scholarly journals New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

1999 ◽  
Vol 14 (6) ◽  
pp. 2644-2654 ◽  
Author(s):  
F. Rajabalee ◽  
V. Métivaud ◽  
D. Mondieig ◽  
Y. Haget ◽  
M. A. Cuevas-Diarte
Keyword(s):  
Phase Diagram ◽  
Binary Systems ◽  
The Other ◽  
Structural Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ordered Phases ◽  
Crystalline Forms ◽  
Mixed Samples

X-ray diffraction analyses of the pure components n-tricosane and n-pentacosane and of their binary mixed samples have enabled us to characterize the crystalline phases observed at “low temperature.” Contrary to what was announced in literature on the structural behavior of mixed samples in odd-odd binary systems with Δn = 2, the three domains are not all orthorhombic. This work has enabled us to show that two of the domains are, in fact, monoclinic (Aa, Z = 4), and the other one is orthorhombic (Pca21, Z = 4). The conclusions drawn in this work can easily be transposed to other binary systems of n-alkanes.

scholarly journals Effects of strain on La0.67-x Prx Ca0.33 MnO3, LaMn1-x Cox O3 and LaMn1-x Nix O3 magnetite samples

DYNA ◽  
2019 ◽  
Vol 86 (211) ◽  
pp. 278-287
Author(s):  
Javier Alberto Olarte Torres ◽  
María Cristina Cifuentes Arcila ◽  
Harvey Andrés Suárez Moreno
Keyword(s):  
Compressive Strength ◽  
Magnetic Susceptibility ◽  
Sol Gel ◽  
Morphological Characterization ◽  
Electric Resistivity ◽  
The Other ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
X Ray

This paper presents the results obtained from the synthesis and morphological characterization of different magnetite samples:  La0.67-x Prx Ca0.33 MnO3.LaMn1-x Cox O3 and LaMn1-x Nix O3 at 0.13 ≤ 𝑥𝑥 ≤ 0.67 produced by a solid-state reaction mechanism and 𝐿𝐿𝐿𝐿𝑀𝑀𝑀𝑀1−𝑥𝑥(𝐶𝐶𝐶𝐶/𝑁𝑁𝑁𝑁)𝑥𝑥𝑂𝑂3 at 0.0 ≤ 𝑥𝑥 ≤ 0.5 produced by the sol-gel method. These samples were characterized using X-ray diffraction spectroscopy and by measuring electric resistivity and magnetic susceptibility which were carried out as a function of temperature. Notably, the effects of strain and compressive strength on the lattices of magnetite samples were highly dependent on the concentration of 𝑃𝑃𝑟𝑟, 𝐶𝐶𝐶𝐶, and 𝑁𝑁𝑁𝑁. Moreover, the transition temperatures of metal-insulator and ferromagnetic-paramagnetic phases also largely depend on these strength effects, e.g., at higher concentrations of 𝑃𝑃𝑟𝑟, effects of increased strain strength were observed, relocating the shifts of ferromagnetic-paramagnetic transitions to lower temperatures. On the other hand, effects of increased compressive strength were observed at higher concentrations of 𝑁𝑁𝑁𝑁 and 𝐶𝐶𝐶𝐶, relocating the shifts of ferromagnetic-paramagnetic and metal-insulator transitions to higher temperatures.

Identification of Different Crystalline Forms of Diatrizoic Acid

1978 ◽  
Vol 61 (1) ◽  
pp. 72-75
Author(s):  
Victor A Folen ◽  
George Schwartzman ◽  
Millard Maienthal ◽  
Wilson L Brannon
Keyword(s):  
Weight Loss ◽  
The Other ◽  
Reference Standard ◽  
Thermal Gravimetric ◽  
X Ray Diffraction ◽  
X Ray ◽  
No Weight Loss ◽  
Diffraction Patterns ◽  
Crystalline Forms ◽  
Reference Samples

Abstract Standard reference samples of diatrizoic acid gave 2 different infrared (IR) spectra, x-ray diffraction patterns, and differential thermal and thermal gravimetric curves. One form, the anhydrous acid, shows no weight loss when heated to 170°C. The other form, the dihydrate, loses 5.36% of its weight when heated from 86 to 144°C. The anhydrous diatrizoic acid is the preferred reference standard, because it has an IR spectrum and x-ray diffraction pattern suitable for identification purposes.

