Integrated Intensity Data Research Articles

Spectrometry studies of Ag implanted silicon carbide thin films for application as a diffusion barrier against transition metals

A diffusion kinetics study of implanted silver (Ag) ions into SiC films is conducted. SiC thin films have been processed on Si (1 0 0) substrates by electron beam deposition from a commercial high purity hot-pressed SiC sheet. The as-deposited films were thereafter implanted with Ag+ ions. Realtime Rutherford backscattering spectrometry experiments showed that Ag+ is stable until 600 °C, which is the highest temperature that the heater in the system used could achieve. Conventional RBS studies on isochronally annealed films at higher temperatures in the range between 650 °C and 950 °C reveal that there is no significant change in the spectra up to a temperature of ∼ 750 °C. At 850 °C a change in the Ag implantation profile was observed, suggesting that Ag is mobile at that temperature. The corresponding depth profile at 850 °C suggests that there is significant Ag in- diffusion, however the overall integrated intensity data indicate that most of the Ag+ is escaping out of the films. Upon annealing for one hour at 950 °C, all the Ag ions have essentially escaped out of the films and/or spread throughout the layer below the detection limit of RBS. Isothermal annealing studies over varied duration times at 850 °C confirm Ag in-diffusion, but at the same time there is evidence of depletion of Ag near-surface regions as the annealing time increases; the overall out-diffusion of the implanted metal, although steady, is found to be slow in an isothermal process. FTIR investigations point to a diffusion model through pores and grain boundaries.

Influence of Fe on Microstructure and Physical Properties of Cu90 – xFexPd10 Ternary Alloys with x = 5, 10, 15, and 20

The structural and physical properties of Cu90 – xFexPd10 ternary alloys with x = 5, 10, 15, and 20 are studied using X-ray diffraction, resistivity measurements, Vickers hardness tester, and tensile testing machine. The samples were prepared by using arc-melting furnace under an atmosphere of purified Argon. The integrated intensity data obtained from X-ray diffraction are used to determine microstructure and hence lattice parameter. The lattice parameter has shown a negative deviation from Vegard’s rule. The addition of Fe in Cu90 – xFexPd10 alloy improves the structure, and increases the electrical resistivity and the hardness of alloy. With the addition of Fe, the mechanical properties of alloy such as ultimate tensile strength, Young’s modulus, and elongation are decreasing, while the elastic limit is increasing.

Mag2Pol: a program for the analysis of spherical neutron polarimetry, flipping ratio and integrated intensity data

Mag2Pol is a graphical user interface program which is devoted to the treatment of data from polarized neutron diffractometers with spherical polarization analysis. Nuclear and magnetic structure models can be introduced using space-group symbols and individual symmetry operators, respectively, and viewed in an OpenGL widget. The program calculates nuclear/magnetic structure factors, flipping ratios and polarization matrices for magnetic Bragg reflections, taking into account structural twins and magnetic domains. Spherical neutron polarimetry data can be analyzed by refining a magnetic structure model including magnetic domain populations in a least-squares fit and can also be correlated with an integrated intensity data set in a joint refinement. Further features are the simultaneous refinement of nuclear and magnetic structures with integrated intensity data and the analysis of flipping ratios either with tabulated magnetic form factors or using a multipole expansion of the magnetization density.

The structure and thermal parameters of ordered Cu65Fe10Pd25 ternary alloy

Structural and thermal parameters have been studied in Cu65Fe10Pd25 alloy during order–disorder (O–D) transformation using differential scanning calorimetry (DSC) and high temperature X-ray diffraction (HTXRD). The results reveal that the Cu65Fe10Pd25 alloy undergoes an O–D transformation at Tc=797K. The alloy shows L12 type ordering below Tc and has disordered face centered cubic (fcc) structure above Tc. The lattice parameter shows a positive deviation from Vegard’s rule which may be related to the weakening of interatomic forces by the addition of Fe. The integrated intensity data obtained from the diffraction experiments was utilized to determine the coefficient of thermal expansion (α(T)), mean square amplitude of vibration (u2¯(T)) and Debye temperatures (ΘD) during the O–D transformation. The abrupt change in the value of lattice parameter and coefficient of thermal expansion at Tc shows that the nature of O–D transition is first order. These results have been discussed by comparing them to those for Cu3Pd alloy.

