Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

Solvothermal Synthesis of Bi2Se3 Hexagonal Nanosheet Crystals

2011 ◽  
Vol 236-238 ◽  
pp. 1712-1716 ◽  
Author(s):  
Hai Tao Liu ◽  
Jun Dai ◽  
Jia Jia Zhang ◽  
Wei Dong Xiang
Keyword(s):  
Electron Microscope ◽  
Solvothermal Synthesis ◽  
Solvothermal Method ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Electron

Bismuth selenide (Bi2Se3) hexagonal nanosheet crystals with uniform size were successfully prepared via a solvothermal method at 160°C for 22 h using bismuth trichloride(BiCl3) and selenium powder(Se) as raw materials, sodium bisulfite(NaHSO3) as a reducing agent, diethylene glycol(DEG) as solvent, and ammonia as pH regulator. Various techniques such as X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), and selected area electron diffraction (SAED) were used to characterize the obtained products. Results show that the as-synthesized samples are pure Bi2Se3 hexagonal nanosheet crystals. A possible growth mechanism for Bi2Se3 hexagonal nanosheet crystals is also discussed based on the experiment.

Direct observation of ordering in (GaIn) P

1988 ◽  
Vol 3 (3) ◽  
pp. 406-409 ◽  
Author(s):  
S. McKernan ◽  
B. C. De Cooman ◽  
C. B. Carter ◽  
D. P. Bour ◽  
J. R. Shealy
Keyword(s):  
Electron Microscope ◽  
Direct Observation ◽  
Vapor Phase ◽  
Growth Conditions ◽  
Dark Field ◽  
Growth Surface ◽  
Organometallic Vapor Phase Epitaxy ◽  
Planar Defects ◽  
Group Iii ◽  
Gaas Substrates

Gax In1 − x Pepilayers grown under a range of growth conditions by organometallic vapor phase epitaxy (OMVPE) on GaAs substrates have been studied in the electron microscope. The results show the presence of an ordering of the group III sublattice parallel to some of the {111} planes. Dark-field images directly reveal ordered domains of different orientations that appear not to be perfect, but contain many planar defects parallel to the growth surface.

Fabrication, Structural Characterization and Formation Mechanism of Multiferroic BiFeO3 Nanotubes

2008 ◽  
Vol 8 (1) ◽  
pp. 335-339 ◽  
Author(s):  
Satyendra Singh ◽  
S. B. Krupanidhi
Keyword(s):  
Electron Microscope ◽  
Formation Mechanism ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Multiferroic Bifeo ◽  
High Resolution Tem ◽  
Perovskite Crystal

Multiferroic BiFeO3 (BFO) nanotubes have been successfully fabricated by the modified sol–gel method within the nanochannels of porous anodic aluminum oxide (AAO) templates. The morphology, structure and composition of the nanotubes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), selected-area electron diffraction (SAED), high resolution TEM, (HRTEM) and energy-dispersive X-ray spectroscopy (EDX). Postannealed (650 °C for 1 h), BFO nanotubes were polycrystalline and X-ray diffraction study revealed that they are of the rhomohedrally distorted perovskite crystal structure. The results of SEM and TEM revealed that BFO nanotubes possessed a uniform length (up to 60 μm) and diameter (about 200 nm), which were controlled by the thickness and the pore diameter of the applied AAO template, respectively and the thickness of the wall of the BFO nanotube was about 15 nm. Y-junctions in the BFO nanotubes were observed. EDX analysis demonstrated that stoichiometric BiFeO3 was formed. HRTEM analysis confirmed that the obtained BFO nanotubes made up of nanoparticles (3–6 nm). The possible formation mechanism of BFO nanotubes was discussed.

Preparation of Single-Crystal BiOCl Nanorods via Surfactant Soft-Template Inducing Growth

2005 ◽  
Vol 23 ◽  
pp. 79-82 ◽  
Author(s):  
Chuan Bao Cao ◽  
Ruitao Lv ◽  
He Sun Zhu
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Saed Pattern ◽  
Soft Template ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Triton X

Nanorods of a compound semiconductor, BiOCl, have been prepared from BiCl3 solutions containing a nonionic surfactant, t-octyl-(OCH2CH2)xOH, x=9, 10 (Triton X-100). Powder X-ray diffraction (XRD) pattern indicated that the product was pure tetragonal phase bismoclite (BiOCl). The product was also characterized by the techniques of scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscope (TEM). The as-obtained BiOCl nanorods possess mean diameters less than 40nm and lengths ranging in 160-400nm. Selected area electron diffraction (SAED) pattern showed the single-crystal nature of as-prepared BiOCl nanorods. The growth mechanism of BiOCl nanorods has also been proposed.

