Crystal Structure Control of Zinc-Blende CdSe/CdS Core/Shell Nanocrystals: Synthesis and Structure-Dependent Optical Properties

2012 ◽  
Vol 134 (48) ◽  
pp. 19685-19693 ◽  
Author(s):  
Wennuan Nan ◽  
Yuan Niu ◽  
Haiyan Qin ◽  
Fan Cui ◽  
Yu Yang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Core Shell ◽  
Structure Control ◽  
Zinc Blende

Crystal Structure Control of ZnxCd1−xS Alloyed Nanocrystals and Structural Dependent Fluorescence Properties

NANO ◽  
2019 ◽  
Vol 14 (08) ◽  
pp. 1950098
Author(s):  
Kaili Qin ◽  
Jingling Li ◽  
Yanqing Zhu ◽  
Xueqing Xu ◽  
Xiudi Xiao ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Phase ◽  
Fluorescence Properties ◽  
Pure Zinc ◽  
Structure Control ◽  
Zinc Blende ◽  
Coating Method ◽  
Ratio Condition ◽  
One Step ◽  
Zinc Blende Structure

Crystal structure control is so important to the fluorescence properties that each element should be considered carefully. In conventional synthesis of ZnxCd[Formula: see text]S alloyed nanocrystals (NCs), most of studies focus on ligand–surface interaction on the formation of either zinc blende or wurtzite ZnxCd[Formula: see text]S nanocrystals, instead of the reactant source. In this work, mixed crystal phase was found easily in ZnxCd[Formula: see text]S alloyed NCs when reaction proceeded at high Zn/Cd source ratio condition. Therefore, we regulate the Zn/Cd ratio to obtain relative pure zinc-blende structure, and study the influence of structure change on the fluorescence properties. Further, we have proposed a two-step ZnS coating method to acquire ZnxCd[Formula: see text]S/ZnS NCs with separated crystal-phase between core and shell. Compared with maximum QY of 81% for ZnxCd[Formula: see text]S/ZnS NCs synthesized by conventional one-step coating method, the performance of the optimized NCs has significantly improved with maximum QY of 93%.

scholarly journals Structural Profiles of Nanocrystals from ASAXS and Crystallographic Techniques

2014 ◽  
Vol 70 (a1) ◽  
pp. C1583-C1583
Author(s):  
Rainer Lechner ◽  
Gerhard Fritz-Popovski ◽  
Maksym Yarema ◽  
Wolfgang Heiss ◽  
Armin Hoell ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Rock Salt ◽  
Structural Information ◽  
Shell Growth ◽  
Infrared Emission ◽  
Core Shell ◽  
Detailed Knowledge ◽  
The Core ◽  
The Impact

The chemical synthesis of core/shell colloidal nanocrystals (NCs) have lead to an pronounced improvement in the optical properties and the chemical stability of semiconducting NCs [1]. The main topic of this work is the structural characterisation of core/shell NCs with anomalous small angle x-ray scattering (ASAXS) in combination with diffraction techniques (XRD) at laboratory- and synchrotron sources (HZB-BESSY and ESRF). Furthermore we complete these findings with complementary microscopy techniques (TEM). The detailed knowledge of the structural properties of the core/shell NCs allows to study the impact of the nanometer sized dimensions on their optical properties. The infrared emission of lead chalcogenide nanocrystals (NCs) in the size range of 5 - 10 nm can be drastically increased stabilising the core with a hard protective shell [1,2]., e.g., PbS/CdS NCs shows a higher efficiency and stability [2] with respect to pure PbS-NCs. In contrast to a shell growth on top of a core, we investigated in this study the CdS-shell growth on PbS NCs driven by Cd for Pb cation exchange [2]. Especially, we studied three different final shell thicknesses of 0.9, 1.5 and 2 nm. The chemical composition profile of the CdS-shell as a function of reaction time are derived from ASAXS experiments in sub-nanomter resolution. The crystal structure of the shell was derived by XRD combined with TEM measurements, respectively. We relate the chemical and structural information to the measured PL intensities of the core/shell NCs. We reveal the existence of two different crystalline phases, i.e. the metastable rock salt and the equilibrium zinc blende phase within the chemically pure CdS-shell. The highest improvement in the PL emission was achieved for 0.9 nm shells depicting a large metastable rock salt phase fraction matching the crystal structure of the PbS core. These results could be only achieved using ASAXS that gieves a mean chemical profile of a large ensemble of single core/shell NCs, but in sub-nanometer resolution [3].