TWO-PHASE NUCLEI IN PARAELECTRIC PHASE OF Pb1-x(Li1/2La1/2)x(Zr1-yTiy)O3 SOLID SOLUTIONS

2001 ◽  
Vol 15 (24n25) ◽  
pp. 3366-3368
Author(s):  
V. L. SOBOLEV ◽  
V. M. ISHCHUK
Keyword(s):  
Phase Transition ◽  
Phase Diagram ◽  
Paraelectric Phase ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Ordered Phases ◽  
Ti Content ◽  
Temperature Phase Diagram

The phase transition from the paraelectric phase to ordered phases in Pb1-x(Li1/2La1/2)x(Zr1-yTiy)O3 with compositions close to the ferroelectric - antiferroelectric - paraelectric triple point in the Ti-content - temperature phase diagram is studied. X-ray diffraction is used to identify two - phase (antiferroelectric and ferroelectric) nuclei embeded in a paraelectric matrix. The relation between these two-phase nuclei in paraelectric phase and the diffuseness of the phase transition is discussed.

Characterization of Clay from Vale do Mulembá - ES

2008 ◽  
Vol 591-593 ◽  
pp. 487-492 ◽  
Author(s):  
Monica Castoldi Borlini Gadioli ◽  
J.C.G. Correia ◽  
A. Caranassios
Keyword(s):  
Particle Size ◽  
Chemical Analysis ◽  
Thermal Analyses ◽  
The Other ◽  
High Plasticity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Characterization Studies ◽  
And Behavior

This work has for objective to characterize the clay from Vale do Mulembá-ES. The Vale do Mulembá is located in Joana D´Arc, Vitória in Espírito Santo State, Brazil. That clay is used in the production of the traditional clay pans of the State, what contributes to the economy of the area. The clay from Vale do Mulembá presents characteristics and behavior different from the other clays used for the production of clay pans. The characterization studies were carried out through chemical analysis, X-ray diffraction, particle size distribution, plasticity and thermal analyses (DTA, TGA). The results showed that the clay is typical kaolinitic, present relatively to the amount high of Al2O3 and high plasticity.

Metallographic, Structural and Mechanical Characterization of a Low Density Fe-Mn-Al-C Steel Microalloyed with Ti/B in As-Cast and Homogenized Conditions

MRS Advances ◽  
2018 ◽  
Vol 3 (64) ◽  
pp. 3971-3978 ◽  
Author(s):  
O.E. Villanueva-Perez ◽  
I. Mejía ◽  
V. García-García ◽  
A. Bedolla-Jacuinde
Keyword(s):  
Grain Size ◽  
Mechanical Characterization ◽  
The Other ◽  
Low Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Other Hand ◽  
Average Grain Size ◽  
Cast Condition

ABSTRACTLow density (LD) steels have shown particular characteristics in terms of mechanical properties and microstructure, since they have high strength, high ductility and density reduction up to 18%. On the other hand, the addition of microalloying elements such as Ti and B generate hardening by solid solution and precipitation, as well as grain refinement effect. LD steels generate nano-sized kappa phase precipitated from the austenite matrix, and these advanced steels can reach strength and elongation up to 780 MPa and 60%, respectively. The main objective of this research work is the metallographic, structural and mechanical characterization of a LD steel microalloyed with Ti/B in as-cast and -homogenized conditions. For this purpose a Fe-27Mn-7Al-1.2C (%wt) LD steel microalloyed with Ti/B was melted in a vacuum-induction furnace and cast in metallic mold. LD-Ti/B steel samples were homogenized at 1100 °C during 20, 50, 100, 150 and 200 minutes followed by water quenching. Metallographic, structural and mechanical characterization was carried out by optical (LOM) and scanning electron (SEM) microscopy, X-ray diffraction (XRD) and microhardness Vickers testing (HV10), respectively. In general, results showed a typical dendritic microstructure with average grain size of 1256 μm in the as-cast condition. On the other hand, the as-homogenized condition showed an austenitic equiaxial microstructure with average grain size from 164 to 940 μm. Austenite, ferrite and kappa phases were detected by X-ray diffraction (XRD). Also, second-phase particles such as AlN, TiC and MnS were detected by LOM and SEM-EDS analysis. LD steel microalloyed with Ti/B exhibited the highest microhardness Vickers value (235 HV10) in the as-cast condition, whilst in the as-homogenized condition microhardness gradually decreases from 223 to 198 HV10 as holding time increases.