Studies on conducting nanocomposite with gallium nitride–doped ferrite, part – I

2016 ◽  
Vol 231 (1) ◽  
pp. 43-52 ◽  
Author(s):  
Rajani Indrakanti ◽  
V Brahmaji Rao ◽  
C Udaya Kiran
Keyword(s):  
Electron Microscope ◽  
Magnetic Measurements ◽  
Sol Gel ◽  
Ferromagnetic State ◽  
Energy Dispersive ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Scherrer Formula

This article presents the synthesis and the structural, morphological, magnetic and spectroscopic characterisations of GaN-doped Fe2O3 nanoparticles prepared by the sol–gel method. The ‘Sci find’ software was unable to trace any of the references to point out the earlier knowledge and existence of this novel compound in the literature. We claim our contribution for the same. The structural analysis is done using the X-ray diffraction and energy-dispersive X-ray analysis, while the morphological analysis is done by the scanning electron microscope and the transmission electron microscope. The samples show a simple cubic crystalline structure. The morphological and energy-dispersive X-ray analysis and the infrared studies confirm the composition of the material and the particle sizes of the samples are found to be in the range of 9–27 nm (for x = 0.5) and 23–30 nm (for x = 0.75). The particle sizes, obtained from the histogram evaluations, the Debye–Scherrer formula in X-ray diffraction and the selected area electron diffraction measurements are all in good agreement. The room temperature magnetic measurements obtained using the vibration sample magnetometer for x = 0.5, 0.75,1 and 5 are presented as the hysteresis curves and their related plots. The discussion about the conclusions drawn therein infers that the coercivity increases with the concentration. The compound exhibits spinel structure and vivid changes from the super paramagnetic to the ferromagnetic state.

Multistep Controllability Synthesis and Growth Mechanism of ZnO Nanopagoda for Schottky Diode Device

NANO ◽  
2016 ◽  
Vol 11 (02) ◽  
pp. 1650024 ◽  
Author(s):  
Yang Liu ◽  
Guishan Liu ◽  
Yongbing Wang ◽  
Wenyuan Gao ◽  
Hongshun Hao ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Schottky Diode ◽  
Hexagonal Wurtzite Structure ◽  
Synthesis Process ◽  
Zno Films ◽  
X Ray Diffraction ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Potentiostatic Electrodeposition ◽  
Set Up

Ordered ZnO arrays with a peculiar nanostructure were synthesized by a multistep synthesis process. The first step was the preparation of ZnO seed to induce the formation of ZnO array via potentiostatic electrodeposition method using a typical three electrode set-up. The second step was fabricating ZnO array along seed by Chemical Bath Deposition. Structural analysis of ZnO was carried out with X-ray diffraction (XRD), which showed a hexagonal wurtzite structure, and the selected area electron diffraction (SAED) patterns indicated that nanocrystalline is a part of monocrystal. The scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to study the microstructure, and showed a pagoda-like microstructure with a tiny top and large bottom, which had an average top diameter of exceeding 800[Formula: see text]nm at seed-depositing time of 60[Formula: see text]s, and then growth mechanisms are subsequently given a further explanation, viewed from kinetics and thermodynamics. In addition, the current–voltage curves of schottky diode devices with ZnO nanopagoda arrays revealed that ZnO films arrays along grown ZnO seed had a higher reverse saturation current than ZnO films grown without seed, which are [Formula: see text] A and [Formula: see text] A, respectively. The minimum turn-on voltage of the diode with ZnO seed deposited 60[Formula: see text]s is 0.18[Formula: see text]V, without seed is 0.52[Formula: see text]V.

