scholarly journals Механизмы частотно-зависимой проводимости мезопористого кремния при гамма-облучении малыми дозами

2019 ◽  
Vol 45 (11) ◽  
pp. 6
Author(s):  
В.В. Галушка ◽  
Э.А. Жаркова ◽  
Д.В. Терин ◽  
В.И. Сидоров ◽  
Е.И. Хасина
Keyword(s):  
Fermi Level ◽  
Band Gap ◽  
Low Dose ◽  
Low Frequency ◽  
Lattice Vibrations ◽  
Γ Irradiation ◽  
Mesoporous Silicon ◽  
Γ Radiation ◽  
The Creation

Abstract — The effect of low-dose γ radiation on the mechanisms of low-frequency conductivity of mesoporous silicon has been studied. It has been shown that γ irradiation preserves the hopping character of conductivity at a change of the frequency of phonon lattice vibrations, a decrease in the size of the hop, and a shift of the level of the capture of traps to the Fermi level in the band gap, which makes the structure with mesoporous silicon irradiated by γ radiation promising for the creation of multifunctional resistive and capacitive devices.

scholarly journals The effect of low dose γ-irradiation on the optoelectric properties of n-GaN based MSM structure

2021 ◽  
Author(s):  
Leyla Barghamadi ◽  
Shahab Norouzian Alam ◽  
Bijan Ghafari ◽  
Seyed Hassan Sedighy
Keyword(s):  
Dark Current ◽  
Low Dose ◽  
Prolonged Exposure ◽  
Localized States ◽  
Abnormal Behavior ◽  
Γ Irradiation ◽  
Space Applications ◽  
Γ Radiation ◽  
Metal Semiconductor Metal ◽  
Msm Structure

Abstract The room temperature effect of a low dose rate (10-4 rad (Si)/s) 60 Co γ-irradiation on the structural propertiesand dark current of the GaN-based metal-semiconductor-metal (MSM) structure has been studied. In contrast to previous studies, a non-monotonous dependence of the dark current with the γ-irradiation dose is observed. The intensity and linewidth of the photoluminescence (PL) peaks correlate with the changes in electrical characteristics and eventually degrade after prolonged exposure to the γ-radiation. The abnormal behavior of the MSM structure and particularly its I-V and PL characteristics are explained by considering the carrier transfer mechanism in the localized states. These phenomena are associated with the decrease of shallow donors’ density in localized states and the activation of the non-radiative centers as radiation dose increases. These experimental results and the mechanism presented are essential for understanding the interaction of the γ-irradiation with n-GaN and for estimation of reliability of GaN-based (opto)electronics in harsh conditions of γ-radiation (space applications, liquidation of consequences of technogenic catastrophes, etc.).

Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20402
Author(s):  
Kaoutar Benthami ◽  
Mai ME. Barakat ◽  
Samir A. Nouh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Color Difference ◽  
Band Gap Energy ◽  
Polybutylene Terephthalate ◽  
Γ Irradiation ◽  
Gap Energy ◽  
Vis Spectroscopy ◽  
Oxygen Atoms

Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.

scholarly journals Application of low‐dose CT to the creation of 3D‐printed kidney and perinephric tissue models for laparoscopic nephrectomy

2021 ◽  
Vol 10 (9) ◽  
pp. 3077-3084
Author(s):  
Guan Li ◽  
Jie Dong ◽  
Zhiqiang Cao ◽  
Jinbao Wang ◽  
Dongbing Cao ◽  
...  
Keyword(s):  
Low Dose ◽  
Laparoscopic Nephrectomy ◽  
Low Dose Ct ◽  
3D Printed ◽  
The Creation ◽  
Tissue Models

scholarly journals Tunable Low Frequency Band Gap and Waveguide of Phononic Crystal Plates with Different Filling Ratio

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 828
Author(s):  
Shaobo Zhang ◽  
Jiang Liu ◽  
Hongbo Zhang ◽  
Shuliang Wang
Keyword(s):  
Band Gap ◽  
Composite Structure ◽  
Structural Parameters ◽  
Phononic Crystal ◽  
Low Frequency ◽  
Filling Ratio ◽  
Height Ratio ◽  
Road Vehicles ◽  
Aluminum Base ◽  
Gap Width

Aiming at solving the NVH problem in vehicles, a novel composite structure is proposed. The new structure uses a hollow-stub phononic-crystal with filled cylinders (HPFC) plate. Any unit in the plate consists of a lead head, a silicon rubber body, an aluminum base as outer column and an opposite arranged inner pole. The dispersion curves are investigated by numerical simulations and the influences of structural parameters are discussed, including traditional hollow radius, thickness, height ratio, and the new proposed filling ratio. Three new arrays are created and their spectrum maps are calculated. In the dispersion simulation results, new branches are observed. The new branches would move towards lower frequency zone and the band gap width enlarges as the filling ratio decreases. The transmission spectrum results show that the new design can realize three different multiplexing arrays for waveguides and also extend the locally resonant sonic band gap. In summary, the proposed HPFC structure could meet the requirement for noise guiding and filtering. Compared to a traditional phononic crystal plate, this new composite structure may be more suitable for noise reduction in rail or road vehicles.

Tuning Fermi Level and Band Gap in Li 4 Ti 5 O 12 by Doping and Vacancy for Ultrafast Li + Insertion/Extraction

2021 ◽  
Author(s):  
Zhenya Wang ◽  
Hao Guo ◽  
De Ning ◽  
Xiaobai Ma ◽  
Lirong Zheng ◽  
...  
Keyword(s):  
Fermi Level ◽  
Band Gap

Far Infrared Group Frequencies. V. Oximes and Aldoximes

1973 ◽  
Vol 27 (1) ◽  
pp. 22-26 ◽  
Author(s):  
S. M. Craven ◽  
F. F. Bentley ◽  
D. F. Pensenstadler
Keyword(s):  
Hydrogen Bond ◽  
Infrared Spectra ◽  
Low Frequency ◽  
Far Infrared ◽  
Torsional Vibrations ◽  
Lattice Vibrations ◽  
Dilute Solutions ◽  
Solid Samples ◽  
Bending Modes ◽  
Bond Stretch

The low frequency infrared spectra from 450 to 75 cm−1 of seven oximes and five aldoximes have been recorded for pure samples and for dilute solutions in cyclohexane. An intense characteristic band is present in the solution spectra at 367 ± 10 cm−1. This characteristic band shifts to 275 ± 10 cm−1 in the spectra of the OD compounds. The 367 ± 10 cm−1 and 275 ± 10 cm−1 bands are assigned to OH and OD torsional vibrations. A comparison of the solution spectra with spectra of the solid samples indicated that the OH … N hydrogen bond stretch of oximes and aldoximes occurs in 300 to 200 cm−1 region. Strong bands also are present in 140 to 100 cm−1 region which are due to OH … N bending modes or perhaps lattice vibrations.

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