Influence of Initial Crystallization Temperature of Form II on the Nucleation and Growth of Form I IPBu Crystals during II–I Phase Transition

2021 ◽  
Author(s):  
Rui Xin ◽  
Yunpeng Li ◽  
Zhixin Guo ◽  
Jian Hu ◽  
Shaojuan Wang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Crystallization Temperature ◽  
Nucleation And Growth ◽  
Initial Crystallization Temperature

Phase separation in undercooled molten Pd80Si20: Part I

1999 ◽  
Vol 14 (9) ◽  
pp. 3653-3662 ◽  
Author(s):  
K. L. Lee ◽  
H. W. Kui
Keyword(s):  
Growth Rate ◽  
Phase Separation ◽  
Crystal Growth ◽  
Grain Refinement ◽  
Crystallization Temperature ◽  
Sharp Decrease ◽  
Nucleation And Growth ◽  
Crystal Growth Rate ◽  
Large Undercooling ◽  
Kinetic Crystallization

Three different kinds of morphology are found in undercooled Pd80Si20, and they dominate at different undercooling regimens ΔT, defined as ΔT = T1 – Tk, where T1 is the liquidus of Pd80Si20 and Tk is the kinetic crystallization temperature. In the small undercooling regimen, i.e., for ΔT ≤ 190 K, the microstructures are typically dendritic precipitation with a eutecticlike background. In the intermediate undercooling regimen, i.e., for 190 ≤ ΔT ≤ 220 K, spherical morphologies, which arise from nucleation and growth, are identified. In addition, Pd particles are found throughout an entire undercooled specimen. In the large undercooling regimen, i.e., for ΔT ≥ 220 K, a connected structure composed of two subnetworks is found. A sharp decrease in the dimension of the microstructures occurs from the intermediate to the large undercooling regimen. Although the crystalline phases in the intermediate and the large undercooling regimens are the same, the crystal growth rate is too slow to bring about the occurrence of grain refinement. Combining the morphologies observed in the three undercooling regimens and their crystallization behaviors, we conclude that phase separation takes place in undercooled molten Pd80Si20.

Enhanced crystallization and phase transformation of amorphous silicon nitride under high pressure

2001 ◽  
Vol 16 (1) ◽  
pp. 67-75 ◽  
Author(s):  
Ya-Li Li ◽  
Yong Liang ◽  
Fen Zheng ◽  
Xian-Feng Ma ◽  
Suo-Jing Cui ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Crystallization Temperature ◽  
Amorphous Materials ◽  
Normal Pressure ◽  
Nucleation And Growth ◽  
Amorphous Silicon Nitride ◽  
Amorphous Si

The crystallization and phase transformation of amorphous Si3N4 ceramics under high pressure (1.0–5.0 GPa) between 800 and 1700 °C were investigated. A greatly enhanced crystallization and α–β transformation of the amorphous Si3N4 ceramics were evident under the high pressure, as characterized by that, at 5.0 GPa, the amorphous Si3N4 began to crystallize at a temperature as low as 1000 °C (to transform to a modification). The subsequent a–b transformation occurred completed between 1350 and 1420 °C after only 20 min of pressing at 5.0 GPa. In contrast, under 0.1 MPa N2, the identical amorphous materials were stable up to 1400 °C without detectable crystallization, and only a small amount of a phase was detected at 1500 °C. The crystallization temperature and the a–b transformation temperatures are reduced by 200–350 °C compared to that at normal pressure. The enhanced phase transformations of the amorphous Si3N4 were discussed on the basis of thermodynamic and kinetic consideration of the effects of pressure on nucleation and growth.

Study on the Melting Mechanism of Maleic Anhydride

2020 ◽  
Vol 10 (1) ◽  
pp. 65-78
Author(s):  
Bratati Das ◽  
Ashis Bhattacharjee
Keyword(s):  
Phase Transition ◽  
Activation Energy ◽  
Maleic Anhydride ◽  
Temperature Dependence ◽  
Growth Models ◽  
Melting Process ◽  
Nucleation And Growth ◽  
Crystalline Solid ◽  
Scanning Calorimetry ◽  
Melting Mechanism

Background: Melting of a pure crystalline material is generally treated thermodynamically which disregards the dynamic aspects of the melting process. According to the kinetic phenomenon, any process should be characterized by activation energy and preexponential factor where these kinetic parameters are derivable from the temperature dependence of the process rate. Study on such dependence in case of melting of a pure crystalline solid gives rise to a challenge as such melting occurs at a particular temperature only. The temperature region of melting of pure crystalline solid cannot be extended beyond this temperature making it difficult to explore the temperature dependence of the melting rate and consequently the derivation of the related kinetic parameters. Objective: The present study aims to explore the mechanism of the melting process of maleic anhydride in the framework of phase transition models. Taking this process as just another first-order phase transition, occurring through the formation of nuclei of new phase and their growth, particular focus is on the nucleation and growth models. Methods: Non-isothermal thermogravimetry, as well as differential scanning calorimetry studies, has been performed. Using isoconversional kinetic analysis, temperature dependence of the activation energy of melting has been obtained. Nucleation and growth models have been utilized to obtain the theoretical temperature dependencies for the activation energy of melting and these dependencies are then compared with the experimentally estimated ones. Conclusion: The thermogravimetry study indicates that melting is followed by concomitant evaporation, whereas the differential scanning calorimetry study shows that the two processes appear in two different temperature regions, and these differences observed may be due to the applied experimental conditions. From the statistical analysis, the growth model seems more suitable than the nucleation model for the interpretation of the melting mechanism of the maleic anhydride crystals.

