The thermal decomposition of chrysotile

1977 ◽  
Vol 41 (320) ◽  
pp. 453-459 ◽  
Author(s):  
C. J. Martin
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Thermal Treatment ◽  
High Temperatures ◽  
Lattice Parameters ◽  
Atomic Arrangement ◽  
Observable Change ◽  
Infra Red ◽  
Magnesium Silicates

SummaryThe decomposition of chrysotile fibres heated in air has been studied in the range 100–1400°C by electron microscopy and infra-red absorption. The first observable change in the structure occurred at 580°C, where cavities started to open up between the (001) layers of chrysotile as the fibres were dehydrated, giving rise to strong low-angle diffraction. There was no evidence of any structure in the remaining material but some degree of the original atomic arrangement was preserved for the magnesium silicates, forsterite, and enstatite, later developed in certain preferred orientations. The manner of this crystallization was determined by the thermal treatment, for in samples held between 600°C and 800°C forsterite developed slowly with little further disruption of the fibre while above 800°C the remaining amorphous areas rapidly recrystallized to a mixture of forsterite and enstatite. It is suggested that the mechanisms described by other investigators to explain the development of forsterite in preferred orientations may serve simply to nucleate the crystallization and a similar mechanism to account for the nucleation of the enstatite crystallization is considered. At high temperatures a possible doubling of some of the lattice parameters of the silicates was observed.

Structural Investigation of Ba2+ and Sr2+ Diphyllosilicates Doped with Yb3+ Ions

2007 ◽  
Vol 555 ◽  
pp. 219-224 ◽  
Author(s):  
B. Nedić ◽  
V. Dondur ◽  
A. Kremenović ◽  
R. Dimitrijević
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Thermal Treatment ◽  
Crystal Structures ◽  
Structural Investigation ◽  
Ceramic Materials ◽  
Scanning Calorimetry ◽  
Infra Red ◽  
Scanning Electron

Ceramic materials, barium and strontium diphyllosilicates doped with ytterbium ions, were obtained by thermal treatment from Ba–LTA and Sr–LTA zeolites. The samples were characterized with Differential Scanning Calorimetry, Infra–Red Spectroscopy and Scanning Electron Microscopy. The crystal structures of diphyllosilacetes have been refined.

Electron Microscopy of Human Gallstones

1971 ◽  
Vol 29 ◽  
pp. 296-297
Author(s):  
C. Wolpers ◽  
R. Blaschke
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
Bile Pigment ◽  
X Ray Diffraction ◽  
Triclinic Crystal System ◽  
X Ray ◽  
Follow Up Study ◽  
Infra Red ◽  
Main Components

Scanning microscopy was used to study the surface of human gallstones and the surface of fractures. The specimens were obtained by operation, washed with water, dried at room temperature and shadowcasted with carbon and aluminum. Most of the specimens belong to patients from a series of X-ray follow-up study, examined during the last twenty years. So it was possible to evaluate approximately the age of these gallstones and to get information on the intensity of growing and solving.Cholesterol, a group of bile pigment substances and different salts of calcium, are the main components of human gallstones. By X-ray diffraction technique, infra-red spectroscopy and by chemical analysis it was demonstrated that all three components can be found in any gallstone. In the presence of water cholesterol crystallizes in pane-like plates of the triclinic crystal system.

Applications of Photoelectron Microscopy

1976 ◽  
Vol 34 ◽  
pp. 506-507
Author(s):  
William J. Baxter
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Chemical Composition ◽  
Ultraviolet Radiation ◽  
Thin Layer ◽  
Edge Effects ◽  
Electron Optics ◽  
Surface Layers ◽  
Crystalline Orientation ◽  
Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

scholarly journals The Importance of Thermal Treatment on Wet-Kneaded Silica–Magnesia Catalyst and Lebedev Ethanol-to-Butadiene Process

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 579
Author(s):  
Sang-Ho Chung ◽  
Adrian Ramirez ◽  
Tuiana Shoinkhorova ◽  
Ildar Mukhambetov ◽  
Edy Abou-Hamad ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Calcination Temperature ◽  
Catalytic Properties ◽  
Catalyst Preparation ◽  
Preparation Methods ◽  
Calcination Temperatures ◽  
Alternative Process ◽  
Magnesium Silicates

The Lebedev process, in which ethanol is catalytically converted into 1,3-butadiene, is an alternative process for the production of this commodity chemical. Silica–magnesia (SiO2–MgO) is a benchmark catalyst for the Lebedev process. Among the different preparation methods, the SiO2–MgO catalysts prepared by wet-kneading typically perform best owing to the surface magnesium silicates formed during wet-kneading. Although the thermal treatment is of pivotal importance as a last step in the catalyst preparation, the effect of the calcination temperature of the wet-kneaded SiO2–MgO on the Lebedev process has not been clarified yet. Here, we prepared and characterized in detail a series of wet-kneaded SiO2–MgO catalysts using varying calcination temperatures. We find that the thermal treatment largely influences the type of magnesium silicates, which have different catalytic properties. Our results suggest that the structurally ill-defined amorphous magnesium silicates and lizardite are responsible for the production of ethylene. Further, we argue that forsterite, which has been conventionally considered detrimental for the formation of ethylene, favors the formation of butadiene, especially when combined with stevensite.

