X-ray structural studies of epitaxial yttrium silicide on Si(111)

1994 ◽  
Vol 9 (6) ◽  
pp. 1434-1440 ◽  
Author(s):  
L.J. Martínez-Miranda ◽  
J.J. Santiago-Avilés ◽  
W.R. Graham ◽  
P.A. Heiney ◽  
M.P. Siegal
Keyword(s):  
Unit Cell Volume ◽  
Film Growth ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Correlation Lengths ◽  
X Ray ◽  
Lattice Constants ◽  
Glancing Angle ◽  
Out Of Plane ◽  
The Mean

We performed a series of glancing angle and reflection x-ray diffraction experiments to study both the in-plane and out-of-plane structure of epitaxial YSi2−x films grown on Si(111), with thicknesses ranging from 85 Å to 510 Å. These measurements allowed us to characterize the mean film lattice constants, the position correlation lengths of the film, and the presence and extent of strain as a function of film thickness. We find that the strain along the basal plane increases as a function of increasing thickness to approximately 1% in the 510 Å film; the corresponding out-of-plane strain is such that the film unit cell volume increases as a function of thickness. The corresponding in-plane microscopic strain varies from 0.5% for the 85 Å film to 0.3% for the 510 Å film. We relate our results to the mode of film growth and the presence of pinholes in the films.

Crystal Structure of Tris(1,10-phenanthroline)mercury(II) Trifluoromethanesulfonate

1979 ◽  
Vol 32 (10) ◽  
pp. 2195 ◽  
Author(s):  
GB Deacon ◽  
CL Raston ◽  
D Tunaley ◽  
AH White
Keyword(s):  
Crystal Structure ◽  
Aqueous Solution ◽  
Title Compound ◽  
Unit Cell Volume ◽  
Octahedral Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ethanol Solvate ◽  
The Mean ◽  
Trigonal Prismatic

The crystal structure of the ethanol solvate of the title compound, [Hg(phen)3](CF3S03)2 (phen =1,10-phenanthroline), has been determined at 295(1) K by single-crystal X-ray diffraction and refined by least squares to a residual of 0�043 for 2939 'observed' reflections. Crystals are monoclinic: C2/c, a 25�25(1), b 10�960(4), c 18�949(6) �, β 129�32(2)�, Z 4. The cation is centred on a crystallographictwofold axis and has approximate D3 point symmetry. The deviation of the mercury(II) environment from octahedral symmetry toward the trigonal-prismatic limit is considerable, the mean trans N-Hg-N angle being 154�52�. <Hg-N> is 2�400 �. The unit cell volume is considerablydependent on crystallization solvent, being larger for the ethanol solvate than for solvent-free crystals obtained from aqueous solution.

An X-Ray Diffraction Attachment tor Thin Filam Analysis of High Sensitivity

1985 ◽  
Vol 54 ◽  
Author(s):  
Kun Tao ◽  
Zhili Dong ◽  
Shunying Chen ◽  
Bingju Wang
Keyword(s):  
High Sensitivity ◽  
Scanning Speed ◽  
Solid Surfaces ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Glancing Angle ◽  
Good Pattern ◽  
Diffraction Peaks ◽  
Very High

ABSTRACTA Seemann-Bohlin X-ray diffration attachment has been developed recently. In addition, two new intensity factors are introduced to existing intensity formula of Seemann-Bohlin diffractometer. Its characteristic is that the glancing angle is rather small and that no crystal monochromator is put in the incident path. Compared with the conventional diffractometer, it is superior in many aspects: (1). Very high sensitivity in identifying the structures of solid surfaces and thin films, with the intensities being 7–20 times those of the conventional method. For example, in analysing a gold film of 70 Å thick by 1KW X-ray, a fairly good pattern was obtained up to 2θ=120° with the scanning speed of 4°(2θ)/min. (2). All diffraction peaks obtained give the information of the surface layer in nearly the same depth. It thus enables one to study the variation of the composition, the lattice constants, and the structures with depth. (3). It can also be used for thick polycrys-talline samples, and the intensities are 3–20 times those of the conventional diffractometer. This method can be used for various ordinary diffractometers.

