Sulphophosphate melts of the type SO3-P2O5-EO-A(2)O (E={Zn2+, Ca2+, Sr2+, Ba2+, Mg2+, Mn2+}; A={Li+, Na+, K+}) enable fabrication of surprisingly stable ionic glasses. Depending on the P/S ratio, their structure may be characterized by chemical heterogeneity on short length scales, where different cations cluster in the vicinity of different anions. To evaluate the topological origin and the kinetics of phase separation and crystallisation, in situ small angle x-ray scattering, transmission electron microscopy, laboratory x-ray diffraction and calorimetric analyses were employed. Volume crystallisation occurs in a two-step process of microscopic phase separation and diffusion-controlled two-dimensional growth of sulphate phases. The crystallisation mechanism depends largely on SO3 content and appears to be directly related to the topological heterogeneity of the precursor melt.

We report on Brillouin and in situ small angle X-ray scattering (SAXS) analyses of topological heterogeneity in compressed sodium borosilicate glasses. SAXS intensity extrapolated to very low angular regimes, I(q = 0), is related to compressibility. From Brillouin scattering and analyses of the elastic properties of the glass, the Landau-Placzek ratio is determined and taken as a direct reflection of the amplitude of frozen-in density fluctuations. It is demonstrated that with increasing fictive pressure, topological (mid- and long-range) homogeneity of the glass increases significantly. Heating and cooling as well as isothermal scans were performed to follow the evolution of density fluctuations upon pressure recovery. For a sample with a fictive pressure p(f) of 470 MPa, complete recovery to p(f) = 0.1 MPa was observed to occur close to the glass transition temperature. The values of fictive and apparent fictive temperature, respectively, as obtained via the intersection method from plots of I(q = 0) vs. temperature were found in good agreement with previous calorimetric analyses. Isothermal scans suggest that mid- and long-range recovery govern macroscopic density relaxation.

Structural properties deduced from Fourier Transform Infrared spectroscopy, ellipsometric porosimetry (EP), X-ray reflectivity and grazing incidence small-angle X-ray scattering (GISAXS) are correlated with dielectric and mechanical properties of Ultra Low k layers prepared by spin coating. Different sacrificial polymers were used as porogens and different porogen loadings were tested. After crosslinking and porogen removal by thermal treatment, the GISAXS images indicate a fairly isotropic distribution, with a slight in-plane correlation of the pores. Dielectrics having the same dielectric constant close to 2.2, have almost the same pore volume fraction ~40%, but the azimuthally averaged GISAXS profiles display porogen-dependent shapes, leading to different sizes and inter-pore correlations. For a given porogen, the increase of the volume fraction from ~10% to ~50% causes k to decrease from 2.7 to 1.9, with a slight increase in the pore size. Thermal curing, supplemented or not by UV illumination, hardly changes the porous structure, as observed by EP and GISAXS. Finally, the influence of the pore size on the elastic properties appears to be weak in the range studied (2.5–10 nm), while changes in the mechanical properties are governed mainly by the pore volume fraction and skeleton cross-linking.

This paper focuses on the structure of nanoporous SiOCH thin films deposited using a porogen approach by plasma enhanced chemical vapor deposition (PECVD). The grazing incidence small angle x-ray scattering signal demonstrates the existence of a biphase pattern in hybrid films, deposited by PECVD. After porogen removal, there are few differences between pore pattern of optimized ultraviolet (UV) illuminated and thermally treated samples: anisotropy of the pore pattern is observed in both samples, probably due to the porogen degradation. Finally, a kinetic study of porogen degradation by UV shows that the porous structure develops in only a few minutes.

The structural and magnetic properties of 3-nm-thick CoPt alloys grown on WSe2(0001) at various temperature are investigated. Deposition at room temperature leads to the formation of a chemically disordered fcc CoPt alloy with [111] orientation. Growth at elevated temperatures induces L10 chemical order starting at 470K accompanied with an increase in grain size and a change in grain morphology. As a consequence of the [111] growth direction, the CoPt grains can adopt one of the three possible variants of the L10 phase with tetragonal c-axis tilted from the normal to the film plane direction at 54°. The average long-range order parameter is found to be 0.35(±0.05) and does not change with the increase in the deposition temperature from 570 to 730K. This behavior might be related to Se segregation towards the growing facets and surface disorder effects promoted by a high surface-to-volume ratio. Magnetic studies reveal a superparamagnetic behavior for the films grown at 570 and 730K in agreement with the film morphology and degree of chemical order. The measurements at 10K reveal the orientation of the easy axis of the magnetization lying basically in the film plane.

