scholarly journals X-Ray Analysis of Alpha Mercuric Iodide Crystal Structure and Processing Effects

1993 ◽  
Vol 302 ◽  
Author(s):  
L. Keller ◽  
E.X. Wang ◽  
A.Y. Cheng
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Device Fabrication ◽  
Mercuric Iodide ◽  
Rocking Curve ◽  
X Ray ◽  
Processing Effects ◽  
Crystal Damage ◽  
Iodide Crystal

ABSTRACTX-ray topography and rocking curve experiments were performed on α-mercuric iodide samples. As-grown crystals were examined for intrinsic defects and crystallinity. Orientation of certain defects depends on the direction of crystal growth. The propagation of as-grown crystalline features was documented. The extent of crystal damage introduced during various steps of device fabrication such as sawing, polishing, etching and contact deposition was explored. Coefficients of linear thermal expansion of α33 = 54 ± 5 (10−6/°C) along the tetragonal c-axis, \001] direction and ±ll = 11 ± 4 (10−6/°C) in the \100] direction were measured.

CRYSTAL STRUCTURE, ELECTRICAL CONDUCTIVITY AND THERMAL EXPANSION OF Pr1-xSrxFeO3-δ(0 ≤ x ≤ 0.6)

2012 ◽  
Vol 26 (32) ◽  
pp. 1250174 ◽  
Author(s):  
V. PRASHANTH KUMAR ◽  
Y. S. REDDY ◽  
P. KISTAIAH ◽  
C. VISHNUVARDHAN REDDY
Keyword(s):  
Crystal Structure ◽  
Electrical Conductivity ◽  
Thermal Expansion ◽  
Room Temperature ◽  
Small Polaron ◽  
Linear Thermal Expansion ◽  
Lattice Parameter ◽  
Polaron Hopping ◽  
X Ray ◽  
Perovskite Type

The crystal structure at room temperature (RT), thermal expansion from RT to 1000°C and electrical conductivity, from RT to 600°C, of the perovskite-type oxides in the system Pr 1-x Sr x FeO 3(x = 0, 0.2, 0.4, 0.6) were studied. All the compounds have the orthorhombic perovskite GdFeO 3-type structure with space group Pbnm. The lattice parameters were determined by X-ray powder diffraction. The Pseudo cubic lattice parameter decreases with an increase in x, while the coefficient of linear thermal expansion increases. The thermal expansion is almost linear for x = 0 and 0.2. The electrical conductivity increases with increasing x while the activation energy decreases. The electrical conductivity can be described by the small polaron hopping conductivity model.

The novel borate Lu5Ba6B9O27 with a new structure type: synthesis, disordered crystal structure and negative linear thermal expansion

2019 ◽  
Vol 75 (4) ◽  
pp. 697-703 ◽  
Author(s):  
Stanislav K. Filatov ◽  
Yaroslav P. Biryukov ◽  
Rimma S. Bubnova ◽  
Andrey P. Shablinskii
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Linear Thermal Expansion ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Monoclinic Crystal ◽  
X Ray ◽  
Cell Parameters ◽  
Vertex Sharing ◽  
Disordered Crystal

Single crystals of Lu5Ba6B9O27 were obtained by cooling from a melt and polycrystals of the borate were prepared using a multi-step solid-state synthesis. The crystal structure was determined from single-crystal X-ray diffraction data. The borate crystallizes in a new structure type in the monoclinic crystal system in space group C2/c, with cell parameters a = 13.0927 (3), b = 9.9970 (2) and c = 20.4884 (4) Å, β = 106.827 (1)°, V = 2566.86 (9) Å3 and Z = 4. It is described as a framework composed of rings consisting of vertex-sharing [BO3] triangles and [LuO6] octahedra. The Ba atoms are in the cavities of the framework. The structure is disordered: one of the B atoms is surrounded by six O atoms with partial occupancies of 0.5. The thermal properties of Lu5Ba6B9O27 were investigated by thermal analysis and high-temperature X-ray powder diffraction. Its thermal expansion is highly anisotropic. The negative expansion (contraction) is along the b axis, i.e. parallel to the planes of the largest number of [BO3] triangles. The coefficient of negative linear expansion ranges from −1.42 (at 20°C) to −5.57 × 10–6 °C–1 (at 1000°C). Thermal deformation of the ac plane is described in terms of the theory of shear deformation of monoclinic crystals. The Lu5Ba6B9O27 sample melts at 1170°C.

