Neutron and X-ray Diffraction Study on the Structure of Ultraphosphate Glasses

1997 ◽  
Vol 52 (3) ◽  
pp. 259-269 ◽  
Author(s):  
Uwe Hoppe ◽  
Günter Walter ◽  
Dörte Stachel ◽  
Andrea Barz ◽  
Alex C. Hannon
Keyword(s):  
Crystal Structures ◽  
Coordination Number ◽  
Real Space ◽  
The Other ◽  
Oxide Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Resolution ◽  
Epithermal Neutrons ◽  
The Mean

Abstract The high real-space resolution of neutron diffraction experiments which is provided by use of the epithermal neutrons from spallation sources was exploited in order to differentiate the unlike P-O bonds existing in the PO4 units of phosphate glass networks. The 2 P-O distance peaks, separated by about 12 pm, which were found in the zinc and the calcium ultraphosphate glasses studied are assigned to oxygen sites on bridging (OB) and terminal (OT) positions. The mean P-O distances are nearly invariable versus the growing metal oxide content which results from an elongation of the P-OB and P-OT bonds. The bond lengths which are known from the related crystal structures and from ab initio calculations show almost the same behaviour. The discussion of further details of the crystal structures leads to the conclusion that P-OB rather than P-OT distances should show more details in case of diffraction measurements of even higher real-space resolution. The change of the Zn-O coordination number from 6 to 4 versus increasing ZnO content, which was obtained in previous X-ray diffraction experiments, is confirmed by the recent combination of neutron and X-ray diffraction data. On the other hand, the Ca-O coordination number of about 6 is almost invariable.

The structures of marialite (Me6) and meionite (Me93) in space groups P42/n and I4/m, and the absence of phase transitions in the scapolite series

2011 ◽  
Vol 26 (2) ◽  
pp. 119-125 ◽  
Author(s):  
Sytle M. Antao ◽  
Ishmael Hassan
Keyword(s):  
Phase Transitions ◽  
High Resolution ◽  
Crystal Structures ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Space Groups ◽  
Cell Parameters ◽  
The Mean

The crystal structures of marialite (Me6) from Badakhshan, Afghanistan and meionite (Me93) from Mt. Vesuvius, Italy were obtained using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data and Rietveld structure refinements. Their structures were refined in space groups I4/m and P42/n, and similar results were obtained. The Me6 sample has a formula Ca0.24Na3.37K0.24[Al3.16Si8.84O24]Cl0.84(CO3)0.15, and its unit-cell parameters are a=12.047555(7), c=7.563210(6) Å, and V=1097.751(1) Å3. The average ⟨T1-O⟩ distances are 1.599(1) Å in I4/m and 1.600(2) Å in P42/n, indicating that the T1 site contains only Si atoms. In P42/n, the average distances of ⟨T2-O⟩=1.655(2) and ⟨T3-O⟩=1.664(2) Å are distinct and are not equal to each other. However, the mean ⟨T2,3-O⟩=1.659(2) Å in P42/n and is identical to the ⟨T2′-O⟩=1.659(1) Å in I4/m. The ⟨M-O⟩ [7]=2.754(1) Å (M site is coordinated to seven framework O atoms) and M-A=2.914(1) Å; these distances are identical in both space groups. The Me93 sample has a formula of Na0.29Ca3.76[Al5.54Si6.46O24]Cl0.05(SO4)0.02(CO3)0.93, and its unit-cell parameters are a=12.19882(1), c=7.576954(8) Å, and V=1127.535(2) Å3. A similar examination of the Me93 sample also shows that both space groups give similar results; however, the C–O distance is more reasonable in P42/n than in I4/m. Refining the scapolite structure near Me0 or Me100 in I4/m forces the T2 and T3 sites (both with multiplicity 8 in P42/n) to be equivalent and form the T2′ site (with multiplicity 16 in I4/m), but ⟨T2-O⟩ is not equal to ⟨T3-O⟩ in P42/n. Using different space groups for different regions across the series implies phase transitions, which do not occur in the scapolite series.

