TEM Line Research Articles

Investigation of Oxide Layer Development of X6CrNiNb18-10 Stainless Steel Exposed to High-Temperature Water.

The oxide layer development of X6CrNiNb18-10 (AISI 347) during exposure to high-temperature water has been investigated. Stainless steels are known to form a dual oxide layer in corrosive environments. The secondary Fe-rich oxide layer has no significant protective effect. In contrast, the primary Cr-rich oxide layer is known to reach a stabilized state, protecting the base metal from further oxidation. This study's purpose was to determine the development of oxide layer dimensions over exposure time using SEM, TEM and EDX line scans. While a parabolic development of Cr in the protective primary layer and Fe in the secondary layer was observed, the dimensions of the Ni layer remained constant. Ni required the presence of a pronounced Fe-rich secondary layer before being able to reside on the outer secondary layer. With increasing immersion time, the Ni element fraction surpassed the Cr element fraction in the secondary layer. Oxide growth on the secondary layer could be observed. After 480 h, nearly the entire surface was covered by the outer oxide layer. In the metal matrix, no depletion of Cr or Ni could be observed over time; however, an increased presence of Cr and Ni in the primary layer was found at the expense of Fe content. The Nb-stabilized stainless steel was subject to the formation of Niobium pentoxide (Nb2O5), with the quantity and magnitude of element fraction increasing over exposure time.

Effects of surface property on loading octaaza bis-α-diimine Ni complex, charge separation, and H2 production activity of MnS@ZnS photocatalysts

The MnS@ZnS photocatalyst was prepared using a microwave-assisted solvothermal method. Then, the octaaza bis-α-diimine Ni complex was loaded to prepare a composite photocatalyst. The adsorption of metal complex on photocatalyst depends on the anchoring groups of the Ni complex and the colloidal surface charge of the photocatalyst. The effects of the zeta potential of MnS and MnS@ZnS photocatalysts on the loading of Ni complex, separation of photogenerated carriers, and activity of Ni complex-modified composite photocatalysts were studied. The loading of NiC complex in photocatalysts was analyzed by Raman spectra, TEM line scan, mapping images, and total reflection x-ray fluorescence spectrometer. MnS@ZnS photocatalyst exhibits negative zeta potential that provides a strong electrostatic attraction force between photocatalysts and the Ni complex (Columb attraction), leading to increased Ni complex loading. MnS@ZnS/Ni complex exhibits better photocatalytic activity than MnS/Ni complex. Loading the Ni complex facilitates the photosensitization of photocatalysts, resulting in improved light absorbance. Besides, the electron-hole separation was further improved because the Ni complex acted as a redox mediator, enabling the transfer of electrons from MnS@ZnS to the Ni complex. The H2 production activity of MnS@ZnS/Ni complex photocatalyst reaches 3997 μmol h−1g−1, which is 1.72 times the pristine MnS.

Carbothermal reduction synthesis of sulfide-modified biochar for heavy metal removal

Although sulfide is effective for heavy metal immobilization, it rarely exists in pristine pyrogenic biochar and easily undergoes intensive hydrolysis. In this work, carbothermal reduction of sulfate for on-site sulfide formation and simultaneous carbon layer encapsulation was developed to synthesize sulfide (CaS) modified biochar for enhancing heavy metal immobilization capacity. The initial reaction temperature for this carbothermal reduction was 700 °C. Increasing the pyrolysis temperature, modifier electron accepting ability and loading content could facilitate carbothermal reduction as further partly confirmed by on-site MS of pyrolysis gas and S 2p XPS of biochar analysis. The formed CaS on biochar could be greatly inhibited from hydrolysis due to the encapsulation effect of carbon layer and reached nearly 100% utilization efficiency in Cd2+ fast immobilization. TEM line scan and XRD of post-adsorbed biochar indicated that high heavy metal immobilization capacity was mainly attributed to the coprecipitation reaction governed by the formation of metal-sulfur bond. Compared with reported absorbents, CaS-modified biochar via carbothermal reduction with on-site encapsulation exhibited an excellent stability and outstanding immobilization capacity for various heavy metal ions (such as Cd2+, Pb2+, Cu2+, Zn2+, Ag+).Graphical

