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An investigation of 60Co gamma radiation-induced effects on the properties of nanostructured α-MoO3 for the application in optoelectronic and photonic devices
摘要： Gamma ray has sufficient energy to ionize and displace of atoms when interacts with optoelectronic and photonic devices that are placed at γ-radiation exposure environment, can be exposed to gamma radiation, resulting the alteration of the physical properties and hence the performances of devices. A comprehensive investigation of physical properties of the semiconductor materials under the influence of gamma radiation is essential for the effective design of devices for the application in the radiation exposure environment. In this article, a potential candidate for optoelectronic and photonic devices, orthorhombic MoO3 nanoparticles with average crystallite size of 135.31 nm successfully synthesized by hydrothermal method. Then, the properties of nanoparticles exposed to low (10 kGy) and high (120 kGy) absorbed dose of γ-rays from 60Co source were characterized by XRD, FESEM, FTIR and UV–Vis–NIR spectrophotometer and effects of absorbed doses was investigated for the first time. A significant change is observed in different physical properties of α-MoO3 nanoparticles after gamma exposure. The XRD patterns reveal the average crystallite size, intensity and the degree of crystallinity decrease for low dose (10 kGy) and increases for high dose (120 kGy). The calculated average crystallite size exposed to low and high doses are 127.79 nm and 136 nm, respectively. The lattice strain and dislocation density, however, shows the opposite trend of crystallite size with absorbed doses. This result is good evidence for the deterioration of crystallinity for low dose and improvement for high dose. The FESEM results reveal the significant effects of gamma doses on the micrographs of layered structure and on grain size. The optical studies disclose that band gap increases gradually from 2.78 to 2.90 eV, this behavior is associated with the reduction of electronic localized states. These results suggest that α-MoO3 nanoparticles could tolerate high doses of gamma radiation, making it a promising candidate for optoelectronic and photonic devices for γ-ray exposure environment applications.
关键词： Optoelectronic and photonic devices,α-MoO3 nanoparticles,Co-60 gamma radiation,Optical bandgap,Structural properties
更新于2025-10-22 19:40:53
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Changes of optical transition models caused by crystal structural changes in CaSe2O5
摘要： The present work concerns calcium pyroselenites CaSe2O5 with two independent crystal structures, their di?erence physical properties and phase transformations. α-CaSe2O5 in orthorhombic form shows 2D calcium oxide anionic layers whereas new compound β-CaSe2O5 crystallizes in monoclinic space group C2/c. It's a new structure type with 1D calcium oxide thick chains which are further connected by Se2O5 dimers. Rietveld re?nement indicates that the weight fraction for α/β-CaSe2O5 mixture phase was found to be 84.5% and 15.5% for α- and β-CaSe2O5, respectively. Optical di?use re?ectance spectrum coupled with Kubelka–Munk ?t gives a result that α-CaSe2O5 adopts direct optical transition model while β-CaSe2O5 is an indirect semiconductor. The experimental result matches well with the prediction of theory calculation. The optical bandgap values were ?tted to be 4.74 and 4.12 eV for α- and β-CaSe2O5, respectively. Thermal analysis coupled with variable temperature powder XRD indicates the phase transformation between these two phases.
关键词： Selenite,Optical bandgap,Rietveld re?nement,Phase transformation
更新于2025-09-23 15:23:52
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Hydrothermal synthesis and photocatalytic properties of CuGaO2/ZnO hexagonal platelet hybrids
摘要： Delafossite CuGaO2 as a p-type semiconductor is classified as a wide band-gap semiconductor owing to direct transitions on the high energy side. Solid state reaction and sol-gel synthesis are applicable as traditional methods for synthesizing delafossite CuGaO2. However, both synthesis methods require high temperatures, and the sol-gel method additionally requires a nitrogen gas atmosphere. In this study, hexagonal-platelet CuGaO2 is synthesized using a hydrothermal method, which can also be adapted to the synthesis of the CuGaO2/ZnO hybrids. As a result, it was found that the surface of platelet CuGaO2 particles could be used to create hybrids with n-type ZnO semiconductors. This paper also presents the optical band-gap energy and photocatalytic properties of hexagonal-platelet CuGaO2 and CuGaO2/ZnO hybrids.
