Electron backscatter diffraction study of changes in the grain structure of Ni3Fe ordering alloy upon an A1 → L12 phase transition

The rearrangement of the grain structure of Ni₃Fe alloy upon an A1 → L1₂ phase transition is studied via transmission electron microscopy in combination with the electron backscatter diffraction. It is established that the formation of fresh grain boundaries of general and special types occurs, with the proportion of special-type grain boundaries in the grain boundary ensemble growing. The spectrum of the special grain boundaries changes, due to an increase of the proportion of grain boundaries Σ3 and Σ9. This strengthens the texture of the long-range ordered alloy.     

Ordering and grain growth of FePt thin films by annealing

Microstructure variation of FePt thin film upon annealing at elevated temperatures was investigated by transmission electron microscopy (TEM). A special shape aperture was employed to observe the ordered L1₀ phase in the dark-field TEM images. With increasing the annealing temperature, crystal grains formed clusters with gathering of neighboring grains, and crystal grain growth proceeded within the cluster. L1₀ ordered crystal grains were preferentially formed near the grain boundaries, and their sizes grew with increasing the annealing temperature.     

Preparation and photoluminescent properties of europium complexes with methoxy derivatives of 2′-hydroxy-2-phenylacetophenones

The complexes Eu(L₁)₃·2H₂O (I) [where L₁=2′-hydroxy-4′-methoxy-2-phenylacetophenone], Eu(L₂)₃·2H₂O (II) [where L₂=2′-hydroxy-4′-methoxy-2-(p-methoxyphenyl) acetophenone], Eu(L₃)₃·2H₂O (III) [where L₃=2′-hydroxy-4′, 6′-dimethoxy-2-phenylacetophenone] and Eu(L₄)₃·2H₂O (IV) [where L₄=2′-hydroxy-4′, 6′-dimethoxy -2-(p-methoxyphenyl) acetophenone] were synthesized. Energy dispersive X-ray analysis (EDX) results showed the presence of europium in all the complexes. These complexes were further characterized by infra-red spectroscopy, thermal analysis, scanning electron microscopy (scanning electron microscope) and elemental analysis. The synthesized complexes emit red luminescent with main peak at 612 nm on exposure to UV light at 354 nm. The complexes emitting bright red color might be applicable for optical devices and solid-state lamps for general illumination purposes.     

Influence of the degree of long-range atomic order on parameters of the solid solution and the granular structure of the Pd3Fe alloy with superstructure L12

It has been established using X-ray structural analysis and scanning electron microscopy that the lattice parameter and total root-mean-square (rms) atomic displacements increase in the Pd₃Fe polycrystal-line alloy during the A1 → L1₂ phase transition and with an increase in the degree of long-range atomic order, while the microdistortions of the crystal lattice and the fraction of the Σ3 twin boundaries in the spectrum of special boundaries decrease; the latter leads to strengthening the texture.     

FePt L10 ordering and grain growth using millisecond pulse laser processing

The structural and magnetic properties of ∼12 nm thick FePt thin films grown on Si substrates annealed using a 1064 nm wavelength laser with a 10 ms pulse have been examined. The A1 to L1₀ ordering phase transformation was confirmed by electron and X-ray diffraction. An order parameter near 50% and a maximum coercivity of 12 kOe were obtained with laser energy densities of 25-32 J/cm². Grain growth, quantified by dark field transmission electron microscopy, occurred during chemical ordering at the laser pulse widths studied.     

High-temperature shape memory effect and the B2-L10 thermoelastic martensitic transformation in Ni-Mn intermetallics

The properties and structure of the martensitic phase of alloys with a near-stoichiometric equiatomic Ni₅₀Mn₅₀ composition, as well as martensitic transformations in them, are investigated in a wide temperature range by measuring the resistivity and thermal expansion coefficient and applying transmission electron microscopy, scanning electron microscopy, electron diffraction, and X-ray diffraction. It is found that Ni₅₀Mn₅₀ and Ni₄₉Mn₅₁ alloys experience the B2 → L1₀ highly reversible thermoelastic martensitic transformation and its related high-temperature deformation of the transformation and shape memory effect. Critical temperatures, volume (ΔV/V = ?1.7%) and linear size effects attributed to the direct and reverse martensitic transformations, and the high-temperature dependences of the martensitic and austenite lattice parameters are determined. It is found that the morphology of tetragonal L1₀ martensitic represents a hierarchy of thin coherent sheets of submicrocrystallites and nanocrystallites with plane near-{111}L1₀ habit boundaries, the crystallites being pairwise twinned according to the {111}〈11 $\bar 2$ 〉 _L10 ∥ {011}〈-1 $\bar 1$ 〉 _B2 twinning shear scheme.     

