Effects Of 60Co Γ-ray Irradiation Research Articles

Study on the preservation effect of 60Co-γ ray irradiation on potatoes

To evaluate the effect of irradiation on the preservation of potatoes, fresh potatoes were selected as the irradiation objects, and irradiated with 60Co-γ radiation source for 0, 100, 200, 500 and 1000 Gy, respectively. During the irradiation, the well-packaged Y1.79Bi0.01Eu0.2MgTiO6 novel thermoluminescence dosimeter material was placed together with the potatoes at the same position. Then, the potatoes were stored in the same temperature and humidity environment, and the quality changes of the potatoes were observed. The Y1.79Bi0.01Eu0.2MgTiO6 material had good performance indicators, and was used to measure the irradiation dose of the potatoes. The experiment showed that irradiation could appropriately extend the storage time of potatoes, and gamma irradiation of about 1000 Gy could achieve the best preservation effect. The main pathogenic fungi that cause dry rot of potatoes were Fusarium solani and Fusarium oxysporum, and the appropriate dose of 60Co-γ irradiation could effectively inhibit the spread and growth of these fungi.

Investigation of high resistivity [formula omitted]-type FZ silicon diodes after 60Co [formula omitted]-irradiation

In this work, the effects of 60Co γ-ray irradiation on high resistivity p-type diodes have been investigated. The diodes were exposed to dose values of 0.1, 0.2, 1, and 2MGy. Both macroscopic (I–V, C–V) and microscopic investigations, by means of Thermally Stimulated Current (TSC) and Deep Level Transient Spectroscopy (DLTS) techniques, were conducted to characterize the radiation-induced changes. The investigated diodes were manufactured on high resistivity p-type Float Zone (FZ) silicon and were further classified into two types based on the isolation technique between the pad and guard ring: p-stop and p-spray. After irradiation, the macroscopic results of current–voltage and capacitance–voltage measurements were obtained and compared with existing literature data. Additionally, the microscopic measurements focused on the development of the concentration of different radiation-induced defects, including the Boron interstitial-Oxygen interstitial (BiOi) complex, the Carbon interstitial-Oxygen interstitial (CiOi) defect, the H40K, and the so-called IP∗.To investigate the thermal stability of induced defects in the bulk, isochronal annealing studies were performed in the temperature range of 100°C to 300°C. These annealing processes were carried out on diodes irradiated with doses of 1 and 2MGy. Furthermore, in order to investigate the unexpected results observed in the C–V measurements after irradiation with high dose values, the surface conductance between the pad and guard ring was measured as a function of both dose and annealing temperature.

Influences of gamma-ray irradiation on PVDF membrane behavior: An experimental study based on simulation and numerical analysis

This study aims to explore the effects of gamma rays on various properties of poly(1,1-difluoroethylene) (PVDF) membranes under different irradiation conditions. The effects of 60Co γ-ray irradiation on the hydrophilicity, permeability, and mechanical performances of the PVDF membranes were discussed. Results showed that the size of the radiation dose rate had almost no effect on the performance of the membranes, as determined by the total radiation dose. The fracture and collapse of the PVDF structure under anaerobic conditions were obviously lower than those under aerobic conditions. Advanced characterization methods confirmed that the initial impact of gamma rays on the PVDF membranes occurred between 50 and 200 kGy. When the total dose exceeded 200 kGy, structural collapse and chain scission caused by the oxidative degradation mechanism became widespread, thereby leading to the relaxation of the PVDF network and the decline in properties. This study provides valuable information for the application of PVDF membranes to radioactive wastewater and clarifies the mechanism of membrane irradiation degradation to help prolong the service life of membranes. In addition, low total irradiation dose can embellish polymers and thus provide a feasible method for modifying and grafting polymer membranes in the future.

Effect of 60Coγ ray irradiation on adhesion of LIE coatings

ABSTRACTA new gamma-ray irradiation method was used to modify the inorganic silicate binder for improving the adhesion of low infrared emissivity (LIE) coatings. First, the spectral characteristic of the solidified irradiated inorganic silicate was characterised by FTIR and the cross-section morphology of the coatings was observed by SEM. Then, the adhesion of LIE coatings containing irradiated inorganic silicate was systematically investigated by the scratch test. In addition, the adhesion of coatings in high-temperature conditions was also studied. The results indicated that the LIE coatings could exhibit better adhesion after irradiated due to the Si–O–Fe chemical bonding. At last, the infrared emissivity of the LIE coatings at different temperature was measured by IR-2. The irradiated coatings still kept LIE and the lowest infrared emissivity (500°C) was 0.41.