scholarly journals Modeling of single cell cancer transformation using phase transition theory: application of the Avrami equation

2021 ◽  
Author(s):  
Krzysztof W. Fornalski ◽  
Ludwik Dobrzyński
Keyword(s):  
Phase Transition ◽  
Probability Function ◽  
Single Cells ◽  
Cell Cancer ◽  
Transition Process ◽  
Nucleation And Growth ◽  
Kolmogorov Equation ◽  
Avrami Equation ◽  
Oncogenic Mutations ◽  
Theory Application

AbstractThe nucleation and growth theory, described by the Avrami equation (also called Johnson–Mehl–Avrami–Kolmogorov equation), and usually used to describe crystallization and nucleation processes in condensed matter physics, was applied in the present paper to cancer physics. This can enhance the popular multi-hit model of carcinogenesis to volumetric processes of single cell’s DNA neoplastic transformation. The presented approach assumes the transforming system as a DNA chain including many oncogenic mutations. Finally, the probability function of the cell’s cancer transformation is directly related to the number of oncogenic mutations. This creates a universal sigmoidal probability function of cancer transformation of single cells, as observed in the kinetics of nucleation and growth, a special case of a phase transition process. The proposed model, which represents a different view on the multi-hit carcinogenesis approach, is tested on clinical data concerning gastric cancer. The results also show that cancer transformation follows DNA fractal geometry.

Effects of A site doping on the crystallization of perovskite films

2021 ◽  
Author(s):  
Caiyi Zhang ◽  
Yanbo Wang ◽  
Xuesong Lin ◽  
Tianhao Wu ◽  
Qifeng Han ◽  
...  
Keyword(s):  
Phase Transition ◽  
Growth Phase ◽  
Crystal Orientation ◽  
Nucleation And Growth ◽  
A Site ◽  
Growth Phase Transition

The effects of A site doping on the crystallization, including the morphology and crystallinity of the PbI2 layer, nucleation and growth, phase transition and crystal orientation.

Kinetic Study of the Rotator Phase Transition in ann-Alkane (n-C25H52) Crystal: Nucleation and Growth on Cooling

2001 ◽  
Vol 40 (Part 1, No. 12) ◽  
pp. 6918-6926 ◽  
Author(s):  
Koji Nozaki ◽  
Masanao Munekane ◽  
Masamichi Hikosaka ◽  
Takashi Yamamoto
Keyword(s):  
Phase Transition ◽  
Kinetic Study ◽  
Nucleation And Growth ◽  
Crystal Nucleation ◽  
Rotator Phase

scholarly journals Effect of Adding Co on Crystallization Behavior and Magnetoimpedance Effect of Amorphous/Nanocrystalline FeCuNbSiB Alloy Strips

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Da-guo Jiang ◽  
Yuan-xiu Ye ◽  
Bin Guo
Keyword(s):  
Heat Treatment ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Amorphous Structure ◽  
Initial Permeability ◽  
Peak Temperature ◽  
Crystallization Peak ◽  
Magnetic Cores ◽  
Nanocrystalline Structures ◽  
Initial Crystallization Temperature

After one of the B atoms in Fe73.5Cu1Nb3Si13.5B9 alloy was replaced by both 0.7 Si and 0.3 Co, Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons were prepared by single roll fast quenching method. The obtained alloy ribbons were subsequently wound into ring magnetic cores, and then these magnetic cores were annealed at different temperatures in air. The effects of adding Co on the crystallization behavior and soft magnetic properties of the as-quenched alloy ribbons with and without heat treatment were studied. The results show that the amorphous structure of the prepared Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons is transformed into the coexistence of amorphous and nanocrystalline structures after heat treatment at 550°C. Comparing with Fe73.5Cu1Nb3Si13.5B9 alloy ribbons, the first initial crystallization temperature (Tx1) and crystallization peak temperature (Tp1) of Fe73.5Co0.3Cu1Nb3Si14.2B8 alloy ribbons were reduced by 1.6 and 1.7°C, respectively, While the second initial crystallization temperature (Tx1) and crystallization peak temperature (Tp2) were increased by 6.5 and 5.7°C, respectively, resulting in that the difference between the first and the second initial crystallization temperatures (∆Tx) are increased by 8.1°C; the initial permeability (μi) and saturation induction density (Bs) of the amorphous/nanocrystalline Fe73.5Co0.3Cu1Nb3Si14.2B8 magnetic cores were reduced by 0.15 H/m and 0.39 T, respectively, while the coercivity (Hc) is increased by 0.34 A/m.

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