Quantum Dots: Properties and Applications

2021 ◽  
pp. 331-348
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Cadmium Sulphide ◽  
The Body ◽  
X Ray Diffraction ◽  
Precise Control ◽  
Chemical Treatments ◽  
Hands On ◽  
Anti Cancer ◽  
Visual Properties

Quantum dots (QDs) are very small nanoparticles and are composed of hundreds to thousands of atoms. These semiconducting materials can be made from an element, such as silicon or germanium, or compounds such as cadmium sulphide (CdS) or cadmium selenide (CdSe). The colour of these small particles does not depend on the type of semiconducting material from which the dots are made, but rather on its diameter. Besides, ODs attract the most attention because of their unique visual properties. Therefore, these are used in all kinds of applications where precise control of coloured light is important. As these dots are of great importance in chemical, biological and medical applications, they can be designed to deliver anti-cancer drugs and direct them to specific areas of the body. Therefore, with this technique, the harmful side effects of chemical treatments can be reduced. It is possible to examine and study the properties of these nanomaterials and make sure they are analyzed using some scientific devices and techniques, the most important of which are: transmittance electron microscopy (TEM), scanning electron microscopy (SEM), atomic forces microscopy (AFM) with dielectrics, and X-ray diffraction (XRD). This chapter opens horizons towards knowing what quantum dots are and their unique properties, as well as methods of preparation and then placing our hands on the chemical, and biological applications of these dots.

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...

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.

Composition and Microstructure of a Natural Nano-Structure Mineral: Six-Ring Rock

2011 ◽  
Vol 295-297 ◽  
pp. 869-872
Author(s):  
Qing Shan Li ◽  
Xin Wang ◽  
Jun Liu ◽  
Guang Zhong Xing
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Energy Dispersive Spectrometer ◽  
The Body ◽  
X Ray Diffraction ◽  
Nano Structure ◽  
X Ray ◽  
Transmission Electron ◽  
Nano Size ◽  
Scanning Electron

Six-ring Rock is widely used as containers of water and additives to produce health care products. In this paper, the composition and microstructure of Six-ring Rock have been investigated by using scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, x-ray diffraction and other technologies. Results show that Six-ring Rock is composed of CaMg(CO3)2, SiO2 and KAlSi3O8. Fe atoms exist in CaMg(CO3)2 by replacing Mg atoms. Six-ring Rock shows nano-size lamellar and acerose microstructures on the surface, and nano-size monocrystals in the body. Six-ring Rock is a natural nano structure mineral.

scholarly journals Hydrothermal synthesis of ZnO quantum dot/KNb3O8 nanosheet photocatalysts for reducing carbon dioxide to methanol

2017 ◽  
Vol 8 ◽  
pp. 2264-2270 ◽  
Author(s):  
Xiao Shao ◽  
Weiyue Xin ◽  
Xiaohong Yin
Keyword(s):  
Electron Microscopy ◽  
Quantum Dots ◽  
Uv Light ◽  
Formation Rate ◽  
X Ray Diffraction ◽  
Methanol Production ◽  
X Ray ◽  
Transmission Electron ◽  
Methanol Formation ◽  
Zno Quantum Dots

ZnO quantum dots and KNb3O8 nanosheets were synthesized by a two-step hydrothermal method for the photocatalytic reduction of CO2 to methanol where isopropanol is simultaneously oxidized to acetone . The as-prepared photocatalysts were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and UV–vis absorption spectroscopy (UV–vis). The photocatalytic activity of the materials was evaluated by formation rate of methanol under UV light irradiation at ambient temperature and pressure. The methanol formation rate of pure KNb3O8 nanosheets was found to be 1257.21 μmol/g/h, and after deposition of 2 wt % ZnO quantum dots on the surface of KNb3O8 nanosheets, the methanol production rate was found to increase to 1539.77 μmol/g/h. Thus, the ZnO quantum dots obviously prompted separation of charge carriers, which was explained by a proposed mechanism for this photocatalytic reaction.

