Arrangement of C atoms in the SiC–C solid solution

1999 ◽  
Vol 55 (3) ◽  
pp. 297-305 ◽  
Author(s):  
O. O. Mykhaylyk ◽  
M. P. Gadzira
Keyword(s):  
Solid Solution ◽  
Point Defects ◽  
Strain Field ◽  
Field Model ◽  
Fine Powder ◽  
Lattice Parameter ◽  
Acta Cryst ◽  
Planar Defects ◽  
X Ray ◽  
Higher Temperature

The microstructure of a silicon carbide–carbon solid-solution powder (SiC–C), obtained from a fine powder of silicon and thermal expansive graphite, is investigated by X-ray powder diffraction methods. The microstructure is characterized by Williamson–Hall analysis and the strain-field model suggested by van Berkum et al. [Acta Cryst. (1996), A52, 730–747]. SiC–C adopts a layered structure like the solid solutions formed by compounds possessing a diamond-like structure, e.g. SiC–AlN. Superstoichiometric C atoms are located as planar defects. The SiC–C solid solution is destroyed on heating in a vacuum in the temperature range of graphitization of diamond but is maintained after sintering at high pressure (4–8 GPa) and high temperature (1673 and 2073 K). However, at the higher temperature (2073 K), it is observed that planar defects formed by C atoms decompose to non-correlated point defects accompanied simultaneously by a decrease in the lattice parameter from 4.3540 (2) to 4.35234 (5) Å.

The Defect Fluorite Phase in the ZrO2-PrO1.5 System and Its Relationship to the Structure of Pyrochlore

1992 ◽  
Vol 45 (9) ◽  
pp. 1375 ◽  
Author(s):  
RL Withers ◽  
JG Thompson ◽  
PJ Barlow ◽  
JC Barry
Keyword(s):  
Solid Solution ◽  
Point Defects ◽  
Phase Field ◽  
Fluorite Phase ◽  
X Ray ◽  
Average Structure ◽  
Transmission Electron ◽  
Solution Field ◽  
Close Relationship ◽  
Fluorite Type

A detailed transmission electron microscope and X-ray powder diffraction study has been made of the so-called 'defect fluorite' phase field in the ZrO2-PrO1.5 system and of its close relationship to the pyrochlore solid solution field in the same system. Even for the lowest possible PrO1.5 content within the 'defect fluorite' phase field, it is clear that the sharp Bragg reflections characteristic of the underlying fluorite average structure are accompanied by some of the 'satellite reflections' characteristic of the pyrochlore solid solution field. As the PrO1.5 content increases, these satellite reflections increase systematically in intensity as well as sharpening very considerably. It is shown that this 'defect fluorite' phase field cannot be adequately described either in terms of random point defects within an average fluorite-type matrix or in terms of a diphasic texture of pyrochlore domains embedded coherently into a fluorite matrix, but must be regarded as enuinely intermediate between these two end-member structures and of commensurately modulated fluorite type. A group theoretical approach is used to propose a model for the structural deviation from the underlying fluorite average structure.

Elaboration, Structure and Mössbauer Spectroscopy of Nanostructured Fe100−xSix Powders Elaborated by Mechanical Alloying

SPIN ◽  
2017 ◽  
Vol 07 (02) ◽  
pp. 1750002 ◽  
Author(s):  
M. Hemmous ◽  
A. Guittoum
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Mechanical Alloying ◽  
Hyperfine Magnetic Field ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Mean ◽  
Xrd Studies

We have studied the effect of the silicon concentration on the structural and hyperfine properties of nanostructured Fe[Formula: see text]Six powders ([Formula: see text], 20, 25 and 30[Formula: see text]at.%) prepared by mechanical alloying. The X-ray diffraction (XRD) studies indicated that after 72[Formula: see text]h of milling, the solid solution bcc-[Formula: see text]-Fe(Si) is formed. The grain sizes, [Formula: see text]D[Formula: see text] (nm), decreases with increasing Si concentration and reaches a minimum value of 11[Formula: see text]nm. We have found that the lattice parameter decreases with increasing Si concentration. The changes in values are attributed to the substitutional dissolution of Si in Fe matrix. From the adjustment of Mössbauer spectra, we have shown that the mean hyperfine magnetic field, [Formula: see text]H[Formula: see text] (T), decreases with increasing Si concentration. The substitutional dependence of [Formula: see text]H[Formula: see text] (T) can be attributed to the effect of p electrons Si influencing electrons d of Fe.

