Meyer-Neldel Rule on thermal stability parameters (trap depth and frequency factor) of luminescence signals in quartz

2021 ◽  
Author(s):  
Zuzanna Kabacińska ◽  
Alida Timar-Gabor ◽  
Benny Guralnik
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Hydrogen Diffusion ◽  
Dose Range ◽  
Accurate Determination ◽  
Frequency Factor ◽  
Proton Conduction ◽  
High Dose ◽  
Compensation Law ◽  
Thermal Stability Of

<p>Thermally activated processes can be described mathematically by the Arrhenius equation. The Meyer-Neldel Rule (MNR), or compensation law, linearly relates the pre-exponent term to the logarithm of the excitation enthalpy for processes that are thermally driven in an Arrhenian manner. This empirical rule was observed in many areas of materials science, in physics, chemistry, and biology. In geosciences it was found to uphold in hydrogen diffusion (Jones 2014a) and proton conduction (Jones 2014b) in minerals.</p><p>Trapped charge dating methods that use electron spin resonance (ESR) or optically or thermally stimulated luminescence (OSL and TL) are based on the dose-dependent accumulation of defects in minerals such as quartz and feldspar. The thermal stability of these defects in the age range investigated is a major prerequisite for accurate dating, while the accurate determination of the values of the trap depths and frequency factors play a major role in thermochronometry applications. </p><p>The correlation of kinetic parameters for diffusion has been very recently established for irradiated oxides (Kotomin et al. 2018). A correlation between the activation energy and the frequency factor that satisfied the Meyer–Neldel rule was reported when the thermal stability of [AlO<sub>4</sub>/h<sup>+</sup>]<sup>0</sup> and [TiO<sub>4</sub>/M<sup>+</sup>]<sup>0</sup> ESR signals in quartz was studied as function of dose (Benzid and Timar-Gabor 2020). Here we compiled the optically stimulated luminescence (OSL) data published so far in this regard, and investigated experimentally the thermal stability of OSL signals for doses ranging from 10 to 10000 Gy in sedimentary quartz samples. We report a linear relationship between the natural logarithm of the preexponent term (the frequency factor) and the activation energy E, corresponding to a Meyer-Neldel energy of 45 meV, and a deviation from first order kinetics in the high dose range accompanied by an apparent decrease in thermal stability. The implications of these observations and the atomic and physical mechanisms are currently studied.</p><p> </p><p><strong>References</strong></p><p>Benzid, K., Timar Gabor, A. 2020. The compensation effect (Meyer–Neldel rule) on [AlO<sub>4</sub>/h<sup>+</sup>]<sup>0</sup> and [TiO<sub>4</sub>/M<sup>+</sup>]<sup>0</sup> paramagnetic centers in irradiated sedimentary quartz. <em>AIP Advance</em>s 10, 075114.</p><p>Kotomin, E., Kuzovkov, V., Popov, A. I., Maier, J., and Vila, R. 2018. Anomalous kinetics of diffusion-controlled defect annealing in irradiated ionic solids. <em>J. Phys. Chem. A</em> 122(1), 28–32</p><p>Jones, A. G. (2014a), Compensation of the Meyer-Neldel Compensation Law for H diffusion in minerals, <em>Geochem. Geophys. Geosyst.</em>, 15, 2616–2631</p><p>Jones, A. G. (2014b), Reconciling different equations for proton conduction using the Meyer-Neldel compensation rule, <em>Geochem. Geophys. Geosyst</em>., 15, 337–349</p>

scholarly journals О термической устойчивости некоторых квазифуллеренов

2019 ◽  
Vol 61 (3) ◽  
pp. 604
Author(s):  
А.И. Подливаев ◽  
Л.А. Опенов
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Thermal Stability ◽  
Frequency Factor ◽  
Arrhenius Law ◽  
Method Of Molecular Dynamics ◽  
Temperature Dependences ◽  
Thermal Stability Of

AbstractThe thermal stability of recently predicted quasi-fullerenes С_20, С_42, С_48, and С_60 is studied by the method of molecular dynamics. The routes of their decomposition and the temperature dependences of their lifetimes are determined. The activation energy and frequency factor values that appear in the Arrhenius law are found. New isomers are detected.

scholarly journals Crystallization, mechanical and electrochemical behavior of Al-Ce-TM (TM = Fe, Co, Ni and Cu) amorphous alloys

2019 ◽  
Vol 4 (2) ◽  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Electrochemical Behavior ◽  
Amorphous Alloys ◽  
Frequency Factor ◽  
Onset Crystallization Temperature ◽  
Nano Crystalline ◽  
Thermal Stability Of

