Photoinduced Amorphous ↔ Crystalline Transitions In Sbx Sc1−x Films

1993 ◽  
Vol 321 ◽  
Author(s):  
Paul Stradins ◽  
Ojars Balors ◽  
Vyatcheslav Gerbreder
Keyword(s):  
Pulse Length ◽  
Amorphous State ◽  
Local Maximum ◽  
Threshold Intensity ◽  
Optical Contrast ◽  
Intensity Dependence ◽  
Stationary Temperature Field ◽  
Time Required ◽  
Crystallization Tendency ◽  
Induced Crystallization

ABSTRACTWe present a study of laser pulse induced crystallization and amorphization in SbxSc1−x films. The time required to reach stable amorphous state after the pulse increases with exciting pulse length and becomes constant when stationary temperature field is approached by the end of the pulse. The time dependence of the excited spot's local temperature is deduced directly from amorphization threshold intensity dependence on the pulse length and is used to calculate the cooling times after the amorphizing pulse. Two photocrystallization regimes are distinguished depending on whether the melting starts before or after the end of crystallization, the condition depending on crystallization tendency for given composition x. The occurrence of melting limits the maximum optical contrast during photocrystallization. The results show that the crystallization tendency of SbxSei-x rises with x and has a local maximum between x = 0.5 and x = 0.7.

scholarly journals Comparative Physical Study of Three Pharmaceutically Active Benzodiazepine Derivatives: Crystalline versus Amorphous State and Crystallization Tendency

2021 ◽  
Vol 18 (4) ◽  
pp. 1819-1832
Author(s):  
Sofia Valenti ◽  
Maria Barrio ◽  
Philippe Negrier ◽  
Michela Romanini ◽  
Roberto Macovez ◽  
...  
Keyword(s):  
Amorphous State ◽  
Physical Study ◽  
Benzodiazepine Derivatives ◽  
Crystallization Tendency

Phase Change Materials - From Structures to Kinetics

2006 ◽  
Vol 918 ◽  
Author(s):  
Matthias Wuttig ◽  
Wojciech Welnic ◽  
Ralf Detemple ◽  
Henning Dieker ◽  
Johannes Kalb ◽  
...  
Keyword(s):  
Phase Change ◽  
Crystalline State ◽  
Phase Change Materials ◽  
Amorphous State ◽  
Structural Difference ◽  
Fast Time ◽  
Optical Contrast ◽  
Fast Time Scale ◽  
Kinetics Of ◽  
Structure Properties

AbstractPhase change materials possess a unique combination of properties which include a pronounced property contrast between the amorphous and crystalline state, i.e. a high electrical and optical contrast. In particular the latter observation is indicative for a considerable structural difference between the amorphous and crystalline state. At the same time the crystallization of the amorphous state proceeds on a fast time scale. This raises the question how structure, properties and kinetics are related in phase change alloys. It will be demonstrated that only a small group of covalent semiconductors with octahedral-like coordination has the required property combination. This is related to their thermodynamic properties which govern the kinetics of crystallization.

Phase Stability of Crystalline and Amorphous Phases and Formation of Nanostructure in Zr-Pd and Zr-Pt Alloys Under Electron Irradiation

2007 ◽  
Vol 1048 ◽  
Author(s):  
Yukichi Umakoshi ◽  
Takeshi Nagase ◽  
Takashi Hosokawa
Keyword(s):  
Electron Irradiation ◽  
Crystalline Phase ◽  
Amorphous State ◽  
Nano Composite ◽  
Phase Selection ◽  
Amorphous Phases ◽  
Nano Crystalline ◽  
Residual Amorphous Phase ◽  
Pt Alloys ◽  
Induced Crystallization

AbstractElectron irradiation induced phase transition behavior of Zr-Pd and Zr-Pt alloys was investigated focusing on phase selection in crystallization by thermal annealing and electron irradiation. Nano quasi-crystalline (QC) phase was formed by thermal crystallization in Zr66.7Pd33.3 and Zr80Pt20 alloys, while nano two-type f.c.c. super-saturated solid solutions were formed by irradiation induced crystallization at 298K. In Zr66.7Pt33.3 alloy, polycrystalline Zr5Pt3 and Zr9Pt11 phases transformed to two-type f.c.c. nano-crystalline phase through an amorphous state by crystal-to-amorphous-to-crystal (C-A-C) transition during electron irradiation. Nano-composite phase composed of f.c.c. super-saturated solid solution and residual amorphous phase was stable rather than an amorphous single phase, thermal equilibrium crystalline phase and quasi-crystalline phase under 2.0MV electron irradiation at 298K, resulting in the formation of nano-composite structure by irradiation induced amorphization and crystallization.

Crystal packing and crystallization tendency from the melt of 2-((2-ethylphenyl)amino)nicotinic acid

2018 ◽  
Vol 233 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Arjun Kalra ◽  
Mingtao Zhang ◽  
Sean Parkin ◽  
Tonglei Li
Keyword(s):  
Nicotinic Acid ◽  
Crystal Packing ◽  
Amorphous State ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Scanning Calorimetry ◽  
Glass Forming ◽  
Planar Conformation ◽  
Acid Acid ◽  
Crystallization Tendency

Abstract2-((2-ethylphenyl)amino)nicotinic acid (2EPNA) was synthesized and its crystal structure was determined. It was observed that alkylation of the phenyl ring with ethyl group disrupts the planar conformation of the molecule by steric repulsion, resulting in formation of an acid-pyridine heterosynthon (instead of acid-acid homosynthon) in the crystal. Crystallization tendency from the melt state of the polymorph was studied by differential scanning calorimetry (DSC). It was revealed that this compound could form a very stable amorphous phase on melt quenching and not crystallize even on re-heating. The formation of acid-pyridine hydrogen bonding in the amorphous state is believed to be responsible for its good glass forming ability.

