An HREM study of superstructures in Ca4Al6SO16

1990 ◽  
Vol 48 (4) ◽  
pp. 1066-1067
Author(s):  
Y.G. Wang ◽  
H.Q. Ye ◽  
K.H. Kuo
Keyword(s):  
Calcium Aluminate ◽  
Structural Model ◽  
Bright Spot ◽  
Sulphur Atom ◽  
Synthetic Compound ◽  
Space Group ◽  
Lattice Images ◽  
Cubic Structure ◽  
Good Agreement

A synthetic compound Ca4Al6SO16 (usually abbreviated as C4A3S) obtained by mixing CaO, A12O3 and CaSO4 powders and finally sintered at 1380°C is a cement with excellent hydraulicity and greatly expanding in application. It is hydralysed rapidly by water to form predominatly calcium aluminate hydrates and therefore unlikly to occur naturally, although structurally it may be regarded as an end member of the sodalite-hauynite series of naturally occuring minerals. C4A3S has a cubic structure with ao=9.19Å and space group . Fig.1 is the projection viewed down axis, in which there are two sets of 8C position in , namely CaI and CaII, occupied by the calcium atoms, respectively, and the ratio of occupations in these two sets of positions is about 3:1. This suggests that the calcium atoms can freely occupy these sites in various degrees and usually they almost locates on the CaI positions. A through-focus series of the lattice images were found in good agreement with the simulated ones. Each bright spot in the image taken at Scherzer defocus correspounds to a colunm of sulphur atom in the structural model (Fig.1).

Packing Effect on the Transfer Integrals and Mobility in α,α′-bis(dithieno[3,2-b:2′,3′-d]thiophene) (BDT) and its Heteroatom-Substituted Analogues

2011 ◽  
Vol 64 (12) ◽  
pp. 1587 ◽  
Author(s):  
Ahmad Irfan ◽  
Abdullah G. Al-Sehemi ◽  
Shabbir Muhammad ◽  
Jingping Zhang
Keyword(s):  
Electron Transfer ◽  
Electron Mobility ◽  
Hole Mobility ◽  
Experimental Investigations ◽  
Hole Transfer ◽  
Space Group ◽  
Space Groups ◽  
Transfer Integrals ◽  
Packing Effect ◽  
Good Agreement

Theoretically calculated mobility has revealed that BDT is a hole transfer material, which is in good agreement with experimental investigations. The BDT, NHBDT, and OBDT are predicted to be hole transfer materials in the C2/c space group. Comparatively, hole mobility of BHBDT is 7 times while electron mobility is 20 times higher than the BDT. The packing effect for BDT and designed crystals was investigated by various space groups. Generally, mobility increases in BDT and its analogues by changing the packing from space group C2/c to space groups P1 or . In the designed ambipolar material, BHBDT hole mobility has been predicted 0.774 and 3.460 cm2 Vs–1 in space groups P1 and , which is 10 times and 48 times higher than BDT (0.075 and 0.072 cm2 Vs–1 in space groups P1 and ), respectively. Moreover, the BDT behaves as an electron transfer material by changing the packing from the C2/c space group to P1 and .

scholarly journals Ekstraksi Kalsium dari Cangkang Kerang Hijau (Perna viridis L.) dan Kerang Batik (Paphia undulata B.) dengan Metode Kalsinasi sebagai Sediaan Effervescent

2020 ◽  
Vol 8 (2) ◽  
pp. 101-107
Author(s):  
Mohammad Rofik Usman ◽  
Rifka Nabila ◽  
Lutfiah Nurul Hakiki
Keyword(s):  
Water Content ◽  
Rietveld Method ◽  
Perna Viridis ◽  
Particle Sizes ◽  
Clam Shell ◽  
Space Group ◽  
Organoleptic Test ◽  
Test Water ◽  
Cubic Structure ◽  
Calcination Method

One of the solutions is the supplying of calcium effervescent powder as a source of calcium. The source of calcium that has not been processed maximally is the clam shell. Calcium from the clam shells will be extracted by calcination method at 900 °C for 4hours. The extracted clam shells powder are tested using XRD and analyzed using the Rietveld method. The particle sizes of calcium are determined by the Scherer equation. The best calcium is formulated into 3 formulations with several variations in composition. Evaluation of calcium effervescent powder includes organoleptic test, water content and dispersion time. The extracted calcium crystal diffractogram shows the CaO compound with cubic structure and space group FM3M. The particle sizes of CaO nanoparticles from green shells and batik were 88.7597nm and 96.66566nm, respectively. The best CaO based on χ2 values ​​and particle sizes are CaO from green clamshells. The organoleptic test of the three formulations produced the same data as yellow, granular shape, and citrus aroma. Formulation three is the best formulation based on the low water content and short dispersion time.