An Approach to the Solid Solution Problem Using a Computerized Identification Technique

1969 ◽  
Vol 13 ◽  
pp. 539-549
Author(s):  
Gerald G. Johnson ◽  
Frank L. Chan
Keyword(s):  
Solid Solution ◽  
Powder Diffraction ◽  
Lattice Parameter ◽  
Powder Diffraction File ◽  
X Ray ◽  
Complete Solid Solution ◽  
Vegard’S Law ◽  
Identification Technique ◽  
Approximate Composition ◽  
End Members

Since for most real systems, solid solution effects influence the position and intensity of the x-ray powder diffraction pattern, it is desirable and necessary to have an automatic system which will identify standard reference phases regardless of the amount of solid solution. Using the system CdS-ZnS, where the lattice parameter a0 changes from 4.136 to 3.820Å, with complete solid solution over the entire range of composition, an illustrative study was made. This work presents the results obtained from a computer analysis of the powder pattern obtained. It has been found that if the starting chemistry is known and the end members of the series are in the ASTM Powder Diffraction File, that the solid solution can be identified. Once the phases present are identified, a plot following Vegard's law yields the approximate composition of the sample under consideration. These two methods of compositional determination agree quite well. Examples of the computer system and description of the program input and output with interpretation of the results will be discussed.

Structural Behaviour of Solid Solution in the SmAlO3−TbAlO3 System

2015 ◽  
Vol 230 ◽  
pp. 39-44 ◽  
Author(s):  
Natalja Ohon ◽  
Leonid Vasylechko ◽  
Yurii Prots ◽  
Marcus Schmidt ◽  
I.I. Syvorotka
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Continuous Solid Solution ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Structural Behaviour ◽  
X Ray ◽  
Synchrotron Powder Diffraction ◽  
Orthorhombic Perovskite

Phase and structural behaviour in the SmAlO3–TbAlO3system has been studied in a whole concentration range by means of laboratory X-ray diffraction,in situhigh temperature synchrotron powder diffraction and differential thermal analysis. Formation of the continuous solid solution Sm1−xTbxAlO3with the orthorhombic perovskite structure (space groupPbnm) has been established. Peculiarity of the investigated system is lattice parameter crossovers resulted in the existence of three regions with different relations of the lattice parameters. Based on the results obtained, as well as an available literature data for the “pure” SmAlO3and TbAlO3, a phase diagram of the pseudo-binary SmAlO3–TbAlO3system has been constructed.

scholarly journals X-Ray Powder Diffraction Study on the MgB2 Superconductor Reacted with Nano-SiC: The Effects of Sintering Temperature

2010 ◽  
Vol 173 ◽  
pp. 78-83
Author(s):  
Kwee Yong Tan ◽  
Tan Kim Lee ◽  
Lim Kean Pah ◽  
Shaari Abdul Halim ◽  
Tan Kar Ban ◽  
...  
Keyword(s):  
Phase Formation ◽  
Sintering Temperature ◽  
Lattice Parameter ◽  
Primary Phase ◽  
Superconducting Transition ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Higher Temperature ◽  
Addition Level

SiC added MgB2 polycrystalline samples were synthesized at low (650°C) and high (850°C) temperatures in order to study the sintering effect on the phase formation and superconducting properties. The MgB2 bulks with additions of 0wt%, 1wt%, 3wt% and 5wt% SiC were studied with powder X-ray diffraction technique. We observed that MgB2 remained as the primary phase for both sintering temperatures in all samples with the presence of MgO and Mg2Si as the main impurities. Some diffraction peaks associated with unreacted SiC is also noticeable. The relative intensity of the Mg2Si peaks was found to decrease in samples sintered at higher temperature. Temperature dependent magnetic moment measurements showed that the superconducting transition temperature, Tc decreases as the SiC addition level increases while lower sintering temperature degrades Tc to a greater extent. The changes in the physical properties is discussed based on the results of phase formation, full width half maximum (FWHM), lattice parameter and crystallite size.

Study of Aluminium-Titanate Based Ceramics in Fe2O3-Al2O3-TiO2 System

2010 ◽  
Vol 659 ◽  
pp. 31-36
Author(s):  
Támas Korim
Keyword(s):  
Heat Treatment ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Self Healing ◽  
X Ray Diffraction ◽  
Repeated Heating ◽  
X Ray ◽  
Aluminium Titanate ◽  
Complete Solid Solution ◽  
Constructed Self

Solid solutions formed within the Al2O3-TiO2-Fe2O3 (Fe2xAl2(1-x)TiO5) system upon heat treatment were investigated by adjusting the substituting Fe3+ content in the range of x=0.0 to 1.0. X-ray diffraction phase analyses and lattice parameter determinations confirmed that substitution of Fe3+ ions within the aluminium titanate lattice was complete. For this complete solid solution, however, the trends observed for changes in d-spacing values indicated that there were certain discrete compositions to identify with Fe3+ substitution. Within these, Fe0.4Al1.6TiO5 and Fe1.6Al0.4TiO5 crystalline phases were investigated in detail and their X-ray diffraction cards were constructed. Self-healing effect occurring in repeated heating-cooling cycles in Fe3+ doped AT ceramics were proved; it was demonstrated that Fe3+ doped AT ceramics do not decompose even if exposed to repeated thermal shock.

