Selected Area Electron Diffraction Patterns Research Articles

Synthesis and characterisation of zeolite LTA with sheet structure

This work reports a simple and effective method for the rapid synthesis of zeolite Linde Type A (LTA) with sheet structure from kaolin. X-ray diffraction results confirm the purity and crystallinity of the synthesised zeolite LTA with sheet structure. Transmission electron microscopy images clearly show the sheet-like structure of the synthesised zeolite LTA. The selected area electron diffraction pattern indicates that the crystal structure type of the synthesised zeolite LTA with sheet structure is the body-centred cube. Meanwhile, the elemental mapping confirms the coexistence and uniform distribution of Si, Al, O and Na elements in the lamellar structure of the synthesised zeolite LTA. In addition, N2 adsorption–desorption technique indicates that the surface area of the synthesised zeolite LTA with sheet structure increases up to 39.7994 m2·g−1, a much higher value than that of zeolite LTA.

Effect of sintering treatment on the microstructure of NiFe2O4 synthesized by the sonochemical method and the conventional method

Nickel ferrite ultrafine nanoparticles were synthesized by the sonochemical method. The sample was sintered at temperatures ranging from 1273 K to 1673 K for 3 h. XRD peaks of as-synthesized NiFe2O4, their Transmission Electron Microscopy (TEM), high resolution TEM, and selective area (electron) diffraction pattern demonstrate that the particles are in the completely crystalline state. The initial particle size of as-synthesized NiFe2O4 was found to be approximately <5 nm. Besides, NiFe2O4 samples were also synthesized by a conventional double sintering technique. The purpose was to compare the effect of sintering treatment on the microstructure quality of the NiFe2O4 prepared by these two techniques. Homogeneous coaxial grains did not form until 1573 K for conventionally prepared samples, while for the sonochemical method, homogeneous grains started to form even as low as 1373 K. Furthermore, other measurements were done only for the sintered samples prepared by the sonochemical method to evaluate the magnetic properties. An abrupt change in B–H loops was found with Ts for a maximum applied field of 1500 A/m. M–H loops with the maximum applied field of 1.6 × 103 KA/m and Mössbauer spectroscopy demonstrate that the samples are all at the ferrimagnetic stage. Curie temperatures Tc, determined from the temperature dependence of the initial permeability μ′, for the same samples almost remained unchanged, which confirms that the cation distribution is almost unchanged with the variation of Ts. A slight variation of cation distribution manifested in the variation of Tc with Ts conforms with the site occupancy of Fe3+ analyzed by Mössbauer spectroscopy.

Biosynthesis of Ag/Cu bimetallic nanoparticles using Ricinus communis and their antibacterial and antifungical activity

This work demonstrates an efficient, low-cost and environmentally friendly synthetic method of Ag/Cu bimetallic nanoparticles (NPs), which allows taking advantage of renewable resources, using Ricinus Communis leaf extract as bioreducing and passivating agent. By varying the metal salt precursors of AgNO3 and CuSO4.5H2O concentrations, the stable bimetallic NPs were obtained. The Ag/Cu bimetallic NPs were characterised using ultraviolet-visible absorption spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FTIR), X-ray dispersive energy spectroscopy (EDS), and scanning and transmission electron microscopy (SEM and TEM). In all cases, the particles size is less than 100 nm. The 10:90 Ag/Cu system has the best control of morphology (spheroid) and size in range of 10–25 nm ( σ = 9). Selected area electron diffraction patterns (SAED) are in concordance with JCPDF cards for silver and copper face-centered cubic (fcc) crystal structures. Microbiological susceptibility was tested by disc diffusion, minimum inhibitory concentration (MIC) and minimal lethal concentration (MLC) methods, with the following microorganism strains: Staphylococcus aureus (gram +), Escherichia coli (gram −) and Aspergillus niger (fungus). The MIC concentration for the three strains was found to range from 1.25 to 2.45 μg and the MLC allowance ranges from 2.45 to 9.81 μg.

