphor lie. The CP levels are also calculated and observed to be ~ 90 percent. The quantum efficiency of the prepared nanopowders is found to be ~ 88. 62%. The above findings substantiate the ability of BZO: Sm3+ phosphor to be used in photovoltaic applications as a high thermal stability orange-red light producing element.

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Layer spacing gradient (NaLi)1−xCoO2 for electrochemical Li extraction

Simple one-step synthesis process of novel MoS2@bentonite magnetic nanocomposite for efficient adsorption of crystal violet from aqueous solution

Toxic dye effluents from textile wastewater can cause hazardous effects on human health. Hence, the removal of these effluents is crucial. In this study, a novel MoS2@bentonite magnetic nanocomposite (M-MoS2@bentoniteNC) was synthesized using a new, simple, and one-step process to remove crystal violet (CV). The samples of the M-MoS2@bentoniteNC were characterized using field emission scanning electron microscopy, elemental mapping with energy-dispersive X-ray analysis, transmission electron microscopy, selected area diffraction, Fourier transform infra-red spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, Barrett-Joyner-Halenda and Brunauere-Emmette-Teller surface area analysis, thermogravimetric analysis, and vibrating-sample magnetometry techniques. The synthetic M-MoS2@bentoniteNC exhibited a sufficiently large Langmuir maximum adsorption capacity towards CV (384.61 mg g−1) and remarkable reusability (92.55 % CV removal in the third adsorption–desorption cycle). The adsorption isotherm results were best fitted using the Freundlich model, which refers to multilayer adsorption of CV onto the M-MoS2@bentoniteNC.

Modified microstructures in proton irradiated dual phase 308L weldment filler material

The effect of proton irradiation on the microstructure of δ ferrite—γ austenite mixed phase 308L filler material in a 508–304 dissimilar metal weldment was investigated over a depth of 0 to 10 µm. Ni–Si–Mn G-phase precipitates were observed with SEM and TEM in δ ferrite but not in γ austenite. Our density functional theory based calculations show that the G/Fe interface energy in δ-Fe is significantly lower than that in γ-Fe (0.35 versus 1.25 J/m2), which provides a thermodynamics-based explanation for our experimental observations of preferential formation of G-phase in δ ferrite. STEM-EDS, TEM dark field imaging, and diffraction patterns confirmed the Ni–Si–Mn enriched precipitates were G-phase precipitates with a stoichiometry of Mn6Ni16Si7. Intragranular voids and Ni–Si enriched clusters were observed in irradiated γ austenite. Additionally, Ni and Si segregation was observed along the void interfaces. In both cases, Ni–Si clusters and segregation to voids, selected area diffraction patterns did not reveal the existence of a second phase. Proton irradiation induced Cr depletion and Si and Ni enrichment at γ−γ austenite grain boundaries that was characterized with STEM/EDS.

A Rational Fabrication Method for Low Switching-Temperature VO2.

Due to its remarkable switching effect in electrical and optical properties, VO is a promising material for several applications. However, the stoichiometry control of multivalent vanadium oxides, especially with a rational deposition technique, is still challenging. Here, we propose and optimize a simple fabrication method for VO rich layers by the oxidation of metallic vanadium in atmospheric air. It was shown that a sufficiently broad annealing time window of 3.0–3.5 h can be obtained at an optimal oxidation temperature of 400 °C. The presence of VO was detected by selected area diffraction in a transmission electron microscope. According to the temperature dependent electrical measurements, the resistance contrast (R30 °C/R100 °C) varied between 44 and 68, whereas the optical switching was confirmed using in situ spectroscopic ellipsometric measurement by monitoring the complex refractive indices. The obtained phase transition temperature, both for the electrical resistance and for the ellipsometric angles, was found to be 49 ± 7 °C, i.e., significantly lower than that of the bulk VO2 of 68 ± 6 °C.

