A physicochemical study on organic eutectics and addition compound; benzidine–pyrogallol system

1992 ◽  
Vol 70 (12) ◽  
pp. 2869-2874 ◽  
Author(s):  
U. S. Rai ◽  
Santhi George
Keyword(s):  
Phase Diagrams ◽  
Growth Front ◽  
Physicochemical Study ◽  
Addition Compound ◽  
X Ray Diffraction ◽  
Organic System ◽  
X Ray ◽  
Solidification Behaviour ◽  
Mechanical Mixtures ◽  
Microscopic Investigations

The phase diagrams of the binary organic system of benzidine–pyrogallol was determined by the thaw–melt method. The solidification behaviour of the pure components, their eutectics, and the addition compound were studied by measuring the movement of growth front in a capillary. From the data on X-ray diffraction, thermal and microscopic investigations it can be inferred that the eutectics are not simple mechanical mixtures of the components involved. The IR and NMR spectral investigations were carried out to throw light on the nature of bonding between the two components forming the addition compound.

Some physicochemical studies on organic eutectics and 1:1 addition compound; p-phenylenediamine – benzoic acid system

1989 ◽  
Vol 67 (2) ◽  
pp. 239-244 ◽  
Author(s):  
U. S. Rai ◽  
K. D. Mandal
Keyword(s):  
Phase Diagram ◽  
Benzoic Acid ◽  
Cluster Formation ◽  
Growth Front ◽  
Spectral Studies ◽  
Acid System ◽  
Addition Compound ◽  
X Ray Diffraction ◽  
X Ray ◽  
Entropy Of Fusion

The phase diagram of p-phenylenediamine – benzoic acid system, determined by the thaw–melt method, shows the formation of two eutectics and a 1:1 addition compound. The linear velocity of crystallization of pure components, eutectics and addition compound, determined by measuring the movement of growth front in a capillary, suggests that crystallization data obey the Hillig–Turnbull equation. Using experimental values of heats of fusion, entropy of fusion and excess thermodynamic functions were calculated and the results are explained on the basis of cluster formation in the melts. X-ray diffraction data infer that these eutectics are not simply the mechanical mixture of the two components and there is preferential ordering of atomic planes during their formation. The infrared spectral studies suggest the formation of intermolecular hydrogen bonding between the components forming the molecular complex. Keywords: organic eutectics, growth kinetics, phase diagram, thermochemistry, X-ray diffraction studies.

Transmission electron microscope studies in special ceramics

1978 ◽  
Vol 36 (1) ◽  
pp. 268-269
Author(s):  
A. Zangvil ◽  
L.J. Gauckler ◽  
G. Schneider ◽  
M. Rühle
Keyword(s):  
Phase Diagrams ◽  
Crystal Structures ◽  
Thin Foil ◽  
Limited Extent ◽  
Complex Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Lattice Resolution

The use of high temperature special ceramics which are usually complex materials based on oxides, nitrides, carbides and borides of silicon and aluminum, is critically dependent on their thermomechanical and other physical properties. The investigations of the phase diagrams, crystal structures and microstructural features are essential for better understanding of the macro-properties. Phase diagrams and crystal structures have been studied mainly by X-ray diffraction (XRD). Transmission electron microscopy (TEM) has contributed to this field to a very limited extent; it has been used more extensively in the study of microstructure, phase transformations and lattice defects. Often only TEM can give solutions to numerous problems in the above fields, since the various phases exist in extremely fine grains and subgrain structures; single crystals of appreciable size are often not available. Examples with some of our experimental results from two multicomponent systems are presented here. The standard ion thinning technique was used for the preparation of thin foil samples, which were then investigated with JEOL 200A and Siemens ELMISKOP 102 (for the lattice resolution work) electron microscopes.

Structural Characterization of the Growth Front of 4H-SiC Boules Grown Using the Physical Vapor Transport Growth Method

2018 ◽  
Vol 924 ◽  
pp. 15-18
Author(s):  
Masashi Sonoda ◽  
Kentaro Shioura ◽  
Takahiro Nakano ◽  
Noboru Ohtani ◽  
Masakazu Katsuno ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Morphology ◽  
Defect Structure ◽  
Growth Front ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growth Method

The defect structure at the growth front of 4H-SiC boules grown using the physical vapor transport (PVT) method has been investigated using high resolution x-ray diffraction and x-ray topography. The crystal parameters such as the c-lattice constant exhibited characteristic variations across the growth front, which appeared to be caused by variation in surface morphology of the as-grown surface of the boules rather than the defect structure underneath the surface. X-ray topography also revealed that basal plane dislocations are hardly nucleated at the growth front during PVT growth of 4H-SiC crystals.

scholarly journals Transmission Electron Microscopy and X-ray Diffraction Investigation of the Microstructure of Nanoscale Multilayer TiAlN/VN Grown by Unbalanced Magnetron Deposition

2004 ◽  
Vol 19 (4) ◽  
pp. 1093-1104 ◽  
Author(s):  
Q. Luo ◽  
D.B. Lewis ◽  
P.Eh. Hovsepian ◽  
W-D. Münz
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Growth Model ◽  
Growth Front ◽  
Columnar Structure ◽  
Layer Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Unbalanced Magnetron

Cubic NaCl-B1 structured multilayer TiAlN/VN with a bi-layer thickness of approximately 3 nm and atomic ratios of (Ti+Al)/V = 0.98 to 1.15 and Ti/V = 0.55 to 0.61 were deposited by unbalanced magnetron sputtering at substrate bias voltages between -75 and -150 V. In this paper, detailed transmission electron microscopy and x-ray diffraction revealed pronounced microstructure changes depending on the bias. At the bias -75 V, TiAlN/VN followed a layer growth model led by a strong (110) texture to form a T-type structure in the Thornton structure model of thin films, which resulted in a rough growth front, dense columnar structure with inter-column voids, and low compressive stress of -3.8 GPa. At higher biases, the coatings showed a typical Type-II structure following the strain energy growth model, characterized by the columnar structure, void-free column boundaries, smooth surface, a predominant (111) texture, and high residual stresses between -8 and -11.5 GPa.