1/6 type diffraction patterns and double P-E hysteresis loops in Bi(Mg2/3Nb1/3)O3 modified NaNbO3 ceramics

To promote the development of NaNbO3-based antiferroelectrics, it is necessary to stabilize the antiferroelectric phase over ferroelectric phase through compositional design strategy. In this work, Bi(Mg2/3Nb1/3)O3 was doped into NaNbO3 for decreasing the Goldschmidt tolerance factor, and double P-E hysteresis loop was observed. Raman spectra showed the enhanced antiferroelectricity in Bi(Mg2/3Nb1/3)O3 doped samples, and 1/6(100) rather than the usually reported 1/4(100) diffraction spots were observed from selected area electron diffraction patterns. This work is helpful in promoting the research of NaNbO3-based antiferroelectric systems.

Preparation of Cr–Si–N–O thin films epitaxially grown on MgO substrates by pulsed laser deposition

Cr–Si–N–O thin films were epitaxially grown on MgO substrates by pulsed laser deposition. The composition of these films was analyzed by Rutherford backscattering spectroscopy. X-ray diffraction analysis revealed them to be single-crystal-like (Cr,Si) (N,O) thin films. In addition, the diffraction of B1 and D51 observed in the selected area electron diffraction patterns indicated the presence of stacking faults. Therefore, it was concluded that the (Cr,Si) (N,O) thin films exhibited solid-solution hardening due to the addition of Si, and stacking faults induced by the addition of oxygen. Measurements by the nanoindentation method determined that the hardness of the Cr–Si–N–O thin films was about 35 GPa. The hardness did not vary with oxygen content.

Influence of SiO2 nanoparticles on morphology, optical, and conductivity properties of Poly (ethylene oxide)

In this work, a detailed insight to the microstructure, morphology, surface topography, electrical and optical properties in visible and terahertz range was presented for polyethylene oxide (PEO)/silicon dioxide SiO2 nanocomposites. PEO-filled with various contents of SiO2 nanoparticles were synthesized via the solution cast technique. The polycrystalline nature of PEO/SiO2 films was affirmed by the selected area electron diffraction pattern (SAED) recorded by HRTEM measurement and it was found to nearly conformable with X-ray diffraction data. The energy-dispersive X-ray analysis (EDAX) proved the existence of SiO2 with wt% ranged from 0 to 5% as starting fillers. The high-resolution scanning electron microscope planar images indicated uniform distribution of SiO2 nanoparticles within the PEO films. The atomic force microscope 3D images depicted the surface changed from rough to smooth upon the filling with SiO2. The composite samples exhibit absorption spectra that extended from UV–Vis to near infrared regions. Based on Tauc's formula, it was found that the absorption edge shifted from 4.90 to 3.20 eV as the filler fraction increased from 0 to 5 wt%. The analysis of reflective index in the UV–Vis–NIR regions displayed decrement with increasing filler content. Moreover, the refractive index in Vis–NIR regions is good extension to that in THz region expressing the optical quality of studied films. The optical dispersion parameters were analyzed in the view of Wemple-Didomenico single oscillator and Sellmeier model. The values of nonlinear optical parameters (nonlinear susceptibility χ(3) and nonlinear refractive index (n2) were influenced by the filler fractions. Upon the rise of filler content, the conductivity values show slightly decrement.

Single-crystalline GePb alloys formed by rapid thermal annealing-induced epitaxy

Single-crystalline GePb alloys have been successfully achieved by implanting Pb into Ge, followed by rapid thermal annealing under N2 atmosphere. The high crystallinity and the thickness of around 20 nm of the GePb alloys was determined by high-resolution x-ray diffraction and high-resolution transmission electron microscopy. The root-mean-square value of the as-implanted GePb sample is evaluated to be 1.25 nm in the 5 × 5 um scan area, which indicates a rather smooth surface. After being annealed at 400 °C, the result of a selected area electron diffraction pattern suggested that a single-crystalline alloy film was formed for the first time. The Pb composition of this sample is approximately 0.23% according to the x-ray photoelectron spectroscopy results. This value corresponds with the measurement result of the secondary ion mass spectroscopy. In addition, mobility enhancement in GePb/Ge samples has been identified by temperature-dependent Hall measurement, which indicates GePb alloys have great potential to be a promising high-mobility channel material for future monolithic optoelectronics integration application.

