Nanostructured ZnS with random close-packed structure: Synthesis, formation rate, and crystal structure study

2016 ◽  
Vol 470 (2) ◽  
pp. 141-144 ◽  
Author(s):  
A. S. Vorokh ◽  
N. S. Kozhevnikova ◽  
A. A. Uritskaya ◽  
V. G. Bamburov
Keyword(s):  
Crystal Structure ◽  
Formation Rate ◽  
Structure Study ◽  
Structure Synthesis ◽  
Close Packed Structure ◽  
Packed Structure

scholarly journals Role of halogen substituents in a series of polymorphic 2,5-diamino-3,6-dicyanopyrazine derivatives with highly flexible groups

2017 ◽  
Vol 232 (5) ◽  
pp. 395-405 ◽  
Author(s):  
Yoko Akune ◽  
Risa Hirosawa ◽  
Atsushi Koseki ◽  
Shinya Matsumoto
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Electrostatic Interactions ◽  
Crystal Structure Analysis ◽  
Stable Form ◽  
Thermally Stable ◽  
Close Packed Structure ◽  
Packed Structure ◽  
Stable Forms ◽  
Metastable Forms

AbstractThe crystal structures of the ortho-X-benzyl derivatives, where X=F, Cl, Br, I, and Me, of 2,5-bis(N,N-dibenzylamino)-3,6-dicyanopyrazine dyes (C34H24N6X4) were analysed to evaluate the effect of a systematic series of structures on the occurrence of polymorphism. Detailed crystal structure analysis indicated that the thermally stable forms of the polymorphic derivatives (Cl and Br derivatives) were close-packed, whereas those of the non-polymorphic derivatives (F and I derivatives) were stabilised by an intermolecular interaction involving the ortho-substituents. In the thermally metastable forms of the polymorphic derivative, halogen-halogen and halogen-nitrogen interactions contributed to the stabilisation of these crystals in the same way as the thermally stable form of the non-polymorphic derivatives. This indicated that the ease of polymorph occurrence would require an appropriate balance between the crystal energy of the close-packed structure and that of the crystal structure generated mainly by the electrostatic interactions involving the halogens in these halogenated pyrazine derivatives. In addition, the similar tendency of the occurrence of polymorphs in these halogenated pyrazine derivatives was found in 19 sets of halogenated compounds having known crystal structures of F, Cl, Br and I derivatives including at least one polymorphic derivative in the crystal structure database.

Stacking sequences of the crystallites in Co-Sm films

1996 ◽  
Vol 54 ◽  
pp. 714-715
Author(s):  
B. W. Robertson ◽  
Y. Liu
Keyword(s):  
Crystal Structure ◽  
Equilibrium Phase ◽  
High Resolution Electron Microscopy ◽  
Magnetic Thin Films ◽  
Equilibrium Phase Diagram ◽  
Stacking Sequence ◽  
Close Packed Structure ◽  
Resolution Electron ◽  
Layer Stacking ◽  
Packed Structure

Magnetic thin films sputtered from the Co-Sm system have been shown to be promising as recording media. High coercivities of up to 4.0 kOe have been obtained from Co-Sm films. Recent microstructure characterization of Co-Sm films deposited by the DC magnetron sputtering has shown that the microstructure is composed of the amorphous matrix and crystallites with a grain size of about 5nm . As different sputtering processes have different dynamics for the formation of the nanostructure, phases formed could be different from those predicted by the equilibrium phase diagram. Crystal structure determination is important for understanding the high anisotropy and epitaxy growth of the Co-Sm films. The crystal structure of the crystallites was identified to be a close-packed structure. However, the stacking sequence changes from crystallite to crystallite. This paper describes the detailed high resolution electron microscopy (HREM) study of the stacking sequence of the crystallites in Co-Sm films. It is found that the stacking near the Cr underlayer tends to be hexagonal (ABAB) stacking. As the film grows, the stacking sequence is disturbed and three layer stacking, four layer stacking and random stacking are formed.

scholarly journals Crystal Structure, Synthesis and Biological Activity of Ether and Ester <i>Trans</i>-Ferulic Acid Derivatives

