This paper presents the results of the analytical study of the microstructural evolution of forged and rolled rings with a diameter greater than 2 meters, since the raw material, set-up forgings, ring rolling and heat treatments, including normalizing, quenching and tempering. Also, great care will be taken on the chemical micro-segregation. Four rings, were instrumented with 20 thermocouples each one in order to follow the thermal profile during heating and quenching. Cooling rates will be used to predict the microstructure developed under the different heat treatments and it will be compared at different positions inside the rings. It can be seen that the cooling curves obtained show no presence of soft phases, as shown in the microstructures in the figure shown below. With the results of microstructure obtained, which show martensitic structure to a greater extent, it meets the desirable mechanical properties, which are shown below.

Deep-level densities of p-GaAs1−xBix and at the GaAs/p-GaAs1−xBix heterointerface have been shown to be sufficiently low for device applications based on the results of deep-level transient spectroscopy, isothermal capacitance transient spectroscopy and admittance spectroscopy. Although the metastable alloy of GaAs1−xBix is grown by molecular beam epitaxy at low temperature (370 °C), the deep-level density of p-GaAs1−xBix is suppressed such that it is on the order of 1015 cm−3. The state density at the heterointerface was determined to be 8 · 1011 cm−2eV−1, which is comparable to other III–V heterointerfaces formed at high temperatures. The surfactant-like effect of Bi is believed to prevent defect formation during low-temperature growth.

Optical fibers have been successfully used in long-haul communication, endoscopy, and other optical systems to transmit optical power as well as information from one point to another, serving as interconnects at various scales. In integrated sensor systems, optical fibers have been frequently employed to connect the source and the detector, due to their flexibility, compactness, and low loss. However, optical fibers can provide more functions than a simple transmission channel. In this paper, we review our work on optical fibers as a platform for molecular sensors based on Raman spectroscopy (RS) and surface enhanced Raman scattering (SERS). The fibers serve to significantly increase the sensitivity of RS/SERS and to facilitate the integration of a compact sensor system. We will discuss the principles of operation of various building blocks, demonstrate our recent results, and highlight some potential applications.

Clays were used intensively in cultural heritage’s monuments and objects. Conservation procedures can be performed specifically for earthen materials using stabilized clays, considering that the aesthetic features must be preserved in order to avoid drastic differences and the lost of their patrimonial value.

This work presents the study of the mechanical behavior of clay stabilized with different materials following the norm ASTM D 6276 – 99a, for lime stabilization. The effects of other stabilizers on the clay were studied as well. For these purposes, lime, gypsum, Portland cement (type II), sodium hydroxide, and dehydrated cactus fibers of white cactus opuntia in concentrations of 2, 4, 6, 8 and 10 wt% were added to a clay from Morelia region.

Atterberg limits were determined to calculate the linear and volumetric stabilization. The best volumetric stabilization values were chosen to prepare samples to measure the mechanical behavior under compression, tension and flexion strengths. Colorimetric measurements were also performed on the stabilized clays to determine the best preparation with the most suitable aesthetic qualities to perform conservation treatments on monuments and cultural heritage constructions made with earthen materials.

The highest values for compression were observed for gypsum and mucilage additions while the highest tension was obtained for mucilage ones. Gypsum addition had the bigger rupture module under flexion. On the other hand, the color of the stabilized clay is closer to the original clay color for cement, lime and mucilage preparations.

Knowledge of the mechanical and petrographic properties of limestone rocks is an important issue to different areas of science and engineering. Sedimentary limestone rock is one of the most abundant materials in the Peninsula of Yucatán used for decorative and building construction. This work studies the petrographic, mineralogical, and physical properties of three different types of limestone slabs of the state of Yucatán.

A bottom-up approach for poly(vinyl alcohol) (PVA) - graphene oxide (GO) nanocomposites using a spraying method is presented. Very simple and versatile, spraying allows to build-up uniform layered composite films with good control on the structure of each layer. 150 bi-layers were deposited to create a transparent film with improved mechanical properties at a loading of 5.4 wt.% GO. The Young’s modulus and strength of these films doubled or nearly doubled which is believed to be due to a synergic effect as a result of the nanoscale organization of the composite by the 2D nanofiller, and hydrogen bonding between the PVA and the GO.