X-ray powder diffraction data for ω and C2 phases of Al–Cu–Ir

2008 ◽  
Vol 23 (4) ◽  
pp. 356-359 ◽  
Author(s):  
B. Grushko ◽  
D. Pavlyuchkov
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Tetragonal Structure ◽  
Powder Diffraction Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Cubic Structure

Ternary Al–Cu–Ir phases, isostructural to the Al–Cu–Rh ω and C2 phases, were found to be around the Al70Cu20Ir10 and Al60Cu15Ir25 compositions, respectively. Using powder X-ray diffraction, the former was found to have a tetragonal structure (space group P4/mnc) with a=6.4142(9) Å and c=14.842(4) Å, and the latter has a cubic structure (space group Fm3) with a=15.3928(6) Å.

scholarly journals Pelvic Construct Prediction of Trabecular and Cortical Bone Structural Architecture

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Dan T. Zaharie ◽  
Andrew T. M. Phillips
Keyword(s):  
Cortical Bone ◽  
Structural Model ◽  
Thickness Distribution ◽  
Bone Adaptation ◽  
The Body ◽  
Lower Limbs ◽  
Fe Model ◽  
Adaptation Algorithm ◽  
Modeling Framework ◽  
Good Agreement

The pelvic construct is an important part of the body as it facilitates the transfer of upper body weight to the lower limbs and protects a number of organs and vessels in the lower abdomen. In addition, the importance of the pelvis is highlighted by the high mortality rates associated with pelvic trauma. This study presents a mesoscale structural model of the pelvic construct and the joints and ligaments associated with it. Shell elements were used to model cortical bone, while truss elements were used to model trabecular bone and the ligaments and joints. The finite element (FE) model was subjected to an iterative optimization process based on a strain-driven bone adaptation algorithm. The bone model was adapted to a number of common daily living activities (walking, stair ascent, stair descent, sit-to-stand, and stand-to-sit) by applying onto it joint and muscle loads derived using a musculoskeletal modeling framework. The cortical thickness distribution and the trabecular architecture of the adapted model were compared qualitatively with computed tomography (CT) scans and models developed in previous studies, showing good agreement. The sensitivity of the model to changes in material properties of the ligaments and joint cartilage and changes in parameters related to the adaptation algorithm was assessed. Changes to the target strain had the largest effect on predicted total bone volumes. The model showed low sensitivity to changes in all other parameters. The minimum and maximum principal strains predicted by the structural model compared to a continuum CT-derived model in response to a common test loading scenario showed good agreement with correlation coefficients of 0.813 and 0.809, respectively. The developed structural model enables a number of applications such as fracture modeling, design, and additive manufacturing of frangible surrogates.

Na6Pt8Ge8, eine ternäre intermetallische Phase mit tetraedrischen Platinclustern / Na6Pt8Ge8, a Ternary Intermetallie Phase with Tetrahedral Platinum Clusters

1979 ◽  
Vol 34 (6) ◽  
pp. 781-783 ◽  
Author(s):  
Werner Thronberens ◽  
Hans-Uwe Schuster
Keyword(s):  
Structural Elements ◽  
Space Group ◽  
Structure Space ◽  
Platinum Clusters ◽  
Cubic Structure

Abstract Na6Pt8Ge8 was prepared from the elements; it crystallizes in a cubic structure, space group I4̄3m, a= 761.4 pm. The phase contains two structural elements:The Pt-atoms form tetrahedra, which are covered by bigger Ge-tetrahedra. The Na-atoms build a 3-D-network consisting of chains crossed under right angels.

X-ray powder diffraction data of CoSi

1997 ◽  
Vol 12 (4) ◽  
pp. 252-254 ◽  
Author(s):  
G. Ghosh ◽  
G. V. Narasimha Rao ◽  
V. S. Sastry ◽  
A. Bharathi ◽  
Y. Hariharan ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Melting Process ◽  
Lattice Parameter ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Arc Melting ◽  
Cubic Structure

X-ray powder diffraction data of CoSi are reported. The sample was prepared by an arc melting process and has a cubic structure (space group P213, space group No. 198) with lattice parameter a=4.4427 Å, Dx=6.591 gcm−3, Z=4, and I/Ic=1.03.

Scheme of Model Updating and Implement for Structural Dynamics Analysis

2012 ◽  
Vol 252 ◽  
pp. 140-143
Author(s):  
Dong Sheng Yao ◽  
Li Bin Zhao
Keyword(s):  
Cylindrical Shell ◽  
Shell Structure ◽  
Structural Model ◽  
Model Updating ◽  
Modal Assurance Criterion ◽  
Mass System ◽  
Actual Structure ◽  
Modal Data ◽  
Global And Local ◽  
Good Agreement

Model updating techniques are used to modify structural model for more accurate predictions of dynamics behavior. A simple survey on the model updating methods and correlation criteria is presented. Based on the inverse eigensensitivity method (IESM) and modal assurance criterion (MAC), a scheme of model updating for structures is presented and realized by user defined subroutine combined with APDL in commercial software ANSYS®. A four-DOF spring-mass system is assumed and updated, from which the predicted frequencies and MAC values are satisfied compared to the actual dynamics characteristics. This gives evidence that the presented model updating scheme is feasible and efficient. Furthermore, a cylindrical shell structure containing global and local modal information is established to research the updating ability of the scheme on some focused local modal information. The results due to the updated model of cylindrical shell structure show that not only the global modal data but also the local modal data have a good agreement with that of the actual structure.

