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Effect of NiO NPs doping on the structure and optical properties of PVC polymer films
摘要： The goal of this study was to investigate the structure and optical properties of the prepared PVC/NiO nanocomposites. The samples were characterized via XRD, TEM, SEM, and UV–Vis spectrophotometer experimental measurements. The partial crystal structure of PVC/NiO nanocomposites and cubic structure of NiO nanoparticles were explored by X-ray diffraction. SEM exhibited the good distribution of the nanoparticles in PVC films. Linear optical parameters: refractive index and normalized absorption, increased whenever transmission and reflection reduced by adding NiO nanoparticles. Direct and indirect optical band gaps were obtained from Tauc’s formula, and it was found that both direct and indirect optical band gaps decrease as more NiO nanoparticles added. The direct optical band gap decreases from 5.20 to 5.15 eV. The optical conductivity increased by increasing the content of NiO nanoparticles. The dispersion parameters: oscillator energy E0, dispersion energy Ed, and static refractive index, were calculated by using Wemple and DiDominco model. The nonlinear optical susceptibility x(3) and nonlinear refractive index n2 were evaluated from the linear optical parameters using semiempirical relation. The increasing in nonlinear parameters x(3) and n2 suggest the use of PVC/NiO nanocomposites for nonlinear optical applications.
关键词： PVC nanocomposites,Nonlinear refractive index,Optical dispersion,XRD
更新于2025-09-23 15:21:21
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Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis
摘要： In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are con?rmed by X-ray di?raction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 °C exhibited a linear dose response in the range of 0.1–10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The e?ects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576–710 nm assigned to the 5D0→7FJ (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition 5D0→7F2 was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition 5D0→7F2 is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.
关键词： Thermoluminescence,Zinc borates,XRD,Cathodoluminescence,Rare earth
更新于2025-09-23 15:21:21
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Investigations on structural, optical and dielectric properties of Mn doped ZnO nanoparticles synthesized by co-precipitation method
摘要： Mn doped ZnO (ZnO:Mn) nanopowders with Mn:ZnO ratio from 0 to 3% were successfully synthesized by co-precipitation method. Their structural, optical, dielectric and conducting properties were investigated. All samples crystallize in the hexagonal wurtzite structure. The change in lattice parameters, bond length and preferential crystalline orientation for Mn doped ZnO samples indicates Mn2+ ions incorporation in ZnO lattice. Both micro-strain and dislocation density decrease due to doping whereas the average crystallite size increases suggesting the improvement of crystalline quality. The optical transmission in the visible region was improved as a result of doping. The observed decrease in ac conductivity (??????) with increasing Mn content is associated with the increase of defects amount. Cole-Cole plots of all samples were fitted to a circuit consisting in a parallel combination of a resistance and a constant phase element (CPE).
关键词： conductivity,optical properties,Mn doped ZnO,dielectric properties,XRD
更新于2025-09-23 15:21:21
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Multimodal Approach for Rationalization and Quantification of Structural Disorder in Transition Al 2 O 3
摘要： Transition aluminas form a basis of important catalytic and catalytic support materials due to their unique surface acidity, high temperature structural stability, and their viability for synthesis as high surface area materials. The origin of transition aluminas attractive properties has been extensively studied in the past 50+ years, but despite this effort, there are number of structural, electronic and surface properties that remain poorly understood. The poor understanding stems mostly from the inadequate crystallographic description of transition alumina polymorphs of γ-Al2O3, δ-Al2O3, θ-Al2O3 that evolve as a continuum of metastable structures. This work focuses on rationalization and quantification of structural disorder in Boehmite derived transition aluminas by using a suite of complementary imaging, spectroscopy and quantum calculation techniques. Based on aberration corrected STEM HAADF imaging, it will be shown that the individual polymorphs of δ?Al2O3 and θ-Al2O3 accommodate a significant degree of structural disorder, which leads to loss of crystallographic periodicity. The complexity of this disorder can be rationalized as an atomic scale intergrowth of closely related crystallographic variants. As a part of this work, we present a crystallographic approach based on real space interpretation of projected atomic potential that enabled us to unambiguously derive Al3+ coordination in δ-Al2O3 and θ-Al2O3 from a series of low-index STEM HAADF images. This work lead to a full crystallographic description of the crystallographic variants belonging to δ-Al2O3 and θ-Al2O3 family. To quantify the heterogeneous microstructure of transition aluminas on statistically relevant bases, we employed novel approaches for characterization of structural disorder using XRD and NMR techniques. XRD is one of the most employed methods for crystallographic bulk characterization, but historically it has not been successfully used on transition alumina. It will be shown that the crystallographic polymorphs and their structural disorder can be quantified with the use of recursive algorithms as implemented in DIFFAX and TOPAS XRD simulation packages. To further validate the quantification of structural disordered in transition Al2O3, we also employed complementary NMR spectroscopy, combined with DFT NMR simulation methods. As a part of this talk, we also discuss results from DFT energetic calculations explaining how energetic degeneracy between the number of crystallographic variants leads to structural disorder in transition aluminas.
