scholarly journals Ultra-bright emission from Sr doped TiO 2 nanoparticles through r-GO conjugation

2019 ◽  
Vol 6 (3) ◽  
pp. 190100 ◽  
Author(s):  
Sanhita Mandal ◽  
Neha Jain ◽  
Mukesh Kumar Pandey ◽  
S. S. Sreejakumari ◽  
Prashant Shukla ◽  
...  
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Synthesis Method ◽  
Visible Absorption ◽  
Bacterial Surface ◽  
Wet Chemical Synthesis ◽  
Reduced Graphene ◽  
Microscopic Studies ◽  
Photocatalytic Reactions ◽  
Bright Emission

Graphene and semiconductor nanocomposite garnered much interest in nanoscience and nanotechnology. In this research, TiO 2 , TiO 2 : Sr and TiO 2 : Sr/r-GO (reduced graphene oxide) nanocomposites have been successfully synthesized via a wet chemical synthesis method. The microscopic studies confirmed the formation of graphene sheets which looked like a paper which could easily wrap over the bacterial surface killing them. The optical band gap of these nanocomposites is determined by UV–visible absorption spectra which inferred that optical band gap decreases with Sr 2+ incorporation and r-GO attachment. Furthermore, photoluminescence (PL) study revealed that the intensity of emission is prominent for TiO 2 : Sr/r-GO. The enhancement in PL intensity with r-GO is due to creation of more oxygen vacancies and defects which generally capture the photoinduced carriers inhibiting recombination rate of free carriers promoting the photocatalytic reactions.

Spectroscopic, Structural, and Morphology of Nickel Oxide Nanoparticles Prepared Using Physalis angulata Leaf Extract

2018 ◽  
Vol 917 ◽  
pp. 167-171 ◽  
Author(s):  
Najmawati Sulaiman ◽  
Yoki Yulizar
Keyword(s):  
Electron Microscopy ◽  
Particle Size ◽  
Nickel Oxide ◽  
Band Gap ◽  
Leaf Extract ◽  
Optical Band Gap ◽  
Oxide Nanoparticles ◽  
Nickel Oxide Nanoparticles ◽  
Microscopic Studies ◽  
Nio Nps

Green synthesis of nickel oxide nanoparticles (NiO NPs) usingPhysalisangulataleaf extract (PALE) as weak base sources and stabilizing agents has been reported. Chemical bonding and vibration spectroscopy, crystallographic structure, optical band gap, particle size and microscopic studies of NiO NPs were also investigated. Ni-O vibration modes of NiO NPs were analyzed by FTIR and Raman instrument at ~400 and ~900 cm-1wavenumber. XRD pattern of NiO NPs confirmed cubic crystal structure with space groupFm-3m.Optical band gap of NiO NPs determined by using Tauc plot method was about 3.42 eV. Particle size analyzer showed size distribution of NiO NPs was 64.13 nm which confirm NiO formed in nanoscale. Electron microscopic studies of NiO NPs were observed by using scanning electron microscopy and transmission electron microscopy.

The Role of Reduced Graphene Oxide Concentration as Ablated Material on Optical Properties of Graphene Quantum Dots

2019 ◽  
Vol 948 ◽  
pp. 267-273 ◽  
Author(s):  
Fiqhri Heda Murdaka ◽  
Ahmad Kusumaatmaja ◽  
Isnaeni ◽  
Iman Santoso
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Graphene Quantum Dots ◽  
Absorption Peak ◽  
Oxygen Defect ◽  
Reduced Graphene

We report the synthesize of Graphene Quantum Dots (GQDs) using ablation method with reduced Graphene Oxide (rGO) solution as a starting material. We have varied the concentration of rGO as following: 0.5, 2, 5 mg/ml and then have ablated them using 800 nm Ti-Sapphire femtosecond laser to obtain GQDs. From the UV-Vis data, we observed that the more concentration of rGO is being ablated, the more secondary absorption peak at 255.1 nm appeared. This secondary absorption peak is a characteristic of n-π* bonding due to the presence of oxygen defect which occurs as a result of the interaction between the laser and the water in rGO solution. We conclude that the population of oxigen defect in GQDs is increasing, following the increase of rGO concentration and could alter the optical properties of GQD. On the other hand, using Tauc’s plot, we confirm that the increase of rGO concentration as the ablated material does not alter GQDs optical band gap. However, it will slightly reduce both, direct and indirect Oxygen defect related optical band gap.

