scholarly journals Effect of Excess Silicon on the Formation of Ti3SiC2 Using Free Ti/Si/C Powders Synthesized via Arc Melting

ISRN Ceramics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Mohamad Johari Abu ◽  
Julie Juliewatty Mohamed ◽  
Zainal Arifin Ahmad
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Relative Density ◽  
Stoichiometric Ratio ◽  
Secondary Phases ◽  
X Ray ◽  
Excess Silicon ◽  
Arc Melting ◽  
Equiaxed Grains ◽  
Scanning Electron

The aim of this study is to investigate the effect of excess silicon on the formation of Ti3SiC2 from free Ti/Si/C powders synthesized via arc melting. The reactant mixture was prepared according to the off-stoichiometric ratio of 3Ti : (x+1)Si : 2C, where x (excess Si) varied from 0 to 0.5. Samples were analyzed using X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive spectroscopy (EDS). The relative density and porosity of products were calculated using the Archimedes method. Through optimization of the arcing schedules (time) and excess Si amounts, 86.9 wt% of Ti3SiC2 with a relative density of 86% was obtained. For all products, Ti3SiC2 was identified as the main phase, while TiC, TiSi2, and Ti5Si3 were identified as secondary phases. Ti3SiC2 grains were in the form of elongated platelets; they were nucleated and grew on the surface of equiaxed TiC grains. The microporosity present in the TiC-equiaxed grains affected the density and porosity of the products.

Solidification Behavior and Phase Relation of Arc Melting La-Fe-Si Alloys

2012 ◽  
Vol 602-604 ◽  
pp. 2130-2135
Author(s):  
Zhong Qi Dong ◽  
Jin Chen ◽  
Jun Li Jia
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Diffraction Analysis ◽  
Phase Relation ◽  
Induction Melting ◽  
Solidification Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Scanning Electron

Solidification behavior and phase relation of LaFe13-xSix alloys was investigated using arc melting. Phase formation and structure in arc melted LaFe13-xSix alloys has been investigated by means of power X-ray diffraction analysis and scanning electron microscopy. The results have shown that La(Fe,Si)13 (1:13) phase is a peritectic phase and the solidification behavior and phase relations of LaFe13-xSix alloys are different with Si contents. Under arc melting condition, composition with low Si contents (x=0.5 to 1.5) consist mainly of α-(Fe,Si) phase the same as induction melting. Composition with high Si contents (x=2.0 to 3.0) consists mainly of 1:13 phase. The results were discussed with respect to the effect of cooling rate.

Growth of CuInS2 Films on Crystalline Substrates

1996 ◽  
Vol 426 ◽  
Author(s):  
R. Hunger ◽  
R. Scheer ◽  
M. Alt ◽  
H. J. Lewerenz
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Molecular Beam ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Growth Morphology ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

AbstractCuInS2 films were grown by molecular beam epitaxy (MBE) on hydrogen terminated Si(111) substrates with 4° miscut. X-ray diffraction (XRD) texture analysis reveals that CuInS2 was grown heteroepitaxially with the epitaxial relationships CuInS2(112) II Si(111) and [111] II [111]. Moreover, a substantial amount of rotational twins is observed. The crystalline order is maintained across the interface as observed by cross-sectional transmission electron microscopy (XTEM). XRD and scanning electron microscopy (SEM) investigations show that nonstoichiometric preparation greatly influences the growth morphology and leads to the formation of secondary phases.

Synthesis and Stability of the Strontium Cobaltite Thermally Treated in Air

2019 ◽  
Vol 70 (9) ◽  
pp. 3330-3334
Author(s):  
Alina Melinescu ◽  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Cristian Hornoiu ◽  
Maria Preda
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Raw Materials ◽  
Stoichiometric Ratio ◽  
Chemical Transformations ◽  
Vitreous Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

This paper reports, the studies on chemical transformations at thermal treatment of a mixture of SrCO3 and Co3O4 corresponding to stoichiometric ratio of SrCoO3 compound. The mixture of raw materials was prepared by mechanical activation. Thermal analysis, X-ray diffraction and scanning electron microscopy were used for these studies. It was found that SrCoO3 forms at 930oC but is not stable and turn immediately into Sr2Co2O5 by eliminating of oxygen. This compound, Sr2Co2O5, is unstable and by increasing of the temperature decomposes in Sr3Co2O6 and cobalt oxide. At temperatures above the 1250oC, the samples melt and Sr3Co2O6 crystallizes from vitreous phase by cooling.