Characterization of particle dispersion and volume fraction in alumina-filled epoxy nanocomposites using photo-stimulated luminescence spectroscopy

A novel method is presented to validate the dispersion of α-alumina nanoparticles within a polymer matrix, as well as to create a calibration for filler particle volume fraction identification. Using photo-stimulated luminescence spectroscopy (PSLS), spectral information from α-alumina-filled epoxy nanocomposites consisting of varying volume fraction quantities of alumina nanoparticles was collected and analyzed. Surface contour maps of each nanocomposite were created by comparing integrated intensity data from the R1 curve of α-alumina throughout each specimen. These maps show satisfactory dispersion of alumina in the 5 and 25% volume fraction composites, whereas agglomerations were detected in various regions of the 38% nanocomposite, establishing the capability of this method to characterize photo-luminescent particle dispersion. This new approach also provides high spatial resolution, which can be used to determine the exact locations of voids, inclusions and/or agglomerations, while also predicting the volume percentage of photo-luminescent particle content within a specimen, lending itself as a quality control method in the manufacturing of these composites. Photo-stimulated luminescence spectra (PSLS) emission from alumina-filled epoxy nanocomposites consisting of varying volume fractions of alumina nanoparticles was collected and analyzed to characterize dispersion within the sample through intensity maps. The measurements are based on integrated intensity data from the R1 curve of α-alumina throughout each specimen. This novel method has potential as a quality control method to determine the location of voids, inclusions and/or agglomerations, while in addition predicting the volume percentage of particles within a specimen.

Critical behavior of three organosiloxane de Vries-type liquid crystals observed via thedielectric response

Dielectric measurements have been made on three organosiloxane liquid crystal compoundsexhibiting a smectic A (SmA) to smectic C* (SmC*) transition, the SmA phase being ofthe de Vries type. The electroclinic response of the molecules in the de Vries phase of thesecompounds exhibits a double-peak profile, and is thus different from the conventional chiralSmA phase, a feature explained on the basis of an antiferroelectric (AF) block model(Krishna Prasad et al 2009 Phys. Rev. Lett. 102 147802). The differential interactionsarising from the different molecular ends of these siloxane-based compounds, whichare the basis for the AF block model, can also be expected to enhance the layertranslational order. We present x-ray integrated intensity data that show a high (∼0.9) translational order in the SmA phase. Dielectric relaxation spectra bring out the fact thatthe magnitude of the soft mode relaxation parameters is dependent on the number ofsiloxane groups in the terminal part of the molecule. A range-shrinking analysis of thetemperature-dependent dielectric relaxation strength has been carried out, using apower-law expression. The characteristic exponent shows a systematic growth with rangeshrinking and reaches limiting values comparable to that predicted for the 2D Isinguniversality class.

The structure and physical properties of CuMPd 6 (M = Ti, V, Mn and Fe) ternary alloys

In situ X-ray diffraction and magnetic susceptibility measurements were performed to determine the structure, thermal and magnetic properties of the ternary alloys CuMPd 6 (M = Ti, V, Mn and Fe). The X-ray diffraction experiments of the polycrystalline specimens annealed at 1273 K have shown that a single phase (A1-type face-centered cubic (fcc) structure) is formed at this stoichiometric composition up to a temperature of 1178 K. The integrated intensity data obtained from the diffraction experiments were utilized to determine the lattice parameters, Debye temperatures ( Θ D), the mean linear thermal expansion (MLTE) and the coefficients of thermal expansion ( α( T)). The lattice parameters showed a positive deviation from the Vegard's law, whereas the Debye temperatures were found to be of the same order as for CuPd 3 alloy. The contribution of the static displacements to the temperature factors was found to be nearly zero for the four alloys. The linear thermal expansion follows the classical Grüneisen relationship in these alloys. The trend of magnetic properties in these alloys was observed to be similar to that for CuMPt 6 alloys (see text) i.e. paramagnetic – spin glass – ferromagnetic with the increasing atomic number of the metal M. The results have been discussed by comparing with those given in literature.

