scholarly journals Microstructure Properties of Rapidly Solidified Al-Zn-Mg-Cu Alloys

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Emad M. Ahmed
Keyword(s):  
Crystal Structure ◽  
Weight Fraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cu Content ◽  
Cu Alloys ◽  
Melt Spun ◽  
Rapidly Solidified ◽  
Structure And Microstructure ◽  
Good Agreement

The Rietveld X-ray diffraction analysis was applied to analyze the weight fraction of precipitation phases and microstructure characterizations of rapidly solidified Al-8Zn-4Mg-xCu, x = 1, 4, 8, and 10 alloys (in wt.%), prepared by melt spun technique. A good agreement between observed and calculated diffraction pattern was obtained and the conventional Rietveld factors (Rp, Rwp, and GOF) converged to satisfactory values. Solid solubilities of Zn, Mg, and Cu in α-Al were extended to high values. Besides, metastable Al0.71Zn0.29, intermetallic Al2CuMg, Al2Cu, and CuMgZn phases have been observed for x = 4, 8, and 10 Cu alloys. The crystal structure and microstructure characterizations exhibit strong Cu content dependence.

Darstellung, Schwingungsspektren und Normalkoordinatenanalyse der 10B-und 11B-Isotopomeren von [B2(NCS)6]2- sowie Kristallstruktur von (Ph3P=N=PPh3)2[B2(NCS)6] / Preparation, Vibrational Spectra and Normal Coordinate Analysis of the 10B and 11B Isotopomers of [B2(NCS)6]2- and Crystal Structure of (Ph3P=N=PPh3)2[B2(NCS)6]

1996 ◽  
Vol 51 (4) ◽  
pp. 551-556 ◽  
Author(s):  
W. Preetz ◽  
B. Steuer
Keyword(s):  
Crystal Structure ◽  
Normal Coordinate Analysis ◽  
Force Constants ◽  
Potential Energy Distribution ◽  
X Ray Diffraction ◽  
Normal Coordinate ◽  
Triclinic Space Group ◽  
X Ray ◽  
Fractionated Crystallization ◽  
Good Agreement

Abstract By reaction of [B6H6]2- with a solution of (SCN)2 in dichloromethane in the presence of solid KOH the hexaisothiocyanatodiborate anion [B2(NCS)6]2- is formed and can be isolated by fractionated crystallization. The crystal structure of (PNP)2[B2(NCS)6] has been determined by single crystal X-ray diffraction analysis; triclinic space group P1̄ with a=12,282(5), b=12,416(5), c=14,155(5)Å, a=68,36(5), β=70,59(5), γ=80,93(5)°.The [B2(NCS)6]2- anion reveals a staggered conformation with nearly local D3d symmetry and a B-B bond length of 1,73(2) Å. Using the crystallographic data a normal coordinate analysis has been performed. With a set of 12 force constants (e.g. fd(BB)=3,62, fd(BN)=4,21 mdyn/Å) a good agreement between observed and calculated frequencies for the 10B and 11B isotopomers has been achieved. The potential energy distribution on the force constants reveals strong vibrational couplings within the B2N6 framework.

scholarly journals The pseudo-single-crystal method: a third approach to crystal structure determination

2009 ◽  
Vol 42 (3) ◽  
pp. 535-537 ◽  
Author(s):  
Tsunehisa Kimura ◽  
Chengkang Chang ◽  
Fumiko Kimura ◽  
Masataka Maeyama
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Single Crystal Diffraction ◽  
Uv Curable ◽  
X Ray ◽  
Novel Method ◽  
Good Agreement ◽  
Pseudo Single Crystal

A novel method that enables single-crystal diffraction data to be obtained from a powder sample is presented. A suspension of LiCoPO4microrods was subjected to a frequency-modulated dynamic elliptical magnetic field to align the microrods; the alignment achieved was consolidated by photopolymerization of the suspending UV-curable monomer. The composite thus obtained (referred to as a pseudo single crystal) gave rise to X-ray diffraction data from which the crystal structure was solved using the standard method for single-crystal X-ray analyses. The structure determined was in good agreement with that reported using a conventional single crystal.

scholarly journals Microstructure and Microhardness Evolutions of High Fe Containing Near-Eutectic Al-Si Rapidly Solidified Alloy

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Emad M. Ahmed ◽  
M. R. Ebrahim
Keyword(s):  
Length Distribution ◽  
Spherical Shape ◽  
Solidification Process ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fe Content ◽  
Melt Spun ◽  
Solid Solubility Extension ◽  
Rapidly Solidified

Al-11 wt.% Si-11 wt.% Fe (11.29 at.% Si-5.6 at.% Fe) melt was rapidly solidified into ribbons and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and microhardness technique. The Rietveld X-ray diffraction analysis was applied successfully to analyze microstructure and phase precipitations. On the basis of the aluminum peak shifts measured in the XRD scans, a solid solubility extension value of 1 at.% Si in α-Al was determined. SEM investigations confirmed presence of a spherical shape α-phase particles in addition to needle and spherical shape β-phase particles with contents of 1.1 wt.% and 10.1 wt.% as deduced by XRD analysis. During prolonged annealing process at 350°C/25 h, α-phase disappeared, β-phase content increased to 30 wt.%, and Si presence becomes more evident as deduced by XRD analysis. EDS analysis confirmed that these β particles observed in the as-melt spun alloy are of lower Fe content comparing to those usually observed in the as-cast counter-part alloy. Besides, the length distribution of needle shape β-particles has been shortened to be diverse from 1 to 5 μm. The as-melt spun ribbons exhibited enhancement of hardness to 277 HV and further increased during heat treatment (150°C/12 h) to 450 HV. This improvement of microstructure and hardness are the influence of microstructural refinement and modification obtained during the rapid solidification process.