Hafnium dioxide gate dielectrics, prepared by DC magnetron with low-power sputtering deposition followed by a low-temperature thermal oxidation, show greatly improved interfacial and electrical properties. Ellipsometry and X-ray photoelectron spectroscopy (XPS) measurements show a good stoichiometric HfO2 thin films with a refractive index of 1.9 and an Hf:O ratio of 1:2. The results obtained after analysis, quantification and calculation through XPS depth profile method, angle resolved XPS and interface modeling by XPS data processing software suggest a development of a complex three layer dielectric stack, including hafnium dioxide layer, a narrow interface of hafnium silicate and broad region of oxygen diffusion into silicon wafer. The measured dielectric constant of the HfO2 was about 22. The film band-gap was found to be ∼ 5.2 eV.

Unzipping carbon nanotubes (CNTs) is considered one of the most promising approaches for the controlled and large-scale production of graphene nanoribbons (GNR). These structures are considered of great importance for the development of nanoelectronics because of its dimensions and intrinsic nonzero band gap value. Despite many years of investigations some details on the dynamics of the CNT fracture/unzipping processes remain unclear. In this work we have investigated some of these process through molecular dynamics simulations using reactive force fields (ReaxFF), as implemented in the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code. We considered multi-walled CNTs of different dimensions and chiralities and under induced mechanical stretching. Our preliminary results show that the unzipping mechanisms are highly dependent on CNT chirality. Well-defined and distinct fracture patterns were observed for the different chiralities. Armchair CNTs favor the creation of GNRs with well-defined armchair edges, while zigzag and chiral ones produce GNRs with less defined and defective edges.

Rotary atomization was used to synthesize spheres of CaSi2-based compositions in order to understand issues relative to primer performance for military applications. Elemental silicon and calcium were used to synthesize the line compound CaSi2 or the eutectic composition between CaSi2 and Si. Fe was added to form FeSi2 as a secondary phase in selected compositions. Rietveld analysis showed that CaSi2 polytypes in the synthesized materials consisted primarily of 6R, with less 3R and some hexagonal material. Synthesized materials had low surface areas (≈0.1 m2/g), but short milling times increased the surface area by an order of magnitude. Peak pressures, pressure rise time, and ignition voltage showed no significant differences between experimentally prepared samples and existing commercial samples. Stoichiometric CaSi2 performed as well as CaSi2-Si or CaSi2-FeSi2-Si mixtures. The military specification for calcium disilicide should be changed to reflect the broad chemistry which can be used for primer performance.

Magnetoelectric (ME) (CoFe2O4)0.3-(BaTiO3)0.7 (CFO-BTO) nanostructures have been synthesized by a combinative using of hydrothermal reaction and polymer-assisted deposition. The feather-like nanostructures have an average diameter of 250nm and lengths up to 5μm, with the single-crystal CFO nanopillars embedded in the BTO matrix. The CFO-BTO nanostructures exhibit good magnetic (Ms=21.0emu/g, Mr=10.4emu/g and Hc=560.7Oe) and ferroelectric properties (Ps=10.5μC/cm2, Pr=5.6μC/cm2), as well as a large ME coefficient of 51.8mV/cmOe. A prominent phonon abnormality has also been detected between 110°C and 140°C. With emphasis on the novel microstructure, the ME response and phonon abnormality of the CFO-BTO nanostructures have been discussed.

In the present work modified titanium dioxide products are prepared. The influence of introduced modifiers (phosphorus, potassium, aluminium, and tin) on the photoactivity, optical properties, and phase composition of titanium dioxide is studied. The molar contents of P2O5, K2O, Al2O3, and SnO2 in relation to TiO2 are 0.10, 0.18, 0.24, and 0.08-1.32 mol%, respectively. The research is aimed at obtaining the pigmentary rutile TiO2 with the highest possible photostability and improved optical properties.

The nickel-aluminum (Ni/Al) intermetallic system is useful for a variety of reactive material applications, and reaction characteristics are well studied at the normal self-heating rates of 103–106 K/s. Recent experiments at 1011–1012 K/s have measured the kinetic energy of material ejected from the reaction zone, indicating additional kinetic energy from the reactive system despite high heating rates. In order to better probe reaction phenomena at these time scales, and determine the presence of expected elements and their temperatures, we report on emission spectroscopy of electrically heated, patterned Ni/Al bridge wires, time resolved over 350 ns through the use of a streak camera. Unlike previous studies where emission was dominated by Ar and N from residual gasses in the vacuum test chamber, here we report on experiments with encapsulated laminates allowing better quantification of Al and Ni emission. We were able to identify all major spectral lines from the dominant elements present in the films, and found the multilayered Ni/Al laminates to exhibit a brighter and longer duration emission than either Al or Ni control samples. We also found the measured electrical energy absorption of the Ni/Al laminates to follow that of the Al samples up to 150 ns following the onset of emission, indicating that the exothermic mixing of vapor phase Ni and Al was the most likely source for the higher emission intensity. These results will be important for new, energetically enhanced, high efficiency bridge wire applications, where shock initiation of subsequent energetic reactions may be accomplished with less electrical energy than is currently required.