Pressure/Temperature/Reaction Phase Diagrams for Several Nitramine Compounds

1992 ◽  
Vol 296 ◽  
Author(s):  
T. P. Russell ◽  
P. J. Miller ◽  
G. J. Piermarini ◽  
S. Block
Keyword(s):  
Phase Diagrams ◽  
Diamond Anvil Cell ◽  
Temperature Reaction ◽  
Ammonium Dinitramide ◽  
X Ray Diffraction ◽  
Reaction Phase ◽  
X Ray ◽  
Ft Raman Spectroscopy ◽  
Diamond Anvil ◽  
Ft Raman

AbstractPressure/temperature/reaction phase diagrams for several nitramine compounds, including hexanitrohexaazaisowurtzitane (HNIW), 1,3,5-trinitrohexahydro-l,3,5-triazine (RDX), ammonium dinitramide (ADN), and p-nitroaniline (PNA) are presented. A diamond anvil cell was used in conjunction with optical polarizing light microscopy (OPLM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray diffraction (EDXD), and micro FT-Raman spectroscopy to determine these diagrams. A description is given of the diamond anvil cell and the associated techniques employed.

The applicability of powder X-ray diffraction to the quantification of drug substance polymorphs using a model organic system

1993 ◽  
Vol 8 (3) ◽  
pp. 180-187 ◽  
Author(s):  
W. Christopher Kidd ◽  
Peter Varlashkin ◽  
Chia-yu Li
Keyword(s):  
Powder Diffraction ◽  
Drug Substance ◽  
X Ray Diffraction ◽  
Organic System ◽  
Crystal Forms ◽  
X Ray ◽  
Drug Substances ◽  
Polymorphic Forms ◽  
Crystalline System ◽  
Pharmaceutical Production

With a new emphasis on the control of polymorphism in pharmaceutical production, the need for methods to quantify polymorphic forms has arisen. Techniques using X-ray powder diffraction are increasingly being used to characterize the phases of drug substances that exist in multiple crystal forms. Current methods to identify the polymorphic phases in a drug substance include microscopy, infrared spectroscopy, thermal analysis (DSC/TGA), solid state NMR, and X-ray powder diffraction. Of the aforementioned techniques, X-ray powder diffraction provides the most effective approach to identify and quantify the different crystal phases of a pharmaceutical compound. This work is intended as a guide to the characterization and quantification of an organic crystalline system using X-ray diffraction. The approaches suggested are intended to provide assistance not only from an in-process pharmaceutical manufacturing standpoint, but also for routine quality assurance screening of polymorphic drug substances.

scholarly journals In‐situ Electrochemical X‐ray Diffraction: A Rigorous Method to Navigate within Phase Diagrams Reveals β‐Fe 1+ x Se as Superconductor for All x

2019 ◽  
Vol 58 (43) ◽  
pp. 15401-15406 ◽  
Author(s):  
Bertold Rasche ◽  
Minjun Yang ◽  
Lothar Nikonow ◽  
Joshaniel F. K. Cooper ◽  
Claire A. Murray ◽  
...  
Keyword(s):  
Phase Diagrams ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rigorous Method

Thin-film reactions of Al with Co, Cr, Mo, Ta, Ti, and W

1989 ◽  
Vol 4 (4) ◽  
pp. 815-820 ◽  
Author(s):  
E. G. Colgan ◽  
J. W. Mayer
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Diagrams ◽  
Refractory Metals ◽  
Rutherford Backscattering ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The thin-film interactions of Al with refractory metals (Co, Cr, Mo, Ta, Ti, and W) have been investigated. The composition and thickness of the reacted aluminide layers were determined by Rutherford backscattering and phase identification was made by x-ray diffraction. Scanning electron microscopy was used to examine the lateral uniformity. The initial aluminide phases to grow are the Al-rich phases: Co2Al9, Cr2Al13, MoAl12, TaAl3, TiAl3, and WAI12. These are the most Al-rich phases on the phase diagrams. The reaction temperatures varied between 350 and 525 °C.

On the complex zonality in grandite garnets and implications

1998 ◽  
Vol 62 (6) ◽  
pp. 857-868 ◽  
Author(s):  
T. I. Ivanova ◽  
A. G. Shtukenberg ◽  
Yu. O. Punin ◽  
O. V. Frank-Kamenetskaya ◽  
P. B. Sokolov
Keyword(s):  
Structural Characteristics ◽  
Growth Front ◽  
The Self ◽  
Oscillatory Zoning ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Compositional Zoning ◽  
Linear Dynamics ◽  
X Ray ◽  
High Degree

AbstractThe available data on compositional zoning in grossular-andradite (grandite) garnets occurring at different scales, mainly due to the variations of their Fe3+/Al ratios, and the hypotheses on the origin of this zoning are reviewed. Four zoned crystals of grandites showing different optical properties have been studied by means of X-ray diffraction. Optical and structural studies suggest three superimposed scales of Fe3+/Al zonality along [110]. The drastic change of the structural characteristics from sample to sample correlates with the change of their optical patterns. The superfine oscillatory zoning has been described in terms of irregular interstratified structures with a high degree of segregation. The self-affinity of zoning at different scales testify to the possible origin of the zonality due to the non-linear dynamics at the growth front. The wide variation of the layer compositions revealed by the modelling of the X-ray diffraction profiles seems to contradict the hypothesis of unmixing in grandite garnets.

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