The crystal and molecular structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane

1984 ◽  
Vol 62 (4) ◽  
pp. 661-666 ◽  
Author(s):  
Willem Anker ◽  
Kathy A. Beveridge ◽  
Gordon W. Bushnell ◽  
Reginald H. Mitchell
Keyword(s):  
Crystal Structure ◽  
Crystal And Molecular Structure ◽  
Variable Temperature ◽  
Phenyl Group ◽  
Outer Side ◽  
X Ray Diffraction ◽  
X Ray ◽  
Out Of Plane ◽  
Boat Form ◽  
The Mean

The crystal structure of syn-9-phenyl-2,11-dithia[3,3]metacyclophane, 6, has been determined by single crystal X-ray diffraction and refined to an R value of 0.0723. The crystal structure is triclinic with a = 9.573(2), b = 12.010(4), c = 8.433(2) Å, α = 108.02(2)°, β = 95.95(2)°, γ = 102.25(3)°, and the space group is [Formula: see text] with two molecules per cell, D(meas) = 1.313 g cm−3, D(calc) = 1.306 g cm−3. The bridging S atoms differ in their conformations so that the S … S distance is 6.391 Å. The metacyclophane rings have a distance of 3.57 Å between their centres and form a dihedral angle of 20.5°. The phenyl substituent forms an angle of 78.6° with the adjacent ring and has an ortho H-atom very close to the internal H-atom of the opposite ring. The phenyl substituted aromatic ring is non-planar and in a shallow boat form, the ring atoms C(11) (internal) and C(14) being 0.038(4) and 0.037(5) Å out-of-plane on the outside, the methylene C substituents are 0.212(5) and 0.199(5) Å out-of-plane on the inside. The first atom of the phenyl group is in the bowsprit position and is 0.274(4) Å above the mean plane on the outer side of the molecule. The opposite metacyclophane ring is less strained but in a similar boat form with the methylene C-atoms 0.092(4) and 0.067(6) Å to the inside. The mean bond angle at S is 103.5(2)°, the angles at C (methylene) range from 113.3(3)° to 118.0(3)°.The variable temperature 1Hmr spectra results are consistent with the syn conformer 6 being dominant in solution and frozen at temperatures <60 °C as conformer A, with only relatively restricted further twisting of the biphenyl being found at ambient temperature.

Effect of Ti Sputtering Current on Structure of TiCrN Thin Films Prepared by Reactive DC Magnetron Co-Sputtering

2016 ◽  
Vol 675-676 ◽  
pp. 181-184 ◽  
Author(s):  
Nirun Witit-Anun ◽  
Amphol Teekhaboot
Keyword(s):  
Thin Films ◽  
Crystal Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Lattice Constants ◽  
Atomic Force ◽  
Glancing Angle ◽  
Deposited Films ◽  
Section Analysis

Titanium chromium nitride (TiCrN) thin films were deposited by reactive DC magnetron co-sputtering. The effect of Ti sputtering current (ITi) on the structure of the TiCrN thin films were investigated. The crystal structure, microstructure, thickness, roughness and elemental composition were characterized by glancing angle X-ray diffraction (GAXRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy (EDS) technique, respectively. The results showed that, all the as-deposited films were formed as a (Ti,Cr)N solid solution. The as-deposited films exhibited a nanostructure with a crystallite size of less than 40 nm. The crystal size decreased from 39.9 nm to 33.5 nm, while the lattice constants increased from 4.139 Å to 4.162 Å, with increasing of the Ti sputtering current. The film thickness and roughness were found to increase from 397 nm to 615 nm and 3.7 nm to 6.3 nm, respectively, with increasing of the Ti sputtering current. The composition of the as-deposited films varied with the Ti sputtering current. Cross section analysis by FE-SEM showed compact columnar and dense morphology as a result of increasing the Ti sputtering current.

