Morphology and Microstructure of A1N Single Crystals on Si (111): A Combination of Surface Electron Spectroscopies and Transmission Electron Microscopies

1998 ◽  
pp. 191-198
Author(s):  
F. Malengreau ◽  
S. Hagège ◽  
R. Sporken ◽  
M. Vermeersch ◽  
R. Caudano ◽  
...  
Keyword(s):  
Single Crystals ◽  
Surface Electron ◽  
Electron Microscopies ◽  
Transmission Electron

scholarly journals Multi-Scale Investigation of Body-Glaze Interface in Ancient Ceramics

Heritage ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 2480-2494 ◽  
Author(s):  
Marie Godet ◽  
Gauthier Roisine ◽  
Emmie Beauvoit ◽  
Daniel Caurant ◽  
Odile Majérus ◽  
...  
Keyword(s):  
Single Crystals ◽  
The Body ◽  
Firing Time ◽  
Body System ◽  
Slow Cooling ◽  
French Renaissance ◽  
Electron Microscopies ◽  
Multi Scale ◽  
Continuous Layer ◽  
Transmission Electron

Bernard Palissy is a French Renaissance ceramist renowned for his masterpieces called Rustiques Figulines on which dozens of glazes of different chemistries (and thus firing behaviors) coexist harmoniously. This study aims at gathering information on the master procedure -never revealed- by investigating the body-glaze interface region (focusing on iron-colored honey transparent glaze-white body system). Optical and electron microscopies including transmission electron microscopy (TEM) are used to characterize the micro and nanostructure of both archaeological and replicas interfaces elaborated in controlled conditions (firing time, cooling rate, addition of Al in the glazing mixture). Both types of interfaces are comparable: a modified paste area from which are growing a relatively continuous layer of interfacial crystals identified as lead feldspars (K,Ca)PbAl2Si2O8 micro-sized single-crystals incorporating mullite 3Al2O3.2SiO2 nano-sized single-crystals. Modification of the firing parameters and removal of Al from the glazing mixture change essentially the interface extension and the micro-crystals morphology. By comparing archaeological and replica interfaces and considering previous studies, we can now state that Palissy was very likely adding clay (Al) in his frit. Moreover, he was probably working with a firing time of more than 1 h followed by slow cooling in the oven.

Compositional and Structural Study of a (K0.5Na0.5)NbO3 Single Crystal Prepared by Solid State Crystal Growth

2009 ◽  
Vol 15 (5) ◽  
pp. 435-440 ◽  
Author(s):  
Andreja Benčan ◽  
Elena Tchernychova ◽  
Matjaž Godec ◽  
John Fisher ◽  
Marija Kosec
Keyword(s):  
Crystal Growth ◽  
Solid State ◽  
Single Crystal ◽  
Single Crystals ◽  
Domain Structure ◽  
Chemical Homogeneity ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Composition And Structure ◽  
Growth Method

AbstractIn this work we investigated the chemical composition and structure of (K0.5Na0.5)NbO3 (KNN) single crystals grown by the solid state crystal growth method. The optical, scanning, and transmission electron microscopies were employed for the analysis of the chemical homogeneity and domain structure of the KNN crystal. No compositional inhomogeneities within experimental error were encountered in the KNN single crystals. The domain structure of the KNN single crystal, with a monoclinic unit cell, is composed of large 90° domains of up to 100 μm width, which further consist of smaller 180° domains with widths from 50 to 300 nm.

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

Transmission Electron Microscopy study of Bi-based superconducting phases

1990 ◽  
Vol 48 (4) ◽  
pp. 50-51
Author(s):  
J.G. Wen ◽  
K.K. Fung
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Space Groups ◽  
Superconducting Phases ◽  
Ceramic Samples ◽  
Transmission Electron ◽  
Modulated Structures

Bi-based superconducting phases have been found to be members of a structural series represented by Bi2Sr2Can−1Cun−1On+4, n=1,2,3, and are referred to as 2201, 2212, 2223 phases. All these phases are incommensurate modulated structures. The super space groups are P2/b, NBbmb 2201, 2212 phases respectively. Pb-doped ceramic samples and single crystals and Y-doped single crystals have been studied by transmission electron microscopy.Modulated structures of all Bi-based superconducting phases are in b-c plane, therefore, it is the best way to determine modulated structure and c parameter in diffraction pattern. FIG. 1,2,3 show diffraction patterns of three kinds of modulations in Pb-doped ceramic samples. Energy dispersive X-ray analysis (EDAX) confirms the presence of Pb in the three modulated structures. Parameters c are 3 0.06, 38.29, 30.24Å, ie 2212, 2223, 2212 phases for FIG. 1,2,3 respectively. Their average space groups are all Bbmb.

scholarly journals V2O3/C composite fabricated by carboxylic acid-assisted sol–gel synthesis as anode material for lithium-ion batteries

2021 ◽  
Author(s):  
G. S. Zakharova ◽  
E. Thauer ◽  
A. N. Enyashin ◽  
L. F. Deeg ◽  
Q. Zhu ◽  
...  
Keyword(s):  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
Sol Gel ◽  
Carbon Sources ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Battery Electrode ◽  
Sol Gel Synthesis

