Phonons and Crystalline Structure of Hg1−xCdxS e Alloys (0 < x ≤ 0.5)

2012 ◽  
Vol 1372 ◽  
Author(s):  
David A. Miranda ◽  
S. A. López-Rivera ◽  
Ch. Power ◽  
J. A. Henao ◽  
M. A. Macías
Keyword(s):  
Experimental Data ◽  
Raman Spectroscopy ◽  
Powder Diffraction ◽  
Molar Fraction ◽  
Face Centered Cubic ◽  
X Ray ◽  
Cell Parameters ◽  
Cubic Structure ◽  
Diffraction Patterns ◽  
Face Centered

ABSTRACTPhonons and crystalline structures of Hg1−xCdxSe alloys (0 ≤ x ≤ 0.5) were studied by Raman spectroscopy and X-ray powder diffraction patterns at 298K. The crystalline alloys were prepared by a special combination of synthesis and the Bridgman method. Experimental data showed a face-centered cubic structure, $F\overline 4 \,3\,m$ (No. 216), for all samples, exhibiting a linear dependence for Cd molar fraction, x, for cell parameters, a, and the mass densities, ρ. Phonon frequencies were analyzed using the Romevi-Romevi model for phonons in multicomponent alloys, obtaining a fair agreement with experimental data. Furthermore, an algorithm to implement the Romevi-Romevi model is proposed.

Electron diffraction detection of ordliking in annealed PbTe thin film

1990 ◽  
Vol 48 (4) ◽  
pp. 1018-1019
Author(s):  
Karimat El-Sayed
Keyword(s):  
Thin Film ◽  
Electron Diffraction ◽  
Lead Telluride ◽  
Structural Basis ◽  
Face Centered Cubic ◽  
X Ray ◽  
Polycrystalline Thin Films ◽  
Stage Process ◽  
Diffraction Patterns ◽  
Face Centered

Lead telluride is an important semiconductor of many applications. Many Investigators showed that there are anamolous descripancies in most of the electrophysical properties of PbTe polycrystalline thin films on annealing. X-Ray and electron diffraction studies are being undertaken in the present work in order to explain the cause of this anamolous behaviour.Figures 1-3 show the electron diffraction of the unheated, heated in air at 100°C and heated in air at 250°C respectively of a 300°A polycrystalline PbTe thin film. It can be seen that Fig. 1 is a typical [100] projection of a face centered cubic with unmixed (hkl) indices. Fig. 2 shows the appearance of faint superlattice reflections having mixed (hkl) indices. Fig. 3 shows the disappearance of thf superlattice reflections and the appearance of polycrystalline PbO phase superimposed on the [l00] PbTe diffraction patterns. The mechanism of this three stage process can be explained on structural basis as follows :

Synthesis of CoPt Nanoparticles by Reduction of Co(CH3COO)2 and Pt(acac)2

2013 ◽  
Vol 712-715 ◽  
pp. 233-236
Author(s):  
Hui Ping Shao ◽  
Zhi Wang ◽  
Tao Lin ◽  
Sen Sun
Keyword(s):  
Diffraction Pattern ◽  
Reaction Temperature ◽  
Tetragonal Structure ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cubic Structure ◽  
Face Centered ◽  
Average Size

CoPt nanoparticles with an average size of 2.8 – 4.7 nm were synthesized by reduction of non-toxic precursors Co(CH3COO)2and Pt(acac)2using trioctylamine as a solvent at reaction temperature of 260 – 280 °C. The X-ray diffraction pattern showed that as-prepared particles have a disordered face-centered cubic structure while annealing at 700 °C caused them to be an ordered face-centered tetragonal structure. The annealing increased magnetic coercivity of the particles from zero to 772.4 Oe and their saturated magnetization from 15.04 to 27.95 emu/g.

