Effect of particle size on activation energy and peak temperature of the thermoluminescence glow curve of undoped ZnS nanoparticles

Luminescence ◽  
2015 ◽  
Vol 31 (2) ◽  
pp. 478-486 ◽  
Author(s):  
B. P. Chandra ◽  
Raju Kumar Chandrakar ◽  
V. K. Chandra ◽  
R. N. Baghel
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Glow Curve ◽  
Peak Temperature ◽  
Zns Nanoparticles ◽  
Effect Of Particle Size ◽  
Thermoluminescence Glow Curve

An Overview on Peak Shape Method for Thermoluminescence Glow Curve Analysis

2018 ◽  
pp. 26-52
Author(s):  
Sukhamoy Bhattacharyya ◽  
Partha Sarathi Majumdar
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
Frequency Factor ◽  
Curve Analysis ◽  
Peak Shape ◽  
Order Of Kinetics ◽  
Symmetry Factor ◽  
Alternative Approach ◽  
General Order ◽  
Thermoluminescence Glow Curve

The shape of a thermoluminescence (TL) glow curve has fundamental importance for calculating the characteristic parameters of trap levels within the band gap. TL analysis are mostly based on the three-parameter general order kinetics model. The parameters are activation energy, order of kinetics, and frequency factor. Peak shape method is one of the most prominent methods for extracting the activation energy from a TL curve. An overview of different peak shape methods along with an alternative approach formulated directly from basic TL equations is presented in this chapter. Generally, peak shape method requires prior knowledge of order of kinetics to determine activation energy which creates a difficulty due to the non-uniqueness of symmetry factor for a particular value of order of kinetics. A modified version of peak shape method which is free from this constraint is discussed here. Activation energies from experimental curves of tremolite and actinolite are estimated using peak shape method. Limitation of peak shape method for saturated TL peaks with heavy retrapping is also discussed.

Effect of Particle Size on Oxidation Reaction Kinetics Parameter of Cu2O Powders

2011 ◽  
Vol 284-286 ◽  
pp. 726-729 ◽  
Author(s):  
Zai Yuan Li ◽  
Yu Chun Zhai ◽  
Myongil Pang
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Apparent Activation Energy ◽  
Reaction Kinetics ◽  
Oxidation Reaction ◽  
Raw Materials ◽  
Particle Sizes ◽  
Oxide Powders ◽  
Effect Of Particle Size ◽  
Kinetics Parameter

The 0.4mol•L-1CuSO4liquor and 5mol•L-1NaOH liquor were prepared by CuSO4·5H2O and NaOH as raw materials. The Cu2O powders were prepared by dextrose reducer and PVP dispersant. The Cu2O oxidation reaction DTA-TG-DTG curves were obtained by SDT 2960 simultaneous DSC-TGA analysis apparatus. The mensuration condition were that rise temperature velocity 15°C·min-1and deoxidize gas air. The Cu2O oxidation reaction kinetics was calculated by DTA-TG-DTG curves data. The results indicate that the cuprous oxide powders shape were spherical, their particle’ sizes were 100,200,1000nm. Their apparent activation energy were 164.38, 175.54, 282.65 KJ·mol-1, the apparent activation energy increase with Cu2O particle’ size. Their frequency factors were 1.22×1013, 1.40×1013, 2.88×1020, the frequency factors increase with particle’ size Cu2O. Their reaction progressions were 1.02, 1.00, 0.96, the reaction progression increase with Cu2O particle’ size decreased.

scholarly journals Effect of Particle Size and pH Value of Slurry on Chemical Mechanical Polishing of SiO2 Film

2022 ◽  
Author(s):  
Fan Xu ◽  
Weilei Wang ◽  
Aoxue Xu ◽  
Daohuan Feng ◽  
Weili Liu ◽  
...  
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Chemical Mechanical Polishing ◽  
Ph Value ◽  
Removal Rate ◽  
Mechanical Action ◽  
Sio2 Film ◽  
Mechanical Polishing ◽  
Chemical Action ◽  
Effect Of Particle Size

Abstract This study investigated the effects of particle size and pH of SiO2-based slurry on chemical mechanical polishing for SiO2 film. It was found that the removal rates and surface roughness of the material was highly dependent on the particle size and pH. As the particle size varied, the main polishing mechanism provided the activation energy to mechanical erasure. In addition, pH affected the particle size and Zeta potential, which had an important effect on the strength of the mechanical and chemical action of the chemical mechanical polishing. The change in mechanical action greatly influenced the removal rate. According to the experimental results, the best polishing of SiO2 film was achieved with 40 nm particle size SiO2 abrasives when the pH was 4.