关键词： photocatalytic properties,p-type semiconductor,Hydrothermal synthesis,optical bandgap,hexagonal platelet hybrid
更新于2025-09-23 15:22:29
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[IEEE 2019 4th International Conference on Electrical Information and Communication Technology (EICT) - Khulna, Bangladesh (2019.12.20-2019.12.22)] 2019 4th International Conference on Electrical Information and Communication Technology (EICT) - Effect of growth temperature on the structural and optical properties of CdS:O thin films for CdTe solar cells
摘要： Oxygenated Cadmium Sulfide (CdS:O) is used as a window layer for high-performance CdTe thin-film solar cells. In this work, the effect of growth temperature on the physical properties of (CdS:O) layer is reported. The CdS:O layer was synthesized on commercially available soda-lime glass (SLG) by using a reactive radio frequency (RF) sputtering in 1.5% oxygen (O2)/argon (Ar) ambient as a function of substrate temperature (25 °C to 300 °C). The structural and optical properties of the as-grown CdS:O thin films were carried out by X-ray diffraction and UV-VIS-Spectroscopy respectively. The XRD patterns revealed intriguing structural natures of the deposited films such as amorphous/semi-amorphous nature in the substrate temperature range 25 – 150 °C, then polycrystalline nature in the range 200 – 250 °C and again amorphous nature at 300 °C. The transmission spectra exhibited higher optical transmission in the visible wavelength which signifies the enhancement of photo generated current of CdTe solar cells. The bandgap of room temperature (RT) deposited CdS:O thin film for 1.5% O2/Ar was found to be increased 12.50% in comparison with CdS film deposited in pure Ar ambient. Besides, the bandgap of CdS:O films for 1.5% O2/Ar was decreased with the increase of the substrate temperature. Thus, it has been concluded that the CdS:O thin film deposited at RT found to be better for CdTe solar cell application.
关键词： optical bandgap,substrate temperature,CdTe,rf-sputtering,O2/Ar ratio,Crystallite size,CdS:O
更新于2025-09-23 15:21:01
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Tuning the Optical Band Gap of Pure TiO2 via Photon Induced Method
摘要： Titanium dioxide, a well known photocatalyst will become more useful if it utilizes visible light. Many efforts have been made to achieve the utilization of visible light by TiO2 for photocatalytic activity by changing the preparation methods or by doping various transition metals. Herein, a novel Photon Induced Method (PIM) is being proposed to produce oxygen-rich TiO2 with modified optical band gap and high stability. The prepared TiO2 nanoparticles have been subjected to various characterizations such as XRD, HRSEM, HRTEM, FTIR, UV-Vis and PL. XRD results reveal that as the calcination temperature is increased, the crystallite size of the TiO2 nanoparticles is seen to increase. Also, the XRD results reveal an increase in pure anatase phase stability upto 750°C when compared to earlier reports of pure anatase phase stability upto 650°C. HRTEM analysis shows the formation of nanosized bullet like structure. A narrowing of optical band gap to 3.09 eV is evident through UV-Vis absorption studies. This tuning of band gap is expected to facilitate the absorption of visible light. The photocatalytic activity of the prepared TiO2 nanoparticles has also been studied. The results reveal that TiO2 nanoparticles prepared by this novel method exhibit an increased photocatalytic activity when compared to the standard Degussa P25 sample reported earlier.
关键词： Pure TiO2 nanoparticles,Optical bandgap,Photocatalytic activity,Visible light
更新于2025-09-23 15:21:01
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Investigation of Statistical Broadening in InGaN Alloys
摘要： Optical and structural properties of thick InGaN layers grown by MOCVD and MBE were studied by photoluminescence, optical transmission and Raman spectroscopies and X-ray diffraction analysis. Optical bandgap, Urbach energy, and full widths at half maximum (FWHM) of photoluminescence and Raman spectra depending on the InGaN alloy composition were determined experimentally. Minimal theoretical linewidth of photoluminescence spectra resulted from random distribution of In and Ga atoms in cation sublattice was calculated.
关键词： optical bandgap,photoluminescence,Urbach energy,X-ray diffraction,InGaN,Raman spectroscopy
更新于2025-09-23 15:19:57
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Study of the optical properties of amorphous As–Se–S thin films
摘要： This study investigates the effects of substitution of selenium by sulfur on the optical constants of amorphous (a-)As20Se80 ? xSx films (x = 0, 4, 8, 12, 16, and 20 at%), where the coordination number for both Se and S is the same. The absorption coefficient, α, and the index of refraction, n, were derived using the transmission spectra in a wide range of wavelengths from 400 to 2500 nm. This revealed that the index of refraction for the a-As20Se80 ? xSx system decreases with increase in sulfur content throughout the range under study. The effective coordination number of As has been determined based on the refractive index dispersion analysis. A decreasing in Nc from 4.022 to 3.752 with increase content of sulfur from 0 to 20 at% has been recorded. In addition, the optical bandgap, Eg, of the a-As20Se80 ? xSx thin films increases with increase in S content which can be explicated in terms of the chemical bond approach.
关键词： optical bandgap,refractive index,amorphous As–Se–S thin films,chalcogenide glasses,optical properties
更新于2025-09-10 09:29:36