X-ray powder diffraction data of anilinium trimolybdate tetrahydrate and anilinium trimolybdate dihydrate

1999 ◽  
Vol 14 (4) ◽  
pp. 280-283 ◽  
Author(s):  
A. Rafalska-Łasocha ◽  
W. Łasocha ◽  
M. Michalec
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

The X-ray powder diffraction patterns of anilinium trimolybdate tetrahydrate, (C6H5NH3)2Mo3O10·4H2O, and anilinium trimolybdate dihyhydrate, (C6H5NH3)2Mo3O10·2H2O, have been measured in room temperature. The unit cell parameters were refined to a=11.0670(7) Å, b=7.6116(8) Å, c=25.554(3) Å, space group Pnma(62) and a=17.560(2) Å, b=7.5621(6) Å, c=16.284(2) Å, β=108.54(1)°, space group P21(4) or P21/m(11) for orthorhombic anilinium trimolybdate tetrahydrate and monoclinic anilinium trimolybdate dihydrate, respectively.

X-ray powder diffraction studies of a new compound: Th13Te24O74

2002 ◽  
Vol 17 (1) ◽  
pp. 32-36 ◽  
Author(s):  
S. N. Tripathi ◽  
S. N. Achary ◽  
P. N. Namboodiri
Keyword(s):  
Thermal Decomposition ◽  
Solid State ◽  
Powder Diffraction ◽  
Solid State Reaction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Direct Solid ◽  
Measured Density

The compound Th13Te24O74 was prepared by three independent methods, namely, thermal decomposition of ThTe2O6 in oxygen and argon and direct solid-state reaction of ThO2 and TeO2. The X-ray powder diffraction patterns of the three products, by and large, are similar, except for some differences in intensities and extra diffraction lines. The thermal decomposition of ThTe2O6 was carried out in the streams of oxygen and argon by thermogravimetry at a heating rate of 5 K/min in the temperature range of 725–840 °C. The solid-state reaction of ThO2 and TeO2 (13:24) was carried out in a sealed ampoule at 700 °C. The measured density of this compound is 8.23 g/cm3. An orthorhombic lattice with unit cell parameters, a=11.310±0.005 Å, b=14.064±0.006 Å, c=9.056±0.004 Å, and volume of 1440.419±1.088 (Å)3 was determined for this compound.

Zýkait z dolu Lehnschafter u Mikulova v Krušných horách (Česká republika) - popis a Ramanova spektroskopie

2021 ◽  
Vol 29 (2) ◽  
pp. 241-248
Author(s):  
Jiří Sejkora ◽  
Roman Gramblička
Keyword(s):  
Crystal Structure ◽  
Raman Spectroscopy ◽  
Czech Republic ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Water Molecules ◽  
Powder Diffraction Data ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

The zýkaite samples were found at abandoned Lehnschafter mine near Mikulov in the Krušné hory Mts. (Czech Republic). It occurs as irregular white to light greenish rounded to spherical aggregates up to 1.5 cm in size composed of tiny acicular crystals up to 5 - 10 μm in length. Its empirical formula can be expressed as (Fe3.79Al0.02)Σ3.81[(AsO4)2.66(PO4)0.20(SiO4)0.07]Σ2.93 (SO4)1.07(OH)0.44·15H2O (mean of 3 spot analyzes; on the basis of As+P+S+Si = 4 apfu).Zýkaite is probably monoclinic, with the unit-cell parameters refined from X-ray powder diffraction data: a 21.195(8), b 7.052(2), c 36.518(17) Å, β 91.07(2)° and V 5458(2) Å3. Raman spectroscopy documented the presence of both (AsO4)3- and (SO4)2- units in the crystal structure of zýkaite. Multiple Raman bands connected with vibrations of water molecules and (AsO4)3- groups indicate the presence of more structurally non-equivalent these groups in the crystal stucture of zýkaite.

