Metastable Phase Formation in the Y-TI System by Ion Mixing

1991 ◽  
Vol 235 ◽  
Author(s):  
S. L. Lai ◽  
Z. J. Zhang ◽  
J. R. Ding ◽  
B. X. Liu
Keyword(s):  
Metastable Phase ◽  
Heat Of Formation ◽  
Crystalline Lattice ◽  
Vacuum Furnace ◽  
Multilayered Films ◽  
Glass Forming ◽  
Transmission Electron ◽  
Metastable Phase Formation ◽  
First Time

ABSTRACTAmorphization behavior was studied for the Y-Ti system, which has rather positive heat of formation being around + 22 kJ/mol, by room temperature 360 keV xenon ion mixing of YxTi100−xmultilayered films to various doses, ranging from 7×1014 to 1×1016 xe/cm2 Single and uniform amorphous phase was obtained in a narrow composition region, i.e. x=65 to 75, after ion mixing to the relevant doses. Moreover, a metastable fee crystalline Y-Ti phase was observed, for the first time, in this system. The crystalline lattice constant of the metastable phase was determined to be 4.012 Å. The re-crystallization temperature of the formed amorphous alloy was found out to be 600°C by in situ transmission electron microscope annealing as well as by vacuum furnace experiments. Possible interpretation is also discussed by comparing the experimental results with those proposed models for predicting glass forming ability.

scholarly journals Spectroscopic and Thermal Analyses of Ortho-Benzylphenol Crystalline Polymorphism

2018 ◽  
Vol 63 (2) ◽  
pp. 95 ◽  
Author(s):  
J. Baran ◽  
N. A. Davydova ◽  
M. Drozd ◽  
E. A. Ponezha ◽  
V. Ya. Reznichenko
Keyword(s):  
Structural Changes ◽  
Metastable Phase ◽  
Thermal Analyses ◽  
Aromatic Rings ◽  
Methylene Bridge ◽  
Glass Forming ◽  
The Difference ◽  
Crystalline Polymorphism ◽  
First Time

In situ, we present the experimental spectroscopic proof of the existence of polymorphism in ortho-benzylphenol. Infrared spectroscopy was used for the first time to investigate the structural changes during the crystallization of a metastable phase, which is transformed, in the course of time, into a stable one. The results show that, in the stable and metastable phases, different conformers of ortho-benzylphenol molecule predominate, which differ in the orientation of the aromatic rings relative to the connecting methylene bridge. Namely, it is shown that the transformation of the metastable phase into a stable one is accompanied by the rotation of the OH-substituted aromatic ring relative to the connecting methylene bridge from 59.9∘ to 180.0∘ in the molecule of ortho-benzylphenol. The DSC experiment has shown that the process of nucleation of a metastable phase preferentially develops below ∼1.1 Tg (243 K), the crystallization occurs at ∼272 K, and the melting happens at 290.2 K. The difference in the temperature regions of nucleation and crystallization explains a good glass-forming status of ortho-benzylphenol.

scholarly journals Direct TEM observation of the “acanthite α-Ag2S–argentite β-Ag2S” phase transition in a silver sulfide nanoparticle

2019 ◽  
Vol 1 (4) ◽  
pp. 1581-1588 ◽  
Author(s):  
S. I. Sadovnikov ◽  
E. Yu. Gerasimov
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transmission Electron Microscopy ◽  
Silver Sulfide ◽  
Transmission Electron ◽  
Silver Sulfide Nanoparticles ◽  
Microscopy Method ◽  
Electron Microscopy Method ◽  
First Time

For the first time, the α-Ag2S (acanthite)–β-Ag2S (argentite) phase transition in a single silver sulfide nanoparticles has been observed in situ using a high-resolution transmission electron microscopy method in real time.

Formation of Sub-100 NM GE Wires on Si by E-Beam Evaporation/Lithography

1995 ◽  
Vol 380 ◽  
Author(s):  
C. Deng ◽  
J. C. Wu ◽  
C. J. Barbero ◽  
T. W. Sigmon ◽  
M. N. Wybourne
Keyword(s):  
Cross Section ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Si Substrates ◽  
Novel Technique ◽  
Atomic Force ◽  
Transmission Electron ◽  
First Time ◽  
Scanning Electron

ABSTRACTA fabrication process for sub-100 nm Ge wires on Si substrates is reported for the first time. Wires with a cross section of 6 × 57 nm2 are demonstrated. The wire structures are analyzed by atomic force (AFM), scanning electron (SEM), and transmission electron microscopy (TEM). Sample preparation for TEM is performed using a novel technique using both pre and in situ deposition of multiple protection layers using a Focused Ion Beam (FIB) micromachining system.