The crystal structure and thermal expansion of the CCl4 adduct of Dianin's compound

1990 ◽  
Vol 68 (8) ◽  
pp. 1352-1356 ◽  
Author(s):  
Walter Abriel ◽  
André Du Bois ◽  
Marek Zakrzewski ◽  
Mary Anne White
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Dianin's Compound

The crystal structure of the title compound has been determined by single crystal X-ray diffraction data collected at 293 K, and refined to a final Rw of 0.057. The crystals are rhombohedral, space group [Formula: see text], with a = 27.134(8) Å, c = 10.933(2) Å, and Z = 18. The mole ratio of Dianin's compound (4-p-hydroxyphenyl-2,2,4-trimethylchroman) to CCl4 is 6:1. The guest molecules are disordered. X-ray powder diffraction was carried out in the temperature range from 10 to 300 K. From this, the thermal expansion coefficients for the a- and c-axes and the volume have been determined. Keywords: thermal expansion, crystal structure, clathrate.

Structure and Thermal Expansion Behavior of Dy2-xGdxMo4O15 Solid Solution

2008 ◽  
Vol 368-372 ◽  
pp. 1665-1667
Author(s):  
M.M. Wu ◽  
X.L. Xiao ◽  
Y.Z. Cheng ◽  
J. Peng ◽  
D.F. Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Thermal Expansion ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Behavior ◽  
Expansion Coefficients ◽  
Cell Volumes

A new series of solid solutions Dy2-xGdxMo4O15 (x = 0.0-0.9) were prepared. These compounds all crystallize in monoclinic structure with space group P21/c. The lattice parameters a, b, c and unit cell volumes V increase almost linearly with increasing gadolinium content. The intrinsic thermal expansion coefficients of Dy2-xGdxMo4O15 (x = 0.0 and 0.25) were obtained in the temperature range of 25 to 500°C with high-temperature X-ray diffraction. The correlation between thermal expansion and crystal structure was discussed.

scholarly journals Crystal structure of propionitrile (CH3CH2CN) determined using synchrotron powder X-ray diffraction

2020 ◽  
Vol 27 (1) ◽  
pp. 212-216
Author(s):  
Helen E. A. Brand ◽  
Qinfen Gu ◽  
Justin A. Kimpton ◽  
Rebecca Auchettl ◽  
Courtney Ennis
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Solar System ◽  
Infrared Spectra ◽  
Lower Stratosphere ◽  
Computational Modelling ◽  
Outer Solar System ◽  
X Ray Diffraction ◽  
Near Surface ◽  
X Ray

The structure and thermal expansion of the astronomical molecule propionitrile have been determined from 100 to 150 K using synchrotron powder X-ray diffraction. This temperature range correlates with the conditions of Titan's lower stratosphere, and near surface, where propionitrile is thought to accumulate and condense into pure and mixed-nitrile phases. Propionitrile was determined to crystallize in space group, Pnma (No. 62), with unit cell a = 7.56183 (16) Å, b = 6.59134 (14) Å, c = 7.23629 (14), volume = 360.675 (13) Å3 at 100 K. The thermal expansion was found to be highly anisotropic with an eightfold increase in expansion between the c and b axes. These data will prove crucial in the computational modelling of propionitrile–ice systems in outer Solar System environments, allowing us to simulate and assign vibrational peaks in the infrared spectra for future use in planetary astronomy.

