scholarly journals Synthesis and study of some properties of colloidal quantum dots of indium antimonide

2021 ◽  
Vol 21 (4) ◽  
pp. 378-381
Author(s):  
Olga Yu. Tsvetkova ◽  
◽  
Sergey N. Shtykov ◽  
Nikolay D. Zhukov ◽  
Tatiana D. Smirnova ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Crystal Lattice ◽  
Indium Antimonide ◽  
Lattice Structure ◽  
Colloidal Quantum Dots ◽  
Fluorescent Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Of Nanoparticles ◽  
Chemical Purity

Colloidal quantum dots of indium antimonide have been synthesized by a known technique. The shape and average diameters of quantum dots have been investigated by transmission electron microscopy using a transmission microscope. Controlling the size and shape of colloidal QDs provides information on the formation of the crystal structure of nanoparticles and their possible physical and optical properties. It has been found that InSb quantum dots are characterized by a polygonal shape. The results obtained for QDs correspond to the crystal lattice system of a semiconductor with a cubic crystal lattice structure. Elemental analysis of nanoparticles has been monitored by X-ray microanalysis. The experimental determination error was no more than one percent. The percentages of indium and antimony in QDs according to X-ray microanalysis data corresponded to the theoretical stoichiometry In: Sb = 1:1. Impurities of other elements constituted the level of trace amounts, which confirmed the chemical purity of the synthesized InSb QDs. The fluorescent properties of indium antimonide nanoparticles have been studied. It has been found that the luminescence intensity of InSb nanoparticles at room temperature is insignificant, which is in agreement with the literature data. The quantum yield does not exceed 1%, and the luminescence maximum lies in the range of 1040 nm.

scholarly journals An Electrochemical Cholesterol Biosensor Based on A CdTe/CdSe/ZnSe Quantum Dots—Poly (Propylene Imine) Dendrimer Nanocomposite Immobilisation Layer

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3368 ◽  
Author(s):  
Kefilwe Mokwebo ◽  
Oluwatobi Oluwafemi ◽  
Omotayo Arotiba
Keyword(s):  
Quantum Dots ◽  
Modified Electrode ◽  
Cholesterol Oxidase ◽  
Shell Growth ◽  
Modified Electrodes ◽  
X Ray ◽  
Transmission Electron ◽  
Vis Spectroscopy ◽  
Poly Propylene ◽  
Cholesterol Biosensor

We report the preparation of poly (propylene imine) dendrimer (PPI) and CdTe/CdSe/ZnSe quantum dots (QDs) as a suitable platform for the development of an enzyme-based electrochemical cholesterol biosensor with enhanced analytical performance. The mercaptopropionic acid (MPA)-capped CdTe/CdSe/ZnSe QDs was synthesized in an aqueous phase and characterized using photoluminescence (PL) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray power diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy. The absorption and emission maxima of the QDs red shifted as the reaction time and shell growth increased, indicating the formation of CdTe/CdSe/ZnSe QDs. PPI was electrodeposited on a glassy carbon electrode followed by the deposition (by deep coating) attachment of the QDs onto the PPI dendrimer modified electrode using 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC), and N-hydroxysuccinimide (NHS) as a coupling agent. The biosensor was prepared by incubating the PPI/QDs modified electrode into a solution of cholesterol oxidase (ChOx) for 6 h. The modified electrodes were characterized by voltammetry and impedance spectroscopy. Since efficient electron transfer process between the enzyme cholesterol oxidase (ChOx) and the PPI/QDs-modified electrode was achieved, the cholesterol biosensor (GCE/PPI/QDs/ChOx) was able to detect cholesterol in the range 0.1–10 mM with a detection limit (LOD) of 0.075 mM and sensitivity of 111.16 μA mM−1 cm−2. The biosensor was stable for over a month and had greater selectivity towards the cholesterol molecule.

scholarly journals Исследование электрофизических свойств квантовых точек антимонида индия: значение формы

2021 ◽  
Vol 55 (3) ◽  
pp. 237
Author(s):  
В.Ф. Кабанов ◽  
А.И. Михайлов ◽  
М.В. Гавриков
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Indium Antimonide ◽  
Spectral Characteristics ◽  
Characteristic Size ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Transmission Electron ◽  
Particle Size Analyzer ◽  
Characteristics Analysis

In this work, we studied the influence of the shape of the indium antimonide quantum dots of on some important electrophysical parameters by spectral characteristics analysis, transmission electron microscopy, scanning tunneling microscopy, a laser particle size analyzer, and scanning electron microscopy. It is shown that the real form of quantum dots (spherical and cubic models) at the same characteristic size will noticeably affect the energy spectrum of the investigated objects and, accordingly, their electrophysical and optical properties.

