A novel model for activation energy calculation in progressive-stress accelerated test

2011 ◽  
Author(s):  
Guo Min ◽  
Lv ChangZhi ◽  
Meng Xianlei ◽  
Ma Weidong ◽  
Xie Xuesong ◽  
...  
Keyword(s):  
Activation Energy ◽  
Energy Calculation ◽  
Accelerated Test ◽  
Novel Model

scholarly journals Thermally stimulated oxygen desorption in Sr2FeMoO6-δ

2018 ◽  
Vol 4 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Nikolay A. Kalanda
Keyword(s):  
Activation Energy ◽  
Oxygen Diffusion ◽  
Gas Flow ◽  
Oxygen Vacancies ◽  
Early Stage ◽  
Diffusion Activation Energy ◽  
Energy Calculation ◽  
Heating Rates ◽  
Oxygen Desorption ◽  
Diffusion Activation

Polycrystalline Sr2FeMoO6-δ specimens have been obtained by solid state synthesis from partially reduced SrFeO2,52 and SrMoO4 precursors. It has been shown that during oxygen desorption from the Sr2FeMoO6-δ compound in polythermal mode in a 5%H2/Ar gas flow at different heating rates, the oxygen index 6-δ depends on the heating rate and does not achieve saturation at T = 1420 K. Oxygen diffusion activation energy calculation using the Merzhanov method has shown that at an early stage of oxygen desorption from the Sr2FeMoO6-δ compound the oxygen diffusion activation energy is the lowest Еа = 76.7 kJ/mole at δ = 0.005. With an increase in the concentration of oxygen vacancies, the oxygen diffusion activation energy grows to Еа = 156.3 kJ/mole at δ = 0.06. It has been found that the dδ/dt = f (Т) and dδ/dt = f (δ) functions have a typical break which allows one to divide oxygen desorption in two process stages. It is hypothesized that an increase in the concentration of oxygen vacancies Vo•• leads to their mutual interaction followed by ordering in the Fe/Mo-01 crystallographic planes with the formation of various types of associations.

scholarly journals Thermally stimulated oxygen desorption in Sr2FeMoO6-δ

2019 ◽  
Vol 21 (1) ◽  
pp. 48-53
Author(s):  
N. A. Kalanda
Keyword(s):  
Activation Energy ◽  
Oxygen Diffusion ◽  
Gas Flow ◽  
Oxygen Vacancies ◽  
Early Stage ◽  
Diffusion Activation Energy ◽  
Energy Calculation ◽  
Heating Rates ◽  
Oxygen Desorption ◽  
Diffusion Activation

Polycrystalline Sr2FeMoO6-δ specimens have been obtained by solid state synthesis from partially reduced SrFeO2.52 and SrMoO4 precursors. It has been shown that during oxygen desorption from the Sr2FeMoO6-δ compound in polythermal mode in a 5%H2/Ar gas flow at different heating rates, the oxygen index 6–δ depends on the heating rate and does not achieve saturation at T = 1420 K. Oxygen diffusion activation energy calculation using the Merzhanov method has shown that at an early stage of oxygen desorption from the Sr2FeMoO6-δ compound the oxygen diffusion activation energy is the lowest Еа = 76.7 kJ/mole at δ = 0.005. With an increase in the concentration of oxygen vacancies, the oxygen diffusion activation energy grows to Еа = 156.3 kJ/mole at δ = 0.06. It has been found that the dδ/dt = f(Т) AND dδ/dt = f(δ) functions have a typical break which allows one to divide oxygen desorption in two process stages. It is hypothesized that an increase in the concentration of oxygen vacancies V ·· leads to their mutual interaction followed by ordering in the Fe/Mo–O1 crystallographic planes with the formation of various types of associations.

Error Correction of Theory Model in Process-Stress Accelerated Test

2011 ◽  
Vol 311-313 ◽  
pp. 1677-1680
Author(s):  
Chun Sheng Guo ◽  
Qian Qian Du ◽  
Shi Wei Feng
Keyword(s):  
Activation Energy ◽  
Theoretical Model ◽  
Theoretical Data ◽  
Theory Model ◽  
Test Method ◽  
Accelerated Test ◽  
New Model ◽  
Computer Aided ◽  
Model Algorithm ◽  
Process Stress

To correct error in theoretical model of process-stress accelerated test, a new calculation method is proposed. The new method, based on computer-aided calculation, can significantly reduce the error of the model. Theoretical data is calculated using both the new model algorithm, which is the root test method, and the old model algorithm. The results show that the old model algorithm can generate error more than 13% in the activation energy and error more than 150% in the extrapolated lifetime (Q≤1.0eV), while the new model algorithm generates error less than 1% in activation energy, and error less than 4.1% in the extrapolated lifetime.

Preparation of Ca modified Li2TiO3 ceramics pebbles and its activation energy calculation

2017 ◽  
Vol 8 (3/4) ◽  
pp. 273 ◽  
Author(s):  
Mohit Kumar ◽  
Rohit Kumar Sinha ◽  
Shlok Yadav ◽  
S.K. Sinha ◽  
P.M. Raole
Keyword(s):  
Activation Energy ◽  
Energy Calculation

scholarly journals Determination of Activation Energy of Surface Diffusion Based on Thermal Oscillations of Atoms

2021 ◽  
Vol 22 (3) ◽  
pp. 522-528
Author(s):  
Yu.V. Syrovatko ◽  
Ye.P. Shtapenko
Keyword(s):  
Activation Energy ◽  
Surface Diffusion ◽  
Substrate Surface ◽  
Geometric Mean ◽  
Harmonic Oscillators ◽  
Energy Calculation ◽  
Potential Well ◽  
Negative Part ◽  
Potential Wells ◽  
Thermal Oscillations

This paper covers calculations of the activation energy of surface diffusion of ad-atoms on the substrate surface from the point of view of thermal oscillations of substrate atoms and ad-atoms. The main characteristic of oscillations of atoms and geometric mean frequency was calculated based on statistical approximation of the Debye model using the reference values of entropy and heat capacity of metals. The basic principle of the model of activation energy calculation presented in the paper is the formation of potential wells and barriers during oscillations of atoms localized in the sites of the lattice. Oscillations of atoms were considered in the framework of quasiclassical quantum approximation as the oscillations of harmonic oscillators in the potential parabolic wells. Dimensions of the negative part of values of the potential well energy were determined by the amplitude of thermal oscillations of atoms. Positive values constituted a significant part of the potential well energy values. Barriers were formed owing to interaction of positive values of the energy of parabolic wells of adjacent atoms. Therefore, in order to make the ad-atom jump, it is necessary to get out of the potential well having the negative values, and to overcome the potential barrier. The energy required for the ad-atom jump on the substrate surface was the activation energy of surface diffusion. The results obtained in this paper agree satisfactorily with the results of another method, which is based on determining the energy of ad-atom binding with the substrate atoms.

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