An ultrahigh-vacuum chamber for surface X-ray diffraction

1998 ◽  
Vol 5 (3) ◽  
pp. 890-892 ◽  
Author(s):  
C. L. Nicklin ◽  
J. S. G. Taylor ◽  
N. Jones ◽  
P. Steadman ◽  
C. Norris
Keyword(s):  
Vacuum Chamber ◽  
Film Growth ◽  
Layer Structure ◽  
Ultrahigh Vacuum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Auger Signal ◽  
Out Of Plane ◽  
Plane Detector

An ultrahigh-vacuum environmental chamber for surface X-ray diffraction on Station 9.4 at the Synchrotron Radiation Source, Daresbury Laboratory, is described. Film growth can be monitored by simultaneously recording the Auger signal and the X-ray intensity at a particular point in reciprocal space. Such in situ measurements are essential for understanding the dynamic processes that occur during adsorption. An example is given in which the specularly reflected X-ray signal is correlated with Auger plots, during growth of Tl on Cu(001). In addition, the diffractometer and chamber combination allow large reconstructions to be investigated as shown by the in-plane structural analysis of the c(4×4) InSb surface. A study of the layer structure of Cr on Ag(001), in which an extended out-of-plane detector assembly was used, is also presented.

scholarly journals CADEM: calculate X-ray diffraction of epitaxial multilayers

2017 ◽  
Vol 50 (1) ◽  
pp. 288-292 ◽  
Author(s):  
Paulina Komar ◽  
Gerhard Jakob
Keyword(s):  
Strain Relaxation ◽  
Diffraction Theory ◽  
Layer By Layer ◽  
Material System ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Out Of Plane ◽  
Xrd Patterns ◽  
Epitaxial Multilayers

Epitaxial multilayers and superlattice (SL) structures are gaining increasing importance as they offer the opportunity to create artificial crystals with new functionalities. These crystals deviate from the parent bulk compounds not only in terms of the lattice constants but also in the symmetry classification, which renders calculation of their X-ray diffraction (XRD) patterns tedious. Nevertheless, XRD is essential to get information on the multilayer/SL structure such as, for example, out-of-plane lattice constants, strain relaxation and period length of the crystalline SL. This article presents a powerful yet simple program, based on the general one-dimensional kinematic X-ray diffraction theory, which calculates the XRD patterns of tailor-made multilayers and thus enables quantitative comparison of measured and calculated XRD data. As the multilayers are constructed layer by layer, the final material stack can be entirely arbitrary. Moreover, CADEM is very flexible and can be straightforwardly adapted to any material system. The source code of CADEM is available as supporting material for this article.

The study of the structure stability of hexagonal Bi(PO4)(H2O)0.67 under high pressure

2017 ◽  
Vol 31 (25) ◽  
pp. 1745020 ◽  
Author(s):  
Jun Zhang ◽  
Zhen Yuan ◽  
Jian-Fa Zhao ◽  
Wen-Min Li ◽  
Ya-Ting Jia ◽  
...  
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Unit Cell Volume ◽  
Ambient Pressure ◽  
Structure Stability ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Experimental Pressure ◽  
Text Unit

In this work, the structure stability of hexagonal Bi(PO[Formula: see text](H2O)[Formula: see text] has been investigated by high-pressure synchrotron X-ray diffraction measurements. The results show that the structure is stable within the pressure up to 18.3 GPa. The diffraction data are refined and the lattice constants [Formula: see text] and [Formula: see text] are determined, which is compressed by 6.3(7)% and 3.5(0)% within the experimental pressure, respectively. By fitting the pressure dependence of [Formula: see text] (unit cell volume divided by that at ambient pressure) with the second-order Birch equation of state, the bulk modulus [Formula: see text] is given to be about 87.1(0) GPa.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

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