scholarly journals Low temperature sintering of mechanically activated BaCO3-TiO2

2002 ◽  
Vol 34 (1) ◽  
pp. 73-77 ◽  
Author(s):  
Vera Pavlovic ◽  
Biljana Stojanovic ◽  
Vladimir Pavlovic ◽  
Ljiljana Zivkovic ◽  
Momcilo Ristic
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Mechanical Activation ◽  
Heating Rate ◽  
High Energy ◽  
Crystallographic Data ◽  
Low Temperature Sintering ◽  
Stoichiometric Mixture ◽  
Scanning Electron

In this article low temperature sintering of mechanically activated BaCO3-TiO2 system was studied. A stoichiometric mixture of BaCO3 and TiO2 powders was mechanically activated in a high-energy vibromill for 0, 30, 90 and 180 min, calcined at 800oC for 1 h and reaction sintered at 1100oC and 1200oC for 2 h (heating rate of 10oC/min). Phase compositions and crystallographic data of initial, activated, calcinated and sintered specimens were obtained by the XRPD method. It was noticed that mechanical activation enhanced and lowered the temperature of the formation of tetragonal BaTiO3. Scanning electron microscopy was used to study and characterize microstructures of the samples.

Mechanochemical Synthesis of Intermetallic Compounds in the Gallium–Iridium System

2019 ◽  
Vol 18 (03n04) ◽  
pp. 1940067
Author(s):  
P. Vitiaz ◽  
N. Lyakhov ◽  
T. Grigoreva ◽  
E. Pavlov
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Activation ◽  
Intermetallic Compounds ◽  
High Energy ◽  
Planetary Mill ◽  
X Ray Diffraction ◽  
X Ray ◽  
Active Liquid ◽  
Scanning Electron

The interaction between a solid inert metal Ir and an active liquid metal Ga during mechanical activation in a high-energy planetary mill is studied by X-ray diffraction and scanning electron microscopy with high-resolution energy dispersive X-ray microanalysis. The effect of mechanical activation on the formation of GaxIry intermetallic compounds and GaxIry/Ir composites and their solubility in acids was investigated. The subsequent extraction of Ga from intermetallic compounds and composites in the mixture of concentrated acids [Formula: see text] makes it possible to produce nanoscale Ir.

scholarly journals Influence of mechanical activation on synthesis of zinc metatitanate

2005 ◽  
Vol 37 (2) ◽  
pp. 115-122 ◽  
Author(s):  
Nebojsa Labus ◽  
Nina Obradovic ◽  
Tatjana Sreckovic ◽  
V. Mitic ◽  
Momcilo Ristic
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Specific Surface ◽  
Mechanical Activation ◽  
Surface Area ◽  
Perovskite Structure ◽  
Mechanical Treatment ◽  
X Ray ◽  
Scanning Electron

Investigations of a ZnO-TiO2 binary oxide mixture during mechanical treatment were mainly focused on obtaining orthotitanate Zn2TiO4 with a spinel structure. Due to the specific way of energy transfer during mechanical treatment using a high-energy ball mill, the system passes through low temperature ZnTiO3 metatitanate phase formation. Mechanical activation was performed on an equimolar ratio mixture of ZnO and TiO2. The anatase phase was previously submitted to heat treatment for achieving a starting mixture rich in a rutile phase. Milling conditions were preset for observing the formation of a low temperature ZnTiO3 phase with a perovskite structure. The powder microstructure was characterized using scanning electron microscopy. A nitrogen gas sorption analyzer with the BET method was used to determine the specific surface area and porosity, indicating changes of powder sample properties during mechanical activation. Also, X ray powder diffractometry was applied to obtain the phase composition. Powders were then pressed into pellets and their compressibility was observed through density changes. According to microstructures obtained by scanning electron microscopy analysis, the system underwent a primary and secondary agglomeration process. Specific surface area measurements supported that conclusion. Compressibility investigations established the difference between compressibility of the non-activated mixture and activated powders. X-ray diffraction analysis revealed that a perovskite structure forms simultaneously with a spinel phase during the process of mechanical activation.

Intracellular structures of rapid frozen biological samples observed by high-resolution low-temperature Scanning Electron Microscopy

1989 ◽  
Vol 47 ◽  
pp. 736-737
Author(s):  
T. Inoué ◽  
H. Koike
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Liquid Nitrogen ◽  
Specimen Preparation ◽  
Chemical Fixation ◽  
Brown Adipose ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) is useful to avoid artifacts such as deformation and extraction, because specimens are not subjected to chemical fixation, dehydration and critical-point drying. Since Echlin et al developed a LTSEM, many techniques and instruments have been reported for observing frozen materials. However, intracellular structures such as mitochondria and endoplasmic reticulum have been unobservable by the method because of the low resolving power and inadequate specimen preparation methods. Recently, we developed a low temperature SEM that attained high resolutions. In this study, we introduce highly magnified images obtained by the newly developed LTSEM, especially intracellular structures which have been rapidly frozen without chemical fixation.[Specimen preparations] Mouse pancreas and brown adipose tissues (BAT) were used as materials. After the tissues were removed and cut into small pieces, the specimen was placed on a cryo-tip and rapidly frozen in liquid propane using a rapid freezing apparatus (Eiko Engineering Co. Ltd., Japan). After the tips were mounted on the specimen stage of a precooled cryo-holder, the surface of the specimen was manually fractured by a razor blade in liquid nitrogen. The cryo-holder was then inserted into the specimen chamber of the SEM (ISI DS-130), and specimens were observed at the accelerating voltages of 5-8 kV. At first the surface was slightly covered with frost, but intracellular structures were gradually revealed as the frost began to sublimate. Gold was then coated on the specimen surface while tilting the holder at 45-90°. The holder was connected to a liquid nitrogen reservoir by means of a copper braid to maintain low temperature.