AbstractThe potential battery electrode material V2O3/C has been prepared using a sol–gel thermolysis technique, employing vanadyl hydroxide as precursor and different organic acids as both chelating agents and carbon sources. Composition and morphology of resultant materials were characterized by X-ray diffraction, Raman spectroscopy, scanning and transmission electron microscopies, physical sorption, and elemental analysis. Stability and electronic properties of model composites with chemically and physically integrated carbon were studied by means of quantum-chemical calculations. All fabricated composites are hierarchically structured and consist of carbon-covered microparticles assembled of polyhedral V2O3 nanograins with intrusions of amorphous carbon at the grain boundaries. Such V2O3/C phase separation is thermodynamically favored while formation of vanadium (oxy)carbides or heavily doped V2O3 is highly unlikely. When used as anode for lithium-ion batteries, the nanocomposite V2O3/C fabricated with citric acid exhibits superior electrochemical performance with an excellent cycle stability and a specific charge capacity of 335 mAh g−1 in cycle 95 at 100 mA g−1. We also find that the used carbon source has only minor effects on the materials’ electrochemical performance.

Physical Simulation of Weldability of Weldox 1300 Steel

2013 ◽  
Vol 762 ◽  
pp. 551-555 ◽  
Author(s):  
Marek Stanislaw Węglowski ◽  
Marian Zeman ◽  
Miroslaw Lomozik
Keyword(s):  
Mechanical Properties ◽  
Impact Toughness ◽  
Physical Simulation ◽  
High Strength ◽  
Parent Material ◽  
Cooling Time ◽  
Electron Microscopies ◽  
Transmission Electron ◽  
Transformation Diagrams ◽  
The Impact

In the present study, the investigation of weldability of new ultra-high strength - Weldox 1300 steel has been presented. The thermal simulated samples were used to investigate the effect of welding cooling time t8/5 on the microstructure and mechanical properties of the heat affected zone (HAZ). In the frame of these investigation the microstructure was studied by the light (LM) and transmission electron microscopies (TEM). It has been shown that the microstructure of the Weldox 1300 steel is composed of tempered martensite, and inside the laths the minor precipitations mainly V(CN) and molybdenum carbide Mo2C were observed. Mechanical properties of parent material were analysed by the tensile, impact and hardness tests. In details the influence of cooling time in the range of 2,5 - 300 s. on hardness, impact toughness and microstructure of simulated HAZ was studied by using welding thermal simulation test. The results show that the impact toughness and hardness decrease with the increase of t8/5 under the condition of a single thermal cycle in simulated HAZ. The continuous cooling transformation diagrams (CCT-W for welding conditions) of Weldox 1300 steel for welding purposes was also elaborated. The steel Weldox 1300 for cooling time in the range of 2,5 - 4 s showed martensite microstructure, for time from 4 s to 60 s mixture of martensite and bainite, and for longer cooling time mixture of ferrite, bainite and martensite. The results indicated that the weldability of Weldox 1300 steel is limited and to avoid the cold cracking the preheating procedure or medium net linear heat input should be used.

Dual Beam Focused Ion Beam and Transmission Electron Microscopies of Nanoscale Sectioned Diatom Frustules

2007 ◽  
Vol 13 (S02) ◽  
Author(s):  
T Gutu ◽  
J Wu ◽  
C Jeffreys ◽  
C-H Chang ◽  
G Rorrer ◽  
...  
Keyword(s):  
Focused Ion Beam ◽  
Ion Beam ◽  
Electron Microscopies ◽  
Dual Beam ◽  
Transmission Electron

scholarly journals Identification of Faults in Asbestos Minerals and Application to Pollution Studies

1976 ◽  
Vol 34 ◽  
pp. 616-617
Author(s):  
K. Seshan ◽  
H.-R. Wenk
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Twin Plane ◽  
Fibre Axis ◽  
Fibre Structure ◽  
Asbestos Fibre ◽  
Fibre Texture ◽  
Transmission Electron ◽  
Diffraction Patterns

Asbestos fibre texture occurs in various mineral groups (e.g. chrysotile, crocidolite, tremolite, grunerite, tourmaline) and it has been established that at least chrysotile is carcinogenic. We are investigating various aspects of the asbestos structure, with transmission electron microscopy (TEM) (1) in order to develop methods for unequivocal asbestos identification using minute samples and also to determine defects responsible for the fibre structure in these minerals which often occur as large, we 11-developed single crystals.In order to do this, we have started by investigating clinoamphibole asbestos such as tremolite Ca2Mg5[Si8O22] (OH, F)2 and crocidolite Na2 (Mg, Al, Fe3+, Fe2+) (Si8O22) (OH, F )2 , from California localities. In crocidoli te - asbestos we observed a high density of very narrow microtwins parallel to the fibre axis [001] (Fig. 1). They are often only 50-100Å wide. Diffraction patterns display the typical twin arrangement of spots and although preliminary contrast experiments are not yet conclusive the twin plane appears to be (100).

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