Amorphization of Aubi Alloys by Laser Quenching and Ion Irradiation

1983 ◽  
Vol 23 ◽  
Author(s):  
A. Wolthuis ◽  
B. Stritzker
Keyword(s):  
Electrical Properties ◽  
Amorphous Phase ◽  
Low Temperatures ◽  
Ion Irradiation ◽  
Pulse Length ◽  
Equilibrium Phase ◽  
Amorphous State ◽  
Ion Bombardment ◽  
Metastable Phases ◽  
Phase Mixture

ABSTRACTCrystalline AulO0−x Bix alloy films (200≤×≤90) could be transformed into an amorphous state by either+laser (20 ns pulse length, 248 nm) or ion bombardment (Ar ions, 300 keV) of these films, which were mounted onto a substrate kept at low temperatures ( <10K). Several metastable Phases could beobtained by annealing of the amorphous phase before the starting equilibrium phase mixture was formed. The different phases were characterized by their different superconducting and electrical properties.

Structural and Transport Properties of Ni45Mn40In15 Thin Films

2015 ◽  
Vol 233-234 ◽  
pp. 670-673 ◽  
Author(s):  
Maria V. Lyange ◽  
Mikhail V. Gorshenkov ◽  
A.V. Bogach ◽  
Makoto Ohtsuka ◽  
Hiroyuki Miki ◽  
...  
Keyword(s):  
Thin Films ◽  
Transport Properties ◽  
Field Dependence ◽  
Heusler Alloys ◽  
Amorphous State ◽  
Structural Ordering ◽  
Spin Disorder ◽  
Induced Crystallization ◽  
Deposited Films ◽  
Disorder Scattering

We report on structural and transport properties of Ni-Mn-In thin films. The results obtained have indicated that transport properties of the thin films strongly depend on the structural ordering of the films. Specifically, annealing converts the semiconducting-like character of the resistivity into that typical for metals. This is due to annealing-induced crystallization of as-deposited films which are in partially amorphous state. In both the as-deposited and the annealed thin films the field dependence of the resistivity is negative, which is typical for thin films of Heusler alloys and can be ascribed to the suppression of the spin disorder scattering.

scholarly journals Coarse-Grained Lattice Modeling and Monte Carlo Simulations of Stress Relaxation in Strain-Induced Crystallization of Rubbers

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1267
Author(s):  
Vladislav Egorov ◽  
Hiroshi Koibuchi ◽  
Chrystelle Bernard ◽  
Jean-Marc Chenal ◽  
Gildas Diguet ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Stress Relaxation ◽  
Monte Carlo Simulations ◽  
Amorphous State ◽  
Coarse Grained ◽  
Large Strains ◽  
Chain Model ◽  
Stress Strain ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Two-dimensional triangulated surface models for membranes and their three-dimensional (3D) extensions are proposed and studied to understand the strain-induced crystallization (SIC) of rubbers. It is well known that SIC is an origin of stress relaxation, which appears as a plateau in the intermediate strain region of stress–strain curves. However, this SIC is very hard to implement in models because SIC is directly connected to a solid state, which is mechanically very different from the amorphous state. In this paper, we show that the crystalline state can be quite simply implemented in the Gaussian elastic bond model, which is a straightforward extension of the Gaussian chain model for polymers, by replacing bonds with rigid bodies or eliminating bonds. We find that the results of Monte Carlo simulations for stress–strain curves are in good agreement with the reported experimental data of large strains of up to 1200%. This approach allows us to intuitively understand the stress relaxation caused by SIC.

scholarly journals PPM Detection Limits in PXRD by Integrating Nonlinear Optics and Synchrotron XRD

2014 ◽  
Vol 70 (a1) ◽  
pp. C1082-C1082
Author(s):  
Scott Toth ◽  
Justin Newman ◽  
Paul Schmitt ◽  
Christopher Dettmar ◽  
Shijie Zhang ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Amorphous Polymer ◽  
Amorphous Material ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Amorphous State ◽  
X Ray ◽  
Long Term Stability ◽  
Amorphous Media ◽  
Time Required

SHG microscopy allows rapid and selective identification of trace chiral crystals within amorphous media, enabling targeted XRD using a 5-10 micrometer diameter "minibeam". The sensitivity of PXRD is increased substantially by reducing the background scattering contributions of amorphous material otherwise encountered with a larger beam. In addition, performing diffraction only at the locations most likely to produce diffraction greatly reduced the overall beam-time required to perform the PXRD analyses. Integration of the SHG microscope directly into a synchrotron X-ray beamline at Argonne National Laboratory recovered high spatial registry between the regions of interest identified by SHG for positioning within the X-ray beam. Using this approach, diffraction was performed on individual griseofulvin nanocrystals suspended within an amorphous polymer, corresponding to a total of ~20 fg of total crystalline material. Additional measurements for ritonavir in hydroxypropylmethylcellulose (HPMC) were also performed, in which a bulk API concentration of 100 ppm produced diffraction peaks with a signal to noise ratio of >3000. Among other applications, sensitive detection of trace crystallinity can inform the design of amorphous formulations, in which the bioavailability of active pharmaceutical ingredients (APIs) is enhanced by maintaining them in an amorphous state. However, the long-term stability of a final dosage form can be negatively impacted by spontaneous transitioning to the typically more stable crystalline forms of the APIs, such that extensive quantitative characterization of the crystallization behaviors of amorphous formulations is routinely performed.

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