Evaluation of dosimetric characteristics of graphene oxide/PVC nanocomposite for gamma radiation applications

Hole-Transport Material Engineering in Highly Durable Carbon-Based Perovskite Photovoltaic Devices

Despite the fast-developing momentum of perovskite solar cells (PSCs) toward flexible roll-to-roll solar energy harvesting panels, their long-term stability remains to be the challenging obstacle in terms of moisture, light sensitivity, and thermal stress. Compositional engineering including less usage of volatile methylammonium bromide (MABr) and incorporating more formamidinium iodide (FAI) promises more phase stability. In this work, an embedded carbon cloth in carbon paste is utilized as the back contact in PSCs (having optimized perovskite composition), resulting in a high power conversion efficiency (PCE) of 15.4%, and the as-fabricated devices retain 60% of the initial PCE after more than 180 h (at the experiment temperature of 85 °C and under 40% relative humidity). These results are from devices without any encapsulation or light soaking pre-treatments, whereas Au-based PSCs retain 45% of the initial PCE at the same conditions with rapid degradation. In addition, the long-term device stability results reveal that poly[bis(4-phenyl) (2,4,6-trimethylphenyl) amine] (PTAA) is a more stable polymeric hole-transport material (HTM) at the 85 °C thermal stress than the copper thiocyanate (CuSCN) inorganic HTM for carbon-based devices. These results pave the way toward modifying additive-free and polymeric HTM for scalable carbon-based PSCs.

Evaluation of dosimetric characteristics of a ternary nanocomposite based on High Density Polyethylene/Bismuth Oxide/Graphene Oxide for gamma-rays

This research aims to investigate a ternary nanocomposite based on High Density Polyethylene/ Bismuth Oxide/Graphene Oxide (HDPE/Bi2O3/GO) at various concentrations. Solution method was used to fabricate the samples. FESEM-EDX mapping, AFM, TEM, XRD, XPS, FTIR, and TGA/DTG analyses were carried out on the samples. XRD analysis demonstrated a semi-crystalline behavior for the samples. TEM analysis exhibited a cauliflower-like structure of the material. The sample was irradiated by gamma-rays of 60Co source over the dose rate of 30–254 mGy/min and the electric current was measured as the response of the real-time dosimeter. Thus, various dosimetric characteristics were performed, namely linearity, angular dependence, energy dependence, bias-polarity, field size, and repeatability of the data. Results showed that response of the dosimeter was linear in the range of the investigated dose rate. The sensitivity of the 60 wt% Bi2O3 sample was measured as 3.4 nC·mGy−1. The angular response variation was 20% for normal beam incidence. The response of the dosimeter to assess the energy dependency was obtained as 2.2% at the radiation field of the 137Cs and 60Co beams. The dosimeter response was dependent on the bias-polarity, with maximum discrepancy of 11.1%. The dosimetry response was highly dependent upon the radiation field size. The repeatability of the dosimeter response was measured with standard deviation less than 1%. As well, the dosimeter response during the one-hour irradiation was stable with a standard deviation of 0.66%. Results showed that considering some correction factors, this material can be used for dosimetry of gamma-rays at the therapy level.

Evaluation of dosimetric characteristics of a ternary nanocomposite based on High Density Polyethylene/Bismuth Oxide/Graphene Oxide for gamma-rays

This research aims to investigate a ternary nanocomposite based on High Density Polyethylene/ Bismuth Oxide/Graphene Oxide (HDPE/Bi₂O₃/GO) at various concentrations. Solution method was used to fabricate the samples. FESEM-EDX mapping, AFM, TEM, XRD, XPS, FTIR, and TGA/DTG analyses were carried out on the samples. XRD analysis demonstrated a semi-crystalline behavior for the samples. TEM analysis exhibited a cauliflower-like structure of the material. The sample was irradiated by gamma-rays of ⁶⁰Co source over the dose rate of 30-254 mGy/min and the electric current was measured as the response of the real-time dosimeter. Thus, various dosimetric characteristics were performed, namely linearity, angular dependence, energy dependence, bias-polarity, field size, and repeatability of the data. Results showed that response of the dosimeter was linear in the range of the investigated dose rate. The sensitivity of the 60 wt% Bi₂O₃ sample was measured as 3.4 nC·mGy^-1. The angular response variation was 20% for normal beam incidence. The response of the dosimeter to assess the energy dependency was obtained as 2.2% at the radiation field of the ¹³⁷Cs and ⁶⁰Co beams. The dosimeter response was dependent on the bias-polarity, with maximum discrepancy of 11.1%. The dosimetry response was highly dependent upon the radiation field size. The repeatability of the dosimeter response was measured with standard deviation less than 1%. As well, the dosimeter response during the one-hour irradiation was stable with a standard deviation of 0.66%. Results showed that considering some correction factors, this material can be used for dosimetry of gamma-rays at the therapy level.