scholarly journals Crystal structure of KNaCuP2O7, a new member of the diphosphate family

2018 ◽  
Vol 74 (2) ◽  
pp. 109-112 ◽  
Author(s):  
Ines Fitouri ◽  
Habib Boughzala
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Charge Distribution ◽  
Structural Model ◽  
Interlayer Space ◽  
Structure Type ◽  
Solid State Reactions ◽  
Space Group ◽  
Potassium Sodium ◽  
Bond Valence Sum

Potassium sodium copper(II) diphosphate(V), KNaCuP2O7, was synthesized by solid-state reactions. It crystallizes in the α-Na2CuP2O7 structure type in space group P21/n. In the crystal, CuO5 square-pyramids are linked to nearly eclipsed P2O7 groups by sharing corners to build up corrugated layers with composition [CuP2O7]2− that extend parallel to (010). The K+ and Na+ cations reside in the interlayer space and are connected to nine and seven O atoms, respectively. The structural model was validated by bond-valence-sum (BVS) and charge-distribution (CHARDI) analysis.

scholarly journals Die Kristallstrukturen von Strontium- und Bariumhexacyanoferrat(III)-Hexamethylentetramin-Hydraten. Strukturmodell für Additionsverbindungen der Alkali- und Erdalkalimetallhexacyanoferrate mit Hexamethylentetramin / The Crystal Structures of Hydrates of Strontium and Barium Hexacyanoferrate(III) with Hexamethylenetetramine. Structural Model for Adducts of the Hexacyanoferrates of Alkaline and Alkaline Earth Metals with Hexamethylenetetramine

1989 ◽  
Vol 44 (5) ◽  
pp. 519-525 ◽  
Author(s):  
Hans-Jürgen Meyer ◽  
Joachim Pickardt
Keyword(s):  
Aqueous Solutions ◽  
Crystal Structures ◽  
General Formula ◽  
Alkaline Earth ◽  
Structural Model ◽  
Earth Metal ◽  
Alkaline Earth Metals ◽  
Alkaline Earth Metal ◽  
Monoclinic Space Group ◽  
Space Group

By reaction of methanolic solutions of hexamethylenetetramine with aqueous solutions of hexacyanoferrates(III) of strontium and barium resp., crystals of the compounds were obtained. Sr3[Fe(CN)6]2 · 3 C6H12N4 · 18 H2O, tetragonal, space group P42/nmc, Z = 4, a = 1931.8(4), c = 1579.9(4) pm, 1358 reflections. R = 0.066. Ba3[Fe(CN)6]2 · 2 C6H12N4 · 11 Η2Ο. monoclinic. space group P21/n, Ζ = 2, a = 1148.0(4), b = 1369.7(4), c = 1584.5(4) pm, γ = 95.79(3)°, 2583 reflections, R = 0.057. The crystal structures of these adducts are compared with those of other hexamethylenetetramine adducts of alkaline and alkaline earth metal hexacyanoferrates of the general formula M,[Fe(CN)6]y · zC6H12N4 · vH2O recently investigated by us. A structural model for the adducts is presented.

The crystal structure of myoglobin III. Sperm-whale myoglobin

1957 ◽  
Vol 238 (1214) ◽  
pp. 305-324 ◽  
Keyword(s):  
Sperm Whale ◽  
Two Dimensional ◽  
Crystal Forms ◽  
Space Group ◽  
Spin Resonance ◽  
Orthorhombic Crystals ◽  
Optical Dichroism ◽  
Sperm Whale Myoglobin ◽  
Identical Crystal ◽  
Good Agreement

Myoglobin of Physeter catodon (sperm whale) forms monoclinic crystals with space group P 2 1 (type A ) in ammonium sulphate, and orthorhombic crystals with space group P 2 1 2 1 2 1 (type B ) in phosphate. Almost identical crystal forms are obtained from related species of whale. Two-dimensional Patterson projections have been computed from some principal zones of reflexions in each type of crystal. They are used to derive the chain directions of the poly­peptide chains in the molecules relative to the crystal axes, and to suggest plausible methods of packing in the two forms. The data are best fitted by a molecule having dimensions about 25 x 34 x 42 Å, the latter dimension being parallel to the chain direction. Measurements of electron-spin resonance (Bennett & Ingram 1956) and of optical dichroism have been used to determine the orientation of the planes of the haem group and the angle between them and the chains. It is concluded that the angle is 40 to 50° in the two forms, in good agreement with the value found for type F crystals in an earlier paper, namely, 41°. Thus in all three crystal types A , B and F the data are consistent with the molecule having the same set of dimensions, associated with a common chain direction and a common relation between chain direction and haem group.

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