Optical Band Gap of Wurtzite Zinc Sulphide Doped with Lanthanum Ions

2012 ◽  
Vol 622-623 ◽  
pp. 752-756
Author(s):  
George Varughese ◽  
Sreeja R. Aswathy ◽  
K.T. Usha ◽  
A.S. Kumar
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Light Transmission ◽  
Photo Luminescence ◽  
Chemical Precipitation ◽  
High Refractive Index ◽  
Zinc Sulphide ◽  
Zns Nanoparticles ◽  
Visible Absorption ◽  
Lanthanum Ions

Pure and doped Zinc Sulfide (ZnS) quantum dots have attracted increasing interest from researchers working on various scientific and engineering applications in electronics, nonlinear optical devices for communication, and optical computers. In this study, ZnS nanoparticles doped with lanthanum (ZnS:La) with approximately 11 nm size was produced at 150°C by chemical precipitation route. Zinc Sulphide is an extensively studied group II-VI semiconductor with wide application in field of Photo Luminescence (PL),Electro Luminescence(EL) and Cathodo Luminescence (CL). It is an excellent light transmission material with high refractive index 2.27. XRD, SEM, FTIR UV-Vis and EDS characterize the samples.In this study, the UV–Visible absorption spectra of ZnS:La showed a red shift in the absorption shoulder compared with the spectra of undoped samples. ZnS nanoparticles could be doped with lanthanum ions during synthesis without altering the X-ray diffraction (XRD) patterns of ZnS. Also, the XRD pattern of the powders showed cubic crystal structures for ZnS:La. The Optical band gap has been found to be 2.7 eV. It was found that energy Band gap Eg decreases with doping of La.

scholarly journals Optical Band Gap and Thermal Diffusivity of Polypyrrole-Nanoparticles Decorated Reduced Graphene Oxide Nanocomposite Layer

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Amir Reza Sadrolhosseini ◽  
Suraya Abdul Rashid ◽  
A. S. M. Noor ◽  
Alireza Kharazmi ◽  
H. N. Lim ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Thermal Diffusivity ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Nanocomposite Layer ◽  
Reduced Graphene ◽  
Visible Spectra ◽  
Polypyrrole Nanoparticles ◽  
Uv Visible

A polypyrrole-nanoparticles reduced graphene oxide nanocomposite layer was prepared using electrochemical method. The prepared samples were characterized using Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and UV-visible spectroscopy. The band gap of nanocomposite layers was calculated from UV-visible spectra and the thermal diffusivity of layers was measured using a photoacoustic technique. As experimental results, the optical band gap was in the range between 3.580 eV and 3.853 eV, and thermal diffusivity was increased with increasing the layer thickness from 2.873 cm2/s to 12.446 cm2/s.

scholarly journals Tuning the Refractive Index and Optical Band Gap of Silk Fibroin Films by Electron Irradiation

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
S. Asha ◽  
Y. Sangappa ◽  
Sanjeev Ganesh
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Band Gap ◽  
Silk Fibroin ◽  
Structural Changes ◽  
Optical Band Gap ◽  
Dielectric Constants ◽  
Visible Absorption ◽  
Optical Responses ◽  
Uv Visible

TheBombyx morisilk fibroin (SF) films were prepared by solution casting method and effects of electron beam on the optical properties and optical constants of the films have been studied by using UV-Visible spectrophotometer. Optical properties like optical band gapEg, refractive indexn, extinction coefficientk, optical conductivityσopt, and dielectric constantsε∗of virgin and electron irradiated films were determined by using UV-Visible absorption and transmission spectra. It was found that the reduction in optical band gap and increase in refractive index with increasing radiation dosage was observed. It is also observed from results that there is increase in dielectric constants with increasing photon energy. The observed optical changes have been tried to be correlated with the structural changes, revealed through FT-IR spectroscopy. The present study is quite important for tailoring the optical responses of SF films as per specific requirements.