Determination of the magnetic structures of the field-induced phases ofHoMnO3

We have determined the magnetic structure of the field-induced phases of the multiferroic hexagonal manganite $\mathrm{Ho}\mathrm{Mn}{\mathrm{O}}_{3}$ by combining integrated intensity data, collected with unpolarized neutrons on a single crystal, with measurements of the polarization dependence of the intensities of the diffraction peaks from the same crystal. The present investigation shows that the magnetic structure of $\mathrm{Ho}\mathrm{Mn}{\mathrm{O}}_{3}$ changes, apparently nearly continuously, with increasing field from the zero field antiferromagnetic (AF1) phase $(P{6}_{3}^{\ensuremath{'}}c{m}^{\ensuremath{'}})$ to a ferromagnetic (F2) phase $(P{6}_{3}{c}^{\ensuremath{'}}{m}^{\ensuremath{'}})$ in which the triangular configuration of Mn moments in the (001) plane is maintained. There is also a significant variation with field in the ordered moments of Ho2 and Mn in the AF1 and F2 phases, respectively. We show that the structures of the field-induced phases cannot be determined completely from the integrated intensity measurements alone.

Higher order structural analysis of stereocomplex‐type poly(lactic acid) melt‐spun fibers

AbstractThe higher order structure of stereocomplex‐type poly(lactic acid) melt‐spun fibers of an equimolar blend of poly(L‐lactic acid) and poly(D‐lactic acid) was analyzed with wide‐angle X‐ray diffraction (WAXD) and birefringence measurements. Two different crystalline structures were observed in the fibers: α‐form homocrystals and stereocomplex crystals. The weight fractions of the two crystals were estimated with the WAXD integrated intensity data. The crystalline orientation factors were obtained from the WAXD measurements. Well‐oriented homocrystals formed during a drawing process at the crystallization temperature of the homocrystal. Drawing above this temperature caused the stereocomplex crystal to be formed. The crystalline orientation tended to be lower with increasing drawing temperatures. Through the combination of the intrinsic birefringence and the fractions of the α‐form homocrystals and stereocomplex crystals, the birefringence of the amorphous phase was evaluated. The amorphous birefringence stayed positive and decreased with increasing drawing temperature. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 218–228, 2007

X-ray diffraction study of the structure and thermal parameters of the ternary Au–Ag–Pd alloys

In situ X-ray diffraction experiments were performed on six samples of the ternary Au–Ag–Pd alloys (with A1 structure) having different compositions using a Cu-target. The integrated intensity data obtained in the temperature range of 373–1200 K was utilized to determine the lattice parameters and the thermal parameters like Einstein's temperatures ( Θ E), the mean-square amplitudes ( u 2 ¯ ( T ) ) and the coefficients of thermal expansion with a high accuracy. The lattice parameter showed a small negative deviation from the Vegard's rule. It is also found that the mean-square amplitudes are independent of the static displacements. The mean-square amplitudes of vibration and the linear thermal expansion follow the classical Grüneisen relationship in these alloys.

Crystal Structure Analysis Using High-Resolution Synchrotron Radiation Powder Diffraction Data.

Instrumentation and data analysis techniques for the crystal structure analysis using SR and laboratory X-ray powder diffraction data have been described. The SR powder diffractometer with the MDS has been developed, and it has been used for obtaining high-resolution powder diffraction intensity data at the PF in Tsukuba. The whole-powder-pattern decomposition method, incorporating the sophisticated profile function, has been developed, and integrated intensities of individual reflections could be extracted easily from complex powder patterns. The integrated intensity data sets thus obtained were used for solving crystal structures ab initio by direct methods and/or direct-space methods. At a final stage of crystal structure analysis of crystalline powder, structural parameters are refined by the Rietveld method. Accuracy of the refined structural parameters has been greatly improved by the introduction of the new weight function into the least-squares refinement. Developments of both the instrumentation and the analysis techniques operate complementarily in order to surmount the difficulty intrinsic in the powder diffraction method

Excess electrons in lithium–ethylamine solutions—density, electrical conductivity and EPR studies

