scholarly journals CARBON STRUCTURES AS EFFECTIVE MODIFIERS OF THE MATERIALS’ BASIC PROPERTIES

2017 ◽  
Vol 5 ◽  
pp. 1135-1142
Author(s):  
Natalia Kamanina
Keyword(s):  
Carbon Nanotubes ◽  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Second Harmonic ◽  
Inorganic Materials ◽  
Mechanical Parameters ◽  
Ir Laser ◽  
Carbon Structures ◽  
Spatial Frequencies

Because of the unique energetic, refractive and photoconductive characteristics of effective nano-objects, especially carbon nanotubes, the modification of optical properties of the organic and inorganic materials can be considered as the preferable one via the use of the nanostructuration process. Emphasis has been given to the incorporation of nanoobjects directly in the materials’ body and on their surface. Under the conditions of a surface treatment of the inorganic structures, an IR-laser at the wavelength of 10.6 micrometers was used to orientate carbon nanotubes deposited in the electric field of 100-600 V×cm-1. Dramatic spectral and mechanical parameters changes have been found. Refractive features of the nanostructured organics have been studied via applying the second harmonic of the pulsed Nd-laser at different spatial frequencies and under the nanoparticles sensitization doping such as fullerenes, carbon nanotubes, shungites, quantum dots, and graphenes. A drastically obtained laser-induced refractive index has been established. A prediction has been proposed to extend the area of the application of the systems considered.

Enhanced Luminescence Efficiency from Hydrogel Microbead Encapsulated Quantum Dots

2006 ◽  
Vol 959 ◽  
Author(s):  
Arup Neogi ◽  
Santaneel Ghosh ◽  
Jianyou Li ◽  
Tong Cai ◽  
Zhibing Hu
Keyword(s):  
Phase Transition ◽  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Index Volume ◽  
Volume Density ◽  
Volume Phase Transition ◽  
Thermoresponsive Polymer ◽  
Luminescence Efficiency ◽  
Enhanced Luminescence

ABSTRACTIn this paper, a novel quantum dot (QD) based nanomaterial system is presented for efficient FRET analysis. The quantum dots have been embedded in hydrogel microspheres based on poly(N-isopropylacrylamide) (PNIPAM) a thermoresponsive polymer that undergoes a volume phase transition across the low critical solution (LCST). The optical properties of the quantum dots entrapped within the gel microspheres has been modified due to change in refractive index, volume density of the surrounding hydrogel medium. The QDs encapsulated in the PNIPAM microspheres showed 100–200 % enhancement in the PL efficiency as the microgels shrank at the temperature above the LCST temperature of the gel.

scholarly journals Nanomaterials: Applications in Electronics

2021 ◽  
Vol 4 (6) ◽  
pp. 7-19
Author(s):  
Mrs. Harshada V. Mhetre ◽  
◽  
Dr. Yuvraj K. Kanse ◽  
Dr. Suhas S. Patil ◽  
◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Quantum Dots ◽  
Optical Properties ◽  
Solar Cells ◽  
Light Emission ◽  
Enabling Technology ◽  
Bulk Materials ◽  
Different Types ◽  
Basic Characteristics

Nanotechnology is steadily transgressing from the laboratory to the commercial sphere and is enhancing products in a variety of sectors. Nanotechnology R&D has evolved from foundational discoveries aimed at understanding and exploiting nanoscale behaviour to an enabling technology. Nanomaterials are materials which are sized between 1 to 100 nm. Due to the basic characteristics of nanomaterials such as optical properties, reflection, transmission, absorption, and light emission, which are different from those of bulk materials, nanomaterials are useful in a variety of applications in different fields. In this paper the different types of nanomaterials have been outlined based upon their dimensions and applications in the field of electronics such as Quantum dots (QD’s) in solar cells and Carbon Nanotubes and graphene in FETs.