The Influence of Sintering Conditions on Microstructure of La-Ca-Sr-Mn-O Magnetocaloric Ceramics

2014 ◽  
Vol 782 ◽  
pp. 503-506 ◽  
Author(s):  
Katarina Zmorayova ◽  
Samuel Piovarči ◽  
Monika Radusovska ◽  
Vitaliy Antal ◽  
Viktor Kavečanský ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Thermal Analyses ◽  
Polarized Light ◽  
Secondary Phases ◽  
X Ray ◽  
Different Temperatures ◽  
Sintering Conditions ◽  
Scanning Electron

A La0.67Ca0.33-xSrxMnO3 (x=0.33; 0.03; 0) perovskite magnetocaloric powders were prepared by solid state synthesis in air. Phase transformations were characterized by thermal analyses and the phase composition was confirmed by X-ray powder diffraction. Pressed pellets were sintered at different temperatures. Microstructure analyses were done by polarized light microscopy and scanning electron microscopy. The influence of sintering conditions on porosity, grain size and content of secondary phases is shown.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Scanning Electron Microscopy and X-Ray Analyses of Dental Tissues from a Hibernator

1976 ◽  
Vol 34 ◽  
pp. 178-179
Author(s):  
M. L. Zimny ◽  
A. C. Haller
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Body Temperature ◽  
Ground Squirrel ◽  
Alveolar Bone ◽  
X Ray ◽  
Dental Tissues ◽  
Bone Minerals ◽  
Apical Tooth ◽  
Scanning Electron

During hibernation the ground squirrel is immobile, body temperature reduced and metabolism depressed. Hibernation has been shown to affect dental tissues varying degrees, although not much work has been done in this area. In limited studies, it has been shown that hibernation results in (1) mobilization of bone minerals; (2) deficient dentinogenesis and degeneration of alveolar bone; (3) presence of calculus and tears in the cementum; and (4) aggrevation of caries and pulpal and apical tooth abscesses. The purpose of this investigation was to study the effects of hibernation on dental tissues employing scanning electron microscopy (SEM) and related x-ray analyses.

Scanning Electron Microscopy and x-ray analysis of microparticles and early hydration effects

1995 ◽  
Vol 53 ◽  
pp. 692-693
Author(s):  
Yun Lu ◽  
David C. Joy
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Morphological Development ◽  
Early Hydration ◽  
X Ray ◽  
Blended Cements ◽  
Powder Particles ◽  
Chemical Wastes ◽  
Scanning Electron

High resolution scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) were performed to investigate microparticles in blended cements and their hydration products containing sodium-rich chemical wastes. The physical appearance of powder particles and the morphological development at different hydration stages were characterized by using high resolution SEM Hitachi S-900 and by SEM S-800 with a EDX spectrometer. Microparticles were dispersed on the sample holder and glued by 1% palomino solution. Hydrated bulk samples were dehydrated by acetone and mounted on the holder by silver paste. Both fracture surfaces and flat cutting sections of hydrating samples were prepared and examined. Some specimens were coated with an 3 nm thick Au-Pd or Cr layer to provide good conducting surfaces. For high resolution SEM S-900 observations the accelerating voltage of electrons was 1-2 KeV to protect the electron charging. Microchemical analyses were carried out by S800/EDS equipped with a LINK detector of take-off angle =40°.

Defects of Platelet Function Recognized by X-Ray Imaging and Scanning Electron Microscopy

1985 ◽  
Vol 43 ◽  
pp. 610-613
Author(s):  
M.G. Baldini ◽  
S. Morinaga ◽  
D. Minasian ◽  
R. Feder ◽  
D. Sayre ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cell Biology ◽  
Imaging Technique ◽  
Human Platelets ◽  
X Rays ◽  
X Ray ◽  
X Ray Imaging ◽  
Complex Phenomena ◽  
Scanning Electron

Contact X-ray imaging is presently developing as an important imaging technique in cell biology. Our recent studies on human platelets have demonstrated that the cytoskeleton of these cells contains photondense structures which can preferentially be imaged by soft X-ray imaging. Our present research has dealt with platelet activation, i.e., the complex phenomena which precede platelet appregation and are associated with profound changes in platelet cytoskeleton. Human platelets suspended in plasma were used. Whole cell mounts were fixed and dehydrated, then exposed to a stationary source of soft X-rays as previously described. Developed replicas and respective grids were studied by scanning electron microscopy (SEM).

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

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