Synthesis and characterization of ZnS-based quantum dots to trace low concentration of ammonia

In the present work, a solution-based co-precipitation method has been adopted to synthesize pure and cobalt-doped ZnS quantum dots and characterized by XRD, SEM, TEM with EDX, FTIR and gas sensing properties. XRD analysis has shown a single phase of ZnS quantum dots having a zinc blend structure. TEM and XRD line broadening indicated that the average crystallite size in the sample is in the range of 2 to 5 nm. SEM micrographs show spherical-shaped quantum dots. FTIR studies show that cobalt has been successfully doped into the ZnS cubic lattice. EDX spectra have analyzed the elemental presence in the samples and it is evident that the spectra confirmed the presence of cobalt (Co), zinc (Zn), oxygen (O), and sulphur (S) elements only and no other impurities are observed. The ZnS-based quantum dot sensors reveal high sensitivity towards 50 ppm of ammonia vapors at an operating temperature of 70 °C. Hence, ZnS-based quantum dots can be a promising and quick traceable sensor towards ammonia sensing applications with good response and recovery time.

Lithospheric flexural modelling of the seaward and trenchward of the subducting oceanic plates

ABSTRACT Based on a two-segment plate flexural modelling, we investigated the effective elastic thickness of global subducting oceanic lithosphere. Our results show that for the plate age of 0 to 50 Ma, the seaward effective elastic thickness T e M values are located between 600 and 900°C isotherms, and do not track any isotherm, while the majority of the trenchward effective elastic thickness T e m values are located between 300 and 600°C isotherms. For the plate age older than 50 Ma, T e M values basically matches the 600°C isotherm with some fluctuations for the age older than 110 Ma, while T e m values mainly fall between 200 and 400°C isotherms. The reduction in effective elastic thickness (T e M-T e m) varies from 2.6 to 30.1 km, or 11–68% of seaward T e M. Thus, the absolute value of the decrease in the effective elastic thicknesses (T e M-T e m) increases with the plate age, while the percentage reduction in the effective elastic thickness (1-T e m/T e M) has no obvious relationship with the age, but more related to the curvature of bending plate. Almost all bending-related earthquakes occurred above the T e M line, but many normal-faulting earthquakes are deeper than the T e M-T e m line, implying that the plate may still retain some thickness of an elastic property core in the areas (depth) where earthquakes occur.

Shell Structure Control of PPy-Modified CuO Composite Nanoleaves for Lithium Batteries with Improved Cyclic Performance

Polypyrrole (PPy)-modified CuO nanocomposites (NCs) with various shell structures have been synthesized by controlling the polymerization time of pyrrole in the presence of leaf-like CuO nanobelts (NBs) as wire templates. The synthesized CuO/PPy NCs and CuO NBs are characterized by XRD, FT–IR, TGA, SEM, TEM, STEM, and EDX line analysis/elemental mapping. The formation mechanism of CuO/PPy core–shell NCs is also illustrated. Electrochemical lithium-storage properties of all the products are evaluated by using them as anode materials for Li-ion batteries (LIBs). It is found that the polymerization time of pyrrole plays a significant role in affecting the shell structures and subsequent lithium-storage properties of the hybrid CuO/PPy NCs. With the extension of polymerization time, CuO/PPy NCs gradually form typical core–shell structures, where the doped PPy with increasing content is steadily and uniformly coated on the CuO surface. Correspondingly, the discharge/charge capacity and cyclic durability of CuO...

Formation and Interpretation of Micro Residual Stresses in Cold Deformed Brass Alloys

The brass alloys CuZn10 and CuZn37 were cold deformed by uniaxial compression in steps of 5 % res. 10 % to 20 %. Using X-ray synchrotron radiation d versus sin2ψ-distributions were measured. All diagrams showed strong non-linearities which were furthermore different for different hkl. The amplitudes of the oscillations increase with increasing deformation but come to a saturation, for CuZn37 at approximately 10 % compression, for instance. The development of the hkl-dependent residual stresses and the oscillations could be related to different microstructures induced by cold deformation. The Voigt-model suits well to describe the oscillations in d-sin2ψ curves associated with the hot extrusion process which was used for the fabrication of the samples. Moreover, it is shown that additional information obtained from TEM and X-ray line profile analysis is necessary to reproduce the experimental oscillations of d versus sin2ψ-distributions measured in cold deformed samples.