Metastable Phase Equilibria in Co-Deposited Ni1−xZrx Thin Films

1991 ◽  
Vol 230 ◽  
Author(s):  
J. B. Rubin ◽  
R. B. Schwarz
Keyword(s):  
Thin Films ◽  
Cooling Rate ◽  
Metastable Phase ◽  
Equilibrium Phase ◽  
Equilibrium Phase Diagram ◽  
Amorphous Structure ◽  
Nucleation Theory ◽  
Glass Forming ◽  
Constant Heating

AbstractWe determine the glass forming range (GFR) of co-deposited Ni1−xZrx (0 < x < 1) thin films by measuring their electrical resistance during in situ constant-heating-rate anneals. The measured GFR is continuous for 0.10 < x < 0.87. We calculate the GFR of Ni-Zr melts as a function of composition and cooling rate using homogeneous nucleation theory and a published CALPHAD-type thermodynamic modeling of the equilibrium phase diagram. Assuming that the main competition to the retention of the amorphous structure during the cooling of the liquid comes from the partitionless crystallization of the terminal solid solutions, we calculate that for dT/dt = 1012 K s−1, the GFR extends to x = 0.05 and x = 0.96. Better agreement with the measured values is obtained assuming a lower ‘effective’ cooling rate during the condensation of the films.

scholarly journals One-pot synthesis of polyaniline/Fe3O4 nanocomposite in ionicliquid: electrical conductivity and magnetic studies

2019 ◽  
Vol 118 ◽  
pp. 01059
Author(s):  
Xiaoyang Li ◽  
Genwang Zhang ◽  
Binwei Wang ◽  
Tan Lin ◽  
Guo Wang ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Oxidative Polymerization ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Imidazolium Chloride ◽  
One Pot ◽  
One Pot Synthesis ◽  
Transmission Electron ◽  
First Time

One-pot synthesis of polyaniline/Fe3O4 nanocomposite in 1-methyl-3-alkylcarboxylic acid imidazolium chloride ([CMMIm]Cl) ionic liquid (IL) was introduced for the first time in this work. Transmission electron microscopy (TEM), X-ray diffraction (XRD), four probes method and vibrating sample magnetometer (VSM) were used to explore the influence of IL on the structure, conductivity and magnetic properties of polyaniline/Fe3O4 composite. Compared with Fe3O4 particles prepared in water, the results show that Fe3O4 particles prepare in imidazolium-based ionic liquid were more regular in shape and dispersed uniformly. So the Fe3O4 nanoparticles prepared in IL can easier serve as cores to form the polyaniline/Fe3O4 nanocomposite via in situ chemical oxidative polymerization of aniline molecule. The saturation magnetization of polyaniline/Fe3O4 nanocomposite prepared in ionic liquid shows about 2 times higher than polyaniline/Fe3O4 composite prepared in water. And the conductivities of PANI/Fe3O4 composite prepared in IL decreased and the saturated magnetization increased with the increasing amount of Fe3O4.

Epitaxial Growth and Stability of C49 TiSi2 ON Si(111).

1990 ◽  
Vol 198 ◽  
Author(s):  
Hyeongtag Jeon ◽  
J. W. Honeycutt ◽  
C. A. Sukow ◽  
T. P. Humphreys ◽  
R. J. Nemanich ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Diffraction ◽  
Metastable Phase ◽  
Plan View ◽  
Transmission Electron ◽  
Temperature Deposition ◽  
The Individual ◽  
Relationship Of

ABSTRACTEpitaxial TiSi2 films have been grown by molecular beam epitaxy (MBE) on atomically clean Si(111)-orientated substrates. The growth procedure involves the ambient temperature deposition of Ti films of 50Å thickness and annealing to 800°C. In situ low energy electron diffraction (LEED) and Auger electron spectroscopy (AES) techniques have been used to monitor the TiSi2 formation process. The epitaxial films have been identified as the C49 metastable phase by both Raman spectroscopy and electron diffraction. Plan view transmission electron microscopy shows three different connected island morphologies. The individual island structures are single crystal and are grown epitaxially with different crystallographic orientations. The orientational relationship of the largest islands is given by [3 1 1] C49 TiSi2//[112]Si and (130) C49 TiSi2//(l1 1)Si. High resolution transmission electron microscopy (HRTEM) cross-section shows a coherent interface extending over several hundred angstroms.

