Crystal structure of a calcium sulfate-urea complex

1975 ◽  
Vol 5 (4) ◽  
pp. 215-226 ◽  
Author(s):  
J. P. R. Villiers ◽  
J. C. A. Boeyens
Keyword(s):  
Crystal Structure ◽  
Calcium Sulfate ◽  
Urea Complex

The preparation and crystal structure of a polymeric (1 : 1)-silver nitrate-urea complex, [(AgNO3)2(CH4N2O)2]n

Polyhedron ◽  
1992 ◽  
Vol 11 (1) ◽  
pp. 49-52 ◽  
Author(s):  
Dalius S. Sagatys ◽  
Raymond C. Bott ◽  
Graham Smith ◽  
Karl A. Byriel ◽  
Colin H.L. Kennard
Keyword(s):  
Crystal Structure ◽  
Silver Nitrate ◽  
Urea Complex

Crystal structure formation of hemihydrate calcium sulfate whiskers (HH-CSWs) prepared using FGD gypsum

Polyhedron ◽  
2019 ◽  
Vol 173 ◽  
pp. 114140 ◽  
Author(s):  
Xiaoting Zhang ◽  
Xiao Wang ◽  
Biao Jin ◽  
Xueping Liu ◽  
Liushuan Yang
Keyword(s):  
Crystal Structure ◽  
Structure Formation ◽  
Calcium Sulfate ◽  
Fgd Gypsum ◽  
Calcium Sulfate Whiskers ◽  
Crystal Structure Formation

The crystal structure of a hydrated gramicidin S–urea complex

Nature ◽  
1978 ◽  
Vol 275 (5677) ◽  
pp. 206-207 ◽  
Author(s):  
S. E. HULL ◽  
R. KARLSSON ◽  
P. MAIN ◽  
M. M. WOOLFSON ◽  
E. J. DODSON
Keyword(s):  
Crystal Structure ◽  
Urea Complex ◽  
Gramicidin S

Hydration Ability of Hemihydrate Calcium Sulphate Whiskers with Different Content of Sodium Phosphate

2014 ◽  
Vol 638-640 ◽  
pp. 1346-1349 ◽  
Author(s):  
Chang Chen ◽  
Yu Bin Wang ◽  
Le Yu ◽  
Ying Jie Song ◽  
Shan Shan Zhang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Calcium Sulfate ◽  
Sodium Phosphate ◽  
Calcium Sulphate ◽  
Standing Time ◽  
Different Content ◽  
Calcium Sulfate Whisker

Different content of sodium phosphate was added into the hemihydrates sulphate whiskers for 30 min to 2h of standing time. The treated products were researched by SEM, TG-DSC and XRD. The results indicate that when the dosage of sodium phosphate was more than 0.10%, the morphology of hemihydrate calcium sulphate whisker was fully maintained. However, the crystal structure of the products had changed and the half water calcium sulfate turned into of dihydrate calcium sulphate when 0.10 wt% sodium phosphate added. With the increase of standing time, half water calcium sulfate whisker converted into dihydrate calcium sulphate whisker. Sodium phosphate could reduce hydration ability of half water calcium sulfate whisker when the content of sodium phosphate was more than 0.10%.

Thermal Behaviour and Crystal Structure of Sodium-Containing Hemihydrates of Calcium Sulfate

1999 ◽  
Vol 130 (10) ◽  
pp. 1179-1193
Author(s):  
Daniela Freyer ◽  
Günter Reck ◽  
Martina Bremer ◽  
Wolfgang Voigt
Keyword(s):  
Crystal Structure ◽  
Thermal Behaviour ◽  
Calcium Sulfate

scholarly journals Optimizing the characteristics of calcium sulfate dihydrate in the flue gas desulfurization process: Investigation of the impurities in slurry-Cl-, Fe3+, Mn2+

2017 ◽  
Vol 23 (3) ◽  
pp. 293-299
Author(s):  
Lina Lv ◽  
Jianbin Yang ◽  
Zhigang Shen ◽  
Yanbo Zhou ◽  
Jun Lu
Keyword(s):  
Crystal Structure ◽  
Particle Size ◽  
Flue Gas ◽  
Calcium Sulfate ◽  
Crystal Morphology ◽  
Flue Gas Desulfurization ◽  
Calcium Sulfate Dihydrate ◽  
Desulfurization Process ◽  
Desulfurization Efficiency ◽  
End Use

The effects of limestone, Cl-, Fe3+ and Mn2+ in slurry on the characteristics of calcium sulfate dehydrate (DH) in flue gas desulfurization (FGD) process were investigated. The moisture content, particle size distribution, and crystal morphology were considered as end use characteristics of DH. As a result, the number of needle-like DH crystals was increased with increasing total contents of MgCO3, Al2O3 and Fe2O3 in limestone. Cl ions were reported to distort the crystal structure and change the crystals from orthorhombic to irregular. Mn2+ can increase the desulfurization efficiency by catalyzing the oxidation of SO2. Finally, Fe3+ will inhibit crystal growth of all faces, except {011} and {111}.

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Transmission Electron Microscopy studies of the vacancy ordering in YSI2-X thin films

1991 ◽  
Vol 49 ◽  
pp. 562-563
Author(s):  
F.-R. Chen ◽  
T. L. Lee ◽  
L. J. Chen
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Thin Films ◽  
Diffraction Pattern ◽  
Annealing Temperature ◽  
Lattice Mismatch ◽  
Si Substrate ◽  
Metal Thin Films ◽  
Transmission Electron ◽  
Vacancy Ordering

YSi2-x thin films were grown by depositing the yttrium metal thin films on (111)Si substrate followed by a rapid thermal annealing (RTA) at 450 to 1100°C. The x value of the YSi2-x films ranges from 0 to 0.3. The (0001) plane of the YSi2-x films have an ideal zero lattice mismatch relative to (111)Si surface lattice. The YSi2 has the hexagonal AlB2 crystal structure. The orientation relationship with Si was determined from the diffraction pattern shown in figure 1(a) to be and . The diffraction pattern in figure 1(a) was taken from a specimen annealed at 500°C for 15 second. As the annealing temperature was increased to 600°C, superlattice diffraction spots appear at position as seen in figure 1(b) which may be due to vacancy ordering in the YSi2-x films. The ordered vacancies in YSi2-x form a mesh in Si plane suggested by a LEED experiment.

Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

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