Effect of 60Co γ-ray irradiation on electrical properties of Ti/Au/GaAs1−xNx Schottky diodes

Current-voltage (I-V), capacitance-voltage-frequency (C-V-f) and conductance-voltage-frequency (G/ω-V-f) measurements at room temperature are used to study 50 kGy 60Co γ-ray electrical properties irradiation dependence of Ti/Au/GaAs1−xNx Schottky diodes with 0.2%; 0.4%; 0.8% and 1.2% nitrogen dilution. This γ-ray irradiation induces a permanent damage that has increased ideality factor and series resistance for all samples. It was accompanied by a decrease in Schottky barrier height with nitrogen content up to 0.4%N and remained constant thereafter. Radiation was also found to degrade the reverse leakage current.At high frequency (1 MHz), capacitance and conductance decreased after radiation due to a decrease in net doping concentration. Interface state density and series resistance were determined from C-V-f and G/ω-V-f characteristics using Hill-Coleman methods. Interface states density exponentially decreased with increasing frequency confirming the behavior of interface traps response to ac signal.Series resistance increases after irradiation is attributed to carrier's removal effect and mobility degradation. It has two peaks in the accumulation and inversion region for some diodes (0.4%N, 0.8%N). γ-ray irradiation produced traps levels and recombination centers that reduce relaxation time. An increase in %N content can impede irradiation damage with even some compensation when the percent of diluted nitrogen is high (1.2%N).

Effects of 60Co γ-ray irradiation on microstructure and ferroelectric properties of Bi3.25La0.75Ti3O12 thin films

Bi3.25La0.75Ti3O12 (BLT) thin films were deposited on Pt/Ti/SiO2/Si substrates through sol–gel method. Films underwent 60Co γ-ray irradiation with different doses; 0, 50, 100 and 150kGy, respectively. Impacts of γ-ray on the microstructure, ferroelectric properties, leakage current density and fatigue characteristic were studied in detail. The results of SEM images show that grain patterns become irregular. Remnant polarization (2Pr) and coercive field (2Ec) decrease with irradiation dose increase. C–V curves reveal obvious asymmetry along y-axis. The irradiated thin films display lower leakage current density and fatigue endurance up to more than 1010 switching cycles. These results suggest that radiation can improve the film performance in some areas.

Utilizing a shallow trench isolation parasitic transistor to characterize the total ionizing dose effect of partially-depleted silicon-on-insulator input/output n-MOSFETs

We investigate the effects of 60Co γ-ray irradiation on the 130 nm partially-depleted silicon-on-isolator (PDSOI) input/output (I/O) n-MOSFETs. A shallow trench isolation (STI) parasitic transistor is responsible for the observed hump in the back-gate transfer characteristic curve. The STI parasitic transistor, in which the trench oxide acts as the gate oxide, is sensitive to the radiation, and it introduces a new way to characterize the total ionizing dose (TID) responses in the STI oxide. A radiation enhanced drain induced barrier lower (DIBL) effect is observed in the STI parasitic transistor. It is manifested as the drain bias dependence of the radiation-induced off-state leakage and the increase of the DIBL parameter in the STI parasitic transistor after irradiation. Increasing the doping concentration in the whole body region or just near the STI sidewall can increase the threshold voltage of the STI parasitic transistor, and further reduce the radiation-induced off-state leakage. Moreover, we find that the radiation-induced trapped charge in the buried oxide leads to an obvious front-gate threshold voltage shift through the coupling effect. The high doping concentration in the body can effectively suppress the radiation-induced coupling effect.

The effects of 60Co γ-ray irradiation on the DC characteristics of enhancement-mode AlGaN/GaN high-electron-mobility transistors

The effects of 60Co γ-ray irradiation on the DC characteristics of AlGaN/GaN enhancement-mode high-electron-mobility transistors (E-mode HEMTs) are investigated. The results show that having been irradiated by 60Co γ-rays at a dose of 3 Mrad (Si), the E-mode HEMT reduces its saturation drain current and maximal transconductance by 6% and 5%, respectively, and significantly increases both forward and reverse gate currents, while its threshold voltage is affected only slightly. The obvious performance degradation of E-mode AlGaN/GaN HEMTs is consistent with the creation of electronegative surface state charges in the source-gate spacer and gate-drain spacer after being irradiated.

Effect of 60Co γ-ray irradiation on electrical properties of GaAs epilayer and GaAs p–i–n diode

GaAs epilayers and p–i–n diodes structures grown using metal–organic vapor phase epitaxy were irradiated at room temperatures by 60Co γ-ray radiation with varying the dose up to 50 kGy. The carrier concentration and mobility on GaAs epilayer decreases while leakage current of p–i–n diode increases at higher radiation dose (10–50 kGy). However at lower dose (<6 kGy) carrier mobility remain same but leakage current still shows significant increase. Furthermore carrier mobility of irradiated GaAs epilayers recovers partially (68%) after annealing at 300 °C while leakage current of p–i–n diode does not show any noticeable recovery. These effects are mainly due to the creation of more deep levels compared to shallow levels as determined from photoluminescence, Hall, current–voltage and electrochemical capacitance voltage analysis.