A comparison of optical properties of disc-like and spherical quantum dots

2018 ◽  
Vol 27 (03) ◽  
pp. 1850034
Author(s):  
Vildan Üstoğlu Ünal ◽  
Erem Birşey ◽  
Ertan Akşahin
Keyword(s):  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Optical Absorption ◽  
Electric Field ◽  
Electronic Structures ◽  
Electric Field Effect ◽  
Total Change ◽  
Absorption Increase ◽  
Mass Approximation

The optical properties of quantum dots (QDs) are of interest to many researchers. In this study, the optical coeefficients analyzed include the optical absorption, the refractive index; both the linear and nonlinear cases together with the electric field effect. The electronic structures of the disc-like and spherical QDs are calculated by using the effective-mass approximation. The results show that the total change in the refractive index and the optical absorption increase with increasing QD size, the peaks are shifted with the changing QD size. The nonlinear optical properties increase with the external electric field and the optical intensity. Comparison of QD types shows that the peaks are red-shifted for the disc-like QD and lower than those in the spherical QD case.

Photodynamic Effects in Nanocomposites Based on Quantum Dots of Cadmium Sulfide Embedded in a Silicate Matrix, in their Interaction with the Laser Beam

2014 ◽  
Vol 213 ◽  
pp. 186-191 ◽  
Author(s):  
Alexander A. Sergeev ◽  
Sergey S. Voznesenskiy ◽  
Anna N. Galkina ◽  
Aleksandr Nepomnyaschiy ◽  
Kseniya M. Sergeeva
Keyword(s):  
Quantum Dots ◽  
Refractive Index ◽  
Optical Properties ◽  
Laser Radiation ◽  
Laser Beam ◽  
Cadmium Sulfide ◽  
Local Change ◽  
Silicate Matrix ◽  
Cds Quantum Dots ◽  
Exposure Conditions

In this paper we study the possibility of modifying the optical properties of nanocomposites based on CdS quantum dots embedded in a silicate matrix, in their interaction with the laser radiation. It was found that the action of laser radiation leads to local change in the refractive index of the nanocomposite, the dynamics of which depends on the exposure conditions.

scholarly journals Quantum Confined Stark Effect on the Linear and Nonlinear Optical Properties of SiGe/Si Semi Oblate and Prolate Quantum Dots Grown in Si Wetting Layer

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1513
Author(s):  
Varsha ◽  
Mohamed Kria ◽  
Jawad El Hamdaoui ◽  
Laura M. Pérez ◽  
Vinod Prasad ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Quantum Dot ◽  
Electric Field ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Wetting Layer ◽  
Non Linear ◽  
Linear Optical Properties ◽  
Linear Optical

We have studied the parallel and perpendicular electric field effects on the system of SiGe prolate and oblate quantum dots numerically, taking into account the wetting layer and quantum dot size effects. Using the effective-mass approximation in the two bands model, we computationally calculated the extensive variation of dipole matrix (DM) elements, bandgap and non-linear optical properties, including absorption coefficients, refractive index changes, second harmonic generation and third harmonic generation as a function of the electric field, wetting layer size and the size of the quantum dot. The redshift is observed for the non-linear optical properties with the increasing electric field and an increase in wetting layer thickness. The sensitivity to the electric field toward the shape of the quantum dot is also observed. This study is resourceful for all the researchers as it provides a pragmatic model by considering oblate and prolate shaped quantum dots by explaining the optical and electronic properties precisely, as a consequence of the confined stark shift and wetting layer.

Optoelectronic and Magnetic Properties of Eu2Si5N8: An Ab-initio Study

2015 ◽  
Vol 70 (11) ◽  
pp. 897-904
Author(s):  
Sikander Azam ◽  
Saleem Ayaz Khan ◽  
R. Khenata ◽  
G. Murtaza ◽  
S. Bin Omran ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Energy Loss ◽  
Loss Function ◽  
Density Functional ◽  
Energy Gap ◽  
Optical Memory ◽  
Inorganic Materials ◽  
Coulomb Energy ◽  
Energy Loss Function

AbstractEu2Si5N8 is considered the most important compound in the development of inorganic materials with high potential and performance. Therefore, the electronic, magnetic and optical properties of Eu2Si5N8 are investigated here using density functional theory. The electronic interactions are described within the generalised gradient approximation, GGA+U (where U is the Hubbard Coulomb energy term). The calculated energy gap was 3.5 eV for the investigated compound, resulting in a direct band gap semiconductor. The optical constants, including the dielectric function, refractive index, absorption coefficient, reflectivity, and energy loss function were calculated for radiation up to 14 eV. The optical properties demonstrate that the main differences in absorption, reflectivity, energy-loss function and refractive index occur in the infrared and visible regions for the spin-up and spin-down states, which makes this material an excellent candidate for optical memory devices.

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