Study of Donor Centres in n-InSb due to the Temperature Annealing

2005 ◽  
Vol 480-481 ◽  
pp. 197-200
Author(s):  
Y. Sayad ◽  
A. Nouiri
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Annealing Time ◽  
Annealing Temperature ◽  
Theoretical Study ◽  
Donor Concentration ◽  
Model Based ◽  
Proposed Model ◽  
Kinetics Of ◽  
Best Fit

An increasing of donor centres has been detected in n-InSb when it was submitted to anneal/quench with various annealing temperature (450 °C - 850 °C) and various annealing time (5 - 100 hours). A theoretical study of the kinetics of the conduction conversion of n-InSb at temperature annealing above 250 °C has been made. The present analysis indicates that the donor concentration increases with increasing of annealing time. In order to study this variation and to give a model for donor centres generated, a proposed model based on the simple kinetic is used to fit the variation of donor concentration as a function of annealing time. However, from the best fit of experimental data using the proposed model, the activation energy is determined.

scholarly journals Modeling of the Kinetics of Polyoxymethylene Decomposition under Oxidative and Non-Oxidative Conditions

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2281
Author(s):  
Tomasz M. Majka ◽  
Gabriela Berkowicz-Płatek ◽  
Witold Żukowski
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Mass Loss ◽  
Kinetic Models ◽  
Entire Range ◽  
Oxidative Degradation ◽  
Influence Of Temperature ◽  
Kinetics Of ◽  
Best Fit ◽  
Thermo Oxidative Degradation

Research on the thermal and thermo-oxidative degradation of polyacetals allows for the development of effective methods of utilization of the waste of these polymers towards the recovery of monomers. For this purpose, in addition to qualitative analysis, it is necessary to understand the mechanisms of chemical reactions accompanying the decomposition process under the influence of temperature. Therefore, in this article, with the experimental results from the thermal analysis of the POM homopolymer of three various stages of life—POM-P—unprocessed sample; POM-R—recycled sample, and POM-O—sample waste—we took steps to determine the basic kinetic parameters using two well-known and commonly used kinetic models: Friedman and Ozawa-Flynn-Wall (OFW). Knowing the values of the course of changes in apparent activation energy as a function of partial mass loss, theoretical curves were fitted to the experimental data. The applied calculation models turned out to be consistent in terms of the nature of the curve changes and similar in terms of Ea in the entire range of mass loss. Both kinetic models showed a very similar course of the Ea curves. The samples that decompose under oxidative conditions obtained the best fit for the reaction of nth order with autocatalysis by product B model and the samples that decompose under inert conditions for the n-dimensional nucleation according to the Avrami–Erofeev model.

Effect of ionizing radiation on the kinetics of hydrogenation on the Ni-MgO mixed catalyst

1982 ◽  
Vol 47 (7) ◽  
pp. 1780-1786 ◽  
Author(s):  
Rostislav Kudláček ◽  
Jan Lokoč
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Liquid Phase ◽  
Ionizing Radiation ◽  
Oxide Catalyst ◽  
Absorbed Dose ◽  
Hydrogenation Rate ◽  
Solution Composition ◽  
Mixed Catalyst ◽  
Kinetics Of

The effect of gamma pre-irradiation of the mixed nickel-magnesium oxide catalyst on the kinetics of hydrogenation of maleic acid in the liquid phase has been studied. The changes of the hydrogenation rate are compared with the changes of the adsorbed amount of the acid and with the changes of the solution composition, activation energy, and absorbed dose of the ionizing radiation. From this comparison and from the interpretation of the experimental data it can be deduced that two types of centers can be distinguished on the surface of the catalyst under study, namely the sorption centres for the acid and hydrogen and the reaction centres.

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

2018 ◽  
Vol 924 ◽  
pp. 333-338 ◽  
Author(s):  
Roberta Nipoti ◽  
Alberto Carnera ◽  
Giovanni Alfieri ◽  
Lukas Kranz
Keyword(s):  
Activation Energy ◽  
Sheet Resistance ◽  
Annealing Time ◽  
Thermal Activation ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Activation Energy ◽  
Electrical Activation ◽  
Temperature Range ◽  
Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

scholarly journals Drying Kinetics of Noni Seeds

2019 ◽  
Vol 11 (5) ◽  
pp. 250 ◽  
Author(s):  
Wellytton Darci Quequeto ◽  
Osvaldo Resende ◽  
Patrícia Cardoso Silva ◽  
Fábio Adriano Santos e Silva ◽  
Lígia Campos de Moura Silva
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Moisture Content ◽  
Mathematical Models ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Kinetics Of