Synthesis and Characterization of Graphene/Cu2SnS3 Quantum Dots Composites

2012 ◽  
Vol 624 ◽  
pp. 59-62 ◽  
Author(s):  
Cai Xia Li ◽  
Jun Guo ◽  
Danyu Jiang ◽  
Qiang Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Raw Materials ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Structures ◽  
Transmission Electron

In this paper, employing Cu(AC)2•H2O, SnCl2•2H2O and thiourea as raw materials, the composites of graphene/Cu2SnS3 quantum dots (QDs) were prepared simply and quickly using the hydrothermal method. Meanwhile, the separate Cu2SnS3 QDs were also synthesized in the same way. The as-obtained Cu2SnS3 QDs and composites’ phase structures were analyzed and characterized by powder X-ray diffraction (XRD), and the results indicated that the size of the Cu2SnS3 QDs in the composites were less than that of the separate Cu2SnS3 QDs. At the same time, their morphologies were also observed and cross-confirmed by Transmission Electron Microscopy (TEM), and the measurements manifested that Cu2SnS3 QDs were uniformly dispersed on the surface of the graphene, while the separate Cu2SnS3 QDs have obvious glomeration. In addition to this, elemental analysis was also made to verify the existence of Cu2SnS3 on the surface of graphene.

scholarly journals Cancer Immunotherapy Based on Carbon-Quantum-Dots

2021 ◽  
Author(s):  
Tao Liang ◽  
Josh Haipeng Lei ◽  
Jinsong Tao ◽  
Sen Guo ◽  
Hanlu Gao ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cancer Immunotherapy ◽  
Cd8 T Cells ◽  
Carbon Quantum Dots ◽  
Clinical Applications ◽  
The Body ◽  
Primary Tumors ◽  
Cancer Antigens ◽  
Anti Cancer ◽  
Personalized Cancer

Abstract Cancer immunotherapy based on carbon-quantum-dots (CQDs) has proven effective. The CQDs composited cancer cell (CM-cancer) exhibit robust customized immunogenicity, which can recruit macrophages and dendritic cells to effectively deliver the cancer antigens into lymph nodes to activate CD8+ T cells, and eventually leads to an anti-cancer immune response all over the body. The CM-cancer is not only able to inhibit primary tumors, but also clearly eliminate metastatic tumors. Our research demonstrates a promising personalized cancer immunotheraputic technology for potential clinical applications.

scholarly journals Nanofabrication of Iron-Cobalt (FeCo) Alloy by Sol-gel Method

2021 ◽  
Vol 1 (1) ◽  
pp. 111-114
Author(s):  
Majid Farahmandjou ◽  
Parastoo Khalili
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Sem Analysis ◽  
The Body ◽  
X Ray Diffraction ◽  
Body Center Cubic ◽  
Transmission Electron ◽  
Structure Morphology ◽  
Bcc Structure ◽  
Body Center

Background and Introduction: Metal oxides (MOs) have been extensively used in a large range of engineering and medical applications. Methods: FeCo nanoparticles (NPs) were successfully synthesized by the solgel method in the presence of a powerful reducing agent-sodium borohydride (NaBH4). The structure, morphology, and optical properties of NPs were analyzed by X-ray diffraction (XRD), field effect scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) at room temperature. Results: The XRD spectrum showed the body center cubic (BCC) structure of the samples after heat treatment at 500 °C. The SEM analysis exhibited that the particle size of as-synthesized and annealed samples was approximately 40 nm and 22 nm, respectively. Conclusion: The TEM investigations showed the rod-shaped sample of annealed NPs. The optical studies of the FTIR analysis revealed the starching bound of Fe-Co at the frequencies of 673 cm-1, 598 cm-1, and 478 cm-1.

Polymorphous silicon nanowires synthesized by plasma-enhanced chemical vapor deposition

2002 ◽  
Vol 737 ◽  
Author(s):  
X.B. Zeng ◽  
X.B. Liao ◽  
H.W. Diao ◽  
Z.H. Hu ◽  
Y.Y. Xu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Vapor Deposition ◽  
Silicon Nanowires ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
The Body ◽  
Si Nanowires ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

ABSTRACTPolymorphous Si nanowires (SiNWS) have been successfully synthesized on Si wafer by plasma enhanced chemical vapor deposition (PECVD) at 440°C, using silane as the Si source and Au as the catalyst. To grow the polymorphous SiNWS preannealing the Si substrate with Au film at 1100 °C is needed. The diameters of Si nanowires range from 15 to 100 nm. The structure, morphology and chemical composition of the SiNWS have been characterized by high resolution x-ray diffraction, scanning electron microscopy, transmission electron microscopy, as well as energy dispersive x-ray spectroscopy. A few interesting nanowires with Au nanoclusters uniformly distributed in the body of the wire were also produced by this technique.

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