scholarly journals Investigation on Structural and Optical Properties of Sodium ion (Na+) Doped Layered Perovskite Sr2CeO4

2020 ◽  
Author(s):  
Dharmendra Yadav ◽  
Gurudeo Nirala ◽  
Upendra Kumar ◽  
Shail Upadhyay
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Blue Emission ◽  
Solid State Reaction Method ◽  
Band Gap Energy ◽  
Layered Perovskite ◽  
Doping Amount ◽  
Electron Microscopic ◽  
Conventional Solid State Reaction ◽  
Microscopic Studies

Abstract Powder and ceramic of a few compositions of system Sr2Ce1-xNaxO4 (x=0, 0.02, 0.04, 0.06 and 0.10) were prepared by the conventional solid-state reaction method. The phase and structure of the synthesized samples were investigated by x-ray diffraction technique. The analysis of XRD data indicated that in Sr2CeO4, substitution sites of Na1+ ions depend on the doping concentration. Na1+ ions occupy Ce-sites when concentration is x = 0.02. With increasing doping amount (x=0.04, 0.06 and 0.10) Na1+ substituted into both Sr and Ce site. Purity of the synthesized samples was reconfirmed using Raman and Fourier Transformation Infrared (FTIR) spectroscopy techniques. The optical band gap was recorded by UV-Vis absorption spectra; optical band gap energy of the samples lies between 2.91 - 3.10 eV. Room temperature photoluminescence (PL) measurements show that there two excitation peaks located around 290 nm and 350 nm. For Na doped samples, intensity of higher wavelength peak is more than the lower wavelength peak making them suitable candidate for UV excitation source. All the Na1+ doped samples display an intense blue emission at 472 nm similar to undoped Sr2CeO4. But the intensity of emission for the doped samples is weak as compared to undoped sample. Scanning electron microscopic studies of fractured surfaces of the sintered pellets have indicated that dopant Na has played a significant role in the grain growth. Grain size and morphology of Na doped samples are different from undoped Sr2CeO4.

The Effect of Annealing Temperature on the Bandgap of Bi3.25La0.75FeTi2O12 Powders

2015 ◽  
Vol 15 (10) ◽  
pp. 8195-8198
Author(s):  
Myoung Geun Song ◽  
Jun Young Han ◽  
Chung Wung Bark
Keyword(s):  
Thermal Treatment ◽  
Oxygen Vacancy ◽  
Band Gap ◽  
Optical Band Gap ◽  
Treatment Time ◽  
Solar Spectrum ◽  
Complex Oxides ◽  
Optical Bandgap ◽  
Crystallographic Structure ◽  
Visible Absorption

In recent years, there has been increasing interest in the bandgap engineering of ferroelectric oxides to improve absorbance of the solar spectrum, which is governed by their band gap. To enhance the photovoltaic efficiency by tuning the optical bandgap of complex oxides, an attempt was recently made to reduce the optical band gap of iron doping of lanthanum-modified Bi4Ti3O12-based oxides (Fe-BLT) using oxygen vacancy doping. To study the tunability of the optical band gap from the generation of oxygen vacancies, the thermal treatment time and temperature were controlled during heat treatment under a vacuum environment. The structural, optical properties of the synthesized podwers were examined by X-ray diffraction, scanning electron microscopy, and ultraviolet-visible spectroscopy. Typically, an oxygen vacancy in a complex oxide can alter their structure very easily. On the other hand, the ultraviolet-visible absorption spectra of iron-doped bismuth titanate ceramics under optimal conditions (12 h, 800 °C) showed a decrease in optical bandgap from 2.02 eV to 1.8 eV without a corresponding change in their crystallographic structure. This study suggests that optimal control of the thermal treatment time and temperature critically effects the optical band gap of complex oxides.

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