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Residual stress states in engineering structures are usually determined by measuring components of stress tensors with depth below the material surface. There are destructive and nondestructive methods to measure strain tensor components and convert them into stress tensor components by a variety of techniques derived from constitutive (material) equations. In this study, four methods for determining the strain tensor components are presented: X-ray diffraction method (XRDM), magnetic Barkhausen noise method (MBNM), hole drilling method (HDM), and cut-and-section method (CSM); the first two are nondestructive, and the third and fourth are semidestructive and destructive, respectively. A complementarity of the experimental and two numerical methods such as boundary element method and finite element method is explained. An application of the experimental and numerical methods to measure residual stress states in an industrial component, an L-shaped part of a supporting column in a high voltage structure, is presented.
X-ray powder diffraction data of voglibose are reported, and its crystal and molecular structures were determined by simulated annealing and rigid-body Rietveld refinement methods. Voglibose was found to be crystallized in triclinic symmetry with space group P-1. The lattice parameters were determined to be a=6.1974(6) Å, b=6.9918(5) Å, c=7.3955(9) Å, α=70.8628(3), β=103.5312(4), γ=94.3867(5)°, V=294.2(2) Å3, and ρcal=1.495 g/cm3. The crystal structure contains isolated C10H21NO7 molecular.
Nickel oxide nanopowder was prepared by a simple method and analyzed by X-ray powder diffraction. A solution of gelatin and NiCl2⋅6H2O salt were prepared and sintered in sequence. Using a synchrotron light source for X-ray powder diffraction analysis, the synthesized material was characterized as a function of temperature in the interval of 375 to 600 °C. Results from thermogravimetric analysis confirm the temperature loss of the organic substance during the sintering process and show that the temperature for NiO attainment is 600 °C.
The compressive stress distribution below the specimen surface of severely surface deformed steels by shot peening was investigated by using laboratory X-rays and high-energy X-rays from a synchrotron radiation source, SPring-8 in the Japan Synchrotron Radiation Research Institute. Medium carbon steel plates were heat treated in two different conditions. The Vickers hardness of materials A and B after heat treatment is 408 and 617 HV, respectively. The specimens were shot peened with fine cast iron particles of the size of 50 μm. The coverage was selected to be 5000%. For the synchrotron radiation, by using the monochromatic X-ray beam with several energy levels, the stress values at the arbitrary penetration depth were measured by the constant penetration depth method. The shot-peened specimens were fatigued under four-point bending. The improvement of fatigue strength of material A was not so large because of large surface roughness. On the other hand, for material B, the surface roughness was smaller and the fatigue strength was higher than that of ground specimens.
BaTiO3 powders were prepared through mechanical activation chemistry and analyzed by Rietveld refinement with X-ray diffraction data. Raw BaCO3 and TiO2 powders were dry milled for 5 and 20 h and then calcinated for 2 and 4 h at 800 °C. The milling process was found to have broken up the BaCO3 and TiO2 crystals into smaller crystals and formed only small amounts (<1.5 wt%) of BaTiO3. Subsequence calcinations for 2 and 4 h at 800 °C successfully produced large amounts (>97.7 wt%) of BaTiO3 crystals. The calcination process also generated microstrains and crystallite-size anisotropy in BaTiO3. An increase in the calcination time from 2 to 4 h increased the BaTiO3 weight percentage and the crystallite-shape anisotropy, but decreased the tetragonal distortion anisotropic microstrains in BaTiO3 crystals.
The crystal structures of LaCo0.5Ni0.5O3−δ and LaCo0.5Fe0.5O3−δ solid solutions, studied by powder X-ray diffraction, were found to be rhombohedral perovskite. The unit cell parameters in the hexagonal setting are a=5.491(6) Å and c=13.231(3) Å for LaCo0.5Fe0.5O3−δ, and a=5.464(4) Å and c=13.125(3) Å for LaCo0.5Ni0.5O3−δ. The space group is R3c (No. 167).
X-ray powder diffractograms from fcc crystals containing high concentration (more than 1%) of planar defects [deformation stacking faults (SF), double deformation SF, twin boundaries (TB)] have been simulated by Monte Carlo method in kinematic approach. It was shown that the characteristics of powder diffraction peak profiles (except peaks with indexes H00) dependent nonmonotonically on PD concentration, during which peak maximums stay in Bragg positions. An addition point to emphasize is that an appearance of TB only in the crystal not affects on position of all peaks. Several types of PD to be occurred simultaneously in the crystal influence on powder diffractograms additively. Peculiarities of the powder diffraction pattern inherent in different types of PD have been revealed to permit predominant PD type to be found with a high degree of accuracy based on experimental data.
