scholarly journals Study of the effect of band gap and photoluminescence on biological properties of polyaniline/CdS QD nanocomposites based on natural polymer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Azita Alipour ◽  
Moslem Mansour Lakouraj ◽  
Hamed Tashakkorian
Keyword(s):  
Band Gap ◽  
Emission Intensity ◽  
Energy Gap ◽  
Conductive Polymer ◽  
Biological Properties ◽  
Synergy Effect ◽  
Natural Polymer ◽  
Toxicity Effect ◽  
Heterogeneous Chemical ◽  
Cell Tissue

AbstractIn this work, band gap, photoluminescence and biological properties of new bionanocomposites based on polyaniline (PANi)/hydrolyzed pectin (HPEc)/cadmium sulfide (CdS) QD nanoparticles (NPs) were studied. In order to improve the morphology and properties, CdS NPs were modified with epichlorohydrin to obtain the modified CdS (mCdS). The CdS@HPEc-g-PANi and mCdS@HPEc-g-PANi samples were synthesized via heterogeneous chemical polymerization and characterized by FTIR, 1HNMR, SEM/XRD, EDX/TEM/EDX-mapping and TGA analyses. The objective of this work is the study of physical, optical and cytotoxicity properties of the nanocomposites and comparison between them. The SEM, XRD and TGA images showed that the modification of NPs resulted in homogeneous morphology, increase of crystalline structure and high thermal stability which influenced on physical and biological property. According to UV-DRS analysis, the mCdS@HPEc-g-PANi indicated lower energy gap compared to the CdS@HPEc-g-PANi nancomposite. The presence of conductive polymer and synergy effect between the PANi and CdS caused higher PL intensity in the CdS@HPEc-g-PANi nanocomposite compared to pure CdS. The emission intensity in the mCdS@HPEc-g-PANi nanocomposite was reduced since the organic modifying agent cause reducing emission intensity. The mCdS@HPEc-g-PANi nanocomposite, due to more compatibility of organic agent with cellular walls of biological cells that help to the diffusion of metal CdS NPs into cell tissue indicated more toxicity effect on cell growth.

scholarly journals Influence of Calcination Temperature on Crystal Growth and Optical Characteristics of Eu3+ Doped ZnO/Zn2SiO4 Composites Fabricated via Simple Thermal Treatment Method

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 115
Author(s):  
Suhail Huzaifa Jaafar ◽  
Mohd Hafiz Mohd Zaid ◽  
Khamirul Amin Matori ◽  
Sidek Hj. Ab Aziz ◽  
Halimah Mohamed Kamari ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Band Gap ◽  
Calcination Temperature ◽  
Emission Intensity ◽  
Emission Spectra ◽  
Treatment Method ◽  
Absorption Bands ◽  
Vis Spectroscopy ◽  
Doped Zno ◽  
Zno Crystal

This research paper proposes the usage of a simple thermal treatment method to synthesis the pure and Eu3+ doped ZnO/Zn2SiO4 based composites which undergo calcination process at different temperatures. The effect of calcination temperatures on the structural, morphological, and optical properties of ZnO/Zn2SiO4 based composites have been studied. The XRD analysis shows the existence of two major phases which are ZnO and Zn2SiO4 crystals and supported by the finding in the FT-IR. The FESEM micrograph further confirms the existence of both ZnO and Zn2SiO4 crystal phases, with progress in the calcination temperature around 700–800 °C which affects the existence of the necking-like shape particle. Absorption humps discovered through UV-Vis spectroscopy revealed that at the higher calcination temperature effects for higher absorption intensity while absorption bands can be seen at below 400 nm with dropping of absorption bands at 370–375 nm. Two types of band gap can be seen from the energy band gap analysis which occurs from ZnO crystal and Zn2SiO4 crystal progress. It is also discovered that for Eu3+ doped ZnO/Zn2SiO4 composites, the Zn2SiO4 crystal (5.11–4.71 eV) has a higher band gap compared to the ZnO crystal (3.271–4.07 eV). While, for the photoluminescence study, excited at 400 nm, the emission spectra of Eu3+ doped ZnO/Zn2SiO4 revealed higher emission intensity compared to pure ZnO/Zn2SiO4 with higher calcination temperature exhibit higher emission intensity at 615 nm with 700 °C being the optimum temperature. The emission spectra also show that the calcination temperature contributed to enhancing the emission intensity.