An EXAFS Investigation of Local Structure around Rb+ in Aqueous Solution

1994 ◽  
Vol 49 (6) ◽  
pp. 727-729 ◽  
Author(s):  
Yoshihiro Kubozono ◽  
Akiko Hirano ◽  
Hironobu Maeda ◽  
Setsuo Kashino ◽  
Shuichi Emura ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Coordination Number ◽  
Local Structure ◽  
The Other ◽  
Alkaline Metal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Exafs Spectra

Abstract EXAFS spectra have been measured in order to elucidate the local structure around Rb+ in aqueous solution. It has been found that the Rb+ is surrounded by ca. six O atoms of H2O molecules. The Rb -O distance was determined to be 2.90 (3) Å. The coordination number and Rb -O distance compare well with those of the other alkaline metal ions estimated by X-ray diffraction.

scholarly journals High real-space resolution structure of materials by high-energy x-ray diffraction

1999 ◽  
Vol 590 ◽  
Author(s):  
V. Petkov ◽  
S. J. L. Billinge ◽  
J. Heising ◽  
M. G. Kanatzidis ◽  
S. D. Shastri ◽  
...  
Keyword(s):  
Pair Distribution Function ◽  
High Energy ◽  
Real Space ◽  
Function Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Resolution ◽  
Atomic Pair Distribution Function ◽  
Atomic Pair ◽  
Resolution Structure

ABSTRACTResults of high-energy synchrotron radiation experiments are presented demonstrating the advantages of the high-resolution atomic Pair Distribution Function technique in determining the structure of materials with intrinsic disorder.

Synthesis, lead lability and ring deformation of three 1,4,8,11,15,18,22,25-octasubstituted phthalocyaninato lead derivatives

2006 ◽  
Vol 10 (10) ◽  
pp. 1202-1211 ◽  
Author(s):  
Paul M. Burnham ◽  
Isabelle Chambrier ◽  
David L. Hughes ◽  
Benjamin Isare ◽  
Richard J. Poynter ◽  
...  
Keyword(s):  
The Other ◽  
Lead Ion ◽  
X Ray Diffraction ◽  
Steric Interactions ◽  
X Ray ◽  
The Core ◽  
Benzene Rings ◽  
Methylene Groups ◽  
The Mean ◽  
Work Up

The syntheses and attempted syntheses of some non-peripherally (1,4,8,11,15,18,22,25) octasubstituted lead phthalocyanines from their corresponding metal-free derivatives are described. Some compounds exhibited lability of the lead ion during work-up to regenerate the starting material. The results of single crystal X-ray diffraction analyses of 1,4,8,11,15,18,22,25-octahexyl-, 1,4,8,11,15,18,22,25-octa-iso-pentyl- and 1,4,8,11,15,18,22,25-octahexylsulfanyl lead phthalocyanines are reported and cast some light on the greater stability of 1,4,8,11,15,18,22,25-octahexylsulfanyl lead phthalocyanine, in terms of ease of loss of the lead ion, over the other two substituted lead phthalocyanines studied. The phthalocyanine cores of all three derivatives adopt a saddle-shaped geometry rather than the saucer-shaped conformation exhibited by unsubstituted lead phthalocyanine. The saddle-shaped conformation would appear to offer a means of relieving steric interactions between the substituents on adjacent benzene rings. That steric interactions are a feature of these molecules is perhaps reflected in the different distortions of the saddle conformations. This is greatest for compound 1,4,8,11,15,18,22,25-octa-iso-pentyl lead phthalocyanine bearing the isopentyl groups, expected to introduce the most interactions, and least for compound 1,4,8,11,15,18,22,25-octahexylsulfanyl lead phthalocyanine where S atoms rather than methylene groups are adjacent to the benzene ring. The molecules of 1,4,8,11,15,18,22,25-octahexyl- and 1,4,8,11,15,18,22,25-octahexylsulfanyl lead phthalocyanine pack together in pairs with their nearest neighbouring molecule; their lead atoms, displaced from the core and directed towards each other. The presence of the S atoms in 1,4,8,11,15,18,22,25-octahexylsulfanyl lead phthalocyanine leads to close Pb … S contacts between the molecules. Attractive Pb … S interactions in this compound may also account for the larger displacement of the Pb from the mean-plane of the four coordinated nitrogen atoms at the centre of the phthalocyanine core than is found for 1,4,8,11,15,18,22,25-octahexyl- and 1,4,8,11,15,18,22,25-octa-iso-pentyl lead phthalocyanines. The molecular packing of 1,4,8,11,15,18,22,25-octa-iso-pentyl lead phthalocyanine is more complex because of the presence of tetrahydrofuran molecules (the solvent of recrystallisation) within the crystal, offering additional interactions with the Pb atoms.