2018 ◽  
Vol 08 (04) ◽  
pp. 359-377 ◽  
Author(s):  
Marco A. Obregón-Mendoza ◽  
M. Mirian Estévez-Carmona ◽  
Yair Alvarez-Ricardo ◽  
William Meza-Morales ◽  
Carolina Escobedo-Martínez ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biological Activity ◽  
Ferulic Acid ◽  
Structure Synthesis

Oxycalcioroméite, Ca2Sb2O6O, from Buca della Vena mine, Apuan Alps, Tuscany, Italy: a new member of the pyrochlore supergroup

2013 ◽  
Vol 77 (7) ◽  
pp. 3027-3037 ◽  
Author(s):  
C. Biagioni ◽  
P. Orlandi ◽  
F. Nestola ◽  
S. Bianchin
Keyword(s):  
Crystal Structure ◽  
Detection Limit ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Structure Study ◽  
New Mineral ◽  
X Ray ◽  
New Mineral Species ◽  
Single Crystal Study ◽  
Apuan Alps

AbstractThe new mineral species oxycalcioroméite, Ca2Sb5+2O6O, has been discovered at the Buca della Vena mine, Stazzema, Apuan Alps, Tuscany, Italy. It occurs as euhedral octahedra, up to 0.1 mm in size, embedded in dolostone lenses in the baryte + pyrite + iron oxides ore. Associated minerals are calcite, cinnabar, derbylite, dolomite, hematite, 'mica', pyrite, sphalerite and 'tourmaline'. Oxycalcioroméite is reddish-brown in colour and transparent. It is isotropic, with ncalc = 1.950.Electron microprobe analysis gave (wt.%; n = 6) Sb2O5 63.73, TiO2 3.53, SnO2 0.28, Sb2O3 10.93, V2O3 0.68, Al2O3 0.28, PbO 0.68, FeO 5.52, MnO 0.13, CaO 13.68, Na2O 0.83, F 1.20, O = F – 0.51, total 100.96. No H2O, above the detection limit, was indicated by either infrared or micro-Raman spectroscopies. The empirical formula, based on 2 cations at the B site, is (Ca1.073Fe2+0.338Sb3+0.330Na0.118Pb0.013Mn0.008)Σ=1.880(Sb5+1.734Ti0.194V0.040Al0.024Sn0.008)Σ=2.000(O6.682F0.278)Σ6.960. The crystal structure study gives a cubic unit cell, space group Fdm, with a 10.3042(7) Å, V 1094.06(13) Å3, Z = 8. The five strongest X-ray powder diffraction lines are [d(Å)I(visually estimated)(hkl)]: 3.105(m)(311); 2.977(s)(222); 2.576(m)(400); 1.824(ms)(440); and 1.556(ms)(622). The crystal structure of oxycalcioroméite has been solved by X-ray single-crystal study on the basis of 114 observed reflections, with a final R1 = 0.0114. It agrees with the general features of the members of the pyrochlore supergroup.

scholarly journals Solidified Fillings of Nanopores

2005 ◽  
Vol 876 ◽  
Author(s):  
Patrick Huber ◽  
Klaus Knorr
Keyword(s):  
Pore Diameter ◽  
Stacking Faults ◽  
Pore Geometry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Medium Length ◽  
Close Packed Structure ◽  
Packed Structure ◽  
Diffraction Patterns ◽  
Selection Of

AbstractWe present a selection of x-ray diffraction patterns of spherical (He, Ar), dumbbell- (N2, CO), and chain-like molecules (n-C9H20, n-C19H40) solidified in nanopores of silica glass (mean pore diameter 7nm). These patterns allow us to demonstrate how key principles governing crystallization have to be adapted in order to accomplish solidification in restricted geometries. 4He, Ar, and the spherical close packed phases of CO and N2 adjust to the pore geometry by introducing a sizeable amount of stacking faults. For the pore solidified, medium-length chainlike n-C19H40 we observe a close packed structure without lamellar ordering, whereas for the short-chain C9H20 the layering principle survives, albeit in a modified fashion compared to the bulk phase.

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