scholarly journals The Band-Gap Studies of Short-Period CdO/MgO Superlattices

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Ewa Przeździecka ◽  
P. Strąk ◽  
A. Wierzbicka ◽  
A. Adhikari ◽  
A. Lysak ◽  
...  
Keyword(s):  
Band Gap ◽  
Layer Thickness ◽  
Energy Gap ◽  
Band Gaps ◽  
Short Period ◽  
Wide Range ◽  
Salt Structure ◽  
Short Period Superlattices ◽  
Direct Band ◽  
Sublayer Thickness

AbstractTrends in the behavior of band gaps in short-period superlattices (SLs) composed of CdO and MgO layers were analyzed experimentally and theoretically for several thicknesses of CdO sublayers. The optical properties of the SLs were investigated by means of transmittance measurements at room temperature in the wavelength range 200–700 nm. The direct band gap of {CdO/MgO} SLs were tuned from 2.6 to 6 eV by varying the thickness of CdO from 1 to 12 monolayers while maintaining the same MgO layer thickness of 4 monolayers. Obtained values of direct and indirect band gaps are higher than those theoretically calculated by an ab initio method, but follow the same trend. X-ray measurements confirmed the presence of a rock salt structure in the SLs. Two oriented structures (111 and 100) grown on c- and r-oriented sapphire substrates were obtained. The measured lattice parameters increase with CdO layer thickness, and the experimental data are in agreement with the calculated results. This new kind of SL structure may be suitable for use in visible, UV and deep UV optoelectronics, especially because the energy gap can be precisely controlled over a wide range by modulating the sublayer thickness in the superlattices.

Optical Detection of Band Gap Variations Due to Ordering in Ga0.47In0.53As on InP

1992 ◽  
Vol 281 ◽  
Author(s):  
D. J. Arent ◽  
K. A. Bertness ◽  
Sarah R. Kurtz ◽  
M. Bode ◽  
J. M. Olson
Keyword(s):  
Band Gap ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Energy Gap ◽  
Growth Conditions ◽  
Band Gap Energy ◽  
Optical Energy Gap ◽  
Lower Growth ◽  
Transmission Electron ◽  
High Resolution Images

ABSTRACTA reduction in the optical energy gap of more than 65 meV has been observed in In0.53Ga0.47 As grown on (100) InP by atmospheric pressure metalorganic vapor phase epitaxy. The band gap energies were deduced from room temperature photocurrent spectroscopic measurements, accounting for differences in composition and strain. Spontaneous CuPt type ordering of In and Ga atoms on the (111) subplanes of the InGaAs2 was confirmed by transmission electron microscopy. Superlattice signatures in the transmission micrographs were observed only for samples with associated reduced band gap energies, and were confirmed by visible double periodicity in high resolution images. In0.53Ga0.47 As was grown under a variety of conditions, some which promoted ordering. In general, lower growth temperatures and moderate (∼4 μ/hr) growth rates promoted a greater degree of ordering and reduction of the band gap energy. The influence of growth conditions on the ordered structure is considered within the context of current theories.

The Role of Rare Earths in Narrow Energy Gap Semiconductors

1990 ◽  
Vol 216 ◽  
Author(s):  
D.L. Partin ◽  
J. Heremans ◽  
D.T. Morelli ◽  
C.M. Thrush
Keyword(s):  
Rare Earth ◽  
Band Gap ◽  
Indium Antimonide ◽  
Energy Band ◽  
Energy Gap ◽  
Lattice Parameter ◽  
Molecular Beam Epitaxy Growth ◽  
Lead Chalcogenide ◽  
Energy Band Gap

ABSTRACTNarrow energy band gap semiconductors are potentially useful for various devices, including infrared detectors and diode lasers. Rare earth elements have been introduced into lead chalcogenide semiconductors using the molecular beam epitaxy growth process. Europium and ytterbium increase the energy band gap, and nearly lattice-matched heterojunctions have been grown. In some cases, valence changes in the rare earth element cause doping of the alloy. Some initial investigations of the addition of europium to indium antimonide will also be reported, including the variation of lattice parameter and optical transmission with composition and a negative magnetoresistance effect.