Noni seeds have been used for years as an important medicinal source, with wide use in the pharmaceutical and food industry. Drying is a fundamental process in the post-harvest stages, where it enables the safe storage of the product. Therefore, the present study aimed to fit different mathematical models to experimental data of drying kinetics of noni seeds, determine the effective diffusion coefficient and obtain the activation energy for the process during drying under different conditions of air temperature. The experiment used noni seeds with initial moisture content of 0.46 (decimal, d.b.) and dehydrated up to equilibrium moisture content. Drying was conducted under different controlled conditions of temperature, 40; 50; 60; 70 and 80 ºC and relative humidity, 24.4; 16.0; 9.9; 5.7 and 3.3%, respectively. Eleven mathematical models were fitted to the experimental data. The parameters to evaluate the fitting of the mathematical models were mean relative error (P), mean estimated error (SE), coefficient of determination (R2), Chi-square test (c2), Akaike Information Criterion (AIC) and Schwarz’s Bayesian Information Criterion (BIC). Considering the fitting criteria, the model Two Terms was selected to describe the drying kinetics of noni seeds. Effective diffusion coefficient ranged from 8.70 to 23.71 × 10-10 m2 s-1 and its relationship with drying temperature can be described by the Arrhenius equation. The activation energy for noni seeds drying was 24.20 kJ mol-1 for the studied temperature range.

scholarly journals Mathematical modeling of pequi pulp drying and effective diffusivity determination

2017 ◽  
Vol 21 (7) ◽  
pp. 493-498 ◽  
Author(s):  
Elisabete P. de Sousa ◽  
Rossana M. F. de Figueirêdo ◽  
Josivanda P. Gomes ◽  
Alexandre J. de M. Queiroz ◽  
Deise S. de Castro ◽  
...  
Keyword(s):  
Experimental Data ◽  
Effective Diffusivity ◽  
Drying Kinetics ◽  
Convective Drying ◽  
Drying Time ◽  
Air Speed ◽  
Drying Curves ◽  
Increasing Temperature ◽  
Kinetics Of ◽  
Best Fit

ABSTRACT The aim of this work was to study the drying kinetics of pequi pulp by convective drying at different conditions of temperature (50, 60, 70 and 80 °C) and thickness (0.5, 1.0 and 1.5 cm) at the air speed of 1.0 m s-1, with no addition of adjuvant. The experimental data of pequi pulp drying kinetics were used to plot drying curves and fitted to the models: Midilli, Page, Henderson & Pabis and Newton. Effective diffusivity was calculated using the Fick’s diffusion model for a flat plate. It was found that, with increasing thickness, the drying time increased and, with increasing temperature, the drying time was reduced. The Midilli model showed the best fit to the experimental data of pequi pulp drying at all temperatures and thicknesses, presenting higher coefficients of determination (R2), indicating that this model satisfactorily represents the pequi pulp drying phenomenon. There was a trend of increase in the effective diffusivity with the increase in pulp layer thickness and temperature.

scholarly journals Drying kinetics of baru flours as function of temperature

2018 ◽  
Vol 22 (10) ◽  
pp. 713-719 ◽  
Author(s):  
Douglas R. Reis ◽  
Fabrício B. Brum ◽  
Eduardo J. O. Soares ◽  
Jessiana R. Magalhães ◽  
Fabrício S. Silva ◽  
...  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Food Industry ◽  
Nutritional Value ◽  
Effective Diffusivity ◽  
Drying Kinetics ◽  
Statistical Parameters ◽  
Noticeable Effect ◽  
Different Temperatures ◽  
Kinetics Of

ABSTRACT Several types of seeds have been initially used in the food industry due to the great potential that vegetable proteins have. Baru is a fruit commonly found in the Cerrado biome, having a high nutritional value. This paper aimed to determine and analyze the drying kinetics of whole and defatted baru almond flours at different temperatures. The flour resulting from almond milling was defatted using petroleum ether. The drying processes were performed at temperatures of 40, 50 and 60 ºC. The mathematical models of Page, Henderson and Pabis, Midilli & Kucuk, Thompson and Approximation of Diffusion were fitted to the experimental data. The results showed a noticeable effect of air temperature on the drying kinetics of whole and defatted baru almond flours. According to the statistical parameters of analysis, the models Midilli & Kucuk and Page were the ones with the best fits to the experimental data. The effective diffusivity values found ranged from 8.02 × 10–10 to 19.90 × 10–10 m2 s-1 and for the activation energy were 22.39 and 39.37 KJ mol-1 for whole and defatted almonds, respectively.

