Hydrothermal-Based Synthesis of CdS/ZnO Quantum Dots

In this article, the CdS and CdS/ZnO quantum dots (QDs) were prepared by hydrothermal synthesis method. The optimal reaction conditions of CdS/ZnO QDs were obtained through experiment as follows: the pH value of solution is 10.0, the reaction temperature is 140 °C and reaction time is 24 h. While the pH value is up to10.0, Zinc ion exist in solution with Zn (OH)2 and Zn (OH)42-, which is apt to adsorb on the surface of CdS, and form to ZnO shell under the hydrothermal condition, so CdS/ZnO QDs are synthesized successfully. The photographic images and fluorescence emission spectra results showed that the colour and the peak position of fluorescence spectra of CdS/ZnO QDs is consistent with literatures, which confirming the feasibility of this method.

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Studies on Optical Properties of CdS/ZnO Quantum Dots Prepared by Sol-Gel Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.364.129 ◽

2011 ◽

Vol 364 ◽

pp. 129-133 ◽

Cited By ~ 1

Author(s):

Liyana Mohd Lawi Ruhana ◽

Taqiyuddin Mawardi Ayob Muhammad ◽

Radiman Shahidan ◽

Irman Abdul Rahman ◽

Bohari M. Yamin

Keyword(s):

Quantum Dots ◽

Sol Gel ◽

Emission Spectra ◽

Blue Shift ◽

Mixture Ratio ◽

Gel Method ◽

Sol Gel Method ◽

Transmission Electron ◽

Zno Quantum Dots ◽

Zno Qds

CdS/ZnO quantum dots (QDs) were prepared at a temperature of 293 K by the sol-gel method with Triethanolamine (TEA) as a capping agent. The effect of CdS/ZnO mixture ratio of 1:9, 1:1 and 9:1 on the optical absorption and fluorescence spectra were investigated by UV-Vis and Fluorescence spectroscopy. By increasing ZnO composition, a blue-shift of absorption edge and emission spectra were observed. The band gap for 1:9, 1:1 and 9:1 were found to be 4.13, 3.93 and 3.11 eV, respectively. The morphology of the CdS/ZnO QDs for each mixing ratio was obtained by transmission electron microscope (TEM). The size of the QDs was found to be in the range of 5-10 nm with some agglomerated particles.

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Preparation ZnS Quantum Dots via Water-Phase Synthesis Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.706-708.230 ◽

2013 ◽

Vol 706-708 ◽

pp. 230-233

Author(s):

Wei Liu ◽

Xian Lan Chen ◽

Ju Cheng Zhang ◽

Yun Hui Long ◽

Ling Shi ◽

...

Keyword(s):

Quantum Dots ◽

Ph Value ◽

Synthesis Method ◽

Emission Spectra ◽

Water Phase ◽

Complexing Agents ◽

Complex Ions ◽

Aqueous Synthesis ◽

Phase Synthesis ◽

Optimal Reaction

With water as the medium, PVP as stabilizer and ammonia as complexing agents and adjusting pH value of the solution, we report an all-aqueous synthesis of highly photoluminescent and stable ZnS quantum dots (QDs) by water-phase synthesis reaction between ZnCl2 and NaS at different temperatures and times. The optimal reaction conditions of PVP-capped ZnS QDs were obtained through experiment as follows: the concentration ZnCl2 and NaS solution both are 1 mM, (PVP):(ZnCl2) = 0.0167 (v/v), (NH3):(ZnCl2)=1:300 (v/v), the optimal reaction temperature is 40 °C, the optimal reaction time is 30 min. With ammonia as complexing agents, Zn(OH)2 can dissolve in ammonia and form to complex ions ((Zn(NH3)4)2+), which make Zn2+ release slowly to control the nucleus growth rate of ZnS, thus obtain small size of nanoparticles. The fluorescence spectra shows that the emission peaks of ZnS QDs around ~395 nm and ~470 nm on the emission spectra, which are consistent with literatures, so nano-ZnS QDs was synthesized successfully in this paper.

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CdTe Quantum Dots Embedded in Multidentate Biopolymer Based on Salep: Characterization and Optical Properties

Journal of Chemistry ◽

10.1155/2013/202061 ◽

2013 ◽

Vol 2013 ◽

pp. 1-6 ◽

Cited By ~ 1

Author(s):

Ghasem Rezanejade Bardajee ◽

Zari Hooshyar

Keyword(s):

Quantum Dots ◽

Optical Properties ◽

Fluorescence Emission ◽

Emission Spectra ◽

Water Soluble ◽

Cdte Quantum Dots ◽

Fluorescence Emission Spectra ◽

Cdte Qds ◽

Transmission Electron ◽

Ft Ir

This paper describes a novel method for surface modification of water soluble CdTe quantum dots (QDs) by using poly(acrylic acid) grafted onto salep (salep-g-PAA) as a biopolymer. As-prepared CdTe-salep-g-PAA QDs were characterized by Fourier transform infrared (FT-IR) spectrum, thermogravimetric (TG) analysis, and transmission electron microscopy (TEM). The absorption and fluorescence emission spectra were measured to investigate the effect of salep-g-PAA biopolymer on the optical properties of CdTe QDs. The results showed that the optical properties of CdTe QDs were significantly enhanced by using salep-g-PAA-based biopolymer.