Hydrazine-assisted preparation of ZnS nanocrystals using N-acetyl-L-cysteine as capping agent

2018 ◽  
Vol 32 (22) ◽  
pp. 1850254
Author(s):  
Reza Sahraei ◽  
Ehsan Soheyli ◽  
Zahra Faraji
Keyword(s):  
Band Gap ◽  
Hydrazine Hydrate ◽  
Absorption Edge ◽  
Emission Intensity ◽  
Band Gap Energy ◽  
Capping Agent ◽  
Time Duration ◽  
Gap Energy ◽  
Ft Ir ◽  
Zns Nanocrystals

Using N-acetyl-L-cysteine (NAC) as capping agent and different amounts of hydrazine hydrate as growth promoter, in this paper, we report a simple way for preparation of aqueous-based ZnS nanocrystals (NCs). The small-sized and well-dispersed NCs with cubic zinc blende structure and size-dependent optical behavior have been characterized by XRD, TEM, FT-IR, UV-Vis, and photoluminescence (PL) measurements. Disappearance of the thiol-related peak in the FT-IR spectrum of NAC-capped ZnS NCs demonstrated the well-passivation of ZnS NCs by deprotonated NAC molecules. Variation of optical properties of ZnS NCs has been studied at different hydrazine amounts and refluxing times. The growth-assisting characteristic of hydrazine hydrate was demonstrated by redshift in absorption edge as the hydrazine amount increased from 5 to 20 mmol, and ensuing decrease in band gap energy of ZnS NCs from 4.47 eV to 4.0 eV. On the other hand, increasing the refluxing time duration up to 20 h, resulted in obvious redshift in absorption edge and subsequent decrease in the band gap energy from 4.56 eV to 3.85 eV. The optical estimation on the size of the as-prepared ZnS NCs was obtained through effective mass approximation. Results indicated that all the NCs are small enough near the excitonic Bohr radius of ZnS which revealed the presence of strong quantum confinement effects. Effect of these parameters on PL emission intensity of ZnS NCs was studied and it was observed that the best emission result is at the presence of 12.5 mmol hydrazine hydrate and during 16 h heating. Finally, analyzing chemical stability of the as-prepared ZnS NCs against H2O2 corrosion demonstrated a well-accepting stability of emission intensity even after 108 min.

scholarly journals Polymeric Composites Based on Carboxymethyl Cellulose Cryogel and Conductive Polymers: Synthesis and Characterization

2020 ◽  
Vol 4 (2) ◽  
pp. 33
Author(s):  
Sahin Demirci ◽  
S. Duygu Sutekin ◽  
Nurettin Sahiner
Keyword(s):  
Polymer Composites ◽  
Carboxymethyl Cellulose ◽  
Conductive Polymers ◽  
Conductive Polymer ◽  
Fold Increase ◽  
Natural Polymer ◽  
Conductive Polymer Composites ◽  
Ft Ir ◽  
Vapor Treatment ◽  
Ft Ir Spectroscopy

In this study, a super porous polymeric network prepared from a natural polymer, carboxymethyl cellulose (CMC), was used as a scaffold in the preparation of conductive polymers such as poly(Aniline) (PANi), poly(Pyrrole) (PPy), and poly(Thiophene) (PTh). CMC–conductive polymer composites were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) techniques, and conductivity measurements. The highest conductivity was observed as 4.36 × 10−4 ± 4.63 × 10−5 S·cm−1 for CMC–PANi cryogel composite. The changes in conductivity of prepared CMC cryogel and its corresponding PAN, PPy, and PTh composites were tested against HCl and NH3 vapor. The changes in conductivity values of CMC cryogel upon HCl and NH3 vapor treatment were found to increase 1.5- and 2-fold, respectively, whereas CMC–PANi composites showed a 143-fold increase in conductivity upon HCl and a 12-fold decrease in conductivity upon NH3 treatment, suggesting the use of natural polymer–conductive polymer composites as sensor for these gases.