Al86Ce10TM4 amorphous alloys (TM=Fe, Co, Ni and Cu) were fabricated using melt-spin fast-quenching method. The crystallization, mechanical and electrochemical behavior of the as-spun and the post-annealed alloys were investigated by X-ray diffraction (XRD), differential scanning calorimetry (DSC), micro-indentation and electrochemical techniques. It was found the completely amorphous Al86Ce10TM4 alloys (TM=Fe, Co, Ni and Cu) go through two crystallization processes, where the first exothermal peak represents nucleation of nano-crystalline particles and the second exothermal peak signifies growth of the nano-crystalline precipitates. Both the nucleation and growth processes rely on diffusion-controlled mechanism. The first onset crystallization temperature Tx1 associated with activation energy E1 and frequency factor Ko1 can be used to evaluate the thermal stability of the amorphous alloys while the second onset crystallization temperature Tx2 associated with activation energy E2 and frequency factor Ko2 can be taken to judge the thermal stability of ideal amorphous-nanocrystalline mixed structure in sustaining optimized mechanical and electrochemical properties. The as-spun and post-annealed alloys exhibit higher mechanical hardness (860~1180 MPa), corrosion resistance (10-8A/cm2 ) and high temperature endurance (284, 300 and 420°C for Al86Ce10Co4 , Al86Ce10Ni4 andAl86Ce10Fe4 , respectively) compared to hardness 500~600 MPa, corrosion resistance 10-7A/cm2 and high temperature durability 200°C of traditional Al crystalline alloys, manifesting the value on scientific studies and engineering applications of the Al86Ce10TM4 amorphous alloys.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

scholarly journals Curing Kinetics and Thermal Stability of Epoxy Composites Containing Newly Obtained Nano-Scale Aluminum Hypophosphite (AlPO2)

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 644 ◽  
Author(s):  
Farimah Tikhani ◽  
Shahab Moghari ◽  
Maryam Jouyandeh ◽  
Fouad Laoutid ◽  
Henri Vahabi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
High Performance ◽  
Frequency Factor ◽  
Curing Temperature ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Nano Scale ◽  
Aluminum Hypophosphite ◽  
Thermal Stability Of

For the first time, nano-scale aluminum hypophosphite (AlPO2) was simply obtained in a two-step milling process and applied in preparation of epoxy nanocomposites varying concentration (0.1, 0.3, and 0.5 wt.% based on resin weight). Studying the cure kinetics and thermal stability of these nanocomposites would pave the way toward the design of high-performance nanocomposites for special applications. Scanning electron microscopy (SEM) and transmittance electron microscopy (TEM) revealed AlPO2 particles having domains less than 60 nm with high potential for agglomeration. Excellent (at heating rate of 5 °C/min) and Good (at heating rates of 10, 15 and 20 °C/min) cure states were detected for nanocomposites under nonisothermal differential scanning calorimetry (DSC). While the dimensionless curing temperature interval (ΔT*) was almost equal for epoxy/AlPO2 nanocomposites, dimensionless heat release (ΔH*) changed by densification of polymeric network. Quantitative cure analysis based on isoconversional Friedman and Kissinger methods gave rise to the kinetic parameters such as activation energy and the order of reaction as well as frequency factor. Variation of glass transition temperature (Tg) was monitored to explain the molecular interaction in the system, where Tg increased from 73.2 °C for neat epoxy to just 79.5 °C for the system containing 0.1 wt.% AlPO2. Moreover, thermogravimetric analysis (TGA) showed that nanocomposites were thermally stable.

Synthesis of Fe-rich Fe–Al nanocrystalline solid solutions using ball milling

1999 ◽  
Vol 14 (5) ◽  
pp. 1760-1770 ◽  
Author(s):  
H. G. Jiang ◽  
H. M. Hu ◽  
E. J. Lavernia
Keyword(s):  
Heat Treatment ◽  
Activation Energy ◽  
Thermal Stability ◽  
Intermetallic Compound ◽  
Ball Milling ◽  
Microstructural Evolution ◽  
Solid Solutions ◽  
Al Alloys ◽  
Time Intervals ◽  
Thermal Stability Of

The synthesis of nanocrystalline Fe, Fe–4 wt% Al, and Fe–10 wt% Al solid solutions by SPEX ball milling has been studied. The microstructural evolution during ball milling, as well as subsequent heat treatment, has been characterized. The results demonstrate that ball milling promotes the formation of αFe–4 wt% Al and αFe–10 wt% Al solid solutions by reducing the activation energy of these alloys and generating thermal energy during this process. For Fe–10 wt% Al powders milled for various time intervals up to approximately 20 min, the FeAl intermetallic compound is formed. For alloys annealed at temperatures ranging from 600 to 1000 °C, the addition of 10 wt% Al to Fe significantly enhances the thermal stability of the nanocrystalline Fe–Al alloys. Interestingly, the addition of Al within the range of 4–10 wt% seems to have little effect on the thermal stability of these alloys annealed under the same conditions. Also, the thermal stability improves for alloys milled in air as opposed to those processed using Ar.