关键词： DFT,transition aluminas,structural disorder,NMR,XRD,STEM HAADF imaging
更新于2025-09-23 15:21:21
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Role of ion energy flux on the structural and morphological properties of silicon oxy-nitride composite films deposited by plasma focus device
摘要： Crystalline silicon oxy-nitride (SiON) composite films are deposited on Si substrate for multiple (5, 15, 25 and 50) focus shots (FS) by plasma focus device. The X-rays diffraction patterns reveal the development of various diffraction peaks related to Si, Si3N4, and SiO2 phases which confirms the formation of SiON composite film. The intensity of Si3N4 (1 0 2) plane is linearly increased with the increase of FS. The Si3N4 (1 0 2) phase does not nucleate for 5 FS. Raman analysis confirms the formation of β–Si–N phase. Raman and Fourier transform infrared spectroscopy analysis reveals that the strength of chemical bonds like Si–N, Si–O formed during the deposition process of SiON composite films is associated with the bonds intensity which in turn depends on the number of FS. The field emission scanning electron microscopic analysis reveals that the surface morphology like size, shape and distribution of micro/nano-dimensional particles, film compactness and the formation of micro-rods, micro-teethes and micro-tubes of SiON composite films is entirely associated with the rise in substrate surface transient temperature which in turn depends on the increasing number of FS. The EDX spectrum confirms the presence of Si (22.5 ± 4.7 at. %), N (13.4 ± 4.5 at. %) and O (54.7 ± 11.3 at. %) in the SiON composite film. The thickness of SiON composite film deposited for 50 FS is found to ～ 15.47 μm.
关键词： composite,crystallite size,micro-tubes,Plasma focus,thickness,XRD
更新于2025-09-23 15:21:21
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Structural, thermal and optical characteristics of laser-exposed Pd/PVA nanocomposite
摘要： Nanocomposite of polyvinyl alcohol (PVA) and nanosize palladium (Pd) were fabricated by ex situ casting technique. The fabricated Pd/PVA nanocomposite film has been exposed to infrared pulsated laser with fluences in the range 2–20 J/cm2. The effect of the laser radiation on the structural, thermal and optical properties of Pd/PVA has been investigated using XRD, TGA and UV–Vis spectroscopy. Exposure of IR laser radiation raises the refractive index from 1.84 to 3.38 at 700 nm which confirms the predominance of crosslinking process in the Pd/PVA nanocomposite. Furthermore, the reduction in the optical energy gap from 1.87 to 1.72 eV could be attributed to the increase in the structural disorder resulting from the coordination reaction between OH of PVA and Pd nanoparticles. The attained results reveal that the IR laser radiation enhances the dispersion of Pd nanoparticles in the PVA matrix resulting in more compact structure of Pd/PVA nanocomposite. Consequently, the onset temperature of decomposition increased upon laser irradiation. Commission Internationale de E’Claire (CIE units x, y and z) methodology was employed to describe the color of the studied samples. The color difference between the exposed nanocomposite films and the non-exposed one was raised from 5.63 to 12.01 as the laser fluence increases up to 20 J/cm2. Thus, the present study suggests that the IR laser radiation affects the microstructure of the Pd/PVA nanocomposite which in turn assists in tailoring the thermal and optical properties of such nanocomposite for usage in optoelectronics applications.
