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At least 1,747 records · Page 97
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Uncertainty reduction in residual stress measurements by an optimised inverse solution using nonconsecutive polynomials

Many destructive methods for measuring residual stresses such as the slitting method require an inverse analysis to solve the problem. The accuracy of the result as well as an uncertainty component (the model uncertainty) depends on the basis functions used in the inverse solution. The use of a series expansion as the basis functions for the inverse solution was analysed in a previous work for the particular case where functions orders grew consecutively. The present work presents a new estimation of the model uncertainty and a new improved methodology to select the final basis functions for the case where the basis is composed of polynomials. Including nonconsecutive polynomial orders in the basis generates a larger space of possible solutions to be evaluated and allows the possibility to include higher-order polynomials. The paper includes a comparison with two other inverse analyses methodologies applied to synthetically generated data. With the new methodology, the final error is reduced and the uncertainty estimation improved.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Superior electro-optical properties of electrically controlled birefringence mode using solution-derived La{sub 2}O{sub 3} films

The authors demonstrate a high performance electrically controlled birefringence (ECB) mode with solution-derived La{sub 2}O{sub 3} films at various molar concentrations. Uniform and homogeneous liquid crystal (LC) alignment was spontaneously achieved on the La{sub 2}O{sub 3} films for lanthanum concentrations at ratios greater than and equal to 0.2. A preferred orientation of LC molecules appeared along the filling direction, and the LC alignment was maintained via van der Waals force by nanocrystals of the La{sub 2}O{sub 3} films. The LC alignment mechanism was confirmed by x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy analysis. Superior electro-optical characteristics of the ECB cells constructed with solution-derived La{sub 2}O{sub 3} films were observed, which suggests that the proposed solution-derived La{sub 2}O{sub 3} films have strong potential for use in the production of advanced LC displays.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Synthesis, X-ray Diffraction Characterization, Mössbauer Spectroscopy, and Dielectric Properties of Solid Solutions in the PbFe{sub 2/3}W{sub 1/3}O{sub 3}–PbSc{sub 2/3}W{sub 1/3}O{sub 3} System

Ceramic Pb(Fe{sub 1–x}Sc{sub x}){sub 2/3}W{sub 1/3}O{sub 3} samples with 0 ≤ x ≤ 1 have been prepared and characterized by X-ray diffraction, Mössbauer spectroscopy, and dielectric and pyroelectric measurements. The stoichiometry ranges of the perovskite solid solutions in this system have been identified, their structural parameters have been determined, and their dielectric permittivity, dielectric loss tangent, resistivity, and thermally stimulated depolarization current have been measured as functions of temperature. The composition dependences of the dielectric properties for the solid solutions have been obtained. The solid solutions have been shown to exhibit ferroelectric relaxor properties, with a well-defined maximum in their permittivity in the range 180–250 K.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Sol–Gel Synthesis and Distinctive Structural Features of Ce{sub x}Zr{sub 1–x}O{sub 2} Solid Solutions

We have synthesized Ce{sub x}Zr{sub 1–x}O{sub 2} solid solutions via the thermal decomposition of xerogels of different compositions prepared by drying appropriate hydrosols. The synthesized materials have been characterized by thermal analysis, X-ray diffraction, and Raman spectroscopy. The results demonstrate that the solid solutions are formed at relatively low temperatures (450–600°C). The Ce{sub x}Zr{sub 1–x}O{sub 2} samples with x = 0.5–0.9 consist of a cubic solid solution. At a lower CeO{sub 2} content (x = 0.2), the material consists of a mixture of cubic and tetragonal phases.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The Influence of Immersion of Porous Silicon in Aqueous Solutions of Fe(NO{sub 3}){sub 3} on Photoluminescence during Long Storage

The interaction of porous silicon (PS) with aqueous solutions of Fe(NO{sub 3}){sub 3} with different molar (M) concentrations causes introduction of iron ions into silicon pores (PS–Fe), formation of adsorbed iron coatings with different thicknesses, and an increase in the stability of PS layers, which is important for development of device structures based of PS. To treat PS layers with solutions by the immersion method, it is necessary to determine how this affects the spectral composition and intensity of photoluminescence (PL), as well as the kinetics of PL changes during long storage under atmospheric conditions. Upon treatment of freshly prepared PS by immersion into in a Fe(NO{sub 3}){sub 3} aqueous solution, it was found that, after short-term storage (up to 5 days) of the PS samples, the PL intensity increases by 7.5 and 3–3.6 times at low (0.2 M) and high (0.7–0.8 M) concentrations of Fe(NO{sub 3}){sub 3}, respectively, compared to the PL intensity of an untreated PS layer. After long-term storage (4 months), the PL intensity of PS–Fe samples with concentrations of 0.1–0.2 and 0.7–0.8 M was observed to considerably increase (by 8–18 times) with unchanged position of the PL peak with respect to untreated PS. However, at the Fe(NO{sub 3}){sub 3} concentration of 0.3 М, the PL intensity decreases and the PL peak shifts to the blue, which is explained by incomplete coverage of the PS surface by an adsorbed iron layer. The kinetics of PL spectra during long-term storage is analyzed, and a model is proposed to explain the PL intensity and spectral composition.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