A simple synthesis and room-temperature magnetic behavior of Co-doped anatase TiO 2 nanoparticles

Co-doped anatase TiO 2 (i.e. Ti 0.93Co 0.07O 2) nanoparticles have been synthesized by a simple chemical route using titanium(diisoproproxide) bis(2, 4-pentanedionate) 75 wt% in 2-propanol, cobalt (II) acetate tetrahydrate and polyvinyl pyrrolidone (PVP) as the starting chemicals. The nanoparticles were obtained after calcination of the precursor at 823 K for 3 h. The morphology of the nanoparticles was revealed by TEM. The particle sizes obtained from TEM and X-ray line broadening were ∼10–15 and 27 nm, respectively. The XRD and FT–IR results indicated that the synthesized Ti 0.93Co 0.07O 2 nanoparticles have the pure anatase TiO 2 structure without any significant change in the structure that would have been affected by Co substitution. Room temperature magnetization results showed a ferromagnetic behavior of the Ti 0.93Co 0.07O 2 nanoparticles, having their hysteresis loop in the range of - 2500 Oe < H < 2500 Oe with the specific magnetizations of 0.03 emu/g (∼6×10 −3 μ B/Co) at 2.5 kOe and 0.08 emu/g (∼17×10 −3 μ B/Co) at 10 kOe.

Biocompatible suspension of nanosized γ-Fe2O3 synthesized by novel methods

The present work deals with the synthesis of nanosized γ-Fe2O3 by methods and its suspension in a biocompatible fluid consisting of cellulose in water whose properties seem different from the conventional ferrofluid and magnetic rheological fluid. From TEM and x-ray diffractions line broadening particle size has been estimated in the nanometer range. Mössbauer and magnetic measurements have been done to investigate the relaxation behavior of these nanoparticles which consists of significant amount of surface spins. Biocompatibilities of suspensions have been confirmed using HeLa cell lines and can be suitable for different bioapplications.

Synthesis and magnetic properties of Au-coated amorphous Fe 20Ni 80 nanoparticles

Gold-coated nanoparticles of Fe 20Ni 80 (permalloy) have been synthesized by a microemulsion process. The as-prepared samples consist of ∼5 nm diameter particles of amorphous Fe 20Ni 80 that are likely encapsulated in B 2O 3. One or more Fe 20Ni 80@B 2O 3 particles are subsequently encapsulated in 8–20 nm gold nanospheres, as determined by TEM and X-ray powder diffraction (XRD) line broadening. The gold shells were found to be under expansive strain. Magnetic data confirm the existence of a superparamagnetic phase with a blocking temperature, T B, of ∼33 K. The saturation magnetization, M S, of the as-prepared, Au-coated sample is ∼65 emu g −1 at 5 K and ∼16 emu g −1 at 300 K. The coercivity, H C, is ∼280 Oe at 5 K.

Plastic Deformation in the Sliding Wear Surfaces of Alumina at Various Temperatures

In order to investigate the sliding wear of alumina, direct observations by TEM and X-ray diffraction line broadening techniques are applied to the wear surfaces and debris particles after the sliding wear tests. of alumina from room temperature to 600degreesC, below the brittle to ductile transition temperature which occurs at approximately 700degreesC. X-ray diffraction of debris particles collected from the test at room temperature reveals heavy deformation within the particles. However, the TEM observations of the wear surface show only isolated dislocations which are mainly associated with grain boundaries, suggesting that the fracture may occur in a broader region than that undergoing the severe deformation. Lattice strain in debris particles estimated by X-ray diffraction line broadening decreases with an increase of the test temperature probably because recovery occurs in the particles by an annealing effect.