The density, electrical conductivity and electron paramagnetic resonance (EPR) of the lithium–ethylamine system have been measured as a function of metal concentration and temperature. The obtained data have been discussed with emphasis on the comparison with those of alkali metal–ammonia or –methylamine solutions which have been well studied in view of the metal–nonmetal transition. Although lithium metal was dissolved into ethylamine up to 18–20 mol% metal, the observed conductivity was nonmetallic, dissimilar to the corresponding ammonia and methylamine systems. From the observed spectral linewidth of EPR it has been suggested that the hyperfine interaction with nitrogen nuclei is dominant in the electron spin–spin relaxation in the concentration range studied. The integrated intensity data of EPR have been analyzed in terms of the spin-pairing equilibrium of excess electrons in the solutions. It is concluded that excess electrons in Li–ethylamine solutions are more strongly localized than those in ammonia or methylamine solutions which exhibit electron delocalization with increasing metal concentration.

The forward and inverse models in time-resolved optical tomography imaging and their finite-element method solutions

Time-resolved optical computerized tomographic imaging has gained widespread attention in biomedical research recently because of its non-invasiveness and non-destructiveness to biological and several attempts, aimed at implementing a practical system, have been made for eliminating the obstacles arising from multiple light scattering of biological tissue. In this paper the basic principle of time-resolved optical absorption and scattering tomography is first presented. The diffusion approximation-based photon transport model in a highly scattering tissue, which offers an advantage in speed in comparison vath other stochastic models, and the procedure for solving this forward model by using the finite-element method (FEM) are then accessed. Theoretically, a commonly used iterative steepest descent algorithm for solving the inverse problem is introduced based on the FEM solution of Jacobian of the forward operator. Owing to the ill-posed Jacobian matrix of the forward operator caused by scatter-dominated photon propagation and unavoidable influence of the noise from the measurement process, a Tikhonov–Miller regularization method is applied to the inverse problem in order to provide an acceptable approximation to its solution. A universal strategy for the FEM solution to the optical tomography problem several numerically simulated images of absorbers and scatters embedded in a homogeneous tissue sample are reconstructed from either mean-time-of-flight or integrated intensity data for the verification of the approach.

Low-field EPR study of the metal–non-metal transition in sodium–ammonia solutions

Solutions of alkali metals in liquid ammonia show a metal–non-metal (MNM) transition at about 4 mol% metal (MPM). In this paper, we present the results of electron paramagnetic resonance (EPR) studies of sodium–ammonia solutions at 200 MHz as a function of temperature and metal concentration. It has been suggested that the transverse spin relaxation rate consists of two contributions: a hyperfine interaction with 14N nuclei, which is dominant at lower metal concentrations, and a spin–orbit interaction, dominant at higher metal concentrations. The cross-over occurs around 1.5 MPM, a little below the bulk MNM transition point of 4 MPM. From the integrated intensity data of EPR we have examined the spin-pairing equilibrium of excess electrons in the solutions.

On the determination of the Debye-Waller factor and structure factors of NiAl by X-ray powder diffraction

A conventional powder X-ray diffraction experiment was performed on close-to stoichiometric β-NiAl (B2 structure) using a Cu target. From the integrated intensity data the lattice parameters and room temperature Debye-Waller factors of β-NiAl were determined. During the analysis of the integrated intensities, great care was taken to ensure proper treatment of extinction which was found to depend on the mosaic crystal size rather than the powder particle size. Other factors such as dispersion, thermal diffuse scattering and preferred orientation were found to have less of an effect on the integrated intensity analysis. As a result of this improved analytical procedure, Debye-Waller factors for β-NiAl were determined which are in close agreement with the accurate values obtained by single crystal X-ray and electron diffraction. This is in contrast with previous powder X-ray diffraction work on β-NiAl, where poor values of the Debye-Waller factor were usually obtained due to the failure to correct for extinction. The effects of bonding in the solid state were also examined and it was found that the use of accurate crystal structure factors for β-NiAl in the analysis as opposed to those calculated from free atom scattering factors had no significant effect on the experimental Debye-Waller factor values.