Self-Organized Lead(II) Sulfide Quantum Dots Superlattice

MRS Advances ◽  
2017 ◽  
Vol 2 (15) ◽  
pp. 841-846 ◽  
Author(s):  
José Maria C. da Silva Filho ◽  
Victor A. Ermakov ◽  
Luiz G. Bonato ◽  
Ana F. Nogueira ◽  
Francisco C. Marques
Keyword(s):  
Quantum Dots ◽  
Interplanar Spacing ◽  
Face Centered Cubic ◽  
X Ray ◽  
Self Organized ◽  
Transmission Electron ◽  
The Mean ◽  
Face Centered ◽  
Pbs Quantum Dots ◽  
Deposited Films

ABSTRACTWe show that superlattice (SL) of PbS quantum dots (QD) can be easily prepared by drop casting of colloidal QD solution onto glass substrate and the ordering level can be controlled by the substrate temperature. A QD solution was dropped on glass and dried at 25, 40, 70 and 100°C resulting in formation of different SL structures. X-ray diffractograms (XRD) of deposited films show a set of sharp and intense peaks that are higher order satellites of a unique peak at 1.8 degrees (two theta), which corresponds, using the Bragg’s Law, to an interplanar spacing of 5.3 nm. The mean particles diameter, calculated through the broadening of the (111) peak of PbS using the Scherrer’s formula, were in agreement with the interplanar spacing. Transmission electron microscopy (TEM) measurements were also used to study the SL structure, which showed mainly a face centered cubic (FCC) arrangement of the QD. The photoluminescence (PL) spectrum of QD in the SL showed a shift toward lower energy compared to one in solution. It can be attributed to the fluorescence resonant energy transfer (FRET) between neighbors QD´s. Moreover, we observed greater redshift of PL peak for film with lower drying temperature, suggesting that it has a more organized structure.

Optical properties and energy transfer processes in Tb3+-doped ZnSe quantum dots

2021 ◽  
Author(s):  
Nguyen Ca ◽  
N. D Vinh ◽  
Phan Van Do ◽  
N. T. Hien ◽  
Xuan Hoa Vu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Chemical Method ◽  
X Ray Diffraction ◽  
Wet Chemical Method ◽  
X Ray ◽  
Transfer Processes ◽  
Transmission Electron ◽  
Wet Chemical

Tb3+-doped ZnSe quantum dots (QDs) with Tb content in the range of 0.5 - 7% were successfully synthesized by a wet chemical method. X-ray diffraction (XRD) and transmission electron microscopy...

scholarly journals The Application of Green-Synthesis-Derived Carbon Quantum Dots to Bioimaging and the Analysis of Mercury(II)

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qianchun Zhang ◽  
Xiaolan Zhang ◽  
Linchun Bao ◽  
Yun Wu ◽  
Li Jiang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Hela Cells ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Limit Of Detection ◽  
Carbon Quantum Dots ◽  
Coefficient Of Determination ◽  
Serum Samples ◽  
X Ray ◽  
Transmission Electron

Ginkgo leaves were used as precursors for the hydrothermal synthesis of carbon quantum dots (CQDs), which were subsequently characterized by transmission electron microscopy as well as Fourier-transform infrared, X-ray powder diffraction, and X-ray photoelectron spectroscopy. The prepared CQDs exhibited a fluorescence quantum yield of 11% and superior water solubility and fluorescence stability, as well as low cytotoxicities and excellent biocompatibilities with A549 and HeLa cells; these CQDs were also used to bioimage HeLa cells. Moreover, owing to the experimental observation that Hg2+ quenches the fluorescence of the CQDs in a specific and sensitive manner, we developed a method for the detection of Hg2+ using this fluorescence sensor. The sensor exhibited a linear range for Hg2+ of 0.50–20 μM, with an excellent coefficient of determination (R2 = 0.9966) and limit of detection (12.4 nM). In practice, the proposed method was shown to be highly selective and sensitive for the monitoring of Hg2+ in lake water and serum samples.