Structure of Multicomponent (Titania/Zirconia) Colloids

The structure of titania/zirconia colloids has been investigated using small-angle neutron scattering (SANS). The colloids were produced by: (i) hydrolysis of a mixture of titanium and zirconium alkoxides and peptization of the resulting hydrolyzate with nitric acid (homogeneous) and (ii) hydrolysis of a titanium alkoxide and peptization of the resulting hydrolyzate with aqueous zirconium(IV) nitrate solution (heterogeneous). The final titania/zirconia and metal oxide/nitrate mole ratios were 16.0 and 10.0, respectively. The sols were concentrated by evaporation, dried under controlled conditions and redispersed in D 2 O/H 2 O mixtures. FT-Raman spectra of the sols, and XRD powder patterns from the gels, showed that the material was crystalline anatase and amorphous zirconia. Both TEM and XRD line broadening indicate that the crystallite size of the dried titania gels is ∼8 nm. The results of SANS contrast variation experiments are described. The minimum-contrast points for the homogeneous and heterogeneous colloids, determined by two different methods, gave similar results which differed significantly from the expected value, due to the sorption of nitrate counterions and hydroxyl species on the surface of the colloids. In both systems, the scattering at minimum contrast was consistent with a network of unidimensional zirconia, with a typical diameter of ∼1.5 nm. At full contrast, the homogeneous colloids have fractal dimensions (d f of1.6) similar to those from static light scattering, that is, consistent with an open, extended, chainlike aggregate structure. However, the heterogeneous colloids have higher fractal dimensions (d f of 2.2-2.4), due to zirconia crystallites packing the interstices between the titania crystallites, that is, consistent with a loosely packed, spherical structure. The apparent fractal dimension of the heterogeneous colloids in H 2 O (d f of 2.4) is higher than that observed in D 2 O (d f of 2.2), whereas no such effect is observed for the homogeneous colloids. These results infer that, in the homogeneous colloids, the zirconia is segregated within the matrix of the titania crystallites (on the ∼1 nm scale), whereas, in the heterogeneous colloids, the zirconia is segregated on the surface of the titania crystallites (on the ∼10 nm scale).

UHF couplers for gas-insulated substations: a calibration technique

Methods that have been used to evaluate the performance of UHF couplers for partial discharge monitoring of gas-insulated substations are briefly reviewed, illustrating the need for a standard test procedure. A measurement scheme is proposed in which the coupler is mounted beneath an aperture in a ground plane and subjected to an incident electric field of known intensity. A TEM line is used to evaluate the technique, and a step excitation is shown to have advantages over swept frequency measurements. The frequency responses of two disc couplers and an external window coupler are measured to demonstrate the technique.

Characteristic impedance of a rectangular double-ridged TEM line

The characteristic impedance of a TEM transmission line, shaped as a double-ridged rectangular coaxial line, is analyzed in this paper as the customary transversal static problem. This type of transmission line is useful, for example, as a part of a cascaded transition between a double-ridged waveguide and a coaxial line. The solution of the transversal problem is achieved by dividing the cross-sectional region into distinct, separable regions, each one being characterized by closed-form Green's functions relating the flux function to the electric field. Surface-type integral equations are then formulated over the boundaries between the regions. Solution of these equations via the method of moments (MoM's) using the Galerkin choice yields the results for the characteristic impedance as a function of cross-sectional dimensions. Convergence of the solution is also studied.

Analysis of Interaction between RuO2and Glass by Growth of RuO2Particles in Glasses

Abstract The RuO2-glass interaction has been studied by analyzing the growth of RuO2 particles in glasses. The size of RuO2 particles was determined by TEM and X-ray line broadening. The RuO2/glass interfacial energy was evaluated by spreading and penetration experiments. Changes in size and shape of RuO2 particles indicated that coarsening proceeded by the diffusion-controlled dissolution-precipitation process. The growth rate of RuO2 particles at temperatures giving the same viscosity was dependent on the glass composition. Kinetics of the Ostwald ripening and values of glass surface energy implied that the solubility of RuO2 in glass is a critical factor. Results indicated that the solubility of RuO2 in glass decreases with increasing PbO content and with increasing SiO2 substitution for B2O3. Dissolution of Al2O3 from substrate retarded the Ostwald ripening.