Criteria for the evaluation of low-temperature Scanning Electron Microscopy

1986 ◽  
Vol 44 ◽  
pp. 902-903
Author(s):  
Alan Beckett
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Conformational Changes ◽  
Chemical Vapour ◽  
List Type ◽  
Dimensional Changes ◽  
Critical Point Drying ◽  
Temperature Scanning ◽  
Scanning Electron

Low temperature scanning electron microscopy (LTSEM) has been evaluated with special reference to its application to the study of morphology and development in microorganisms. A number of criteria have been considered and have proved valuable in assessing the standard of results achieved. To further aid our understanding of these results, it has been necessary to compare those obtained by LTSEM with those from more conventional preparatory procedures such as 1) chemical fixation, dehydration and critical point-drying; 2) freeze-drying with or without chemical vapour fixation before hand.The criteria used for assessing LTSEM for the above purposes are as follows: 1)Specimen immobilization and stabilization2)General preservation of external morphology3)General preservation of internal morphology4)Exposure to solvents5)Overall dimensional changes6)Cell surface texture7)Differential conformational changes8)Etching frozen-hydrated material9)Beam damage10)Specimen resolution11)Specimen life

Titanium Effect on Microstructure and Fracture toughness of Al2O3-BASED Composites

2011 ◽  
Vol 691 ◽  
pp. 32-36
Author(s):  
José G. Miranda-Hernández ◽  
Elizabeth Refugio-García ◽  
Eduardo Térres-Rojas ◽  
Enrique Rocha-Rangel
Keyword(s):  
Electron Microscopy ◽  
Fracture Toughness ◽  
Scanning Electron Microscopy ◽  
Fine Particles ◽  
Ceramic Matrix ◽  
High Energy ◽  
Titanium Content ◽  
Indentation Method ◽  
Sintered Temperature ◽  
Scanning Electron

The effect of different titanium additions (0.5, 1, 2, 3 and 10 vol. %), milling intensity (4 and 8 h) and sintered temperature (1500 and 1600 °C) on microstructure and fracture toughness of Al2O3-based composites was analyzed in this study. After high energy milling of a titanium and Al2O3mixtures, powder mixture presents fine distribution and good homogenization between ceramic and metal. After milling powders during 8 h they were obtained very fine particles with 200 nm average sizes. Microstructures of the sintered bodies were analyzed with a scanning electron microscopy, where it was observed that the microstructure presents the formation of a small and fine metallic net inside the ceramic matrix. From fracture toughness measurements realized by the fracture indentation method, it had that when titanium content in the composite increases, fracture toughness is enhanced until 83% with respect to the fracture toughness of pure Al2O3. This behavior is due to the formation of metallic bridges by titanium in the Al2O3matrix.

Magnesium Nitrate as Additive for Synthesis of Mg(OH)2 Nanoparticles

2012 ◽  
Vol 198-199 ◽  
pp. 99-102
Author(s):  
Qing Gang Kong ◽  
Hai Yan Qian
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Magnesium Nitrate ◽  
Crystal Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Size And Morphology ◽  
Scanning Electron

Magnesium nitrate was used as additive for synthesis of Mg(OH)2 (MH) nanoparticles at low temperature (70°C). Mg(OH)2 nanoparticles have platelet-like structure and approximately 40-60nm in thicknesses. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied to characterize the crystal phase. The supersaturation degree of solution effects the size and morphology of MH nanoparticles.

scholarly journals Development of Tin Oxide-Based Nanosensors for Electronic Nose Environmental Applications

Biosensors ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 21 ◽  
Author(s):  
Isabel Sayago ◽  
Manuel Aleixandre ◽  
José Pedro Santos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Low Temperature ◽  
Tin Oxide ◽  
Chemical Sensors ◽  
High Sensitivity ◽  
Silicon Substrates ◽  
Electronic Noses ◽  
Pollutant Detection ◽  
Scanning Electron

Tin oxide nanofibres (NFs) are used as nanosensors in electronic noses. Their performance is compared to that of oxide commercial chemical sensors for pollutant detection. NFs were grown by electrospinning and deposited onto silicon substrates with integrated micro-hotplates. NF morphology was characterized by scanning electron microscopy (SEM). The NFs presented high sensitivity to NO2 at low temperature.

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