Investigation of volume fraction of omega particles and hardness value of aged Ti-Mo alloy using dark-field TEM imaging

1992 ◽  
Vol 50 (1) ◽  
pp. 310-311
Author(s):  
E. Sukedai ◽  
H. Hashimoto
Keyword(s):  
Volume Fraction ◽  
Alloy System ◽  
Dark Field ◽  
Omega Phase ◽  
X Ray Diffraction ◽  
Bright Field ◽  
X Ray ◽  
X Ray Scattering ◽  
Ti Alloys ◽  
The Matrix

Investigation about omega phase has been carried out in many alloy systems using X-ray diffraction, electron microscope methods and so on. Volume fraction of aged omega particles seems to be the important factors on the view point of industry, because it influences mechanical properties of alloys. The volume fraction has been investigated using X-ray diffraction and small angle X-ray scattering methods. Except one alloy system, it is very hard to distinguish omega particles using bright field TEM imaging because of strain field in the matrix of alloys and/or around omega particles. However, it is known that using dark field TEM imaging, omega particles in Ti alloys can be seen. This method has other advantageous point; particles of individual omega variants can be seen using isolated diffraction spots from variants. In the present paper, volume fractions of omega variants in Ti-20mass%Mo alloy aged at 623K for 12.6ks, 28.8ks and 100.8ks were estimated using this method and the values were evaluated by considering the strength of alloys aged for these periods.

Transmission electron microscope characterization of dislocation structure in BiSrCaCu superconducting oxide

1988 ◽  
Vol 46 ◽  
pp. 956-957
Author(s):  
J.M. Liang ◽  
L. Chang ◽  
Y.C. Chen ◽  
S.F. Tang ◽  
Y.S. Chiao ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Dislocation Structure ◽  
Nominal Composition ◽  
New Wave ◽  
X Ray Diffraction ◽  
Slow Cooling ◽  
New Class ◽  
Thin Foils ◽  
Transmission Electron

The recently discovered new class of BiSrCaCu superconducting oxide with Tc as high as 120 K has generated a new wave of intense research on the high Tc superconducting systems. in this presentation, we report the results of a transmission electron microscope (TEM) study of dislocation structure in a superconducting BiSrCaCuO compound.The superconducting oxide with nominal composition of Bi2Sr2CaCu2Oy was prepared by quenching or slow cooling the solid-state-reaction sintered specimens which had been calcined from mixed Bi2O3, CaCo3, CuO, and SrCO3 powders. Thin foils for TEM examinations were generally prepared by grinding in a pestle and mortar. A JEOL-2000FX transmission electron microscope operating at 200 keV was used.The quencehed specimens exhibited Tc-onset at 120 K and Tc-zero at 90 K, whereas the slowly cooled specimens showed Tc-onset at 104 K and Tc-zero at 75 K. X-ray diffraction and TEM/EDS data showed that the sintered samples were mainly of a phase with nominal composition Bi2Sr2CaCu2Oy, XRD, SAD and CBED identified that the crystal structure is orthorhombic with a=0.541 nm, b=2.69 nm, and c=3.07 nm.

Nano-Structural Alteration of Pyrophyllite by Grinding Revealed by X-Ray Diffraction and High-Resolution Transmission Electron Microscopy

2016 ◽  
Vol 40 ◽  
pp. 72-78 ◽  
Author(s):  
Jia Wei Sheng ◽  
Li Ping Zhang ◽  
Jun Yan ◽  
Qing Sun ◽  
Jian Zhang
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Ball Mill ◽  
Structural Alteration ◽  
X Ray Diffraction ◽  
Mechanical Destruction ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Scanning Electron

The mechanical destruction of the pyrophyllite structure and final ground products upon grinding with a laboratory planetary ball mill were investigated using high-resolution transmission electron microscope (HRTEM) coupled with selected area electron diffraction (SAED), field emission scanning electron microscope (SEM) and X-ray diffraction (XRD). Grinding produced a profound structural alteration, resulting in increasing amorphization. Increasing the intensity of grinding resulted in acceleration of the mechanically induced amorphization of the pyrophyllite structure. The pyrophyllite phase was transformed into its anhydride phase during the process of the prolonged grinding. Increasing the grinding intensity resulted in faster destruction of the pyrophyllite structure. The plate-like microcrystal exhibited the 2M-pyrophyllite crystal structure. The pyrophyllite anhydride phase was existed after grinding.

Sign in / Sign up

Export Citation Format

Share Document