Density and concentration fluctuations have been investigated in a 3mol% GeO2 doped silica glass as a function of the fictive temperature (the temperature at which the structure of the supercooled liquid has been frozen-in to form the glass) by small angle x-ray scattering measurements. The fluctuations increase in a way is quite similar to that observed for pure silica glass as a result of density fluctuation fictive temperature dependence. Fluctuations have also been studied in glasses containing different amounts of GeO2 up to 21mol% GeO2. The fluctuations are shown to increase very strongly with germanium amount as a result of strong concentration fluctuation increase. This observation is in agreement with already observed excess losses in light scattering measurements.

This paper is focused on nanoporous methylsilsesquioxane deposited using a polymer approach and shows the complementarities of three experimental techniques: ellipsometric porosimetry (EP), X-ray reflectivity (XRR), and grazing incidence small-angle X-ray scattering (GISAXS). XRR and EP confirm that the pore volume fraction is larger for smaller dielectric constants. EP and GISAXS find mean pore sizes independent of the porosity, in the range 3–4 nm as diameter. GISAXS is the only technique that can estimate the porosity isotropy. Finally, the impact of integration processes such as surface plasma treatment, etching or stripping on the porosity is evaluated: the porosity remains unchanged except in the superficial layer where an increase of the pore size (or of the roughness) is observed.

The fictive temperature of vitreous silica containing approximately 900wtppm of hydroxyl groups was monitored with small angle x-ray scattering. The measurements were carried out during annealing and while scanning the temperature, with annealing temperatures ranging between 930 and 1330K. Fitting the data to the Adam-Gibbs-Fulcher equation by using the Tool-Narayanaswamy method yields a particularly simple thermorheological behavior for type-III vitreous silica. Unlike the general case for glass kinetics, including vitreous silica with low hydroxyl content, the relaxation time constant is nearly decoupled from the fictive temperature. This high degree of decoupling of the state of the glass and the relaxation rate agrees with the results of viscosity measurements. By improving the data analysis procedure, we have significantly increased the precision of the results, and it was possible to resolve changes of the activation energy of the relaxation processes to within 0.5%. This has made sample aging effects that had previously been undetectable visible.

Porous ultralow-k films are required by the microelectronics industry as interlayer dielectrics for 65 nm technologies and below. These porous insulating films can be deposited by plasma-enhanced chemical vapor deposition using a porogen approach. It consists of the codeposition of a matrix precursor and a sacrificial organic porogen, and then on a post-treatment to remove the organic porogen phase and create porosity in the film. In this work, an e-beam assisted thermal curing was compared to an ultraviolet-assisted thermal curing. Basic film properties such as k, film shrinkage, porosity, pore size, and pore size distribution were evaluated. NMR and Fourier transform infrared analyses were used to study the chemical modifications induced by the post-treatment. These analyses show that the post-treatment impact depends on the radiation used. Both treatments lead to a removal of terminal nonbridging bonds such as Si-OH, Si-H, and Si-CH3 and can contribute to a subsequent formation of Si-O-Si crosslinks. Both treatments remove methyls from Si-CH3, but the e-beam induces a Si-H bond increase while the UV bulb used decreases the Si-H contribution. The cross-linking improvement induces an increase of Young's modulus, the elastic properties being mainly correlated to the Si-O-Si volumic bond concentration in the film. (c) 2007 The Electrochemical Society.

The formation and growth of defects, including nanocavities and extended interstitial-type defects, created by helium implantation in silicon (50keV, 7.1015cm−2) in the temperature range of 100–550°C has been investigated by grazing incidence small-angle x-ray scattering. We show that quantitative information can be obtained on the size distribution, shape dispersion (i.e., anisotropy and faceting versus the size), and depth profile of the nanocavities from the near surface to deeply buried regions up to 1μm. It is thus demonstrated that low temperature implantations (⩽200°C) lead to the formation of spherical nanocavities with a heterogeneous depth distribution whereas implantations at high temperatures (⩾300°C) cause growth of the cavities, broadening of the size distribution, and size-dependent faceting leading to a size-dependent shape anisotropy. Furthermore, we show that the method allows to characterize the morphology (i.e., width and thickness) and the evolution of extended planar {113} defects created during the implantation process at high temperatures.

Abstract The coherent unmixing kinetics of various Al-Zn and Al-Ag-Zn alloys are analysed in terms of nucleation and spinodal models. For large solid-solution supersaturations, as obtained for deep quenches below the miscibility gap, the main feature is a scaling of the structure function of the alloys in the asymptotic or coarsening stage. The scaling function appears to be only slightly dependent on the supersaturation, in agreement with the kinetic Ising model and the two-phase model of Rikvold and Gunton. The scale length is the second-phase particle size, which generally varies with time as t 1/3. However, the kinetics appear to be more rapid than would occur in a simple Lifshitz-Slyozov process, and the possible reasons for this discrepancy are discussed in detail. For small supersaturations or shallow quenches the time variations of the particle size and number density, plotted in reduced units, compare favourably with the Langer-Schwartz theory for nucleation in off-critical fluid mixtures. The va...