Introducing a novel beta-ray sensor based on polycarbonate/bismuth oxide nanocomposite

In this research, for the first time, the polycarbonate/bismuth oxide (PC-Bi₂O₃) composite was studied as a beta-ray sensor using a pure beta-emitter ⁹⁰Sr source. Firstly, the range and stopping power of the electrons in the composite at various loadings of 0, 10, 20, 30, 40, and 50 wt% were calculated using the ESTAR program. Results of simulation demonstrated that the concentration of the heavy metal oxide particles into the polymer matrix played an important role in evaluating the range and stopping power of the electrons in the composite. Secondly, at the experimental phase, the pure Polycarbonate and 50 wt% PC-Bi₂O₃ nanocomposite with dimensions of 4 × 4 × 0.1 cm³ were prepared and irradiated by ⁹⁰Sr. Also, current-voltage (I-V) plot exhibited linear response ranging from 100 to 1000 V at the fixed source-to-surface distance (SSD). Then the amount of electric current as the sensor response was measured in various dose rates at the fixed voltage of 400 V for the pure Polycarbonate and 50 wt% PC-Bi₂O₃ nanocomposite using an electrometer, in which results showed that the sensitivities were found as 20.3, and 33.3 nC mSv^-1 cm^-3, respectively. This study showed that this composite could serve as a novel beta-ray sensor.

Introducing a novel beta-ray sensor based on polycarbonate/bismuth oxide nanocomposite

In this research, for the first time, the polycarbonate/bismuth oxide (PC–Bi2O3) composite was studied as a beta-ray sensor using a pure beta-emitter 90Sr source. Firstly, the range and stopping power of the electrons in the composite at various loadings of 0, 10, 20, 30, 40, and 50 wt% were calculated using the ESTAR program. Results of simulation demonstrated that the concentration of the heavy metal oxide particles into the polymer matrix played an important role in evaluating the range and stopping power of the electrons in the composite. Secondly, at the experimental phase, the pure Polycarbonate and 50 wt% PC–Bi2O3 nanocomposite with dimensions of 4 × 4 × 0.1 cm3 were prepared and irradiated by 90Sr. Also, current–voltage (I–V) plot exhibited linear response ranging from 100 to 1000 V at the fixed source‐to‐surface distance (SSD). Then the amount of electric current as the sensor response was measured in various dose rates at the fixed voltage of 400 V for the pure Polycarbonate and 50 wt% PC–Bi2O3 nanocomposite using an electrometer, in which results showed that the sensitivities were found as 20.3, and 33.3 nC mSv−1 cm−3, respectively. This study showed that this composite could serve as a novel beta-ray sensor.

Beryllium oxide nanoparticles: synthesis, characterization, and thermoluminescence evaluation for gamma radiation detection

In this study, beryllium oxide nanoparticles (BeO NPs) were synthesized by polymer-gel method with schlenk line. The products were then assessed using FESEM, TGA/DSC, XRD and BET analyses. The quality of two nanooxides, that were calcined at 700 and 800 °C, was studied and compared with bulk BeO particles. The results showed that nanoparticles calcined at 800 °C were more uniform and had ellipsoidal morphology with a particle size of ∼35 nm. Investigation thermoluminescence (TL) characteristics of BeO NPs showed that with the decreasing exposed dose/increasing the BeO particle size, TL peaks were observed at higher temperatures. The intensities of glow curves increase linearly with the increasing absorbed dose in the range of 0.001 mGy–1000 Gy. Various other studies including response fading, minimum temperature and minimum time for annealing, and response changes in repeatability cycles of dosimeter also approved the ability of the prepared BeO NPs for use in gamma radiation dosimetry.

Cadmium telluride quantum dots/graphene oxide/poly vinyl acetate (CdTe QDs/GO/PVAc) nanocomposite: a novel sensor for real time gamma radiation detection

The design of organic/inorganic nanoparticles hybrids provides the great potential for the fabrication of γ-ray sensor systems. Herein, structural and dosimetric properties of the gamma irradiated poly vinyl acetate (PVAc) doped with cadmium telluride quantum dots (CdTe QDs) and graphene oxide (GO) nanoflakes have been investigated. Thioglycolic acid (TGA) capped water-soluble CdTe QDs and (GO) nanoflakes are synthesized and characterized. Then, CdTe QDs/GO/PVAc sensors were formed by post-depositing CdTe and GO over polymer matrix. The photophysical interactions between nanoparticles and organic polymer have been investigated using ohmic contact detectors with two gold coated electrodes. Real time dose rate information of the sensors such as sensitivity, repeatability, and the linearity of dose rate response were assessed. A wider photoelectric response range and wider gamma harvesting range were observed in the resultant hybrid gamma sensor at a standard bias voltage with respect to non-hybrid CdTe QDs/PVAc sensors.

Evaluation of gamma radiation response of electrolyte, MKP and MKT capacitors in various frequencies

In this experimental work, the effect of gamma irradiation on the capacitance and impedance of some commercial capacitors namely electrolytic, MKP, and MKT capacitors in different radiation doses up to 120 kGy and a wide range of frequencies between 42 Hz and 5 MHz were studied. Results showed that the capacitances of the electrolytic capacitors exhibited a linear decrease by increasing the radiation dose and frequencies, which can be used for high dosimetry purposes, but non-ceramic capacitors as MKP and MKT showed much higher radiation resistance, particularly for the frequencies less than ~1 MHz.