关键词： Nanocomposite,XRD,UV spectroscopy,Thermal analysis,Color
更新于2025-09-23 15:21:01
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Percolation dependent conducting behavior of poly (3,4-ethylenedioxythiophene): Poly (styrenesulfonate) in the presence of cationic polyelectrolyte
摘要： Conductivity of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin films is highly modified in the presence of cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDADMAC). In-plane electrical conductivity of the thin films of PEDOT:PSS and PDADMAC complex (designated as PED*PDA) are measured for one to five layers, i.e., (PED*PDA)1 to (PED*PDA)5 films prepared by spin-coating method and compared with the pristine PEDOT:PSS films. In addition, PDADMAC and PEDOT:PSS is spin coated on each other to form a bilayer unit (designated as PDA/PED) and one to five layers of such PDA/PED unit, i.e., (PDA/PED)1 to (PDA/PED)5 films are formed by alternate deposition and the conductivity is compared with the complex films. In-plane conductivity of PED*PDA is drastically higher than the pristine PEDOT:PSS and is nearly independent of the layer number, i.e., thickness of the film. However, for PDA/PED films, behavior of conductivity is different in comparison with that of the complex films as the conductivity is found to increase for (PDA/PED)1 to (PDA/PED)2 and then decreases from (PDA/PED)3 to (PDA/PED)5 respectively. With the increase of the applying voltage, the linear nature of I-V curves remain unchanged. The structure, morphology and mechanism of conductivity enhancement are investigated through various characterization techniques. The strong electrostatic attachment between anionic PSS part of PEDOT:PSS and cationic PDADMAC is responsible for the drastic enhancement of conductivity as the percolation pathway enhances.
关键词： PEDOT:PSS,Thin films,Polyelectrolyte,FTIR,Electrical behavior,XRD
更新于2025-09-23 15:21:01
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Optical, Structural and Electrical Studies of Biopolymer Electrolytes Based on Methylcellulose Doped with Ca(NO <sub/>3</sub> ) <sub/>2</sub>
摘要： The intention of this research is to study effect of the different weight percent (wt%) of calcium nitrate, Ca(NO3)2 (CN) salt into biopolymer of Methylcellulose (MC). MC-CN solid biopolymer electrolyte was prepared by using casting technique. The concentrations of CN salt were prepared between 5 to 25 wt%. The optical and electrical characteristics of the samples were study by using Fourier Transform-Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD) and Electrical Impedance Spectroscopy (EIS). The highest conductivity of the samples was containing 25 wt% of CN is 2.21X10-7 Scm-1. The optical study by using FTIR shows that the CN salt act as the conducting ions devoid of effect the molecular structure of the polymer. Additionally, the data of XRD revealed that MC-CN an amorphous phase.
关键词： EIS,Methylcellulose,Biopolymer Electrolytes,FTIR,XRD,Calcium Nitrate
更新于2025-09-23 15:21:01
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High Responsivity Visible Blind Pd/Al2O3/MoS2/ITO MISM UV Photodetector
摘要： In the present paper, Pd/Al2O3/MoS2/ITO MISM UV photodetector structure is proposed and analyzed. For the proposed photodetector, responsivity is 488 A/W, detectivity is 8.22×1013Jones and external quantum efficiency (EQE) is 1.9×105%, at wavelength 308nm, 1V bias and light intensity 13.6μW/cm2. Thus, proposed MISM photodetector device gives significant performance improvement over other UV photodetectors.
关键词： Molybdenum di-sulphide (MoS2),Responsivity,Photodetector,X-ray diffraction (XRD)
更新于2025-09-23 15:21:01
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Effect of substrate temperature on the properties of RF sputtered CdS thin films for solar cell applications
摘要： We report the effect of substrate temperature (25–300 °C) on the structural, optical and electrical properties of Cadmium Sulphide (CdS) thin films deposited onto glass substrate by Radio Frequency (RF) magnetron sputtering. The structural, morphological, optical and electrical properties of the films were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FE-SEM), UV–VIS-NIR spectroscopy and Hall Effect measurement respectively. The XRD studies showed that the films were polycrystalline with hexagonal wurtzite structure preferentially oriented along the (0 0 2) plane parallel to the substrate surface. The XRD data analysis further revealed the crystallite size of the nanocrystalline films i.e. 22–24 nm exhibiting the fact that crystallite size increased with increasing the substrate temperature. The FE-SEM images along with energy dispersive spectroscopy (EDS) studies confirmed the homogeneous, compact and pin-hole free surface morphology. The UV–VIS-NIR studies unveiled the optical transmittance in the range of 75–90% after 540 nm of the wavelength of light. The optical band gaps were found to be decreasing from 2.34 eV to 2.26 eV with increasing the substrate temperature. The films were characterized as n-type as evidenced by the Hall Effect measurement. The carrier mobility was found to be increasing gradually from 5.53 to 12.57 cm2/V·s by increasing the substrate temperature from room temperature to 300 °C due to the improvement of crystalline quality and grain size of the films. The results showed good optical and electrical properties of the films deposited at 300 °C which are suitable to use as window layer in thin film based solar cells.
关键词： CdS,UV–VIS-NIR,XRD,Hall effect measurement,Thin films,Substrate temperature,RF sputtering
更新于2025-09-23 15:21:01