The SIMTRON concept

A theory for a novel form of a high-frequency amplifier which is suitable for realization in a vacuum microelectronics structure is presented. The cathode is a linear array of field emitters or a linear ridge emitter. The RF structure is a coplanar waveguide (CPW) which may be fabricated by planar techniques. The CPW is a TEM transmission line, and the interaction may be regarded as an extended triode with spatial variation according to the wavelength; hence, the name SIMTRON (spatial injection modulation of the electrons). In the SIMTRON the parallel conductance per unit length of the TEM line is modified by the conductance of the electron beam in the interaction region. Because the beam conductance has a negative region in the neighborhood of a transit angle of one-and-a-quarter RF periods, amplification at that frequency range is possible. A numerical design example is presented for the SIMTRON. >

Chromium-for-iron substitution in synthetic goethites

Goethites containing up to about 10 mol% Cr were synthesized both from Fe(III) and Fe(II) systems. The structural incorporation of Cr was proven by a linear decrease in the unit cell edge lengths a, b and c and a corresponding decrease in the cell volume. Crystal size and morphology were also modified as seen from TEM and XRD line widths. The out-of-plane OH bending vibration increased from 793 to 800 cm −1 reflecting a shortening of the M-OH bond length. Cr was incorporated into hematite when a 10% Cr-goethite was heated to 900°C.

A Rigorous Solution for Dispersive Microstrip

Closed-form solutions are presented for the frequency-dependent characteristic impedance of microstrip as defined by the ratio of the electromagnetic power to the square of the electric current. The analysis uses the rigorous spectral-domain approach based on the charge-current formulation. Analytical expressions for the impedance solutions show that the frequency dispersion occurring in microstrip is characterized in terms of three different impedances. The characteristic impedance of a TEM line given in the limit as the frequency decreases is derived from one of these impedances, and the other two are involved in expressing the nature of dispersion to vanish in the limit. Conversely, as the frequency increases, these dispersive parts grow rapidly. Some comments are given in conjunction with previous works.

The Slotted Coax as a Beam Electrode

The slot-coupled TEM line has been employed at CERN as a pick-up electrode in the GHz range. It is a compact and broad band device and will prove itself commercially attractive once its coupling efficiency is competitive with an array of quarter wave loops. The slotted coupler presented in this paper is comprised of two tubes joined along their length. The bottom tube is the beam pipe and the top tube is the TEM line which picks up the electromagnetic energy from the beam particles. Energy is transferred from the beam to the TEM line through a series of slots which are mutual to the two tubes and which occur where the tubes are joined. In this device the signal voltages add in phase when the beam velocity matches the line velocity. The pick-up impedance can thus be large if the structure is long. It turns out, however, that the signal in the synchronous case is weaker than the signal obtained from an equal length array of loop couplers. In this paper the authors derive the response of the slotted line in a general non-synchronous case and explore the possible advantages of designing the coupler with reduced velocity to increasemore » the coupling efficiency. Other properties as well as a theoretical analysis of the TEM line are presented.« less

Slot Coupled Beam Signal Pickup Development at Argonne National Laboratory

The overall performance of slot couplers, at least for frequenciees below 2 GHz, can probably not match that of stripline based pickups. A measured, typical coupling at 2 GHz correesponds to about 6 to 7 ohms/slot-pair and produces about 8/sup 0/ phase shift/slot on the TEM line. Suppose a 12 to 14 slot array were constructed with these parameters. It would have a total 90/sup 0/ phase shift at about 1.7 GHz, and the coupling would be about 80 ohms at 2.0 GHz. Such an array would be 30 cm long. In a 10 m long straight section, one could place perhaps 25 such modules. After power adding, the net coupling would be about 80 x ..sqrt..25 = 400 ohms. This is 75% of the value which can be obtained by stripline structures (e.g. the FNAL Tevatron-I design). On the other hand, stripline structures may be difficult to construct for, let's say, a 4 to 8 GHz band. Slot coupled devices may then prove to be the more attractive choice. Slot couplers for these higher frequencies will be the subject of our R and D program at this time in the future.