Generation and Dissociation of Iron-Boron Pairs in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
Masashi Suezawa ◽  
Koji Sumino
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Reaction Kinetics ◽  
Order Reaction ◽  
Migration Energy ◽  
Paramagnetic Resonance ◽  
First Order ◽  
Pair Generation ◽  
Electron Paramagnetic ◽  
Fe Impurity

AbstractThe generation and dissociation processes of Fe-B pairs in Si crystal are investigated by means of the measurements of electron paramagnetic resonance of Si crystals of various B concentrations doped with Fe. Fe-B pairs are generated due to annealing of the crystals at temperatures around 300 K obeying to the first order reaction kinetics. The activation energy for pair generation is determined to be about 0.65 eV which is almost equal to the migration energy of Fe impurity in a Si crystal. Fe-B pairs are found to be dissociated at tempeatures higher than 150°C leading to the precipitation of Fe.

An Electrolytically Generated, Localized Hole Center in Quartz

1989 ◽  
Vol 44 (4) ◽  
pp. 278-282
Author(s):  
A. B. Vassilikou-Dova ◽  
K. Eftaxias ◽  
G. Lehmann
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Temperature Dependence ◽  
Free Electron ◽  
Room Temperature ◽  
Hole Center ◽  
Paramagnetic Resonance ◽  
Tentative Model ◽  
Hyperfine Splittings ◽  
Electron Paramagnetic

Abstract In natural smoky quartz and neutron-irradiated, initially colorless quartz a new hole center was formed electrolytically at temperatures near 1100 K in addition to the well-known smoky quartz center. Unlike the latter its electron paramagnetic resonance spectra can already be measured at room temperature due to firm localization of the hole on one oxygen. It is characterized by fairly small hyperfine splittings due to Al impurity and significant deviations of all three principal g factors from that of a free electron. A tentative model for the structure of this center is proposed.An activation energy of 215 kJ/mol was determined for this electrolytic coloration from the temperature dependence of the electrolysis currents.

Deep Levels Responsible for Semi-Insulating Behavior in Vanadium-Doped 4H-SiC Substrates

2008 ◽  
Vol 600-603 ◽  
pp. 401-404
Author(s):  
Nguyen Tien Son ◽  
Patrick Carlsson ◽  
Andreas Gällström ◽  
Björn Magnusson ◽  
Erik Janzén
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Thermal Activation ◽  
Activation Energies ◽  
Thermal Activation Energy ◽  
Deep Levels ◽  
Paramagnetic Resonance ◽  
Intrinsic Defects ◽  
Carbon Vacancy ◽  
Electron Paramagnetic

Semi-insulating (SI) 4H-SiC substrates doped with vanadium (V) in the range 5.5×1015 –1.1×1017 cm–3 were studied by electron paramagnetic resonance. We show that only in heavily V-doped 4H-SiC vanadium is responsible for the SI behavior, whereas in moderate V-doped substrates with the V concentration comparable or slightly higher than that of the shallow N donor or B acceptor, the SI properties are thermally unstable and determined by intrinsic defects. The results show that the commonly observed thermal activation energy Ea~1.1 eV in V-doped 4H-SiC, which was previously assigned to the single acceptor V4+/3+ level, may be related to deep levels of the carbon vacancy. Carrier compensation processes involving deep levels of V and intrinsic defects are discussed and possible thermal activation energies are suggested.

Electron Paramagnetic Resonance in Cu2O Compared with Other Semiconducting Properties

1971 ◽  
Vol 49 (10) ◽  
pp. 1275-1283 ◽  
Author(s):  
J. C. W. Taylor ◽  
F. L. Weichman ◽  
R. E. D. McClung
Keyword(s):  
Activation Energy ◽  
Electron Paramagnetic Resonance ◽  
Single Crystals ◽  
Room Temperature ◽  
Starting Material ◽  
Paramagnetic Resonance ◽  
Semiconducting Properties ◽  
Wide Range ◽  
Temperature Activation ◽  
Electron Paramagnetic

Electron paramagnetic resonance spectra have been observed in single crystals of Cu2O at 4.2 °K. Six samples cut from the same starting material were individually heated under a wide range of vacuum conditions and comparison was made between the observed e.p.r. spectrum and the luminescence, activation energy, and photoconductivity in the same sample. No direct relationships between e.p.r. spectra and the luminescence and photoconductivity were found although a good correlation between the complexity of the e.p.r. spectra and the room temperature activation energy was observed.

scholarly journals Antioxidant Activity of Selected Apple Cultivars Studied by Electron Paramagnetic Resonance

2015 ◽  
Vol 57 (1) ◽  
pp. 125-129 ◽  
Author(s):  
Krunoslav Mirosavljević ◽  
Branka Bilić ◽  
Teuta Benković-Lacić
Keyword(s):  
Antioxidant Activity ◽  
Electron Paramagnetic Resonance ◽  
Exponential Decay ◽  
Total Antioxidant Activity ◽  
Paramagnetic Resonance ◽  
First Order ◽  
Golden Delicious ◽  
Total Antioxidant ◽  
Apple Cultivars ◽  
Electron Paramagnetic

Abstract The total antioxidant activity of three apple cultivars conventionally farmed (Jonagold, Golden Delicious and Idared) and two cultivars organically farmed (Jonagold and Golden Delicious) were investigated by electron paramagnetic resonance (EPR) spectroscopy. The spin label used for experiments was TEMPO radical (2,2,6,6-tetramethylpiperidine-1-oxyl) with a well-defined EPR spectrum consisting of three equidistant peaks. The results obtained indicated difference in the total antioxidant activity of apples grown in two different ways, conventional and organic, as well as between different cultivars grown in the same way. The Golden Delicious cultivar is richer in antioxidants than the Jonagold and Idared, regardless of the method of farming. The difference between them is higher in conventionally grown apples than in organically farmed apples. Experimental data was fitted with non-linear curve fit for exponential decay of the first order based on the Levenberg-Marquardt method. The high values of the R2 parameters for all data indicated correctness in the proposition of exponential decay of the first order as a model describing the dynamic properties of spin labels which diminish in the presence of fresh apple juice.

scholarly journals Effect of storage temperature on the decay of catechins and procyanidins in dark chocolate

2017 ◽  
Vol 35 (No. 4) ◽  
pp. 360-366 ◽  
Author(s):  
Pavlović Aleksandra N ◽  
Mrmošanin Jelena M ◽  
Krstić Jovana N ◽  
Mitić Snežana S ◽  
Tošić Snežana B ◽  
...  
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Storage Stability ◽  
Arrhenius Equation ◽  
Storage Temperature ◽  
Order Reaction ◽  
Dark Chocolate ◽  
Total Flavonoids ◽  
Temperature Dependent ◽  
First Order

The storage stability of catechins, procyanidins, and total flavonoids in dark chocolate was investigated. The obtained results showed that the degradation of flavonoids followed first-order reaction kinetics. Temperature-dependent degradation was modelled on the Arrhenius equation. The activation energy for the degradation of dark chocolate flavonoids during storage was 61.2 kJ/mol. During storage, flavonoids degraded more rapidly at 35°C (k = 7.8 × 10<sup>–3</sup>/day) than at 22°C (k = 5.4 × 10<sup>–3</sup>/day) and 4°C (k = 2.2 × 10<sup>–3</sup>/day).

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