Mangifera indica Resin Assisted Synthesis of Nano Silver: Assessing their Photocatalytic Degradation of Methylene Blue, Anticorrosive and Antioxidant Activity

The current work focusses on the silver nanoparticles (Ag-NPs) that are conveniently green synthesized by Mangifera indica gum powder extract. The absorbance is measured by UV–Vis spectrophotometer at a wavelength of 455 nm that represents the Surface Plasmon Resonance of Ag-NPs. Fourier Transform-Infra Red (FT-IR) spectroscopy confirms the functional groups and reaction mechanisms involved in the green synthesis of Ag-NPs. The elemental analysis of Ag-NPs is carried out by Energy dispersive X-ray (EDAX) spectrum and its surface morphology was studied by High resolution transmission electron microscopy (HR-TEM). The average size of Ag-NPs is found to be around 19 nm in diameter. The crystalline nature of the Ag-NPs is investigated by X-ray diffraction (XRD) and Selected area diffraction (SAED). The Ag-NPs shows better antioxidant activity against free radicals such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide anion. Ag-NPs effect on reduction mild steel corrosion is examined using non electrochemical methods. It is proved from experimental tests that the inhibition efficiency increases with increased concentrations of Ag-NPs. The photocatalytic activity of the prepared Ag-NPs under visible light irradiation is assessed by the degradation of methylene blue (MB) dye.

Onset of hard magnetic MnGa thin film on glass substrate

In this study, magnetic properties and microstructure of L10 MnGa thin films deposited at different substrate temperatures (Ts) were carried out in order to determine the onset of the hard magnetic MnGa phase onto glass substrate. The thickness of MnGa thin film was kept at 200 nm while the Ts was varied from room temperature (RT) to 600 °C. When the Ts was below 300 °C, only Mn phases with small grain size were observable. However, the further increase in Ts to 325 °C led to the appearance of L10 (111) peak indicating the presence of the hard magnetic phase in the film on the glass substrate. Also, the continuous rise in Ts enhanced the magnetic properties such as saturation magnetization (Ms) and coercivity (Hc). The crystal size of L10 MnGa phase and surface roughness of the film were also increased with the increase of Ts. The selected area diffraction pattern (SADP) of Transition Electron Microscopy (TEM) effectively identified that the coexistence of pure Mn and A1 MnGa phases were present at Ts < 300 °C and that the L10 MnGa started to appear at Ts = 325 °C while the completion of L10 MnGa phase was seen at Ts > 400 °C. The High-Resolution TEM (HRTEM) images revealed the lattice and amorphous regions present in the MnGa thin film at Ts = 325 °C. Nevertheless, an increase of Ts to 600 °C presented a wide range of L10 (111) lattice signifying the thin film is still in MnGa phase. The onset of hard magnetic L10 MnGa phase is found out to be at 325 °C.

Investigation of the Properties of Ti-TiN-(Ti,Cr,Mo,Al)N Multilayered Composite Coating with Wear-Resistant Layer of Nanolayer Structure

The article describes the results of an investigation focused on the properties of the Ti-TiN-(Ti,Cr,Mo,Al)N multilayered composite coating with a wear-resistant layer of nanolayer structure. A transmission electron microscope was used to study the coating structure. The examination of the phase composition using selected area diffraction electron pattern has detected the presence of two phases, including c-(Ti,Cr,Mo,Al)N and h-AlN. The cutting properties of the tool with the coating under consideration were studied during the turning of AISI 1045 steel at vc = 300 m/min, f = 0.25 mm/rev, and ap = 1.0 mm. After 16 min of cutting, the wear rate for the tool with the Ti-TiN-(Ti,Cr,Mo,Al)N coating was 1.9 times lower compared to the wear rate for the tool with the (Ti,Al)N commercial monolithic coating. As a result of the investigation focused on the fracture pattern on the coating during the cutting, the brittle nature of the fracture has been detected with a noticeable effect of adhesive fatigue mechanisms.

New Ternary Compounds of the Composition Cu2SnTi3 and Their Crystal Structures

A new ternary compound Cu2SnTi3 has been synthesized by vacuum sintering at 900 °C. The atomic structures of CaCu5- and InNi2-like Cu2SnTi3 are calculated using density functional theory methods. The X-ray diffraction (XRD) analysis and selected area diffraction (SAD) patterns of the new ternary compound Cu2SnTi3 are considered to verify the atomic structures of CaCu5- and InNi2-like Cu2SnTi3. The results reveal that the InNi2-like Cu2SnTi3 model has the lowest total energy of −35.239 eV, representing the trigonal crystal structure. The orthorhombic crystal structure of the CaCu5-like Cu2SnTi3 model has the second lowest total energy of −33.926 eV. Our theoretical X-ray diffraction peak profiles of InNi2-like (CaCu5-like) Cu2SnTi3 are nearly identical to experimental one, leading to an error below 2.0% (3.0%). In addition, the hexagonal crystal structure of the CaCu5-like Cu2SnTi3 model has the highest total energy of −33.094 eV. The stability of the Cu2SnTi3 in terms of energy follows the order: the trigonal, orthorhombic, and hexagonal crystal structure.