A Structural Consideration of a Solid Solution La4Ni3-xMnxO10

2006 ◽  
Vol 317-318 ◽  
pp. 877-880
Author(s):  
Shunkichi Ueno ◽  
Halina B. Misram ◽  
Naoki Kamegashira
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Orthorhombic System ◽  
X Ray ◽  
Manganese Ion ◽  
Orthorhombic Cell ◽  
Face Centered

The solubility of manganese ion in layered perovskite La4Ni3O10 phase was examined and the detailed crystal structure of this phase was discussed. The solid solution of La4Ni3-xMnxO10 was prepared by solid state reaction. The crystal structure of La4Ni3-xMnxO10 was analyzed by powder X-ray diffraction and Rietveld methods. The solid solution for x=0.5 had a orthorhombic system with lattice parameter a=0.5485(0), b=0.5433(6) and c=2.8034(9). In detailed observation of the X-ray diffraction data, some superlattice reflections that were forbidden for a face centered orthorhombic cell were identified. A possible space group Pnnn (no.48) was derived from the reflection conditions.

Study of Ti3Si1.2-xAlxC2 (x = 0~1.2) Solid Solution via X-Ray Diffraction

2007 ◽  
Vol 336-338 ◽  
pp. 952-954
Author(s):  
Cui Wei Li ◽  
Hong Xiang Zhai ◽  
Yan Ding ◽  
Yang Zhou ◽  
Shi Bo Li ◽  
...  
Keyword(s):  
Solid Solution ◽  
Cell Volume ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Two Phases

A search for Ti3Si1.2-xAlxC2 (x=0~1.2) solid solution was undertaken using precise X-ray diffraction measurements. The samples covering the whole concentration range were studied. Except very ends of the concentration range, the samples contained two phases, identified as Ti3Si1.2-xAlxC2 solid solution and TiC respectively. Lattice parameter, a increased, c increased, c/a increased, and cell volume increased with the increasing of Al concentration.

X-ray studies of the NaCl:SrCl2 system

1971 ◽  
Vol 27 (4) ◽  
pp. 353-362 ◽  
Author(s):  
E. Laredo ◽  
E. Dartyge
Keyword(s):  
High Temperature ◽  
Point Defects ◽  
Annealing Temperature ◽  
Lattice Parameter ◽  
Thermal Treatments ◽  
X Ray ◽  
X Ray Scattering ◽  
Dilution Enthalpy ◽  
Good Agreement

High-temperature diffraction experiments have been carried out on the NaCl: SrCl2 system, both in its poly- and monocrystalline form. These experiments have led us to the determination of the dilution enthalpy of the SrCl2 precipitates in the NaCl matrix (hD = 0.90 ± 0.05 eV). Brauer's method was used to calculate the distortion around one defect and Eshelby's model was used to evaluate the resulting change in the lattice parameter due to these perturbing centers. The concentrations of defects calculated from these models are in good agreement with those determined chemically. Small-angle X-ray scattering experiments were performed on the same crystals, with suitable thermal treatments, to follow the clustering of defects as a function of the annealing temperature. It is possible to maintain a large amount of nearly dispersed strontium in the lattice by quenching the crystals from high temperature. The point defects agglomerate by successive annealings from 100 to 300°C, forming clusters of increasing sizes. A discussion of the composition of those centers is included.

Residual Stress and Microstructure of CU/W Multilayers

1993 ◽  
Vol 308 ◽  
Author(s):  
Ph. Goudeau ◽  
K.F. Badawi ◽  
A. Naudon ◽  
N. Durand
Keyword(s):  
Solid Solution ◽  
Residual Stress ◽  
Ion Irradiation ◽  
Lattice Parameter ◽  
Free Lattice ◽  
Curvature Radius ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Modification ◽  
20 Nm

ABSTRACTWe have determined residual stresses and the layer microstructure in as-prepared Cu/W multilayers of different periods ranging from 5.2 to 20 nm by both X-ray diffraction and the curvature radius method. The magnitude of the principal in-plane stress is large in the W layers (around - 6 GPa) and small in the Cu layers (-0.5 - + 0.5 GPa). The stress state is independent of the multilayer period. Under the compressive stress, the W cubic unit cell becomes monoclinic-like. The stress-free lattice parameter is found higher than the bulk one.We also studied the stress relaxation and the layer microstructure modification in W layers induced by Kr ion irradiation., the relaxation is almost achieved after only low fluence irradiations and the decrease of the stress-free lattice parameter in W layers observed for higher fluences is attributed to the formation of a sursaturated solid solution W(Cu).

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