Influence of nickel incorporation in CdS: Structural and electrical studies

Microstructural properties of CdS thin film synthesized by chemical bath deposition method and influence of Ni were studied in this present work. X-ray diffraction and selected area electron diffraction pattern reveal the presence of cubic phase. Energy dispersive X-ray analysis confirmed the presence of Ni element in nearly stoichiometric films. The particle size of CdS (~16-26 nm) decreased with nickel doping. Bandgap was found to decrease from ~2.41 eV to ~2.24 eV with increase in nickel incorporation. The Urbach energy increases with Ni doping suggesting increase in disorder in the film. The electrical conductivity and dielectric property were investigated in detail using complex impedance spectroscopy. Conductivity increases with the incorporation of Ni in CdS.

Phase Transitions and Phonon Mode Dynamics of Ba(Cu1/3Nb2/3)O3 and Sr(Cu1/3Nb2/3)O3 for Understanding Thermoelectric Response

We report electrical and thermal properties of perovskite-type Ba(Cu1/3Nb2/3)O3 (BCN) and Sr(Cu1/3Nb2/3)O3 (SCN). The BCN and SCN ceramics were synthesized by using the conventional solid state (CS) reaction method. The transmission electron microscopy analysis exhibited needle- and comb-type domain structures in BCN. Interestingly, SCN did not exhibit domain structure; however, it exhibited superlattice reflections due to ordering that were quite prominent in the selected area electron diffraction patterns. The temperature dependence of the dielectric response for BCN and SCN systems exhibits peaks due to structural phase transitions. The change in the Raman modes with increasing temperature also indicated the presence of phase transition in the temperature range 300–400 °C. BCN exhibited a lower value of the thermal conductivity (1.6 W/m·K at 600 °C) as compared to that of SCN (2.1 W/m·K at 600 °C) because of multiple phonon modes as identified through terahertz frequency domain spectroscopy.

Synthesis and characterization of zinc oxide reinforced aluminum metal matrix composite produced by microwave sintering

The study focuses on the microstructural, phase transformation, and physical and mechanical aspects of aluminum/zinc oxide composite produced by a hybrid microwave sintering technique. In the present case, zinc oxide nanorods were synthesized through a cost-effective thermal decomposition method. The obtained zinc oxide nanorods’ length was in the range of 76–168 nm observed through high-resolution transmission electron microscopy images and crystallinity nature was confirmed by the bright spot in the selected area electron diffraction pattern. Two different wt% (i.e. 0.5 and 2) of zinc oxide nanorods were utilized for the fabrication of the composite material. The diffraction pattern of the milled powder and energy dispersive spectroscopy results shows effective diffusion of zinc oxide nanorods in the aluminum. The elemental mapping of milled powder illustrates the uniform distribution of the reinforcement over matrix material. The micro-hardness results exhibit a higher hardness of 27.78% with a small fraction of 2 wt%. The nano-indentation results confirm the improvement in the nano-hardness by 32.21% with 2 wt% of zinc oxide with a marginal decrease in elastic modulus by 4.92%.

Chemical Route to Twisted Graphene, Graphene Oxide and Boron Nitride.

The recently discovered twisted graphene has attracted considerable interest. A simple chemical route was found to prepare twisted graphene by covalently linking layers of exfoliated graphene containing surface carboxyl groups with an amine-containing linker (trans-1,4-diaminocyclohexane). The twisted graphene shows the expected selected area electron diffraction pattern with sets of diffraction spots out with different angular spacings, unlike graphene, which shows a hexagonal pattern. Twisted multilayer graphene oxide could be prepared by the above procedure. Twisted boron nitride, prepared by cross-linking layers of boron nitride (BN) containing surface amino groups with oxalic acid linker, exhibited a diffraction pattern comparable to that of twisted graphene. First-principles DFT calculations threw light on the structures and the nature of interactions associated with twisted graphene/BN obtained by covalent linking of layers.