Thermal decomposition of formaldehyde at high temperatures

1985 ◽  
Vol 89 (14) ◽  
pp. 3109-3113 ◽  
Author(s):  
Ko Saito ◽  
Terumitsu Kakumoto ◽  
Yoshihiro Nakanishi ◽  
Akira Imamura
Keyword(s):  
Thermal Decomposition ◽  
High Temperatures

Effect of Synthesis Parameters on Size of the Biodegradable Poly (L-Lactide) (PLLA) Microspheres

2013 ◽  
Vol 858 ◽  
pp. 60-66 ◽  
Author(s):  
A.A. Hawari ◽  
C.Y. Tham ◽  
Zuratul Ain Abdul Hamid
Keyword(s):  
Electron Microscopy ◽  
Volume Ratio ◽  
Water Volume ◽  
Synthesis Parameters ◽  
Weight Variation ◽  
Infra Red ◽  
Biodegradable Poly ◽  
Evaporation Technique ◽  
Molecular Weight Variation ◽  
Scanning Electron

In this work, PLLA microspheres were prepared via emulsion solvent evaporation technique. Several synthesis parameters were studied to evaluate their effect on the size of PLLA microspheres. PLLA pallets before emulsion and PLLA microspheres surface chemistry after emulsion were determined using Fourier Transform Infra-red (FTIR). Results showed that PLLA pallets and microspheres FTIR obtained an identical spectrum. Microspheres size and surface morphology were determined using Scanning Electron Microscopy (SEM). In conclusion, the parameters that significantly affect the size of PLLA microspheres were PLLA concentration, DCM to water volume ratio, PVA concentration and stirring speed. PVA molecular weight variation showed no significant change in microspheres size.

High-Resolution Electron Microscopy Studies of Faults and Intergrowth in Nb3O7F

1990 ◽  
Vol 183 ◽  
Author(s):  
Lotta permér ◽  
Monica Lundberg
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
High Pressure ◽  
High Resolution Electron Microscopy ◽  
Two Dimensions ◽  
Resolution Electron ◽  
Shear Type ◽  
Pressure Form ◽  
The Common ◽  
Shear Planes

AbstractHREM studies of the low-pressure form of Nb3O7F, obtained by thermal decomposition of NbO2F or by reacting stoichiometric amounts of NbO2F and Nb2O5, confirmed that the crystals are built up of a shear-type structure in which slabs of ReO3 type, infinite in two dimensions and three octahedra wide, separate the shear planes. Most of the crystals were well-ordered, although faults could occasionally be detected. However, some crystals were found to be intergrown with a structure closely related to the high-pressure form of Nb3O7F. The latter structure is composed of wavy rows of edge-sharing NbX7 pentagonal bipyramids, joined to each other by NbX6 octahedra. The connection between the two atomic arrangements can be understood in terms of the common c-axes and a slight distortion of the polyhedra along the boundary.

Synthesis and application of carbon based heterogeneous catalysts for ultrasound assisted biodiesel production

2015 ◽  
Vol 4 (1) ◽  
Author(s):  
Namrata D. Gaikwad ◽  
Parag R. Gogate
Keyword(s):  
Electron Microscopy ◽  
Heterogeneous Catalysts ◽  
Temperature Programmed Desorption ◽  
Biodiesel Production ◽  
Acid Catalysts ◽  
Infra Red ◽  
Ultrasound Assisted ◽  
Temperature Programmed ◽  
Scanning Electron ◽  
Carbon Based

AbstractIn the present work, carbon based heterogeneous acid catalysts have been prepared using various synthesis approaches based on the use of sustainable starting materials. The properties of the catalysts have been investigated using Fourier transformed infra-red (FTIR), scanning electron microscopy (SEM), temperature-programmed desorption (NH

scholarly journals Development of an Oxcarbazepine Solid Dispersion Using Skimmed Milk to Improve the Solubility and Dissolution Profile

2019 ◽  
Vol 11 (05) ◽  
Author(s):  
M. Shah ◽  
D. Patel
Keyword(s):  
Electron Microscopy ◽  
Solid Dispersion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Infra Red ◽  
Crystalline Nature ◽  
Skimmed Milk ◽  
Scanning Electron

Oxcarbazepine has low solubility and low oral bioavailability, so it’s a challenge to formulate suitable dosage form. In this present investigation, to improve the dissolution rate and solubility, skimmed milk is used as a carrier. Physical mixers were prepared using various drugs to carrier ratio and spray drying technology was used to develop solid dispersion with the carrier. Various techniques were used to characterize the solid dispersion immediately after they were made which includes differential scanning calorimetry, scanning electron microscopy, fourier transform infra- red spectroscopy, X-ray diffraction and in-vitro dissolution profiles. The differential scanning calorimetry thermograms of raw drug indicated of its anhydrous crystalline nature. In thermograms of solid dispersion, the characteristic peak was absent suggesting the change from crystalline nature to amorphous form. X-ray diffraction confirmed those results. X-ray diffraction results of raw drug showed highly intense peak characteristic of its crystalline nature where solid dispersion showed less intense, more diffused peak indicating the change in crystalline form. Fourier transforms infra-red spectroscopy studies showed there was no interaction between drug and carrier. Scanning electron microscopy support the amorphous nature of mixer. The whole formulation showed distinct enhancement in the drug release behavior and solubility. The optimum oxcarbazepine to skimmed milk ratio 1:3 enhances the in-vitro drug release by 3.5 fold and also show distinct increase in solubility. It was concluded that for improvement of solubility of poorly water soluble oxcarbazepine, skimmed milk powder as a carrier can be utilize very well.

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