High-Resolution Dynamic Analysis of the Phase Transformation in Ge2Sb2Te5 Alloy

2007 ◽  
Vol 26-28 ◽  
pp. 1199-1202
Author(s):  
Se Ahn Song ◽  
Wei Zhang ◽  
Hong Sik Jeong ◽  
Jin Gyu Kim ◽  
Youn Joong Kim
Keyword(s):  
Phase Transformation ◽  
Crystal Growth ◽  
High Resolution ◽  
Large Scale ◽  
Voltage Electron ◽  
Transmission Electron ◽  
In Situ Heating ◽  
First Time ◽  
Crystal Growth Behavior

Phase transformation and crystal growth behavior of Ge2Sb2Te5 were investigated systematically by means of in situ heating (from room temperature to 500 oC) of amorphous Ge2Sb2Te5 alloy in a high voltage electron microscope with real-time monitoring. Large-scale crystallization occurred to amorphous Ge2Sb2Te5 around 200 oC. Large crystal growth developed on heating from 200 oC to 400 oC, and single crystalline grains grew up to 150 nm. Eventually the onset of partial melting of thin Ge2Sb2Te5 foil was at 500 oC and liquid Ge2Sb2Te5 was observed for the first time by high-resolution transmission electron microscopy. Hexagonal Ge2Sb2Te5 phase remains after a subsequent cooling.

Metastable Phase Formation in Undercooled Nd-Fe-B Alloys Investigated by In Situ Diffraction Using Synchrotron Radiation

2006 ◽  
Vol 508 ◽  
pp. 81-86 ◽  
Author(s):  
Joern Strohmenger ◽  
Thomas Volkmann ◽  
J.R. Gao ◽  
Dieter M. Herlach
Keyword(s):  
Synchrotron Radiation ◽  
Metastable Phase ◽  
European Synchrotron Radiation Facility ◽  
Wide Composition Range ◽  
Short Period ◽  
Metastable Phase Formation ◽  
Undercooled Melt ◽  
Electromagnetically Levitated ◽  
In Situ Diffraction

Diffraction experiments on electromagnetically levitated Nd-Fe-B alloys during solidification of the undercooled melt have been performed at the European Synchrotron Radiation Facility (ESRF). By using high intensity synchrotron radiation complete diffraction spectra could be detected within a short period of some seconds thus enabling the observation of metastable solidification products that exhibits a limited lifetime. A metastable phase that crystallizes in wide composition range and that initiates the solidification of the stable Nd2Fe14B1-phase (φ-phase) have been observed.

Metastable phase formation by ion mixing of Nb–Al multilayers

1989 ◽  
Vol 4 (6) ◽  
pp. 1385-1392 ◽  
Author(s):  
K. Pampus ◽  
K. Dyrbye ◽  
B. Torp ◽  
R. Bormann
Keyword(s):  
Solid Solution ◽  
Amorphous Phase ◽  
Phase Formation ◽  
Ion Irradiation ◽  
Metastable Phase ◽  
Heavy Ion ◽  
Free Energies ◽  
Transmission Electron ◽  
Radiation Enhanced Diffusion ◽  
Metastable Phase Formation

The structure of Nb–Al thin films after ion mixing was studied for compositions from 20 to 85 at. % Al as a function of temperature in the range between 40 and 620 K. The phase formation was determined by transmission electron microscopy. At lower temperatures, only supersaturated bcc-solid solution, NbAl, and amorphous phase were found throughout the studied composition range. Besides these phases irradiation at temperatures above 470 K causes the formation of a metastable crystalline compound at an overall composition close to Nb25Al75, and for T = 623 K the equilibrium compound NbAl3 is formed. The other intermetallic phases Nb2Al and Nb3Al have not been observed at any irradiation temperature. Calculations of the Gibbs free energies of the various phases are presented, and the reliability of extrapolations to regions of metastability with respect to temperature and composition is commented on. The phase formation during heavy-ion irradiation is discussed in the context of the calculated free energies and kinetic constraints. For temperatures above 300 K, the attainment of a metastable phase equilibrium between the bcc solid solution and the amorphous phase is proposed due to the influence of radiation enhanced diffusion.

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