Scanning electron microscopy of Ancylostoma spp. dog infective larvae captured and destroyed by the nematophagous fungus Duddingtonia flagrans

The interaction between the nematode-trapping fungus Duddingtonia flagrans (isolate CG768) against Ancylostoma spp. dog infective larvae (L₃) was evaluated by means of scanning electron microscopy. Adhesive network trap formation was observed 6 h after the beginning of the interaction, and the capture of Ancylostoma spp. L₃ was observed 8 h after the inoculation these larvae on the cellulose membranes colonized by the fungus. Scanning electron micrographs were taken at 0, 12, 24, 36 and 48 h, where 0 is the time when Ancylostoma spp. L₃ was first captured by the fungus. Details of the capture structure formed by the fungus were described. Nematophagous Fungus Helper Bacteria (NHB) were found at interactions points between the D. flagrans and Ancylostoma spp. L₃. The cuticle penetration by the differentiated fungal hyphae with the exit of nematode internal contents was observed 36 h after the capture. Ancylostoma spp. L₃ were completely destroyed after 48 h of interaction with the fungus. The scanning electron microscopy technique was efficient on the study of this interaction, showing that the nematode-trapping fungus D. flagrans (isolate CG768) is a potential exterminator of Ancylostoma spp. L₃.     

The effect of antiphase domains on the energy spectra of special boundaries in alloys with the <Emphasis Type="Italic">L</Emphasis>1<Subscript>2</Subscript> superstructure

The special grain boundaries in ordering alloys with the L1₂ superstructure have been investigated by optical metallography and transmission diffraction electron microscopy. The relative energy of the boundaries Σ3 and Σ9 in Ni₃Fe alloy with a short-range order is determined. The energy of these boundaries in an alloy with long-range order is estimated. The energy of twin grain boundaries increases at the phase transitions A1 → L1₂ due to the formation of antiphase grain boundaries in those boundaries. The spectra of special boundaries over Σ and their distributions, depending on the relative energy, change as well. The average relative energy of special grain boundaries in alloys with the L1₂ superstructure increases with increasing the energy of antiphase boundaries.     

The effect of different concentrations of Na2SnO3 on the electrochemical behaviors of the Mg-8Li electrode

In this research, the effect of the different concentrations of NaSnO₃ as the electrolyte additive in 0.7 mol L^?1 NaCl solution on the electrochemical performances of the magnesium-8lithium (Mg-8Li) electrode are investigated by methods of potentiodynamic polarization, potentiostatic current-time, electrochemical impedance technique, and scanning electron microscopy (SEM). The corrosion resistance of the Mg-8Li electrode is improved when Na₂SnO₃ is added into the electrolyte solution. The potentiostatic current-time curves show that the electrochemical behaviors of the Mg-8Li electrode in the electrolyte solution containing 0.20 mmol L^?1 Na₂SnO₃ is the best. The electrochemical impedance spectroscopy results indicate that the polarization resistance of the Mg-8Li electrode decreases in the following order with the concentrations of Na₂SnO₃: 0.05 mmol L^?1?>?0.00 mmol L^?1?>?0.30 mmol L^?1?>?0.10 mmol L^?1?>?0.20 mmol L^?1. The scanning electron microscopy studies indicate that the electrolyte additive prevents the formation of the dense oxide film on the alloy surface and facilitates the peeling off of the oxidation products.     

Distinguishing the core from the shell in MnO(x)/MnO(y) and FeO(x)/MnO(x) core/shell nanoparticles through quantitative electron energy loss spectroscopy (EELS) analysis

The structural and chemical characterization of inverted bi-magnetic MnO_x(antiferromagnetic)/MnO_y(ferrimagnetic) and FeO_x(soft-ferrimagnetic)/MnO_x(hard-ferrimagnetic) core/shell nanoparticles has been carried out by means of scanning transmission electron microscopy with electron energy loss spectroscopy analysis, (S)TEM-EELS. Quantitative EELS was applied to assess the local composition of the nanoparticles by evaluating the local Mn oxidation state based on the Mn L₃/L₂ peak intensity ratio and the Mn L₃ peak onset. The analysis allows to unambiguously distinguish the core from the shell and to determine the nature of the involved manganese oxides in both cases. The results evidence that the structure of the nanoparticles is, in fact, more complex than the one designed by the synthesis parameters.     