Emanating cool white light emission from novel down-converted SrLaAlO4:Dy3+ nanophosphors for advanced optoelectronic applications

To improve the current multi-phased white-LEDs, novel down-converted Dy3+ doped layered perovskite SrLaAlO4 nanophosphors emitting cool white light were successfully fabricated by urea assisted solution combustion approach. X-ray diffractometry and Rietveld refinement revealed the 14/mmm (139) space group of tetragonal phase in doped samples (SrLa(1-x)DyxAlO4 (x = 0.01–0.10)). Morphological studies reported the nanocubic crystals (45–55 nm) while their nanocrystalline nature and (101) crystal plane was depicted by selected area electron diffraction patterns. Elemental composition of nanomaterials was detected effectively via energy dispersive X-ray analysis. The vibrational metal-oxygen bonding in the sample was confirmed by FT-IR results. Photoluminescence spectra, on near UV excitation, showed two intense bands of blue and yellow color at 484 and 574 nm subjected to transition from 4F9/2 → 6H15/2 and 6H13/2, respectively. Maximum emission intensity was noticed for 5.0 mol% amount of dopant (Dy3+) ions. Decay life time, band gap and refractive index of optimized sample were noted as 0.413 ms, 4.98 eV and 1.736, respectively. CCT value (7418 K), color purity (23.02 × 10−2) and CIE coordinates (0.308, 0.284) of SrLa0.95Dy0.05AlO4 nanophosphor were approximate to coordinates of commercial LEDs and National Television System Committee, which confirmed their excellent practicability in the advanced optoelectronic devices, especially single-phase WLEDs for the illumination purpose.

Investigation of structural electron density distribution and enhanced electrochemical properties of spinel structured MnCo2O4/polyaniline nanocomposite prepared by facile and economical method

A nanocomposite of AB2O4 structured binary metal oxide and conducting polymer was synthesized by cost effective procedure. The procedure for synthesis of chosen MnCo2O4 was solution combustion method and the composite MnCo2O4/polyaniline was obtained by physical blending. The procedure involved was very simple, speedy and inexpensive. The derived results from Scherrer and size strain plot methods showed good concurrence. The Strain value of the composite from Scherrer was 0.3406 and from SSP was 0.3332. Lattice parameter revealed in Rietveld method also matched well with Scherrer. The observations of functional groups through FT-IR confirmed the purity of the samples and presence of polyaniline and metal oxide. The morphological changes examined through High Resolution Scanning Electron Microscopy, favored enhanced conductivity in the composite showed that the changes occurred have facilitated more conductivity in the MnCo2O4/polyaniline composite. The size of the nanoparticle revealed by High Resolution Transmission Electron Microscopy (HR-TEM) was 8–50 nm, showing good concurrence with the size observed in XRD which was 10–65 nm and shape in SEM. Selected Area Electron Diffraction patterns were also in confirmation of crystallinity of the samples and planes revealed by XRD. The variations in bond length and electron density distribution investigated by MEM technique, a unique report in this work also assured the improved energy storage potential of the nanocomposite material. The electro chemical analyses viz., cyclic voltammetry, chronopotentiometry and Electrochemical Impedance Spectroscopy by a three electrode assemblage with 6 M KOH as electrolyte have supported the above findings by confirming higher specific capacitance and low resistance. In the nanocomposite material synthesized. The maximum specific capacitance of the MnCo2O4/polyaniline nanocomposite was 875 F/g and, the pure MnCo2O4 was 713 F/g at the scan rate 5 mV/S. The ESR value for pure was 4.07 Ω and that of the composite electrode was 2.75 Ω.

Microstructural evolution and stress state related to mechanical properties of electron beam melted Ti-6Al-4V alloy modified by laser shock peening

This work characterizes microstructural evolutions of electron beam melted (EBM) Ti-6Al-4V alloy modified via laser shock peening (LSP). The depth stress distribution and tensile properties of EBM Ti-6Al-4V alloy were measured before and after LSP. The results indicate that microstructure consists of β phase with 7.2% ± 0.4% vol.% and balance α lamellar in EBM sample, and the α lamella was refined into nano-equiaxed grains and submicro-equiaxed grains after LSP. The dominant refinement mechanism is revealed during LSP. Stacking faults were found in the LSP-treated sample, and their corresponding planes were determined as (0001) basal plane, (101¯0) prismatic plane, and (101¯1¯) pyramidal plane obtained by high resolution transmission electron microscopy. The subgrains and high-angle grains formed during dynamic recrystallization were identified by selected area electron diffraction pattern. The LSP treatment produces a significantly residual compressive stress approximately -380 MPa with the depth of compressive stress layer reaching 450 μm. Strength and elongation of the EBM sample were significantly increased after LSP. The strength and ductility enhancements are attributed to compressive stress, grain refinement and grain gradient distribution of α phase.

