Thermal Stability of Zinc and Selenium Implanted GaAs

1989 ◽  
Vol 146 ◽  
Author(s):  
A C T Tang ◽  
B J Sealy ◽  
A A Rezazadeh
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Carrier Concentration ◽  
Initial Rate ◽  
Heat Treatments ◽  
Rate Of Change ◽  
First Time ◽  
Thermal Stability Of

ABSTRACTWe have observed for the first time reversible changes in the sheet carrier concentration of the rapid thermally annealed Se and Zn implanted GaAs samples during subsequent heat treatments. The electrical profiles of the implanted samples have also been modified during the annealing processes. By observing the initial rate of change in the carrier concentration, an activation energy of about 2 eV is obtained which is thought to correspond to the diffusion of gallium atoms/vacancies.

scholarly journals First thermal studies on visible-light-switchable negative T-type photochromes of a nitrile-rich series

RSC Advances ◽  
2021 ◽  
Vol 11 (34) ◽  
pp. 21097-21103
Author(s):  
Mikhail Yu. Belikov ◽  
Mikhail Yu. Ievlev
Keyword(s):  
Thermal Stability ◽  
Visible Light ◽  
Temperature Effect ◽  
Thermal Studies ◽  
First Time ◽  
Thermal Stability Of

The temperature effect on the thermal stability of both the initial and photoinduced forms of nitrile-rich T-type photochromes was studied for the first time.

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>

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 Optimization of Polyamide Pulp-Reinforced Silica Aerogel Composites for Thermal Protection Systems

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1278
Author(s):  
Mariana E. Ghica ◽  
Cláudio M.R. Almeida ◽  
Mariana Fonseca ◽  
António Portugal ◽  
Luísa Durães
Keyword(s):  
Thermal Stability ◽  
Thermal Protection ◽  
Molar Ratio ◽  
Experimental Procedure ◽  
Thermal Protection Systems ◽  
Protection Systems ◽  
Density Values ◽  
Polyamide Fibers ◽  
First Time ◽  
Thermal Stability Of

The present work describes for the first time the preparation of silica-based aerogel composites containing tetraethoxysilane (TEOS) and vinyltrimethoxysilane (VTMS) reinforced with Kevlar® pulp. The developed system was extensively investigated, regarding its physical, morphological, thermal and mechanical features. The obtained bulk density values were satisfactory, down to 208 kg·m−3, and very good thermal properties were achieved—namely a thermal conductivity as low as 26 mW·m−1·K−1 (Hot Disk®) and thermal stability up to 550 °C. The introduction of VTMS offers a better dispersion of the polyamide fibers, as well as a higher hydrophobicity and thermal stability of the composites. The aerogels were also able to withstand five compression-decompression cycles without significant change of their size or microstructure. A design of experiment (DOE) was performed to assess the influence of different synthesis parameters, including silica co-precursors ratio, pulp amount and the solvent/Si molar ratio on the nanocomposite properties. The data obtained from the DOE allowed us to understand the significance of each parameter, offering reliable guidelines for the adjustment of the experimental procedure in order to achieve the optimum properties of the studied aerogel composites.

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.

Tuning the photochromic properties of chromophores containing a nitrile-rich acceptor: a novel branch in the investigation of negative photochromes

2019 ◽  
Vol 43 (22) ◽  
pp. 8414-8417 ◽  
Author(s):  
Mikhail Yu. Belikov ◽  
Mikhail Yu. Ievlev ◽  
Sergey V. Fedoseev ◽  
Oleg V. Ershov
Keyword(s):  
Thermal Stability ◽  
Photochromic Properties ◽  
Photoinduced Form ◽  
First Time ◽  
Thermal Stability Of

High photoswitching contrast and variation of the thermal stability of the photoinduced form for a novel group of reverse photochromes are described for the first time.

Synergistic effect of fluorination and regio-regularity on the long-term thermal stability of polymer solar cells

2016 ◽  
Vol 4 (47) ◽  
pp. 18598-18606 ◽  
Author(s):  
Zidong Li ◽  
Tong Zhang ◽  
Yue Xin ◽  
Xiaoli Zhao ◽  
Dalei Yang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Solar Cells ◽  
Synergistic Effect ◽  
Polymer Solar Cells ◽  
First Time ◽  
Thermal Stability Of

The synergistic effect of fluorination and regio-regularity is proposed for the first time to realize the long-term thermal stability of polymer solar cells.

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.

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