Investigation into the structure of ceramic Li{sub x}Na{sub 1-x}Ta{sub 0.1}Nb{sub 0.9}O{sub 3} solid solutions by X-ray analysis and Raman spectroscopy

The structure of ceramic solid solutions Li{sub x}Na{sub 1-x}Ta{sub 0.1}Nb{sub 0.9}O{sub 3} has been investigated by full-profile X-ray diffraction analysis and Raman spectroscopy. It is shown that their structure for all x values is similar to the NaNbO{sub 3} structure. The structure of NaTa{sub 0.1}Nb{sub 0.9}O{sub 3} solid solutions (x = 0) is characterized by the sp. gr. Pbcm, and the structure of Li{sub x}Na{sub 1-x}Ta{sub 0.1}Nb{sub 0.9}O{sub 3} solid solutions with x = 0.05, 0.1, and 0.16 is characterized by the sp. gr. P2{sub 1}ma. The unit-cell parameters decrease with an increase in x. At x = 0, doubled values of the parameter c and, correspondingly, the unit-cell volume are observed in the antiferroelectric phase. This fact is confirmed by the form of the vibrational spectrum in the region of stretching modes of oxygen atoms along the polar axis.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Small-angle X-Ray analysis of macromolecular structure: the structure of protein NS2 (NEP) in solution

A complex structural analysis of nuclear export protein NS2 (NEP) of influenza virus A has been performed using bioinformatics predictive methods and small-angle X-ray scattering data. The behavior of NEP molecules in a solution (their aggregation, oligomerization, and dissociation, depending on the buffer composition) has been investigated. It was shown that stable associates are formed even in a conventional aqueous salt solution at physiological рН value. For the first time we have managed to get NEP dimers in solution, to analyze their structure, and to compare the models obtained using the method of the molecular tectonics with the spatial protein structure predicted by us using the bioinformatics methods. The results of the study provide a new insight into the structural features of nuclear export protein NS2 (NEP) of the influenza virus A, which is very important for viral infection development.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Exploring plane-symmetric solutions in f(R) gravity

The modified theories of gravity, especially the f(R) gravity, have attracted much attention in the last decade. This paper is devoted to exploring plane-symmetric solutions in the context of metric f(R) gravity. We extend the work on static plane-symmetric vacuum solutions in f(R) gravity already available in the literature [1, 2]. The modified field equations are solved using the assumptions of both constant and nonconstant scalar curvature. Some well-known solutions are recovered with power-law and logarithmic forms of f(R) models.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Unstable behaviors of classical solutions in spinor-type conformal invariant fermionic models

It is well known that instantons are classical topological solutions existing in the context of quantum field theories that lie behind the standard model of particles. To provide a better understanding for the dynamical nature of spinor-type instanton solutions, conformal invariant pure spinor fermionic models that admit particle-like solutions for the derived classical field equations are studied in this work under cosine wave forcing. For this purpose, the effects of external periodic forcing on two systems that have different dimensions and quantum spinor numbers and have been obtained under the use of Heisenberg ansatz are investigated by constructing their Poincaré sections in phase space. As a result, bifurcations and chaos are observed depending on the excitation amplitude of the external forcing in both pure spinor fermionic models.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Transport characteristics of phonons and the specific heat of Y{sub 2}O{sub 3}:ZrO{sub 2} solid solution single crystals

The temperature dependences of the specific heat and transport characteristics of phonons in single crystals of yttrium-stabilized zirconium dioxide Y{sub 2}O{sub 3}:ZrO{sub 2} solid solutions have been studied. It has been shown that the temperature dependences of the specific heat at T > 5 K are almost identical at the degree of stabilization of a solid solution with an Y{sub 2}O{sub 3} content of 5–20 mol %. Differences in the temperature dependences of the specific heat of samples from different sources at T < 5 K are due to the presence of low-energy two-level systems. The features of the transport characteristics of thermal phonons at liquid helium temperatures reflect not only the presence of two-level systems but also the scattering of phonons on low-dimensional domains of another phase coherently conjugate to the main phase of the Y{sub 2}O{sub 3}:ZrO{sub 2} solid solution.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Plane Symmetric Solutions in f(G) Gravity

The purpose of this document is to investigate the universe in f(G) gravity. A wgeneral static plane symmetric space-time is chosen and exact solutions are explored using a viable f(G) gravity model. In particular, power and exponential law solutions are discussed. In addition, the physical relevance of the solutions with Taub’s metric and anti-deSitter space-time is shown. Graphical analysis of energy density and pressure of the universe is done to substantiate the study.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Pure Yang–Mills Solutions on dS{sub 4}