A novel strategy for high color purity virescent Er3+-doped SrLaAlO4 nanocrystals for solid-state lighting applications

Unique down-conversion virescent SrLaAlO4:Er3+ nanocrystals were successfully fabricated by urea-assisted solution combustion route. Presence of tetragonal phase in doped samples [SrLa(1−x)ErxAlO4 (x = 0.1–4.0 mol%)] with a space group of 14/mmm (139) was investigated by powder X-ray diffractometry and Rietveld refinement analysis. Nanocubic crystals with their size ranging from 45 to 55 nm were displayed by scanning electron microscopy and transmission electron microscopy (TEM) techniques while high-resolution TEM highlighted the (105) crystallite plane by representing the resolved fringes of lattice. Nanocrystalline nature and the (101) crystal plane was depicted by selected area electron diffraction patterns of the powder sample. Qualitative as well as quantitative elemental composition of nanophosphors were investigated by mapping and spectra of energy dispersive X-ray analysis, respectively. On near UV excitation, photoluminescence emission spectra showed a prominent band of green color due to 4S3/2 → 4I15/2 transition (549 nm). Energy bandgap and refractive index of optimized sample were determined as 4.97 eV and 1.736, respectively, via diffuse reflectance spectra. Color chromaticity coordinates (0.1735, 0.6909) of SrLa0.98Er0.02AlO4 nanophosphors verified their virescent emission with a color purity of 100% and were found to be consistent with the standard values of European Broadcasting Unit (EBU) as well as International Telecommunication Union, thus reflected their important role as the green component in the solid-state lighting devices, especially red–green–blue pc-white light-emitting diodes.

In-situ investigation via high energy X-ray diffraction of stress-induced(0002)α→(110)β transformation in a Ti-5.5Mo-7.2Al-4.5Zr-2.6Sn-2.1Cr alloy

The deformation and load partitioning mechanisms among phases are critical to the detailed understanding of heterogeneous stress distributions at the submicron scale during the process of elastic-plastic transformation in dual-phase (α+β) titanium alloys. Therefore, in this work, a Ti-5.5Mo-7.2Al-4.5Zr-2.6Sn-2.1Cr titanium alloy was investigated via in-situ high energy X-ray diffraction. We examined the evolution of the lattice strain, peak intensity, and full width at half maximum under uniaxial tensile loading at room temperature. The results indicated that the stress-induced (0002)α→(110)β transformation can be preferentially initiated for lattice strains of 702 × 10−6–1500 × 10−6 and 592 × 10−6–1355 × 10−6 during the elastic loading stage of the {0002}α and {110}β reflections, respectively. In addition, various dog-bone-shaped specimens with interrupted strain amplitudes (0.3%, 3%, 5% and 8.5%) were characterized via transmission electron microscopy. The corresponding selected area electron diffraction pattern confirmed the occurrence of a (0002)α//(110)β Burgers orientation relationship when the alloy was subjected to a strain of ε = 0.3%. Furthermore, the results revealed that the anisotropic non-linear response of specific reflections (i.e., the (0002)α and (110)β reflections) will cause a phase transformation.

Bond length fluctuation in perovskite chromate SrCrO3

Perovskite chromate SrCrO3 containing Cr4+ ions shows anomalous electronic states and physical properties, which are believed to be related to the bonding instability, but this has not been confirmed directly in experiments up to now. In order to address this issue, the crystal structure and electronic structure of SrCrO3 are investigated by using transmission electron microscopy and first-principles calculations. The results demonstrate that there is no fourfold rotational symmetry in the selected area electron diffraction patterns along the three main zone axes of SrCrO3, which is inconsistent with an expected cubic structure. Moreover, the orientation-dependent electron energy-loss spectra demonstrate a clear correlation between the dissimilar spectra and the anisotropic effects derived from the crystal structure, and first-principles calculations support the experimental results. All this strongly supports the bonding instability of ambient pressure and temperature phase of SrCrO3 and highlights the important influence of bonding fluctuation on its electronic structure and transport properties. The influence of the core-hole effect and Hubbard potential on the theoretical spectra is further investigated.