Darstellung, Kristallstruktur, Schwingungsspektren und Normalkoordinatenanalyse von [Os(acac)3]/ Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of [Os(acac)3]

1998 ◽  
Vol 53 (2) ◽  
pp. 232-238 ◽  
Author(s):  
K. Dallmann ◽  
W. Preetz
Keyword(s):  
Crystal Structure ◽  
Normal Modes ◽  
Normal Coordinate Analysis ◽  
Force Constants ◽  
X Ray Diffraction ◽  
Normal Coordinate ◽  
X Ray ◽  
Modes Of Vibration ◽  
Ir And Raman ◽  
Good Agreement

Abstract In the reaction of K2[OsCl6] with boiling water/acetylacetone (1:1) a mixture of different chloro-acetylacetonato complexes is formed, from which [Os(acac)3] can be isolated by column chromatography with dichloromethane on silica gel. The crystal structure of [Os(acac)3] (mo­noclinic, space group P21/c,a = 13.968(5), b = 7.517(5), c = 16.455(5) Å ,β = 98.939(5)°, Z = 4) has been determined by single crystal X-ray diffraction analysis. High resolution IR and Raman spectra were measured at low temperature (10K). Based on the molecular parameters of the X-ray structure determination a normal coordinate analysis has been performed and the normal modes of vibration have been assigned. With a set of 32 force constants, taking into account the intraligand vibrations, a good agreement between observed and calculated frequencies has been achieved. The valence force constants are fd(OsO) = 3.19 and fd(OC) = 6.74 mdyn/Å.

A Comparative X-Ray Diffraction Study of Aqueous MnSO4 and Crystals of MnSO4·5H2O

1982 ◽  
Vol 37 (6) ◽  
pp. 581-586 ◽  
Author(s):  
R. Caminiti ◽  
G. Marongiu ◽  
G. Paschina
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Single Crystal ◽  
Diffraction Study ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Good Agreement ◽  
Single Crystal Analysis

Abstract X-ray single crystal analysis of MnSO4·5H2O shows that the manganese atoms are octahedrally coordinated by oxygen atoms, four of which belong to water molecules and two to sulphate groups. A model derived from the crystal structure was fitted to the X-ray scattering intensities from aqueous MnSO4. Good agreement with experimental data is achieved using a model in which Mn(H2O)6-z(OSO3)z+2-2z interacts with about ten water molecules and each sulphate ion with about seven water molecules.

Crystal structure and microstructure of synthetic hexagonal magnesium–cobalt cordierite solid solutions (Mg2−2xCo2xAl4Si5O18)

2013 ◽  
Vol 69 (2) ◽  
pp. 110-121 ◽  
Author(s):  
Francisco Javier Serrano ◽  
Noemí Montoya ◽  
José Luis Pizarro ◽  
María Mercedes Reventós ◽  
Marek Andrzej Kojdecki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Size Distribution ◽  
Solid Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Microstructure ◽  
Crystalline Microstructure ◽  
Scanning Electron

Co2+-containing cordierite glasses, of nominal compositions (Mg1−xCox)2Al4Si5O18(withx= 0, 0.2, 0.4, 0.6, 0.8 and 1), were prepared by melting colloidal gel precursors. After isothermal heating at 1273 K for around 28 h, a single-phase α-cordierite (high-temperature hexagonal polymorph) was synthesized. All materials were investigated using X-ray powder diffraction and field-emission scanning electron microscopy. The crystal structure and microstructure were determined from X-ray diffraction patterns. Rietveld refinement confirmed the formation of magnesium–cobalt cordierite solid solutions. The unit-cell volume increased with the increase of cobalt content in the starting glass. The crystalline microstructure of the cordierites was interpreted using a mathematical model of a polycrystalline material and characterized by prevalent crystallite shape, volume-weighted crystallite size distribution and second-order crystalline lattice-strain distribution. Hexagonal prismatic was the prevalent shape of α-cordierite crystallites. Bimodality in the size distribution was observed and interpreted as a consequence of two paths of the crystallization: the nucleation from glass of μ-cordierite, which transformed into α-cordierite with annealing, or the nucleation of α-cordierite directly from glass at high temperatures. Scanning electron microscopy images agreed well with crystalline microstructure characteristics determined from the X-ray diffraction line-profile analysis.