scholarly journals Crystal structure of bis{(S)-1-[2-(diphenylphosphanyl)ferrocenyl]-(R)-ethyl}ammonium bromide dichloromethane monosolvate

2017 ◽  
Vol 73 (2) ◽  
pp. 152-154
Author(s):  
Afrooz Zirakzadeh ◽  
Berthold Stöger ◽  
Karl Kirchner
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
The Other ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Interplanar Angle ◽  
X Ray ◽  
The Mean ◽  
Protonated Ligand

During the synthesis of an FeBr2complex with the PNP ligand (R,R,SFc,SFc)-[Fe2(C5H5)2(C38H35NP2)] (1), single crystals of the dichloromethane monosolvate of the Br−salt of the protonated ligand1H+were obtained serendipitously,i.e.[Fe2(C5H5)2(C38H36NP2)]Br·CH2Cl2. The crystal structure of1H·Br·CH2Cl2was determined by single-crystal X-ray diffraction. The mean bond lengths in the ferrocene units are Fe—C = 2.049 (3) Å and C—C = 1.422 (4) Å within the cyclopentadienyl rings. The mean C—N bond length is 1.523 (4) Å. The interplanar angle between the two connected cyclopentadienyl rings is 49.2 (2)°. One ferrocene moiety adopts a staggered conformation, whereas the other is between staggered and eclipsed. The Br−ions and the CH2Cl2molecules are located in channels extending along <100>. One ammonium H atom forms a hydrogen bond with the Br−ion [H...Br = 2.32 (4) Å and C—H...Br = 172 (3)°]. The second ammonium H atom is not involved in hydrogen bonding.

Bildung eines Kupfer-Nitratokomplexes aus einem Azidokomplex und Ozon. Die Kristallstruktur von (PPh4)2[CuCl(NO3)3] · CH2Cl2/ Formation of a Copper Nitrato Complex from an Azido Complex. Crystal Structure of (PPh4)2[CuCl(NO3)3] · CH2Cl2

1992 ◽  
Vol 47 (1) ◽  
pp. 31-34 ◽  
Author(s):  
Karin Ruhlandt-Senge ◽  
Alfred D. Bacher ◽  
Ulrich Müller
Keyword(s):  
Crystal Structure ◽  
Coordination Number ◽  
The Other ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
Complex Crystal Structure ◽  
Monodentate Ligands ◽  
Complex Crystal

(PPh4)2[CuCl(NO3)3] · CH2Cl2 is formed when ozone reacts with (PPh4)2[Cu2(N3)6] in dichloromethane. Its crystal structure was determined by X-ray diffraction. Crystal data: a = 1113(1), b = 1156(1), c = 1965(2) pm , α = 101.02(1), β = 93.74(1), γ = 104.05(2)° at 130 K, space group P1̄, Z = 2, R = 0.057 for 3951 observed reflexions. The structure contains CH2Cl2 molecules and PPh4+ and [CuCl(NO3)3]2- ions, with copper having coordination number 5. One nitrate ligand acts as a bidentate chelating unit, and the other two as monodentate ligands.