An investigation into the structure and morphology of polyamide 6/polyaniline hybrid fibers

2018 ◽  
Vol 38 (1) ◽  
pp. 19-24
Author(s):  
Kamran Zarrini ◽  
Mostafa Youssefi
Keyword(s):  
Phase Diagram ◽  
Ternary Phase ◽  
Ternary Phase Diagram ◽  
Polyamide 6 ◽  
Wet Spinning ◽  
X Ray Diffraction ◽  
Hybrid Fibers ◽  
X Ray ◽  
Structure And Morphology ◽  
Crystalline Forms

Abstract A wet spinning dope composition for the production of hybrid fibers was selected based on the analysis of a ternary phase diagram of polyamide 6 (PA6)/formic acid/water. Polyaniline was later added to this dope with different weight percentages to produce hybrid fibers. The results showed that polyaniline was dispersed uniformly in the PA6 matrix and the spinning dope composition had a great impact on the morphology of the hybrid fibers produced with different quantities of polyaniline. The electrical conductivity of the hybrid fibers was increased with the increase in polyaniline content of the fibers and reached 7.94×10−3 S·cm−1 for the sample that contained 30% polyaniline. The crystalline structure of PA6 in all hybrid fibers was revealed to be only of α form. No other crystalline forms, for example β form, was observed in PA6 due to the presence of polyaniline in the system as revealed from x-ray diffraction results.

Thermal and structural characterization of the ZrO2−x(OH)2xto ZrO2 transition

2001 ◽  
Vol 16 (8) ◽  
pp. 2209-2212 ◽  
Author(s):  
E Torres-GarciÁa ◽  
A. Peláiz-Barranco ◽  
C. Vázquez-Ramos ◽  
G. A. Fuentes
Keyword(s):  
High Resolution ◽  
Metastable Phase ◽  
Nitrogen Adsorption ◽  
The Other ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
X Ray ◽  
Exothermic Process

The exothermic process that occurs around 700 K during calcination of ZrO2−x(OH)2x, associated with the crystallization of the low-temperature tetragonal metastable phase of ZrO2, was analyzed using x-ray diffraction, high-resolution thermogravimetric analysis (TGA), nitrogen adsorption, and modulated differential scanning calorimetry (MDSC). High-resolution TGA allowed us to determine the water loss, resulting from condensation of OH− groups. The amount was 0.137 wt% in our case, equivalent to 1.7 × 10−2 mol of H2O/mol of ZrO2. That corresponds to about one −OH group per nm2 being lost in that process. By using MDSC we determined that the change in enthalpy (∆Hglobal = −15.49 kJ/mol of ZrO2) was the result of two parallel contributions. One of them was reversible and endothermic (∆Hrev = 0.11 kJ/mol of ZrO2), whereas the other was irreversible and exothermic (∆Hirrev = −15.60 kJ/mol of ZrO2). The variability and magnitude of the exotherm, as well as the fact that the accompanying weight loss is so small, are consistent with a mechanism involving the formation of tetragonal nuclei, rather than global crystallization, and hence depend on the number of nuclei so formed.