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Optical Properties and Zinc Nitride Thin Films Prepared Using Magnetron Reactive Sputtering

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.940.11 ◽

2014 ◽

Vol 940 ◽

pp. 11-15

Author(s):

Jun Qin Feng ◽

Jun Fang Chen

Keyword(s):

Thin Films ◽

Band Gap ◽

Near Infrared ◽

Fluorescence Emission ◽

Emission Spectra ◽

Sem Images ◽

Fluorescence Emission Spectra ◽

Glass Substrates ◽

Zinc Nitride ◽

Direct Band

Zinc nitride films were deposited by ion sources-assisted magnetron sputtering with the use of Zn target (99.99% purity) on 7059 glass substrates. The films were characterized by XRD, SEM and EDS, the results of which show that the polycrystalline zinc nitride thin film can be grown on the glass substrates, the EDS spectrum confirmed the chemical composition of the films and the SEM images revealed that the zinc nitride thin films have a dense structure. Ultraviolet-visible-near infrared spectrophotometer was used to study the transmittance behaviors of zinc nitride thin films, which calculated the optical band gap by Davis Mott model. The results of the fluorescence emission spectra show the zinc nitride would be a direct band gap semiconductor material.

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Synthesis and Characterization of Polyvinylpyrrolidone-Modified ZnO Quantum Dots and Their In Vitro Photodynamic Tumor Suppressive Action

International Journal of Molecular Sciences ◽

10.3390/ijms22158106 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8106

Author(s):

Tianming Song ◽

Yawei Qu ◽

Zhe Ren ◽

Shuang Yu ◽

Mingjian Sun ◽

...

Keyword(s):

Quantum Dots ◽

Photodynamic Therapy ◽

Inhibitory Effect ◽

Therapeutic Effects ◽

In Vivo Experiments ◽

Potential Applications ◽

Zno Quantum Dots ◽

Zno Qds

Despite the numerous available treatments for cancer, many patients succumb to side effects and reoccurrence. Zinc oxide (ZnO) quantum dots (QDs) are inexpensive inorganic nanomaterials with potential applications in photodynamic therapy. To verify the photoluminescence of ZnO QDs and determine their inhibitory effect on tumors, we synthesized and characterized ZnO QDs modified with polyvinylpyrrolidone. The photoluminescent properties and reactive oxygen species levels of these ZnO/PVP QDs were also measured. Finally, in vitro and in vivo experiments were performed to test their photodynamic therapeutic effects in SW480 cancer cells and female nude mice. Our results indicate that the ZnO QDs had good photoluminescence and exerted an obvious inhibitory effect on SW480 tumor cells. These findings illustrate the potential applications of ZnO QDs in the fields of photoluminescence and photodynamic therapy.

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Stress and Phase Transformation Phenomena in Oxide Films: Real-Time Spectroscopic Measurements

MRS Proceedings ◽

10.1557/proc-271-319 ◽

1992 ◽

Vol 271 ◽

Cited By ~ 3

Author(s):

Gregory J. Exarhos ◽

Nancy J. Hess

Keyword(s):

Phase Transformation ◽

Applied Pressure ◽

Oxide Films ◽

Fluorescence Emission ◽

Emission Spectra ◽

Film Deposition ◽

Optical Methods ◽

Fluorescence Emission Spectra ◽

Line Intensities ◽

Deposition Parameters

ABSTRACTIn situ optical methods are reviewed for characterization of phase transformation processes and evaluation of residual stress in solution-deposited metastable oxide films. Such low density films most often are deposited as disordered phases making them prone to crystallization and attendant densification when subjected to increased temperature and/or applied pressure. Inherent stress imparted during film deposition and its evolution during the transformation are evaluated from phonon frequency shifts seen in Raman spectra (TiO2) or from changes in the laser-induced fluorescence emission spectra for films containing rare earth (Sm+3:Y3Al5O12) or transition metal (Cr+3 :Al2O3) dopants. The data in combination with measured increases in line intensities intrinsic to the evolving phase are used to follow crystallization processes in thin films. In general, film deposition parameters are found to influence the crystallite ingrowth kinetics and the magnitude of stress and stress relaxation in the film during the transformation. The utility of these methods to probe crystallization phenomena in oxide films will be addressed.

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