scholarly journals High Real-Space Resolution Measurement of the Local Structure ofGa1−xInxAsUsing X-Ray Diffraction

1999 ◽  
Vol 83 (20) ◽  
pp. 4089-4092 ◽  
Author(s):  
V. Petkov ◽  
I-K. Jeong ◽  
J. S. Chung ◽  
M. F. Thorpe ◽  
S. Kycia ◽  
...  
Keyword(s):  
Local Structure ◽  
Real Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Resolution ◽  
Resolution Measurement

The Structure of Amorphous Hydrogenated Silicon:Carbon Alloys Using X-Ray and Neutron Scattering and Computer Simulation - The Effect of Hydrogen Dilution

1992 ◽  
Vol 270 ◽  
Author(s):  
T. M. Burke ◽  
P. J. R. Honeybone ◽  
D. W. Huxley ◽  
R. J. Newport ◽  
Th. Frauenheim ◽  
...  
Keyword(s):  
Computer Simulation ◽  
Diffraction Data ◽  
Density Functional ◽  
Real Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Resolution ◽  
Silicon Carbon ◽  
Two Samples ◽  
Silane Precursor

ABSTRACTNeutron and X-ray diffraction techniques have been applied to the study of two samples of a-Si:C:H. Both samples were prepared using conventional glow discharge methods, but the hydrocarbon/silane precursor gas was diluted with hydrogen in one case. Analysis of the X-ray diffraction data gives a clear picture of the silicon network, since the scattering profile is dominated by the Si-Si correlations. The high real-space resolution neutron diffraction data, however allows one to comment on the effect of this dilution on the silicon-carbon bonding morphology, and in particular on the degree to which the additional hydrogen enhances hetero-coordination. In addition we present the results of a preliminary computer simulation study of the structure of a-C:H and a-Si:H using an approximate molecular dynamic density functional theory, and discuss its viability in the study of the more complex a-Si:C:H ternary alloy.

Crystal structures of rac- and meso-o-Phenylenebis(iodomethylarsine), the latter as its lattice complex with the methiodide of 1,3-Dimethyl-1,3-dihydro-2,1,3-benzoxadiarsole

1977 ◽  
Vol 30 (11) ◽  
pp. 2417 ◽  
Author(s):  
K Henrick ◽  
CL Raston ◽  
AH White ◽  
SB Wild
Keyword(s):  
Charge Transfer ◽  
Single Crystal ◽  
Least Squares ◽  
Crystal Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Lengths ◽  
Iodine Species ◽  
Iodide Anion ◽  
The Mean

The crystal structures of the title compounds, o-C6H4(AsMeI)2 (1), and o- C6H4(AsMeI)2- [o-C6H4(AsMe)(As+Me2)O] I- (2), have been determined at 295 K by single-crystal X-ray diffraction and refined by least squares to residuals of 0.037 and 0.067 for 2095 and 2913 reflections respectively. Crystals of (1) are triclinic, Pī, a 9.865(5), b 9.837(7), c 7.765(4) Ǻ, α 98.89(5), β 96.71(4), γ 60.72(4)�, Z 2. <As- I> is 2.585 Ǻ and <As-C> 1.97 Ǻ. The angles about the arsenic differ only trivially, the mean being 98.4�. Crystals of (2) are monoclinic, P21/n, a 15.315(4), b 21.511(8), c 7.952(2) Ǻ, β 98.19(2)�, Z 4. In the cation As-O distances are unequal [1.75(1) (quaternary As), 1.86(2) Ǻ]; As-O-As is very small being 115.8(8)�. Charge-transfer interactions between iodine species are present in both derivatives; in (2), there is an interaction between the tertiary arsenics of the meso molecule and the iodide anion, As...I being 3.307(3), 3.551(3) Ǻ, with the geometry of the arsenics approaching that of a tetrahedral disposition. Within the cation, the geometry about the quaternary arsenic is typical of arsenic(v), the bond lengths being shorter than those about the ternary arsenic.

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