Microstructure characteristics of non-monodisperse quantum dots: on the potential of transmission electron microscopy combined with X-ray diffraction

CrystEngComm ◽  
2020 ◽  
Vol 22 (21) ◽  
pp. 3644-3655
Author(s):  
Stefan Neumann ◽  
Christina Menter ◽  
Ahmed Salaheldin Mahmoud ◽  
Doris Segets ◽  
David Rafaja
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Cdse Quantum Dots ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microstructure Characteristics ◽  
Scale Bridging ◽  
Transmission Electron ◽  
Hot Injection

Capability of TEM and XRD to reveal scale-bridging information about the microstructure of non-monodisperse quantum dots is illustrated on the CdSe quantum dots synthesized using an automated hot-injection method.

scholarly journals Formation of ZnO/Zn0.5Cd0.5Se Alloy Quantum Dots in the Presence of High Oleylamine Contents

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 999
Author(s):  
Yi-An Chen ◽  
Kuo-Hsien Chou ◽  
Yi-Yang Kuo ◽  
Cheng-Ye Wu ◽  
Po-Wen Hsiao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Particle Size ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
Transmission Electron ◽  
Average Size ◽  
Alloy Quantum Dots ◽  
First Time

To the best of our knowledge, this report presents, for the first time, the schematic of the possible chemical reaction for a one-pot synthesis of Zn0.5Cd0.5Se alloy quantum dots (QDs) in the presence of low/high oleylamine (OLA) contents. For high OLA contents, high-resolution transmission electron microscopy (HRTEM) results showed that the average size of Zn0.5Cd0.5Se increases significantly from 4 to 9 nm with an increasing OLA content from 4 to 10 mL. First, [Zn(OAc)2]–OLA complex can be formed by a reaction between Zn(OAc)2 and OLA. Then, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) data confirmed that ZnO is formed by thermal decomposition of the [Zn(OAc)2]–OLA complex. The results indicated that ZnO grew on the Zn0.5Cd0.5Se surface, thus increasing the particle size. For low OLA contents, HRTEM images were used to estimate the average sizes of the Zn0.5Cd0.5Se alloy QDs, which were approximately 8, 6, and 4 nm with OLA loadings of 0, 2, and 4 mL, respectively. We found that Zn(OAc)2 and OLA could form a [Zn(OAc)2]–OLA complex, which inhibited the growth of the Zn0.5Cd0.5Se alloy QDs, due to the decreasing reaction between Zn(oleic acid)2 and Se2−, which led to a decrease in particle size.

InAs Quantum Dots Grown on an AlGaAsSb Strain-Relief Buffer

2000 ◽  
Vol 642 ◽  
Author(s):  
A.L. Gray ◽  
L. R. Dawson ◽  
Y. Lin ◽  
A. Stintz ◽  
Y.-C. Xin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cross Section ◽  
Gaas Substrate ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Strain Relief ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Transmission Electron

ABSTRACTAn In(Ga)As-based self-assembled quantum dot laser test structure grown on strain-relief Al0.5Ga0.5As1-ySby strain-relief buffer layers (0≤y ≤ 0.24) on a GaAs substrate is investigated in an effort to increase dot size and therefore extend the emission wavelength over conventional InAs quantum dots on GaAs platforms. Cross-section transmission electron microscopy, and high-resolution x-ray diffraction are used to monitor the dislocation filtering process and morphology in the buffer layers. Results show that the buffer layers act as an efficient dislocation filter by drastically reducing threading dislocations, thus providing a relaxed, low dislocation, compositionally modulated Al0.5Ga0.5Sb0.24As0.76 substrate for large (500Å height x 300Å width) defect -free InAs quantum dots. Photoluminescence shows a ground-state emission of the InAs quantum dots at 1.45 μm.

Synthesis and Characterization of Co Nanoparticles by Solventless Thermal Decomposition

2007 ◽  
Vol 119 ◽  
pp. 71-74 ◽  
Author(s):  
Yan Li ◽  
Xiao Li Zhang ◽  
Young Hwan Kim ◽  
Young Soo Kang
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Synthesis And Characterization ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structure Of Nanoparticles ◽  
Co Nanoparticles

Co nanoparticles were synthesized via a solventless thermal decomposition of Co2+-oleate2. The crystalline structure is strongly affected by the thermal treatment of the Co nanoparticles. Further, the annealing also results in the decomposition of surfactant around Co particles. The size of nanoparticles was confirmed by transmission electron microscopy (TEM). The crystal structure of nanoparticles was characterized by X-ray diffraction pattern (XRD). The magnetic properties were characterized by vibrating sample magnetometer (VSM).

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