Structure of a high-pressure polymorph of Mg3BN3 determined from X-ray powder data

The crystal structure of magnesium boron nitride in a high-pressure phase, Mg 3 NB 3 (H), has been determined from X-ray powder diffraction data. The strategy used was: powder pattern indexing, extraction of integrated intensity data by peak decomposition, Patterson function calculation, trial-and-error model building and Rietveld refinement. The cell is orthorhombic (space group Pmmm, Z=1) with a=3.0933 (2), b=3.1336 (2) and c=7.7005 (5) A. The structure contains linear NBN groups with an observed B-N interatomic distance of 1.34 A which is 2% shorter than in the low-pressure form of the material, Mg 3 BN 3 (L)

Tetragonal and cubic crystal structures of some binary and ternary metal dicarbides in the series Ce-Er, Ce-Lu, U-La, and U-Ce

The binary dicarbides LaC 2 and ErC 2 (tetragonal, space group I4/ mmm, Z = 2) and the ternary dicarbides Ce 0.50Er 0.50C 2, Ce 0.75Lu 0.25C 2, Ce 0.50Lu 0.50C 2, Ce 0.25Lu 0.75C 2, U 0.75La 0.25C 2, U 0.50La 0.50C 2, U 0.25La 0.75C 2, U 0.75Ce 0.25C 2, U 0.50Ce 0.50C 2, and U 0.25Ce 0.75C 2 (cubic, space group Fm3 m, Z = 4) have been prepared by arc melting, and their metal compositions confirmed by point energy dispersion X-ray analysis by scanning electron microscopy. Their neutron powder diffraction patterns have been recorded at room temperature and, for the three Ce-Lu compounds, also at 4.2 K (at which temperature the cubic structure is retained). For LaC 2 and ErC 2, mild hydrolysis indicates the presence of acetylide units, and Rietveld profile analysis of the neutron data has enabled the unit-cell dimensions ( a, c = 3.937(1), 6.579(2) Å and 3.622(1), 6.106(1) Å, respectively) and the C-C bond lengths (1.284(6) and 1.275(3)Å, respectively) to be refined. For the ternary compounds (some of which contain two face-centered cubic (f.c.c.) phases), the distinctive martensitic microstructure is absent from micrographs, and the limited neutron integrated intensity data appear to be consistent with f.c.c. structures having either static or rotating C-C groups.

A comparison of some adjustment techniques for use with quantitative spot data from two‐dimensional gels

AbstractQuantitative analysis of polypeptide differences among sets of identically prepared two‐dimensional polyacrylamide gels is facilitated by the use of mathematical transformations of the spot integrated intensity data for each gel in order to make comparisons. Such adjustments are needed because technical factors cause the stained polypeptide spots displayed on a particular gel to simultaneously appear darker or lighter than on another gel. We have compared three different adjustment schemes by applying each to the same set of data and testing to determine which gives smaller coefficients of variation for a large battery of spots. The adjustment that gave the best results is one based on regressing the spot integrated intensities of a standard gel versus each “target” gel and using the fitted line to transform the spot integrated intensities on the target gel. This adjustment is intuitive, easy to compute, and performed well regardless of whether the spots with large variability were included in the data or not.

Magnetic stirrer for diamond-anvil cells

A continuing problem in the performance of high-pressure X-ray diffraction experiments with a diamond-anvil cell is that of interpreting the integrated intensity data. Two primary causes of this are the relatively small number of crystallites in the pressure cavity and possible preferred orientation effects. An electromagnetic attachment has been designed and fabricated to provide a set of three orthogonal, time-varying magnetic fields at the pressure cavity. These are used to continually stir the contents of the pressure chamber when a hydraulic fluid is used. Integrated intensity data taken with this system using a synchrotron radiation source and energy dispersive detection techniques are presented.

Energy dispersive spectroscopy using synchrotron radiation: Intensity considerations

Detailed considerations are given to the reliability of energy dependent integrated intensity data collected from the pressure cavity of a diamond-anvil pressure cell illuminated with heterochromatic radiation from a synchrotron storage ring. It is demonstrated that, at least in one run, the electron beam current cannot be used to correct for energy-intensity variations of the incident beam. Rather, there appears to be an additional linear relationship between the decay of the synchrotron beam and the magnitude of the background intensity.