Epoxy Cured with Anhydride Terminated Polydimethylsiloxane: Cure Kinetics and Thermal Properties

2011 ◽  
Vol 415-417 ◽  
pp. 261-264
Author(s):  
Yuan Ren ◽  
Zheng Xi ◽  
Wen Jun Gan ◽  
Liang Zhang ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Properties ◽  
Succinic Anhydride ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Scanning Calorimetry ◽  
Thermogravimetric Analyses ◽  
Isothermal Measurements ◽  
Thermal Stability Of

A siloxane-containing dianhydride, succinic anhydride terminated polydimethylsiloxane (DMS-Z21) was selected to cure diglycidyl ether of bisphenol-A based epoxy resin (DGEBA). The cure kinetics and thermal properties were investigated by nonisothermal and isothermal differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA), respectively. The activation energy (Ea) of the curing reaction was obtained based on the methods of Kissinger and isothermal measurements. The results of the thermogravimetric analyses of the DGEBA/DMS-Z21 system showed that the thermal stability of the DGEBA/DMS-Z21 system was slightly higher than the DGEBA/MeTHPA system.

Studies on Thermal Stability and Rheological Property of PU/PVDF Blend

2011 ◽  
Vol 311-313 ◽  
pp. 1065-1070
Author(s):  
Guo Lan Huan ◽  
Jian Li Liu ◽  
Qi Yun Du ◽  
Xiao Yu Hu
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Decomposition ◽  
Shear Stress ◽  
Rheological Property ◽  
Decomposition Temperature ◽  
Dynamic Equations ◽  
Thermal Decomposition Temperature ◽  
Thermal Stability Of ◽  
Decomposition Activation Energy

In this article, the thermal stability of PU/PVDF blend was investigated by thermogravimetry (TG), and their rheological property was studied through testing and analyzing the rheological curves. The results showed that, with the increase in PVDF content, the thermal decomposition temperature of PU/PVDF blend increased, and by fitting relevant data to thermal decomposition dynamic equations, it was found that thermal decomposition activation energy of the blend increased gradually, i.e. the thermal stability of the blend increased gradually. Meantime, based on the curves of shear stress vs. shear rate of the blend at 180°C and 200°C, it was shown that for PU/PVDF blend, with the decrease of temperature and the increase in PVDF content, the non-Newtonian index decreased, while the viscosity of the blend increased.

scholarly journals Experimental Investigation of Thermal Characteristics of Kiwira Coal Waste with Rice Husk Blends for Gasification

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Deodatus Kazawadi ◽  
Geoffrey R. John ◽  
Cecil K. King’ondu
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Rice Husk ◽  
Energy Recovery ◽  
Fossil Fuels ◽  
High Energy ◽  
Coal Waste ◽  
Rice Husks ◽  
Weight Percentage ◽  
Thermal Stability Of

Eminent depletion of fossil fuels and environmental pollution are the key forces driving the implementation cofiring of fossil fuels and biomass. Cogasification as a technology is known to have advantages of low cost, high energy recovery, and environmental friendliness. The performance/efficiency of this energy recovery process substantially depends on thermal properties of the fuel. This paper presents experimental study of thermal behavior of Kiwira coal waste/rice husks blends. Compositions of 0, 20, 40, 60, 80, and 100% weight percentage rice husk were studied using thermogravimetric analyzer at the heating rate of 10 K/min to 1273 K. Specifically, degradation rate, conversion rate, and kinetic parameters have been studied. Thermal stability of coal waste was found to be higher than that of rice husks. In addition, thermal stability of coal waste/rice husk blend was found to decrease with an increase of rice husks. In contrast, both the degradation and devolatilization rates increased with the amount of rice husk. On the other hand, the activation energy dramatically reduced from 131 kJ/mol at 0% rice husks to 75 kJ/mol at 100% rice husks. The reduction of activation energy is advantageous as it can be used to design efficient performance and cost effective cogasification process.

Thermal Stability of Z-Type Perfluoro Poly Ether Lubricant Polymers: A Combined Thermogravimetric and Temperature Programmed Desorption Study

2003 ◽  
Author(s):  
Paul M. Jones ◽  
Lei Li ◽  
Yiao-Tee Hsia
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Temperature Programmed Desorption ◽  
Kcal Mole ◽  
Three Samples ◽  
Desorption Study ◽  
Polymer Decomposition ◽  
Temperature Programmed ◽  
Decomposition Chemistry ◽  
Thermal Stability Of

The thermal stability of Zdol 4000, 7800 and Ztetraol perfluoropolyethers (PFPE) have been studied in both the bulk with thermogravimetric analysis (TGA) and in thin film form with temperature programmed desorption spectroscopy (TPD). The TGA results have been interpreted to yield an evaporation activation energy for both Zdol 4000 (13 kcal/mole) and Zdol 7800 (19 kcal/mole). A larger activation energy is also found for all three samples investigated that is consistent with polymer decomposition (22, 27 and 21 kcal/mole respectively). The TPD threshold has been found to be approximately similar all three samples (∼500 K). The temperature of decomposition was also found to be similar for all three samples and was dominated by the CF2O+ mass fragment at ∼660 K. Two desorption maximums were observed for both Zdol 4000 and Ztetraol indicating the similarity in their decomposition chemistry. In contrast only one desorption peak was observed from Zdol 7800 (675 K). A CF3+ fragment was not observed in any of the TPD spectra indicating the absence an acidic decomposition path for all of the Fomblin Z polymers studied.

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