Core–Double-Shell Fe2O3@SiO2@Jarosite Hybrid Nanoparticles Synthesized by Laser Ablation of Turquoise in Ethanol

This work highlights a facile green route for the one-step synthesis of iron oxide core–double-shell nanoparticles (NPs) and aluminum phosphide (AlP) nanosheets by pulsed laser ablation of the mineral turquoise target from Nishapur in the presence of an ethanol solvent. High-resolution transmission electron microscopy, selected-area electron diffraction pattern, and field emission scanning electron microscopy (FESEM) in combination with energy-dispersive X-ray mapping revealed the formation of NPs with a typical core@double-shell structure in which crystalline α-Fe2O3 (iron oxide) formed the core, while SiO2 (quartz) and (K, H3O)Fe3(SO4)2(OH6) (jarosite) participated as the inner and outer shell, respectively. However, the application of laser ablation on the turquoise phase of the target led to the formation of AlP nanosheets which was confirmed by the X-ray diffraction patterns and FESEM images. Strong absorption of the vein-ablated species in the UV region (250–360 nm) was the characteristic feature of α-Fe2O3 and jarosite phases, while the absorption band at 250–300 nm for the turquoise-ablated species was related to the presence of Cu compound species and also the α-Fe2O3 phase in the sample. Photoluminescence emission spectra for the vein-ablated species depicted a peak centered at 370 nm, while a peak located at 364 nm was ascribed to the turquoise-ablated species. In particular, these hybrid NPs with high purity and stability may offer new opportunities for bio-applications such as anticancer agents and water/wastewater applications.

A perspective approach towards appreciable size and cost-effective solar cell fabrication by synthesizing ZnO nanoparticles from Azadirachta indica leaves extract using domestic microwave oven

A simple domestic microwave oven-assisted solvothermal method has been used successfully to synthesize spherical nanoparticles of zinc oxide (ZnO NPs) for solar cell fabrication using Azadirachta indica (Neem) leaves extract as both capping and reducing agent. The hexagonal structure of ZnO nanoparticles was confirmed by X-ray powder diffraction analysis. The Fourier-transform infrared spectrum confirms the presence of Zn–O stretching vibrations. High-resolution transmission electron microscopy images have exhibited the spherical morphology of ZnO nanoparticles which has clearly illustrated the average particle size around 4.2 nm. The selected area electron diffraction pattern contains well uniform rings confirming standard orientation. The maximum absorption wavelength for the synthesized ZnO nanoparticles was found to be more than 352 nm. The electrical measurement demonstrated that the values of dielectric constant and dielectric loss gradually decrease with increase in frequency which is described by the basis Maxwell–Wagner model. The ac conductivity of ZnO nanoparticles was also carried out. The solar cell fabrication of ZnO nanoparticles and photovoltaic devices were displayed. It was further confirmed that smaller size of ZnO nanoparticles was synthesized which had shown better cell efficiency.

From spherical to bone-shaped gold nanoparticles-Time factor in the formation of Au NPs, their optical and photothermal properties.

Using the same synthesis method, which was stopped at different time intervals, gold nanoparticles (Au NPs) with different shapes, from spherical to bone-shaped, were obtained. The physical properties of the synthesized Au NPs were investigated using transmission electron microscopy (TEM) combined with selected area electron diffraction patterns (SAED) and ultraviolet-visible spectroscopy (UV-vis). The TEM images showed, that stopping the synthesis after one minute lead to the formation of small spherical Au NPs, which evolved to the cubic shape, rods and bone-shaped Au NPs after 15 min, 30 min, 2 h, respectively. SAED patterns showed, that all the obtained Au NPs were crystalline. UV-vis spectra revealed, that the light absorbance depends on the shape of the Au NPs. Moreover, the effects of the time factor in the formation of Au NPs on the effective conversion of electromagnetic energy into thermal energy, was studied. Furthermore, simulated photothermal therapy (PTT) in combination with the obtained NPs, was done for two cancer cell lines SW480 and SW620. The mortality of cells after using the differently shaped Au NPs as photosensitizers is between 18 % and 52 % and increases with the decrease of the synthesis time.