The struggle between thermodynamics and kinetics: Phase evolution of ancient and historical ceramics

2019 ◽  
pp. 233-282 ◽  
Author(s):  
R.B. Heimann ◽  
M. Maggetti
Keyword(s):  
Phase Evolution ◽  
Thermodynamics And Kinetics

scholarly journals Microstructural Evolution, Thermodynamics and Kinetics of Mo-Tm2O3 Powder Mixtures during Ball Milling

2016 ◽  
Author(s):  
Yong Luo ◽  
Guang Ran ◽  
Nanjun Chen ◽  
Qiang Shen ◽  
Yaoli Zhang
Keyword(s):  
Solid Solution ◽  
Ball Milling ◽  
Microstructural Evolution ◽  
Driving Force ◽  
Phase Evolution ◽  
Heat Of Mixing ◽  
Powder Mixtures ◽  
Thermodynamics And Kinetics ◽  
Transmission Electron ◽  
Kinetics Of

The microstructural evolution, thermodynamics and kinetics of Mo-21%Tm2O3 (mass fraction, %) powder mixtures during ball milling were investigated using X-ray diffraction and transmission electron microscopy. Ball milling induced Tm2O3 to be decomposed and then dissolved into Mo crystal. The supersaturated nanocrystalline solid solution of Mo (Tm, O) was obtained after 96 h of ball milling. The elements of Mo, Tm and O were distributed uniformly in the ball-milled particles. Based on the semi-experimental theory of Miedema, a thermodynamic model was developed to calculate the driving force of phase evolution. There was no chemical driving force to form a crystal solid solution of Tm atoms in Mo crystal or an amorphous phase because the Gibbs free energy for both processes was higher than zero. For Mo-21%Tm2O3, it was mechanical work, not negative heat of mixing, that provided the driving force to form supersaturated nanocrystalline Mo (Tm, O) solid solution.

Phase evolution, hydrogen storage thermodynamics and kinetics of ternary Mg90Ce5Sm5 alloy

2020 ◽  
Vol 38 (6) ◽  
pp. 633-641 ◽  
Author(s):  
Hui Yong ◽  
Shihai Guo ◽  
Zeming Yuan ◽  
Wei Zhang ◽  
Yan Qi ◽  
...  
Keyword(s):  
Hydrogen Storage ◽  
Phase Evolution ◽  
Thermodynamics And Kinetics ◽  
Kinetics Of

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

Chemical Availability of Bromide Dictates CsPbBr3 Nanocrystal Growth

2019 ◽  
Author(s):  
Je-Ruei Wen ◽  
Benjamin Roman ◽  
Freddy Rodriguez Ortiz ◽  
Noel Mireles Villegas ◽  
Nicholas Porcellino ◽  
...  
Keyword(s):  
Reaction Time ◽  
Growth Mechanism ◽  
Chemical Control ◽  
Critical Role ◽  
Phase Evolution ◽  
Detailed Understanding ◽  
Semiconductor Nanocrystal ◽  
Nanocrystal Growth ◽  
Chemical Availability

Lack of detailed understanding of the growth mechanism of CsPbBr3 nanocrystals has hindered sophisticated morphological and chemical control of this important emerging optoelectronic material. Here, we have elucidated the growth mechanism by slowing the reaction kinetics. When 1-bromohexane is used as an alternative halide source, bromide is slowly released into the reaction mixture, extending the reaction time from ~3 seconds to greater than 20 minutes. This enables us to monitor the phase evolution of products over the course of reaction, revealing that CsBr is the initial species formed, followed by Cs4PbBr6, and finally CsPbBr3. Further, formation of monodisperse CsBr nanocrystals is demonstrated in a bromide-deficient and lead-abundant solution. The CsBr can only be transformed into CsPbBr3 nanocubes if additional bromide is added. Our results indicate a fundamentally different growth mechanism for CsPbBr3 in comparison with more established semiconductor nanocrystal systems and reveal the critical role of the chemical availability of bromide for the growth reactions.<br>

Thermodynamics and kinetics of hydriding of the Zr(Ni0.75V0.25)2 laves phase

2004 ◽  
Vol 29 (2) ◽  
pp. 1-9
Author(s):  
Mustapha Boulghallat ◽  
Ahmed Jouaiti ◽  
Norbert Gérard
Keyword(s):  
Laves Phase ◽  
Thermodynamics And Kinetics ◽  
Kinetics Of
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