Crystal and local structures (long- and short-range order, respectively) of four nanocrystalline zirconia-based solid solutions—ZrO2-6 and 16 mol % CaO and ZrO2-2.8 and 12 mol % Y2O3—synthesized by a pH-controlled nitrate-glycine gel-combustion process were studied. These materials were characterized by synchrotron X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy. Our XRD results indicate that the solid solution with low CaO and Y2O3 contents (6 and 2.8 mol %, respectively) exhibit a tetragonal crystallographic lattice, and those with higher CaO and Y2O3 contents (16 and 12 mol %, respectively) have a cubic lattice. Moreover, our EXAFS study demonstrates that the tetragonal-to-cubic phase transitions, for increasing CaO and Y2O3 contents, are both related to variations in the local symmetry of the Zr–O first neighbor coordination sphere.
Generating compressive stresses in aerospace materials is an important consideration for enhancing fatigue life. Shot peening and cold expansion of holes are two techniques for imparting beneficial compressive stresses. X-ray diffraction is a direct method for measuring elastic strains. Diffraction peak widths are an indication of plastic strain. Elastic and plastic strains can be used to better assess the true condition of a component. This paper presents elastic and plastic strain information from shot peened and cold expanded aerospace materials. Examination of surface data showed which shot peened samples had the deeper layer of compressive stresses. Likewise, elastic and plastic strain data enabled successful ranking of the holes in terms of the maximum amount of cold working.
A new barium copper niobate, Ba4CuNb3O12, was successfully prepared by high-temperature solid-state reaction in an inert atmosphere. Rietveld-refinement analysis of the XRD data of the compound showed that it has the 8H-type hexagonal perovskite structure with space group P63/mmc (#194), a = 5.830(1) Å, c = 19.123(1) Å, and chemical composition of Ba4Cu1.84Nb2.16O12-δ.
Powder diffraction data are presented for two compounds of forensic importance: benzocaine hydrochloride and a monoclinic polymorph of benzocaine base. Data were collected at room temperature using nickel-filtered Cu Kα radiation.
Single-crystal synchrotron X-ray diffraction (XRD) data were collected and refined for congruent lithium niobate crystals 8 and 6 μm in diameter, sizes that are comparable to the size of the powder particles used in powder diffraction. The motivation for using such small crystals is to minimize problems such as extinction, which decrease with crystal size. The R/wR factors were 0.011/0.014 and 0.019/0.018, for the 8 and 6 μm data, respectively, and the goodness of fit factors were 2.3(1) and 1.63(8), which compare favorably with values obtained from previous powder and single-crystal diffraction studies. Results from single-crystal XRD using crystals less than 10 μm in size may rival those obtained from powder diffraction.
In this work we report the synthesis and structural characterization of the elpasolite Cs2NaTbCl6, belonging to the space group Fm3m. The synthesis is by solid state reaction, in controlled atmosphere. By means of thermal analysis (DTA/TGA), the best crystallization temperatures were obtained: 772.2 °C for 2 hours. Structural studies are carried out by means of DRX-powder diffraction and application of the Rietveld profiles refinement method, for the 32 diffraction lines analyzed. The following crystallographic parameters are obtained: a0=10.7636 (Å), Z=4, M=660.44, V=1247.0 (Å)3, Dx=3.519, and Dexp=3.52±0.01.
The compound Ba4Eu3F17 was prepared by heating pre-dried BaF2 and EuF3 (4:3) at 800 °C for 8 h in static vacuum. The colorless polycrystalline product obtained was characterized by Rietveld refinement of the observed powder diffraction data with a starting model of Ba4Y3F17. The title compound Ba4Eu3F17 crystallizes in rhombohedral lattice with lattice parameters, a=11.1787(4) and c=20.5789(10) Å, Z=3 (Space group R 3, No. 148). The Ba4Eu3F17 structure can be described as an ordered anion-rich fluorite type structure with the formation of Eu6F37 clusters. There are two crystallographically distinct Ba (CN=10, 11) and one distinct Eu (CN=8). The typical Ba(1)–F, Ba(2)–F, and Eu–F bond lengths range from 2.56 to 2.83 Å, 2.54 to 3.25 Å, and 2.24 to 2.49 Å, respectively. The salient feature of the structure is that the EuF8 polyhedra share their corner to form a cubo-octahedron of fluoride ions. The cubic BaF8 polyhedra of BaF2 are modified to Ba(1)–F10 and Ba(2)–F11 polyhedra in this structure. The cubo-octahedron encloses extra fluorine F(8) inside it.
X-ray powder diffraction data for synthetic materials MgMnSiO4 and Mg0.6Mn1.4SiO4 are reported. Samples were prepared by firing mixtures of MgO, MnCO3, and SiO2 in prescribed molar ratios at 1523 K. Powder diffraction data were collected with a laboratory X-ray source (CuKα) for refinement of unit-cell parameters and synchrotron radiation (λ=1.1980 Å) for intensity measurement of individual reflections. Crystallographic data were MgMnSiO4, orthorhombic, Pnma (No. 62), a=10.4510(1), b=6.12446(5), c=4.80757(4) Å, V=307.717(4) Å3, Z=4, and Dx=3.697 g·cm−3, and Mg0.6Mn1.4SiO4, orthorhombic, Pnma (No. 62), a=10.5241(1), b=6.17903(6), c=4.83927(5) Å, V=314.692(5) Å3, Z=4, and Dx=3.873 g·cm−3.