Fish mucus mediated biosynthesis of copper oxide nanoparticles: spectral characterization, morphology and biological activity

Simple methodology was developed to synthesize copper oxide nanoparticles (CuO NPs) using mucus of Channa striatus (C. striatus). The mucus of C. striatus is known for its biological properties due to the presence of numerous amino acids. This mucus was used as stabilizing agent for CuO NPs synthesis from copper acetate. The prepared CuO NPs were characterized by fourier transforms infrared spectrometer (FTIR), powder x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy dispersive x-ray analysis (EDX) and transmission electron microscope (TEM) coupled with selected area diffraction pattern (SAED). The FTIR study suggested the utilization of mucus in the synthesis of CuO NPs. The XRD data also confirmed formation of pure crystalline phase of CuO NPs. Fish mucus stabilized CuO NPs exhibited significant activity against HeLa cells. The results of cell death clearly indicated that the synthesized CuO nanoparticles could be served as a biomaterial for anticancer treatment.

Microstructual and Chemical Analysis of Surface Treated Metal Foam Anode for Li Rechargeable Battery

As the amount of power consumed by electronic products increases, a lot of studies focused on high capacity and miniaturization of batteries. In order to overcome the low capacity of carbon anode in Li rechargeable battery, researches on the development of high capacity anode material have been conducted. In particularly, it has been reported that pure lithium was adopted for high capacity of Li ion battery due to its light in weight and excellent theoretical capacity. However, when pure lithium is used, the capacity decreases rapidly as charging and discharging proceeded, which is reported to be formation of dendrite on the Li surface during charging/discharging. In order to suppress the growth of dendrite during charging/discharging, several researches have been focused on the Li impregnated metal foam for Li rechargeable battery. However, due to the poor wettability between metal foam and pure Li, adhesive materials had to be deposited by using expensive processes such as chemical vapor deposition to impregnate the Li into metal foam. In this study we focus on the heat treatment effect on the microstructure and Li-impregnation property of Ni metal foam. We oxidized the metal foam in a high temperature(500-900oC) for 5 min using the furnace to improve the wettability between the Lithium and Ni metal foam. Heat treated metal foam was dip into melted Li at 400 oC in a glove box. As a result, the rate of Li-impregnation in the heat treated metal foam was more than 10 times faster than that of the untreated Ni metal foam. The surface of heat treated Ni metal foam was characterized using transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy(EDS). Figure. 1 shows the TEM image of the untreated and heat treated Ni metal foam surface. It reveals that an additional layer having a thickness of 200 nm was observed in the heat treated Ni foam. The additional layer was identified as polycrystalline NiOx by EDS and selected area diffraction pattern (SADP). It is believed that formation of NiOx was greatly contribute to improvement of the impregnation characteristics. In addition, the impregnation characteristics of Ni alloy foam will be discussed in this presentation. Figure 1

Manganese Ferrite Nanoparticles (MnFe2O4): Size Dependence for Hyperthermia and Negative/Positive Contrast Enhancement in MRI.

We synthesized manganese ferrite (MnFe2O4) nanoparticles of different sizes by varying pH during chemical co-precipitation procedure and modified their surfaces with polysaccharide chitosan (CS) to investigate characteristics of hyperthermia and magnetic resonance imaging (MRI). Structural features were analyzed by X-ray diffraction (XRD), high-resolution transmission electron microscopy (TEM), selected area diffraction (SAED) patterns, and Mössbauer spectroscopy to confirm the formation of superparamagnetic MnFe2O4 nanoparticles with a size range of 5–15 nm for pH of 9–12. The hydrodynamic sizes of nanoparticles were less than 250 nm with a polydispersity index of 0.3, whereas the zeta potentials were higher than 30 mV to ensure electrostatic repulsion for stable colloidal suspension. MRI properties at 7T demonstrated that transverse relaxation (T2) doubled as the size of CS-coated MnFe2O4 nanoparticles tripled in vitro. However, longitudinal relaxation (T1) was strongest for the smallest CS-coated MnFe2O4 nanoparticles, as revealed by in vivo positive contrast MRI angiography. Cytotoxicity assay on HeLa cells showed CS-coated MnFe2O4 nanoparticles is viable regardless of ambient pH, whereas hyperthermia studies revealed that both the maximum temperature and specific loss power obtained by alternating magnetic field exposure depended on nanoparticle size and concentration. Overall, these results reveal the exciting potential of CS-coated MnFe2O4 nanoparticles in MRI and hyperthermia studies for biomedical research.