Σ3 twin boundaries and texture in FCC solid solutions and alloys with <Emphasis Type="Italic">L</Emphasis>1<Subscript>2</Subscript> superstructure

Crystallographic textures in solid solutions (Cu–Al, Cu–Mn) with face-centered cubic lattice, and in alloys (Ni₃Mn, Pd₃Fe) with L1₂ superstructure, are investigated by means of scanning electron microscopy with back-scattered electron diffraction. It is found that an increase in the portion of S3 twin boundaries in a special type of boundary spectrum is accompanied by a strengthening of texture.     

Solid-state synthesis and atomic ordering in thin Cu/Au films (atomic ratio, Cu : Au = 3 : 1)

In situ transmission electron microscopy investigations of the processes of solid-state synthesis and atomic ordering in bilayer Cu/Au nanofilms (atomic ratio, Cu: Au = 3: 1) are conducted. It is found that solid-state synthesis starts at 170°C. A Cu₃Au atomic-disordered structure (Fm3m space group; lattice constant, a = 3.76 ± 0.01 Å) forms at 280°C. Annealing the film for 1 hour at 380°C produced a Cu₃AuI (L1₂ type) atomic-ordered superstructure, a Pm-3m space group, and lattice constant, a = 3.76 ± 0.01 Å in the bulk of the film.     

Effect of thermal treatment and re-doping on the volume fraction of the γ′ phase in complex-doped Ni-Al-Cr-based superalloy

Phase transformations of complex-redoped Ni-Al-Cr-based superalloys under different thermal treatment are investigated by means of diffraction electron microscopy. Alloys are obtained via directional crystallization. The factors affecting the formation of the long-range atomic order of the γ′ phase (an ordered multicomponent phase based on superstructure L1₂) are established from the experimental results. It is shown that the degree of long-range order is directly dependent on the strengthening of the superalloy.     

The effectiveg s factor for the odd proton153Sm nucleus determined by the internal conversion processes

TheK/L ₃,L ₁/L ₃,L ₁/L ₂ andL ₂/L ₃ conversion ratios for the 103 keV transition in¹⁵³Sm were measured by means of a high-resolution π√2 electron spectrometer. The values of theM1 conversion penetration parameter λ=5.0 _?0.7 ^+0.6 and the mixing ratio δ²=0.144±0.006 are deduced. By comparing the experimental penetration parameter with the value obtained from Nilsson model calculations the effective spin gyromagnetic ratio is found to be $$g_s^{eff} = \left( {3.7\begin{array}{*{20}c} { + 0.4} \\ { - 0.5} \\ \end{array} } \right)\mu _n .$$      

Symmetries and the mass ratio of the electron and muon

A model of symmetries and gauge interactions relating the electron and muon is considered. The model is based on the U_L(1)?U_R(1)?R_L?R_R group where U_L(1)?U_R(1) denotes the chiral e-μ rotation and R_L?R_R the chiral reflection of the electron field. The invariance under this group is spontaneously broken by the vacuum expectation values of scalar fields. A zeroth-order vacuum is found for which the zeroth-order electron mass vanishes, while one-loop corrections lead to a finite $\text{m}{}_{\mathrm{<mtext>e</mtext>}}\text{mμ}$ ratio. The decay process μ → e + γ is strictly forbidden in this model.     

L-subshell ionization cross sections for Au,Pb, and Bi by 60–600 keV electron impact

TheL ₁-,L ₂- andL ₃-subshell ionization cross sections of Au, Pb and Bi by 60–600 keV electron impact have been determined from the measured x-ray production cross sections. The experimental results have been compared with the relativistic PWBA, the Binary Encounter Approximation (BEA) and the Kolbenstvedt Approximation (KA) calculations. These calculations, especially the relativistic PWBA, give good agreement with the experimental data for theL ₃-subshell. For theL ₁- andL ₂-subshells there are some deviations and these can explain the disagreement observed for theL _α/L _χ- andL _γ/L _χ intensity ratios.     