New Applications of Electron Diffraction in the Pharmaceutical Industry: Polymorph Determination by Using a Combination of Electron Diffraction and Synchrotron X-ray Powder Diffraction Techniques

2002 ◽  
Vol 8 (2) ◽  
pp. 134-138 ◽  
Author(s):  
Z.G. Li ◽  
R.L. Harlow ◽  
C.M. Foris ◽  
H. Li ◽  
P. Ma ◽  
...  
Keyword(s):  
Pharmaceutical Industry ◽  
Electron Diffraction ◽  
Powder Diffraction ◽  
Unit Cell ◽  
X Ray ◽  
Cell Parameters ◽  
Synchrotron Powder Diffraction ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
New Applications

Electron diffraction has been recently used in the pharmaceutical industry to study the polymorphism in crystalline drug substances. While conventional X-ray diffraction patterns could not be used to determine the cell parameters of two forms of the microcrystalline GP IIb/IIIa receptor antagonist roxifiban, a combination of electron single-crystal and synchrotron powder diffraction techniques were able to clearly distinguish the two polymorphs. The unit-cell parameters of the two polymorphs were ultimately determined using new software routines designed to take advantage of each technique's unique capabilities. The combined use of transmission electron microscopy (TEM) and synchrotron patterns appears to be a good general approach for characterizing complex (low-symmetry, large-unit-cell, micron-sized) polymorphic pharmaceutical compounds.

Powder diffraction investigations of naphthalenesulfonic acids and their complexes with DMAN

2004 ◽  
Vol 19 (4) ◽  
pp. 378-384
Author(s):  
A. Rafalska-Lasocha ◽  
M. Grzywa ◽  
B. Włodarczyk-Gajda ◽  
W. Lasocha
Keyword(s):  
Powder Diffraction ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Acid Hydrate ◽  
M 12 ◽  
Diffraction Patterns

The X-ray diffraction patterns of two organic acids 1-naphthalenesulfonic acid dihydrate and 2-naphthalenesulfonic acid hydrate were measured at room temperature. Complexes of these acids with 1,8-bis(dimethylamino)naphthalene (DMAN) were synthesized, purified and investigated by means of X-ray powder diffraction. 1-Naphthalenesulfonic acid dihydrate as well as its complex with 1,8-bis(dimethylamino)naphthalene crystallize in the monoclinic system with unit cell parameters refined to a=0.91531(8) nm, b=0.7919(1) nm, c=0.8184(1) nm, β=101.618(9)° space group P21/m (11) and a=1.7781(4) nm, b=2.0122(4) nm, c=1.2337(2) nm, β=96.54(3)°, space group C2/m (12), respectively. 2-Naphthalenesulfonic acid hydrate crystallizes in the orthorhombic system with a=2.2749(3) nm, b=0.7745(1) nm, c=0.591 36(9) nm, space group Pnma, whereas its complex with 1,8-bis(dimethylamino)naphthalene crystallizes in the triclinic system a=1.3969(6) nm, b=1.4292(5) nm, c=1.1741(6) nm, α=90.93(3)°, β=98.14(3)°, γ=113.93(3)°, space group P-1 (2).

Barium hollandite-type compounds BaxFe2xTi8−2xO16 with x=1.143 and 1.333

1999 ◽  
Vol 14 (1) ◽  
pp. 31-35 ◽  
Author(s):  
J. M. Loezos ◽  
T. A. Vanderah ◽  
A. R. Drews
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Powder Diffraction ◽  
Framework Structure ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns ◽  
Acta Crystallogr

Experimental X-ray powder diffraction patterns and refined unit cell parameters for two barium hollandite-type compounds, BaxFe2xTi8−2xO16, with x=1.143 and 1.333, are reported here. Compared to the tetragonal parent structure, both compounds exhibit monoclinic distortions that increase with Ba content [Ba1.333Fe2.666Ti5.334O16: a=10.2328(8), b=2.9777(4), c=9.899(1) Å, β=91.04(1)°, V=301.58(5) Å3, Z=1, ρcalc=4.64 g/cc; Ba1.143Fe2.286Ti5.714O16: a=10.1066(6), b=2.9690(3), c=10.064(2) Å, β=90.077(6)°, V=301.98(4) Å3, Z=1, ρcalc=4.48 g/cc]. The X-ray powder patterns for both phases contain a number of broad, weak superlattice peaks attributed to ordering of the Ba2+ ions within the tunnels of the hollandite framework structure. According to the criteria developed by Cheary and Squadrito [Acta Crystallogr. B 45, 205 (1989)], the observed positions of the (0k1)/(1k0) superlattice peaks are consistent with the nominal x-values of both compounds, and the k values calculated from the corresponding d-spacings suggest that the Ba ordering within the tunnels is commensurate for x=1.333 and incommensurate for x=1.143. High-temperature X-ray diffraction data indicate that the x=1.333 compound undergoes a monoclinic→tetragonal phase transition between 310 and 360 °C.