scholarly journals Near-infrared emitting CdTeSe alloyed quantum dots: Raman scattering, photoluminescence and single-emitter optical properties

RSC Advances ◽  
2017 ◽  
Vol 7 (76) ◽  
pp. 47966-47974 ◽  
Author(s):  
Le Xuan Hung ◽  
Pascal D. Bassène ◽  
Pham Nam Thang ◽  
Nguyễn Thu Loan ◽  
Willy Daney de Marcillac ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Raman Scattering ◽  
Near Infrared ◽  
Optimal Synthesis ◽  
Core Shell ◽  
Zinc Blende ◽  
Synthesis Parameters ◽  
Single Emitter

The synthesis of ternary core/shell zinc-blende CdTeSe/ZnSe quantum dots with optimal synthesis parameters is analyzed.

scholarly journals Direct correlation of crystal structure and optical properties in wurtzite/zinc-blende GaAs nanowire heterostructures

2011 ◽  
Vol 83 (4) ◽  
Author(s):  
Martin Heiss ◽  
Sonia Conesa-Boj ◽  
Jun Ren ◽  
Hsiang-Han Tseng ◽  
Adam Gali ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Zinc Blende ◽  
Nanowire Heterostructures ◽  
Gaas Nanowire

Structural/Property Relationships for Optical Materials

1993 ◽  
Vol 329 ◽  
Author(s):  
Vivien D.
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Electronic Structure ◽  
Chemical Composition ◽  
Field Strength ◽  
Optical Materials ◽  
Site Occupancy ◽  
Laser Materials ◽  
Crystal Field Strength ◽  
The Matrix

AbstractIn this paper the relationships between the crystal structure, chemical composition and electronic structure of laser materials, and their optical properties are discussed. A brief description is given of the different laser activators and of the influence of the matrix on laser characteristics in terms of crystal field strength, symmetry, covalency and phonon frequencies. The last part of the paper lays emphasis on the means to optimize the matrix-activator properties such as control of the oxidation state and site occupancy of the activator and influence of its concentration.

Effect of Mn3+ doping on crystal structure, point defects, and optical properties in green Ca3(VO4)2 single crystals

2021 ◽  
pp. 111300
Author(s):  
Galina M. Kuz’micheva ◽  
Liudmila. I. Ivleva ◽  
Irina A. Kaurova ◽  
Evgeny V. Khramov ◽  
Victor B. Rybakov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Optical Properties ◽  
Single Crystals ◽  
Point Defects

scholarly journals Light-Scattering Simulations from Spherical Bimetallic Core–Shell Nanoparticles

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 359
Author(s):  
Francesco Ruffino
Keyword(s):  
Optical Properties ◽  
Light Scattering ◽  
Bimetallic Nanoparticles ◽  
Dominant Role ◽  
Scattered Light ◽  
Specific Interaction ◽  
Surface Enhanced Raman Spectroscopy ◽  
Localized Surface Plasmon ◽  
Core Shell ◽  
The Core

Bimetallic nanoparticles show novel electronic, optical, catalytic or photocatalytic properties different from those of monometallic nanoparticles and arising from the combination of the properties related to the presence of two individual metals but also from the synergy between the two metals. In this regard, bimetallic nanoparticles find applications in several technological areas ranging from energy production and storage to sensing. Often, these applications are based on optical properties of the bimetallic nanoparticles, for example, in plasmonic solar cells or in surface-enhanced Raman spectroscopy-based sensors. Hence, in these applications, the specific interaction between the bimetallic nanoparticles and the electromagnetic radiation plays the dominant role: properties as localized surface plasmon resonances and light-scattering efficiency are determined by the structure and shape of the bimetallic nanoparticles. In particular, for example, concerning core-shell bimetallic nanoparticles, the optical properties are strongly affected by the core/shell sizes ratio. On the basis of these considerations, in the present work, the Mie theory is used to analyze the light-scattering properties of bimetallic core–shell spherical nanoparticles (Au/Ag, AuPd, AuPt, CuAg, PdPt). By changing the core and shell sizes, calculations of the intensity of scattered light from these nanoparticles are reported in polar diagrams, and a comparison between the resulting scattering efficiencies is carried out so as to set a general framework useful to design light-scattering-based devices for desired applications.

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