The effect of 60Co γ-ray irradiation on the 1/f noise of Schottky barrier diodes

Based on the analysis of the mechanism of irradiation damage and total dose effect on Schottky barrier diodes (SBD), using the model of the carrier mobility fluctuation and carrier number fluctuation of 1/f noise, the effect of irradiation damage on 1/f noise of SBD was studied in this paper. The research shows that, the irradiation induced interface states change the distributing of interface state density, and, moreover, modulate the Schottky barrier height and increase the velocity of recombination in the surface, leading to the degradation of device performance as well as the significant increasing of 1/f noise level. So, 1/f noise is closely related to SBD's degradation, namely, the larger the magnitude of 1/f noise and the deviation from standard value, the worse the reliability of device, and it's also an indicator of bad radiation-proof performance, which causes its high failure rate in radiation environment. Thus the 1/f noise acts as a researching tool on the mechanism of irradiation damage of SBD, also provides the theoretical basis for nondestructive irradiation hardness assessment.

Effects of 60Co γ-ray irradiation on the electrical characteristics of Au/n-GaAs (MS) structures

In order to interpret the effect of 60Co γ-ray radiation dose on the electrical characteristics of metal–semiconductor (Au/n-GaAs) Schottky barrier diodes (SBDs), these devices were stressed with a zero bias during 60Co γ-ray source irradiation with the dose rate 2.12 kGy h −1 and the total dose range was 0–500 kGy at room temperature. Experimental results show that γ-irradiation induces an increase in the barrier height Φ b( C–V) obtained from reverse-bias C–V measurements, whereas barrier height Φ b( I–V) obtained from forward-bias I–V measurements remained essentially constant. This negligible change of Φ b( I–V) is attributed to the low barrier height in regions associated with the surface termination of dislocations. The experimental I–V and C–V characteristics prove that there is a reaction for extra recombination centers in case of SBDs exposed to γ-ray radiation. Also, the ideality factor n and donor concentration decrease with increasing dose rate. Both I–V and C–V characteristics of the Schottky diode indicate that the total dose radiation hardness of GaAs devices may be limited by the susceptibility of the Au–GaAs interface to radiation-induced damage. The density of interface states N SS distribution profiles as a function E CC– E SS for each dose rate was extracted from the forward-bias I–V characteristics taking into account the bias dependence of the effective barrier height Φ e at room temperature. N SS decreases with increasing dose rate and above 250 kGy it remains constant. Such a behavior of N SS is attributed to the existence of the native insulator layer between the metal and semiconductor that passivates the surface of semiconductor, and thus the increase of the N SS.

ChemInform Abstract: STUDIES OF THE HYDROUS TITANIUM OXIDE ION EXCHANGER. IV. THE EFFECT OF RADIATION AND HEAT TREATMENT

Abstract60Co‐γ‐Bestrahlung (5.2·108 R) hat keinerlei Einfluß auf die Ionenaustauschkapazität der Na+‐Form des hydratisierten TiO2‐ ‐Austauschers, während die der H+‐Form leicht abnimmt.

Studies of the Hydrous Titanium Oxide Ion Exchanger. IV. The Effect of Radiation and Heat Treatment

Abstract The effects of 60Co γ-ray irradiation and of heat treatment in air have been studied on the properties of the hydrous titanium oxide ion exchanger. The ion-exchange capacity of the sodium form did not change at all, while that of the hydrogen form decreased a little, by the exposure of 5.2×108 R. The color of the exchanger, initially white, turned yellow upon irradiation. This exchanger was stable against heat treatment up to around 80 °C; thereafter the exchange capacity gradually decreased with the temperature until 324 °C, where it was abruptly reduced to about a quarter of the initial value. The examination of the titration curves showed that the most acidic exchange site was weaker than less acidic sites against heat treatment. The structural formula of this hydrous titanium oxide ion exchanger has been suggested on the basis of the ion-exchange capacity, the thermal decomposition curves, and such auxiliary data as the X-ray diffraction and the infrared spectra.

Diffusional Properties of the Stage-III Defect in Copper. I. Experimental Results

Measurements of the effects of 60Co γ-ray irradiation have been made upon the dislocation internal friction and modulus defect in copper single crystals from 333° to 393°K. It is found that the number of pinning points which are nucleated on the in-grown dislocations by the lattice defects produced by the irradiation depends upon the γ-ray flux, or more directly, upon the concentration of defects in the dislocation core. At the smallest flux level available (1.3×109 photons/cm2/sec), it is found that the dislocation-defect trapping curves are essentially linear, and that the slopes of the linear curves vary exponentially with temperature. These results form the basis of the analyses given in Parts II and III of this series.