X-Ray Powder Data for Tetracycline-urea Tetrahydrate, C23H36N4O13 and Tetracycline Hexahydrate, C22H24N2O8·6H2O

1989 ◽  
Vol 4 (3) ◽  
pp. 168-171
Author(s):  
Frank N. Blanchard ◽  
Gus J. Palenik
Keyword(s):  
Powder Diffraction ◽  
Objective Evaluation ◽  
Good Resolution ◽  
Close Correspondence ◽  
Unit Cell Parameters ◽  
Powder Diffraction File ◽  
X Ray ◽  
Cell Parameters ◽  
Low Intensity ◽  
Diffraction Patterns

AbstractIndexed powder diffraction patterns and related crystallographic data are reported for tetracycline-urea tetrahydrate and tetracycline hexahydrate, neither of which is represented in the X-ray Powder Diffraction File. Objective evaluation of the data indicates high precision of d-spacings and unit-cell parameters, intensities that are acceptably reproducible, sensitivity for low intensity reflections, good resolution of closely spaced reflections, and close correspondence with calculated patterns.

Investigation of (Sr4−δCaδ)PtO6 using X-ray Rietveld refinement

1999 ◽  
Vol 14 (3) ◽  
pp. 181-189 ◽  
Author(s):  
W. Wong-Ng ◽  
J. A. Kaduk ◽  
R. A. Young ◽  
F. Jiang ◽  
L. J. Swartzendruber ◽  
...  
Keyword(s):  
Solid Solution ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Solid Solution Series ◽  
X Ray ◽  
Cell Parameters ◽  
Solution Series ◽  
Complete Solid Solution ◽  
Ca Ions ◽  
Diffraction Patterns

The structures of the solid solution series (Sr4−δCaδ)PtO6, with δ=0, 0.85(1), 2, and 3, have been investigated using the Rietveld refinement technique with laboratory X-ray powder diffraction data. A complete solid solution between Sr and Ca was confirmed to exist. These compounds crystallize in the rhombohedral space group R3¯c. The cell parameters of the series range from a of 9.4780(3) to 9.7477(1) Å, and c from 11.3301(4) to 11.8791(1) Å for δ from 3 to 0, respectively. The structure consists of chains of alternating trigonal prismatic (Sr, Ca)O6 and octahedral PtO6 units running parallel to the c axis. These chains are connected to each other via a second type of (Sr, Ca) ions, which are surrounded by eight oxygens, in a distorted square antiprismatic geometry. As Ca replaced Sr in Sr4PtO6, it was found to substitute preferentially in the smaller octahedral (Sr, Ca)1 site (6a) rather than at the eight-coordinate (Sr, Ca)2 site (18e). There appears to be an anomaly of cell parameters a and c at the compound Sr3.15Ca0.85PtO6. Their dependence on Ca content changes at δ≈1.00, where the Ca has fully replaced Sr in the 6a site. The substitution of Sr by Ca reduced the average (Sr, Ca)1–O length from 2.411 to 2.311 Å and (Sr, Ca)2–O from 2.659 to 2.570 Å as the composition varied from Sr4PtO6 to SrCa3PtO6. Reference X-ray powder diffraction patterns were prepared from the Rietveld refinement results for these members of the solid solution series. Magnetic susceptibility measurements of three of the samples (δ=0, 0.85, 2) show electronic transitions at low temperatures.

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