The temperature dependence of the x-ray scattering in the region below the first sharp diffraction peak was measured for silica glasses with low and high OH content (GE-124 and Corning 7980). Data were obtained upon scanning the temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements resolve, for the first time, the hysteresis between heating and cooling through the glass transition for silica glass, and the data have a better signal to noise ratio than previous light scattering and differential thermal analysis data. For the glass with the higher hydroxyl concentration the glass transition is broader and at a lower temperature. Fits of the data to the Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very strong glass. The temperature derivative of the observed X-ray scattering matches that of light scattering to within 14

In this paper, small-angle x-ray scattering measurements are used to determine the different compressibility contributions, as well as the isothermal compressibility chi(T)(0) in thermal equilibrium in silica glasses having different thermal histories. Using two different methods of analysis, in the supercooled liquid and in the glassy state, we obtain, respectively, the temperature and fictive temperature dependences of chi(T)(0). The values obtained in the glass and supercooled liquid states are very close to each other. They agree with previous determinations of the literature. The compressibility in the glass state slightly decreases with increasing fictive temperature. The relaxational part of the compressibility is also calculated and compared to previous determinations. We discussed the small differences between the different determinations.

Single crystals of different Cu–Ni–Co and Cu–Ni–Fe alloys, forming spheroid or plate-like precipitates during decomposition, have been studied by small-angle (SAXS) and wide-angle X-ray scattering (WAXS). The SAXS patterns gave information on the sizes and the organization of the precipitates, while the scattering near Bragg peaks allowed a determination of the distortions of the lattice created by these precipitates. The variations of the SAXS spectra with the atomic scattering factors of Co (or Fe) and Ni were used to determine the composition variation between matrix and precipitates ( i.e. the `chemical' term), while those of the WAXS spectra enabled the determination of the displacements in the matrix and in the precipitates. The precipitates were found to be enriched in respectively Co and Ni, or Fe and Ni, inducing a local contraction of the lattice, while the matrix (mainly Cu) was of course depleted in the same elements, and its lattice was dilated. These precipitates are piled up along one of the three 〈100〉 `soft' directions. The variations of the deformation field with the precipitate sizes (along both directions parallel and orthogonal to the pile-up orientation), and with the distance between precipitates have been determined. From the knowledge of such variations, it was possible to modify the respective deformation fields in such a way that the respective precipitates have the same sizes, but with a different geometry, and then to isolate what was induced solely by the geometry of a precipitate. Moreover, these experiments yielded the determination of the secondary components of the displacement field (displacements orthogonal to the pile-up direction), which were found to be weak compared with the primary one (parallel to the same direction). Finally, from the variation of the aspect ratio of the precipitates with the aging duration, it was possible to estimate the surface energy of the precipitates, and a comparison between SAXS and WAXS results shows the applicability of this new approach to the decomposition process.

We report on the growth of alloys ( CrPt 3 , VPt 3 , FePt) on the (0 0 0 1) surface of the layered compound WSe 2 , by co-deposition of 3d-metal and Pt atoms under ultra-high vacuum conditions. Because of weak interactions with the Se hexagonal dense planes and the strong lattice mismatch, the adatoms self-assemble and form epitaxial 3D nanostructures, which adopt lattice parameters very close to those of bulk phases. This type of growth is called quasi-van der Waals epitaxy and would allow the fabrication of nanostructured media of potential interest for magnetic recording technology. The structure and morphology of the nanostructures were studied by reflection high-energy electron diffraction, scanning tunnelling microscope and grazing incidence small angle X-ray scattering. These first results suggest that both the type of long-range chemical ordering ( L 1 2 or L 1 0 ) and the elastic properties of alloys play a role in the final morphology of nanostructures.

X-ray intensity fluctuation spectroscopy has been used to examine the coarsening kinetics in the classic long-period superlattice Cu-Pd alloy. The evolution of the speckle intensity was examined near the centers of both a superlattice peak (associated with local L1(2) order) and a satellite peak (associated with one-dimensional antiphase correlations). The decay of the two-time correlation function C(t(1),t(2),q) was independent of the direction examined and was similar for the superlattice and satellite peaks. In agreement with published Langevin theory and simulations, the decay time tau of the two-time correlation function increases linearly with average time t(m)=(t(1)+t(2))/2. It is relatively independent of the wave vector near the peak centers. However, tau increases much more slowly with increasing t(m) than is expected.

After the exploratory studies of the 1980s, anomalous small-angle X-ray scattering (ASAXS) is now a mature technique to disentangle complex subjects in materials science: this is illustrated through selected examples.