Indium oxide doped with tin oxide, or ITO, has been widely used as an electrode material for flat panel displays. However, the rare metal in ITO is a limited natural resource. We succeeded in developing a material composed solely of elements with abundant reserves. We present the results of analyzing the electronic structure of an Mg-based compound based on its electrical conductivity. Mg-C thin films were prepared by sputtering method. A new transparent and electrically conductive material, Mg(OH)2-C, was formed after reacting the Mg-C film with moisture in air. On average, its transmittance of visible light was 90%. The mechanism for the effect of carbon on the electrical conductivity of Mg(OH)2 was examined on the basis of XPS spectra and DV-Xa molecular orbital calculations. The value of the band gap shows that Mg(OH)2 is an insulator. It was revealed that a new orbital appears when the number of substituting carbon atoms increases in the Mg(OH)2 lattice. It was possible to measure the new orbital that consisted of C-2s and C-2p. In addition, a comparison between the calculated electronic state around the valence band and the result measured by XPS of the obtained film reveals that they are in extremely close agreement.

Capillary type underfill is still the mainstream underfill for mass production flip chip applications. Flip chip packages are migrating to ultra low-k, Pb-free, 3D and fine pitch packages. Underfill selection is becoming more critical. This paper discusses the performance and potential of underfills using a novel organic-inorganic hybrid polymer technology.

Compared to eutectic and high lead solder, tin-silver-copper solder has lower C.T.E., higher elasticity and greater brittleness. In light of these properties, it is generally better to select high Tg and lower CTE underfill in order to prevent bump fatigue during reliability testing. Given the brittleness of low-k dielectric layers of flip chips, the destruction of low-k layers by stress inside the flip chip packages has become a major issue. Underfills for low-k packages should have low stress, and the warpage should be small. It is expected that as the low-k trend expands, the underfill is required to provide less stress. Low Tg underfill shows lower warpage. New chemical technologies have been developed to address the needs of underfills for low-k/Pb-free flip chip packages, specifically organic-inorganic hybrid polymer compounds. The organic-inorganic hybrid polymer provides excellent cure properties which enable a balanced combination of low stress and good bump protection. The material properties of the underfill were characterized using Differential Scanning Calorimetry (DSC), Thermo-Mechanical Analysis (TMA), and Dynamic Mechanical Analysis (DMA). A daisy-chained test vehicle was used for reliability testing. A detailed study is presented on the underfill properties, reliability data, as well as finite element modeling results.

Novel nanocomposite materials where titanium dioxide nanoparticles were inserted into the walls of a macroporous activated carbon were produced and their efficiency for the removal of As(III) from water was compared with pure activated carbon and titanium dioxide nanoparticles. The nanocomposites were synthesized with different molar ratios by using sol-gel method and were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The nanocomposite system showed excellent capability for the removal of As(III) ions from water by considering feasibility, efficiency and cost. The maximum As(III) removal percentages were ∼4.7% at pH 8 for activated carbon, ∼38 % for titanium dioxide at pH 6, and ∼98 % at pH 7 for activated carbon/titanium dioxide (AC/TiO2) nanocomposite, respectively. According to kinetic sorption data, the higher regression coefficients (R2) were obtained after the application of pseudo-second order to the experimental adsorption data for all adsorbent materials. The equilibrium data were modeled with the help of Langmuir and Freundlich equations. Overall, the data are well fitted with both the models, with a slight advantage for Langmuir model. The maximum arsenic uptake (qmax) value computed from slope of the linearized Langmuir plot was 26.62 mg/g for the adsorption of As(III) onto AC/TiO2 nanocomposite.