Thermogravimetric Study of the Effect of Particle Size on the Spontaneous Combustion of Indonesian Low Rank Coal

2013 ◽  
Vol 330 ◽  
pp. 101-105 ◽  
Author(s):  
Muksin Saleh ◽  
Yulianto Sulistyo Nugroho
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Spontaneous Combustion ◽  
Moisture Loss ◽  
Low Rank ◽  
Low Temperature Oxidation ◽  
Temperature Oxidation ◽  
Isothermal Method ◽  
Size Groups ◽  
Effect Of Particle Size

Low-temperature oxidation of two Indonesian low rank coals was characterized by Thermogravimetric analysis (TGA). The effect of particle size on the spontaneous combustion of coal was examined. Coals were classified to-599+299, -299+249, -249-150, -150+76 and-76 μm size groups and through non-isothermal method scanned from 24 to 600°C at heating rate 5°C/min with air flow rate 50 mL/min. DTA thermogram shows that the transition temperatures decrease by decreasing the particle size. Furthermore, the weight loss increases by decreasing particle size. It is indicated that the propensity of coal to spontaneous combustion increase with decreasing particle size. The moisture loss activation energy and oxidation activation energy were calculated by an integral method using the Coats-Redfern formula. The results show that the propensity for spontaneous combustion of two coal samples (judged by the activation energy) increases by decreasing particle size.

Particle Size Effect on FeS Spontaneous Combustion Characters in Petroleum

2014 ◽  
Vol 608-609 ◽  
pp. 971-975
Author(s):  
Man Yang ◽  
Xian Feng Chen ◽  
Yu Jiao Shang ◽  
Ren Dong Bao
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Reaction Mechanisms ◽  
Spontaneous Combustion ◽  
Oxidation Kinetic ◽  
Mesh Size ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Heating Rates ◽  
Effect Of Particle Size

In order to evaluate the effect of particle size on FeS Spontaneous Combustion Characters, four different grain diameters of FeS particles (100, 170, 220, 320-mesh) were detected in the experiment. The reaction process at heating rates of 5°C /min in air flow from 30°C to 900°C were studied by TG-DSC and oxidation kinetic analysis. The activation energies of samples were calculated by the Coats-Redfern method. It is found that four reaction mechanisms are involved in FeS spontaneous combustion for different particle sizes; the activation energy values change from 307.4 to 398.05 kJ/mol; larger size particles have higher activation energy values; so grain diameters larger than 100-mesh size samples are less inclined to be oxidized and self-ignited.

Dechromization Kinetics of Limonitic Laterite Ores by Alkali-Roasting Method Using Sodium Hydroxide

2011 ◽  
Vol 233-235 ◽  
pp. 798-804
Author(s):  
Qiang Guo ◽  
Jing Kui Qu ◽  
Bing Bing Han ◽  
Guang Ye Wei ◽  
Tao Qi
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
High Temperature ◽  
Liquid Phase ◽  
Avrami Model ◽  
Phase Reduction ◽  
Laterite Ores ◽  
Effect Of Particle Size ◽  
Roasting Temperature ◽  
Kinetics Of

A novel process was proposed for the activation pretreatment of Cr-containing limonitic laterite ores by NaOH roasting. The dechromization kinetics of the laterite ores and the effect of particle size, NaOH-ore ratio, and roasting temperature on Cr extraction were studied in detail. Experimental results indicate that decreasing the particle size and increasing the NaOH-ore ratio and roasting temperature increase the Cr extraction rate. Approximately 96% Cr in the laterite ores could be extracted under the optimal alkali-roasting conditions. The results also indicate that the Avrami model is suitable for the dechromization process and that the apparent activation energy is calculated 11.12 kJ·mol-1. The 99.5% Cr2O3 was obtained from Na2CrO4 leached in the alkali solution by liquid-phase reduction and then calcining at high temperature.

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