Bavsiite, Ba2V2O2[Si4O12], mineral data and crystal structure

2019 ◽  
Vol 83 (6) ◽  
pp. 821-827
Author(s):  
Hans-Peter Bojar ◽  
Franz Walter ◽  
Judith Baumgartner
Keyword(s):  
Crystal Structure ◽  
Structural Formula ◽  
Yukon Territory ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Dimensional Network ◽  
Quartz Monzonite ◽  
Mineral Data ◽  
Good Agreement

AbstractBavsiite from the type locality Gun Claim, Yukon Territory, Canada, occurs as millimetre-sized sky-blue platy crystals in a barium-rich low-temperature skarn related to a porphyritic quartz monzonite stock. Associated minerals are alstonite, baryte, celsian, diopside, fresnoite, mica, suzukiite, walstromite, witherite and minerals of the cerchiaraite group. Bavsiite is optical uniaxial (+), with ω = 1.725(3) and ε = 1.750(3) (589 nm) and pleochroic. Electron microprobe analyses yielded the empirical formula Na0.02Ba1.98Ti0.16Fe2+0.03V4+1.80 Al0.05Si4.00O14 based on 14 oxygen atoms, the simplified chemical formula is Ba2V2Si4O14. Bavsiite is tetragonal, space group I4/m, a = 7.043(1), c = 11.444(2) Å and Z = 2 obtained from single crystal data at 100 K, which are in good agreement with cell parameters from powder diffraction data at 293 K: a = 7.051(1) Å and c = 11.470(1) Å. The eight strongest lines of the powder X-ray diffraction pattern are [d, Å (I,%)(hkl)]: 3.76(30)(112), 3.36(44)(013), 3.004(100)(022), 2.493(43)(220), 2.486(67)(114), 2.286(24)(222), 1.785(39)(116) and 1.763(25)(040). The crystal structure was refined to R = 0.0159 based upon 312 unique reflections with I > 2σ(I). The crystal structure of bavsiite comprises unbranched single [Si4O12]8– rings connected by [VO5]6– square pyramids and BaO12 polyhedra. It can also be considered as cage–like [Si4V2O18]12– clusters built by four SiO4 tetrahedra and two VO5 square pyramids. These clusters are cross–linked to form a pseudo-two-dimensional network (2D) parallel to (001) containing empty channels along the a axis and the 2D networks held together by Ba2+ ions located in channels parallel to the c axis. The structural formula is Ba2V2O2[Si4O12]. Bavsiite is polymorphic to suzukiite, BaVSi2O7, which is orthorhombic.

Enthalpies of formation and lattice parameters of B2 phases in Al-Ni-X systems

2007 ◽  
Vol 79 (10) ◽  
pp. 1653-1673 ◽  
Author(s):  
Rongxiang Hu ◽  
Hsin-Ning Su ◽  
Philip Nash
Keyword(s):  
High Temperature ◽  
Heat Content ◽  
Lattice Parameters ◽  
Enthalpies Of Formation ◽  
X Ray Diffraction ◽  
Interpolation Model ◽  
X Ray ◽  
Cu Alloys ◽  
B2 Phase ◽  
Good Agreement

Enthalpies of formation of Al-Ni-X (X: Fe, Ru, Pd, Pt, and Cu) alloys were measured by high-temperature calorimeter and compared with the calculated value from Miedema's model and interpolation models. The interpolation models generally provide better prediction than Miedama's model. No one interpolation model generated superior predictions. Lattice parameters of B2 phase compounds were determined by X-ray diffraction (XRD). The atomic volumes in the Al-Ni-Fe system were calculated and show that Fe substitutes preferentially on the Al sublattice. The heat content of Al0.5Ni0.2Ru0.3 and Al0.5Ni0.35Cu0.15 at high temperature was obtained, and the results are in good agreement with those heat capacities estimated by the Neumann-Kopp rule.

Effects of Ho-Doping on Crystal Structure and Microstructure of La0.7Sr0.3MnO3 Ceramics

2013 ◽  
Vol 745-746 ◽  
pp. 96-101 ◽  
Author(s):  
Ben Zhe Sun ◽  
Si Lang Zhou ◽  
Tie Shen
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Perovskite Structure ◽  
Volume Fraction ◽  
Partial Substitution ◽  
X Ray Diffraction ◽  
Doping Amount ◽  
X Ray ◽  
Transmission Electron ◽  
Structure And Microstructure

Crystal structure and microstructure of La0.7-xHoxSr0.3MnO3 (x=0.2,0.6) prepared by usual ceramic techniques and grinding procedure were investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). When doping amount x equals to 0.2, incorporation of Ho atoms contributed to phase separation and coexistence of rhombohedral (La0.7Sr0.3MnO3) and hexagonal (HoMnO3) phases. La0.7Sr0.3MnO3 phase is of typical perovskite structure, whereas, HoMnO3 phase is non-perovskite structure. As x reaches 0.6, the volume fraction of HoMnO3 phase was significantly increasing. Meanwhile, an orthorhombic lattice with perovskite structure and space group Pnma can be observed. It prevented from partial substitution of La 3+ or Sr2+ by Ho3+ and the distortion of Mn-O octahedra.

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