Messungen zu den Vibrations- und Zweiquasiteilchenzuständen in172Yb

The Coster-Kronig and Auger spectrum of theL ₁ shell of gaseous argon has been investigated with an electrostatical spectrometer. The ionization in theL ₁ shell of argon was caused by electron impact. Absolute energies and relative intensities of all the Coster-Kronig and Auger transitions have been determined. The relative intensities of transitions within the groupsL ₁ L _{2, 3} M ₁,L ₁ L _{2, 3} M _{2, 3} andL ₁ MM agree fairly well with the theoretical values, calculated byRubenstein for extreme Russel-Saunders coupling, if intermediate coupling theory is used properly. Via the widthγ(L ₁) of theL ₁ level of argon, found in this experiment to be (1.84±0.2) eV, the following absolute group transition probabilities were determined (in units of 10¹⁴ sec^?1):W(L₁ L _{2, 3} M ₁)=(5.5±1.0),W(L₁ L _{2, 3} M _{2, 3})=(20.8±2.8),W(L₁ MM)=(1.44±0.16). The theoretical values are 21.0, 20.4 and 1.27. The possible reason for the large discrepancy between the experimental and theoretical value ofW(L₁ L _{2, 3} M ₁) is the use of the incorrect value of 287 eV for the binding energyE(L₁) byRubenstein. From the energies of theL ₁ MM transitions this value has been determined to beE(L₁)=(326.5±0.5) eV. This is the first direct measurement ofE(L₁) of argon.     

L10 FePt thin films with [0 0 1] crystalline growth fabricated by SiO2 addition—rapid thermal annealing and dot patterning of the films

FePt films that have a high degree of order S in their L1₀ structure (S>0.90) and well-defined [0 0 1] crystalline growth perpendicular to the film plane were fabricated on thermally oxidized Si substrates by the addition of an oxide and successive rapid thermal annealing (RTA). The mechanism of L1₀ ordering and [0 0 1] crystalline growth perpendicular to the film plane arising through the oxide addition and RTA process is also discussed. The L1₀ ordering (S>0.90) and the [0 0 1] crystalline growth were achieved by (1) lowering the activation energy due to in-plane tensile stress and the initiation of L1₀ ordering at a low temperature, (2) [0 0 1] crystalline growth through in-plane tensile stress, and (3) enhancement of atomic diffusion via the addition of an oxide and the resultant lowering of the ordering temperature. Effect (1) was observed in the case of SiO₂ addition, effect (2) was generally observed in the case of oxide addition and the RTA process, and effect (3) was prominent in the case of ZnO addition. With the addition of ZnO, the L1₀ ordering started at below 400 °C and was completed at 500 °C. Finally, dot patterns were successfully fabricated down to a diameter of 15 nm using electron beam lithography, and the magnetic state of the dot pattern was observed by magnetic force microscopy.     

Characterization of copper-exchanged Na-A,X and Y zeolites with X-ray photoelectron spectroscopy and transmission electron microscopy

Copper-exchanged sodium- A, X and Y zeolites have been characterized with X-ray photoelectron Spectroscopy (XPS), with supporting electron microscopy and X-ray diffraction measurements. Under reducing conditions (CO, H₂, 250–450° C), four distinct chemical states of copper have been identified. These are intrazeolite Cu(II), Cu(I) and 1 nm metal clusters, and externally segregated copper metal crystallites. We report spectroscopic data for both the Cu 2p_{$\text{3}\text{2}$} and Auger L₃M_4,5M_4,5 lines. Whereas Cu(II) and metallic copper crystallites have normal spectroscopic parameters, Cu(I) and 1 nm Cu clusters in the reduced zeolites lie in new areas of the two-dimensional chemical state plot.The reduction sequence of Cu(II), Cu(I), Cu clusters and Cu crystallites is different on the A zeolite compared with X and Y. One nm metal clusters are identified as an intermediate phase on the A with transmission electron microscopy (TEM) and XPS prior to external diffusion and crystallite formation. The ease of formation of the cluster intermediate in the A zeolite may be a consequence of the larger diffusion barrier imposed by the 0.42nm supercage aperture compared with the 0.74nm aperture in the X and Y zeolites.     

L-subshell fluorescence and coster-kronig yields atZ=92 and the decay of235Np

TheK andL x-rays emitted in the decay of²³⁵Np have been studied with high resolution Ge(HP) and Si(Li) detectors in coincidence, in order to obtain theL ₂ andL ₃ subshell fluorescence and Coster-Kronig yields atZ=92. The results are:v ₂=0.630±0.036, ω₂=0.560±0.033,f ₂₃=0.147±0.010, and ω₃=0.481±0.029. Results for theL ₁ subshell were derived from singles spectra, by assuming a value off ₁₃ of 0.67, and are:v ₁=0.54±0.04, ω₁=0.21±0.04, andf ₁₂<0.07. With the same assumption, theL ₁/K electron capture ratio and decay energyQ _ec for²³⁵Np were found to be 29.0±3.6 and 123.6±0.7 keV, respectively. RelativeL x-ray intensities forZ=92 also were measured and are compared with the theory of Scofield and with recent diffraction experiments. Electron ejection from theL shell during²³⁵Np decay has been studied byL x-ray-L x-ray coincidences and found to occur with a probability of (1.3±1.0) × 10^?4 per disintegration.