We consider pure SU(2) Yang–Mills theory on four-dimensional de Sitter space dS{sub 4} and construct smooth and spatially homogeneous classical Yang–Mills fields. Slicing dS{sub 4} as R×S{sup 3}, via an SU(2)-equivariant ansatz we reduce the Yang–Mills equations to ordinary matrix differential equations and further to Newtonian dynamics in a particular three-dimensional potential. Its classical trajectories yield spatially homogeneous Yang–Mills solutions in a very simple explicit form, depending only on de Sitter time with an exponential decay in the past and future. These configurations have not only finite energy, but their action is also finite and bounded from below. We present explicit coordinate representations of the simplest examples (for the fundamental SU(2) representation). Instantons (Yang–Mills solutions on the Wick-rotated S{sup 4} ) and solutions on AdS{sub 4} are also briefly discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Molecular beam epitaxy of III-P{sub x}As{sub 1−x} solid solutions: Mechanism of composition formation in the sublattice of a group V element

The effect of substrate temperature, As{sub 2} and P{sub 2} molecular flux densities, and growth rate on the composition of III-P{sub x}As{sub 1−x} solid solution layers prepared by molecular beam epitaxy is experimentally investigated. Experimental data in a wide range of growth conditions are analyzed. The results obtained are presented in the form of a kinetic model for describing the process of formation of the composition in the Group V sublattice of the III-P{sub x}As{sub 1−x} solid solution upon molecular beam epitaxy. The model can be used for choosing the growth conditions of the III-P{sub x}As{sub 1−x} (001) solid-solution layers of a specified composition.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Shape Effect in Layering of Solid Solutions in Small Volume: Bismuth–Antimony Alloy

The regularities of the effect of the shape of interphase boundaries in small volume systems on the separation of solutions with an upper critical solution temperature (UCST) are described by the example of Bi–Sb alloy particles with a core–shell configuration. The change in the shape of interphase boundaries is simulated in general by introducing a parameter corresponding to the degree of deviation of the shape of the boundaries from the spherical one. An analysis of the extrema of the Gibbs function revealed regularities in the effect of the shape of the core and shell phases on phase equilibria, the thermodynamic stability of heterogeneous states, and the phase separation diagram. The deviation of the shape of the interphase boundaries from the spherical shape changes the UCST and the mutual solubility of the components. The deformation of the shell of a core–shell particle increases the thermodynamic stability of the heterogeneous state, which contributes to the separation of the solution. The deformation of the core lowers the thermodynamic stability of the heterogeneous state and expands the range of metastable states.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Weakly Ordered Nanostructured Silver Disilicate and Its Colloidal Solutions: Preparation and Properties

It was shown that the interaction of silver cations in alkaline aqueous solutions with various kinds of silicates, regardless of their chemical and aggregation state, leads to the formation of an exclusively disilicate form of silver salt. We develop procedures for synthesis of nanostructured weakly ordered nonstoichiometric silver disilicate Ag{sub 6 –x}H{sub x}Si{sub 2}O{sub 7} capable of forming aqueous colloids. We study the micellular structure of colloidal particles in these solutions and demonstrate that permeability of silicic acid layers enveloping nanosized salt cores of these micelles depends on pH. Colloidal silver disilicate is found to exhibit a high catalytic activity in photoinduced oxidation of a broad spectrum of different compounds, which is demonstrated for compounds stable in aqueous solutions such as some organic dies and ferrocyanide complex ([Fe(CN){sub 6}{sup −4}).

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Explicit kink solutions in several one-parameter families of higher-order field theory models

Here, we present several one-parameter families of higher-order field theory models some of which admit explicit kink solutions with an exponential tail while others admit explicit kink solutions with a power-law tail. Various properties of these families of kink solutions are examined in detail. Further, by applying the recent Manton formalism, we provide estimates for the kink–kink (KK) and antikink–kink (AK-K) acceleration and hence the ratio of the corresponding AK-K and KK forces.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2013

Continuous Microreactor-Assisted Solution Deposition for Scalable Production of CdS Films

Solution deposition offers an attractive, low temperature option in the cost effective production of thin film solar cells. Continuous microreactor-assisted solution deposition (MASD) was used to produce nanocrystalline cadmium sulfide (CdS) films on fluorine doped tin oxide (FTO) coated glass substrates with excellent uniformity. We report a novel liquid coating technique using a ceramic rod to efficiently and uniformly apply reactive solution to large substrates (152 mm × 152 mm). This technique represents an inexpensive approach to utilize the MASD on the substrate for uniform growth of CdS films. Nano-crystalline CdS films have been produced from liquid phase at ~90°C, with average thicknesses of 70 nm to 230 nm and with a 5 to 12% thickness variation. The CdS films produced were characterized by UV-Vis spectroscopy, transmission electron microscopy, and X-Ray diffraction to demonstrate their suitability to thin-film solar technology.

scalable process↗