The National Atomic Energy Commission of the Argentine Republic is developing a nuclear waste disposal management programme that contemplates the design and construction of a facility for the final disposal of intermediate-level radioactive wastes. The repository is based on the use of multiple, independent and redundant barriers. The major components are made in reinforced concrete so, the durability of these structures is an important aspect for the facility integrity. This work presents an investigation performed on a reinforced concrete specifically designed for this purpose, to predict the service life of the intermediate level radioactive waste disposal facility from data obtained with several techniques. Results obtained with corrosion sensors embedded in a concrete prototype are also included. The information obtained will be used for the final design of the facility in order to guarantee a service life more or equal than the foreseen durability for this type of facilities.

Combinatorial sputtering is one of the useful methods that can be used to search for optimal composition of alloy materials or for new alloy materials. To search materials more efficiently, it is required that compositions and their distribution on samples can be easily controlled for the evaluation of their properties. Moreover, it is desirable that compositions change linearly to search for novel materials systematically. In conventional combinatorial sputtering method, it is difficult to fabricate samples having linear compositions distribution without moving hard masks or rotating substrate.

In this paper, a novel combinatorial sputtering method with New Facing Targets Sputtering (Combi-NFTS) of material search is introduced. In this method, several sputtering targets are placed in opposite direction, and substrates are placed in vertical direction of these targets. From this structure, thin film with binary/ternary composition distribution could be synthesized onto one single substrate. Moreover, it can fabricate samples having relatively linear composition distribution without moving hard masks or rotating substrate. As an example, Cu, Zr and Ti pure targets were used to confirm the performance of Combi-NFTS. Binary system of Cu-Zr and ternary system of Cu-Zr-Ti thin films were fabricated by using Combi-NFTS. After deposition, compositions of the films were characterized by the energy dispersive X-ray spectroscopy. As a result of Cu-Zr binary system, the composition of the thin film was changed as the power of targets was changed. Moreover, composition distribution was expanded as the distance from substrate to targets was decreased. In the Cu-Zr-Ti ternary system, it was obtained similar trend for composition distribution. Moreover, the composition changed two dimensional by changing the substrate position.

These results indicate that combi-NFTS can easily control the composition and composition distribution of thin films by changing the power of targets or the distance from substrate to targets which make combi-NFTS very suitable for combinatorial materials search.

Heterostructures composed of transition metal oxides with strong electron correlation offer a unique opportunity to design new artificial materials whose electrical, magnetic and optical properties can be manipulated by tailoring the occupation of the d-orbitals of the transition metal in the compound. This possibility is an implication of symmetry constraints at interfaces with the consequence of a reconstruction of the coupled charge-, spin-, and orbital states of the constituents and their interactions. Novel architectures can be constructed showing functions well beyond charge density manipulations determining the functionality of conventional semiconductor heterostructures. Success in this endeavor requires the mastering of technological prerequisites such as structurally as well as chemically controlled interface preparation down to atomic scales. Additionally, a fundamental understanding of the modifications of the electronic structure at the interface imposed by structural boundary conditions and consequently by the constituent’s orbital occupation is required. A path towards a new generation of electronic devices with multiple functionalities can thus be opened by exploiting the correlation driven interface phenomena. In this paper, the technological challenges and experimental realizations along this concept are described with an emphasis of growth techniques based on the pulsed laser deposition method. As a case study, results of investigations of YBa2Cu3O7/La2/3Ca1/3MnO3superlattices are compiled and the conclusions regarding the orbital manipulation at the interface are used to pave the way for orbital engineering of oxides with electronic structures similar to the cuprates in order to find novel ordered quantum states at the interfaces including magnetism and superconductivity.

From density functional theory (DFT) based ab initio (Car-Parrinello) metadynamics, we compute the activation energies and mechanisms of water exchange between the first and second hydration shells of aqueous Uranyl (UO2 2+) using the primary hydration number of U as the reaction coordinate. The free energy and activation barrier of the water dissociation reaction [UO2(OH2)5]2+(aq) → [UO2(OH2)4]2+(aq) + H2O are 0.7 kcal and 4.7 kcal/mol respectively. The free energy is in good agreement with previous theoretical (-2.7 to +1.2 kcal/mol) and experimental (0.5 to 2.2 kcal/mol) data. The associative reaction [UO2(OH2)5]2+(aq) + H2O → [UO2(OH2)6]2+(aq) is short-lived with a free energy and activation barrier of +7.9 kcal/mol and +8.9 kca/mol respectively; it is therefore classified as associative-interchange. On the basis of the free energy differences and activation barriers, we predict that the dominant exchange mechanism between [UO2(OH2)5]2+(aq) and bulk water is dissociative.