Research on Pyrolysis Kinetics of Shenhua Coal and Direct Liquefaction Residue

2012 ◽  
Vol 550-553 ◽  
pp. 2758-2762 ◽  
Author(s):  
Xi Jie Chu ◽  
Yong Gang Wang ◽  
Li Hong Zhao
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Kinetic Parameters ◽  
Heating Rate ◽  
Coal Pyrolysis ◽  
Pyrolysis Kinetics ◽  
Differential Heating ◽  
Pyrolysis Behavior ◽  
Direct Liquefaction ◽  
Kinetics Of

The pyrolysis tests of Shenhua coal and Shenhua direct liquefaction residue have been carried out using thermogravimetric at the differential heating rate. The kinetic parameters k and E were calculated using DAEM method. Results show DAME model can describe the pyrolysis behavior of Shenhua coal within the range of 20% to 95%, the activation energy of coal pyrolysis ranges from 53.98 to 279.38 kJ/mol, and DAME model can describe the behavior of Shenhua direct liquefaction residue within the range of 10% to 80%, the activation energy of residue pyrolysis is about 170 kJ/mol. The results of which are basically consistent with the experimental data.

Kinetics of Glyphosate Adsorption on Composite Resin from Aqueous Solution

2013 ◽  
Vol 803 ◽  
pp. 157-160
Author(s):  
Zhen Zhen Kong ◽  
Dong Mei Jia ◽  
Su Wen Cui
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Composite Resin ◽  
Order Equation ◽  
Second Order ◽  
First Order ◽  
Basic Resin ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Best Fit

The composite weakly basic resin (D301Fe) was prepared and examined using scanning electron microscopy and Fourier transform infrared spectroscopy. The adsorption kinetics of glyphosate from aqueous solution onto composite weakly basic resin (D301Fe) were investigated under different conditions. The experimental data was analyzed using various adsorption kinetic models like pseudo-first order, the pseudo-second order, the Elovich and the parabolic diffusion models to determine the best-fit equation for the adsorption of glyphosate onto D301Fe. The results show that the pseudo-second order equation fitted the experimental data well and its adsorption was chemisorption-controlled.

scholarly journals Kinetics of Transesterification of Safflower Oil to Obtain Biodiesel Using Heterogeneous Catalysis

2016 ◽  
Vol 14 (4) ◽  
pp. 929-938 ◽  
Author(s):  
Gabriel E. Galván Muciño ◽  
Rubi Romero ◽  
Armando Ramírez ◽  
María Jesús Ramos ◽  
Ramiro Baeza-Jiménez ◽  
...  
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Heterogeneous Catalysis ◽  
Kinetic Model ◽  
Methyl Esters ◽  
Molar Ratio ◽  
Safflower Oil ◽  
Estimated Parameters ◽  
Kinetics Of ◽  
Best Fit

Abstract The kinetics of the transesterification of safflower oil and methanol catalyzed by K2O/NaX was studied and modeled. The influence of the oil-methanol initial molar ratio and amount of catalyst were investigated to achieve a maximum triglycerides conversion (99 %) and a final methyl esters content of 94 % ±1. A kinetic model based on an Eley–Rideal mechanism was found to best fit the experimental data when assuming methanol adsorption as determining step. Other models derived from Langmuir – Hinshelwood – Hougen –Watson (LHHW) mechanisms were rejected based on statistical analysis, mechanistic considerations and physicochemical interpretation of the estimated parameters.

Generalized Activation Energy Spectrum Theory: A New Approach for modeling Structural Relaxation in Amorphous Solids

1993 ◽  
Vol 321 ◽  
Author(s):  
Jung H. Shin ◽  
Harry A. Atwater
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Structural Relaxation ◽  
Ad Hoc ◽  
Amorphous Solids ◽  
Nucleation Kinetics ◽  
Crystal Silicon ◽  
Time Resolved ◽  
New Approach ◽  
Kinetics Of

ABSTRACTA general approach to the dynamics of structural relaxation in amorphous solids is developed. A form of the recombination kinetics of defects is chosen which removes the ad hoc assumption made in previous theories that defects recombine only with others of identical activation energy. The generalized theory is tested quantitatively by modelling the structural relaxation of amorphous silicon, and comparing the results with the experimental data on structural relaxation. It is found that the generalized theory is necessary in order to accurately describe the time-resolved relaxation data. The generalized theory is also applied to estimate the effect of irradiation on the nucleation kinetics of crystal silicon, and is found to agree well with experimental data.

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