X-Ray Studies in the Ti-O System*

1960 ◽  
Vol 4 ◽  
pp. 175-193 ◽  
Author(s):  
Norman F. H. Bright
Keyword(s):  
Atomic Ratio ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Monoclinic Form ◽  
Wide Range ◽  
Single Well ◽  
Crystalline Forms ◽  
Marked Tendency ◽  
Oxidation Behaviors

AbstractX-ray diffraction studies have revealed that a titanium oxide with an NaCl-type structure is stable over a wide range of nonstoichiometric compositions, both above and below the 1:1 Ti/O atomic ratio. Attempts to prepare a strictly stoichiometric TiO as a single phase have revealed a marked tendency for such a composition to disproportionate into two nonstoichiometric “TiO”-type structures of variable composition, whereas nonstoichiometric compositions can be readily prepared under similar conditions as single, well-crystallized phases.The oxide Ti3O5, which forms a constituent of the titanium-bearing slags produced in ilmenite smelting, has been prepared as a pure compound in two different crystalline forms, both monoclinic in structure, but one being very close to the orthorhombic pseudobrookite, Fe2O3 · TiO2, or ferrous dititanate, FeO · 2TiO2 structure. This “dititanate” form inverts to the other monoclinic form at high temperatures. Single crystals of the latter monoclinic form are readily made. The studies of the “dititanate” form have been restricted to powder diffraction work, since it inverts to the other form after melting. The two forms show different oxidation behaviors,

New ordered phase in the quasi-binary UAl3–USi3system

2014 ◽  
Vol 70 (3) ◽  
pp. 580-585 ◽  
Author(s):  
Gennady Rafailov ◽  
Isaac Dahan ◽  
Louisa Meshi
Keyword(s):  
Phase Diagram ◽  
Binary Phase Diagram ◽  
Nuclear Reactors ◽  
The Other ◽  
Miscibility Gap ◽  
X Ray Diffraction ◽  
Electron Crystallography ◽  
X Ray ◽  
Binary Phase ◽  
The One

The industrial importance of the U–Al–Si system stems from the fact that during processing the Al-based alloy (containing Si as impurity), used for the cladding of U (fuel in nuclear reactors), undergoes heat treatment which stimulates diffusion between the fuel and the cladding. One of the possible ways to represent the ternary U–Al–Si phase diagram is the construction of an UAl3–USi3quasi-binary phase diagram. On the one hand, since the UAl3and USi3phases are isostructural, an isomorphous phase diagram is expected; on the other hand, some researchers observed a miscibility gap at lower temperatures. During our study of the UAl3–USi3quasi-binary phase diagram, a new stable U(Alx,Si1 − x)3phase was identified. The structure of this phase was determined, using a combination of electron crystallography and powder X-ray diffraction methods, as tetragonal [I4/mmm(No.139) space group], with lattice parametersa=b= 8.347 (1),c= 16.808 (96) Å. Its unit cell has 64 atoms and it can be described as an ordered variant of the U(Al,Si)3solid solution. A Bärnighausen tree was constructed using the original U(Al,Si)3structure as an aristotype.

Zum System Ca/Mo/O: Phasendiagramm, Synthese und Charakterisierung der ternären Verbindungen / On the System Ca/Mo/O: Phase Diagram, Synthesis and Characterization of Ternary Compounds

1997 ◽  
Vol 52 (10) ◽  
pp. 1169-1174 ◽  
Author(s):  
U. Steiner ◽  
W. Reichelt
Keyword(s):  
Phase Diagram ◽  
Rietveld Analysis ◽  
Solid State Reactions ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ternary Compounds ◽  
Powder Samples ◽  
O Phase

The phase diagram of the ternary system Ca/Mo/O has been determined. Powder samples of the ternary compounds CaMoO4, CaMoO3, CaMo5O8, Ca16.5Mo13.5O40 and Ca5.45Mo18O32 were prepared by solid state reactions. Rietveld analysis based on powder X-ray diffraction data shows that the compound CaMo5O8 has monoclinic structure (P21/c) with a = 7.549, b = 9.064, c = 9.974 Å, β = 110.04°. CaMo5O8, Ca16.5Mo13.5O40 and Ca5.45Mo18O32 are semiconductors over the temperature range 75 to 300 K.

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