A water-soluble TbIII complex as a temperature-sensitive luminescent probe

2018 ◽  
Vol 96 (9) ◽  
pp. 859-864 ◽  
Author(s):  
Jorge H.S.K. Monteiro ◽  
Fernando A. Sigoli ◽  
Ana de Bettencourt-Dias
Keyword(s):  
Emission Intensity ◽  
Energy Gap ◽  
High Resolution Mass Spectrometry ◽  
Thermal Sensitivity ◽  
Energy Levels ◽  
Water Soluble ◽  
Temperature Sensitive ◽  
Dependent Behavior ◽  
Donor And Acceptor ◽  
Tict States

The water soluble [Tb(dipicCbz)3]3− (dipicCbz = 4-(9H-carbazol-9-yl-)pyridine-2,6-dicarboxylato) complex was isolated and evaluated as a temperature sensor in water. The 1:3 (TbIII:dipicCbz2−) stoichiometry in solution was confirmed by luminescence titration and high-resolution mass spectrometry. The quantum yield of sensitized emission is 3.8% ± 0.4% at 25.0 ± 0.1 °C, and the emission intensity depends on the temperature in the range of 5–70 °C with a relative thermal sensitivity of 3.4% °C−1 at 35 °C and temperature resolution < 0.01 °C in the range of 30–40 °C. The reversibility of this behavior was demonstrated for three heating–cooling cycles. Calculations of the energy gap between donor and acceptor show that the temperature dependence of the emission intensity is due to back-energy transfer from the Tb 5D4 excited state to the triplet and twisted intramolecular charge transfer (TICT) states of the dipicCbz. The assignment of one of the energy levels as a TICT state was confirmed by the temperature-dependent behavior of the phosphorescence band.

Hydrogen-induced Nitrogen Passivation in Dilute Nitrides: A Novel Approach to Defect Engineering

2007 ◽  
Vol 994 ◽  
Author(s):  
Rinaldo Trotta ◽  
Antonio Polimeni ◽  
Marco Felici ◽  
Giorgio Pettinari ◽  
Mario Capizzi ◽  
...  
Keyword(s):  
Electron Beam ◽  
Band Gap ◽  
Electronic Properties ◽  
Energy Gap ◽  
Dilute Nitrides ◽  
Defect Engineering ◽  
Novel Approach ◽  
Hydrogen Implantation

AbstractThe capability of hydrogen to passivate nitrogen in dilute nitrides is exploited to in-plane engineer the electronic properties of Ga(AsN)/GaAs heterostructures. Two methods are presented: i) by deposition of hydrogen-opaque metallic masks on Ga(AsN) and subsequent hydrogen irradiation, we artificially create zones of the crystal having the band gap of untreated Ga(AsN) surrounded by GaAs-like barriers; ii) by employing an intense (∼100 nA) and narrow (∼100 nm) beam of electrons, we dissociate the complexes formed by N and H in a spatially delimited part of a hydrogenated Ga(AsN) sample. As a consequence, in the spatial regions irradiated by the electron beam, hydrogenated Ga(AsN) recovers the smaller energy gap it had before hydrogen implantation.

Synthesis and Characterization of Poly{1,2-bis(2-seleninyl)ethene}, a Novel Electrically Conductive Polymer with Diminished Band Gap

1998 ◽  
Vol 31 (4) ◽  
pp. 1221-1228 ◽  
Author(s):  
S. C. Ng ◽  
H. S. O. Chan ◽  
T. T. Ong ◽  
K. Kumura ◽  
Y. Mazaki ◽  
...  
Keyword(s):  
Band Gap ◽  
Conductive Polymer ◽  
Synthesis And Characterization ◽  
Electrically Conductive

Narrow-Band-Gap Polymer Photovoltaic Materials Synthesis and Photovoltaic Research

2013 ◽  
Vol 273 ◽  
pp. 468-472
Author(s):  
Yong Sen Wei
Keyword(s):  
Band Gap ◽  
Energy Gap ◽  
Narrow Band ◽  
Field Effect Transistors ◽  
Materials Synthesis ◽  
Photovoltaic Properties ◽  
Light Emitting ◽  
Photovoltaic Materials ◽  
Photovoltaic Characteristics ◽  
Photovoltaic Material

In recent years, research of the narrow-band-gap polymer photovoltaic (PV) materials in the field of light-emitting diodes, field effect transistors, solar cells and sensors has made tremendous progress and its application becomes more widely. In order to obtain a better performance of the photovoltaic material, in the process of design the polymer, we must consider the spectral range, the energy gap, the balance between the LUMO and HOMO level. Through the analysis of the narrow-band-gap polymers, this paper described the synthesis of the photovoltaic material, and detailed analyzes its photovoltaic characteristics. This paper introduces the double bonds to combine DTBT receptors and different electron donor, to synthesize new narrow-band-gap polymer photovoltaic materials with photovoltaic properties.

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