Temperature evolution of pentacene crystal structure and phonon dynamics

2002 ◽  
Vol 725 ◽  
Author(s):  
Matteo Masino ◽  
Alberto Girlando ◽  
Raffaele G. Della Valle ◽  
Elisabetta Venuti ◽  
Luca Farina ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Lattice Dynamics ◽  
Low Frequency ◽  
Minimum Potential Energy ◽  
X Ray ◽  
Phonon Dynamics ◽  
Minimum Potential ◽  
Effects Of Temperature ◽  
Experimental Raman Spectrum

AbstractWe investigate the relationships among all currently known X-ray structures of crystalline pentacene by calculating their “inherent” structures of minimum potential energy. We are thus able to show that two distinct bulk crystalline phases of pentacene exist, with very subtle but clear di.erences. We then assess the effects of temperature on the crystal structures, by including both inter- molecular and low-frequency intra-molecular phonons in the framework of quasi harmonic lattice dynamics methods. In this way we properly reproduce the experimental thermal expansion, and obtain a reliable description of the phonon dynamics and of its temperature dependence. The calculated phonon frequencies compare well with the experimental Raman spectrum.

Thermal expansion, elastic and thermoelastic properties including crystal structure analyses of K-, Rb- and Cs-nitrilotriacetates

2004 ◽  
Vol 219 (10) ◽  
Author(s):  
Eiken Haussühl ◽  
Siegfried Haussühl ◽  
Ekkehart Tillmanns
Keyword(s):  
Crystal Structure ◽  
Thermal Expansion ◽  
Aqueous Solutions ◽  
Single Crystals ◽  
Optical Quality ◽  
Thermoelastic Properties ◽  
X Ray

AbstractSingle crystals of the title compounds having optical quality and dimensions up to 60 mm have been grown from aqueous solutions. X-ray crystal structure analyses of K

Thermal expansion and high-temperature phase transformation of the yttrium silicate Y2SiO5

2001 ◽  
Vol 16 (8) ◽  
pp. 2251-2255 ◽  
Author(s):  
J. W. Nowok ◽  
J. P. Kay ◽  
R. J. Kulas
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Linear Thermal Expansion ◽  
Anomalous Behavior ◽  
High Temperature Phase ◽  
Local Order ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Yttrium Silicate

The linear thermal-expansion coefficients of yttrium silicate Y2SiO5, [Y2(SiO4)O] were measured in the temperature range from 20 to 1400 °C using x-ray diffraction. The anomalous behavior of thermal expansion was observed above Tc = 850 °C and was attributed to the displacive phase transformation. The transformation was reversible and resulted from the local order °C the compositional disorder and local fluctuation in the elastic free energy constrained a secondary transformation related to the polymorphic twin transformation. This created an additional peak in x-ray diffraction patterns at 2 's intensity. The characteristic of phase transformation both on heating and on cooling of the sample was also investigated using the differential thermal analysis method. The thermogravimetric technique did not indicate on a change of weight at Tc.

Confirmation of the new technique for measuring the linear thermal expansion of silicon

1993 ◽  
Vol 8 (1) ◽  
pp. 36-38 ◽  
Author(s):  
Liu Fengchao
Keyword(s):  
Thermal Expansion ◽  
Room Temperature ◽  
Accurate Determination ◽  
Linear Thermal Expansion ◽  
Linear Expansion Coefficient ◽  
X Ray ◽  
High Purity Silicon ◽  
Different Temperatures ◽  
Better Than

This paper further confirms that the direct measurement of diffraction angles at different temperatures by using the X-ray diffractometer is better than measurement of the lattice parameters for the rapid and accurate determination of the linear thermal expansion of silicon. High purity silicon has the linear expansion coefficient, α= (2.45±0.05) × 10−6/°C at room temperature. This value does not change for doped P-type and N-type silicon.

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